December 1996 Antiviral Agents Bulletin news stories
    Interferon alpha-2a Approved for Chronic Hepatitis C

    The FDA has approved recombinant interferon alpha-2a (Roferon-A; interferon alfa-2a) from Hoffmann-La Roche Inc. (Nutley, NJ) for treatment of chronic hepatitis C virus infection. According to FDA-approved labeling, "Roferon-A is indicated for use in patients with chronic hepatitis C diagnosed by HCV antibody and/or a history of exposure to hepatitis C who have compensated liver disease and are 18 years of age or older." Previously, recombinant interferon alpha-2b (Intron A) from Schering-Plough Corp. was the only treatment available in the U.S. for chronic hepatitis C. As discussed in the September Bulletin (p. 234), Roche and Gilead Sciences, Inc. (Foster City, CA) will co-promote Roferon-A for chronic hepatitis C treatment in the U.S. Roferon-A had previously been approved in the U.S. for treatment of AIDS-related Kaposi's sarcoma, hairy cell leukemia and Ph-positive chronic myelogenous leukemia.

    Roferon-A has been shown effective for treatment of chronic hepatitis C in clinical trials in 1,831 adult patients. Doses studied ranged from 1 to 9 MIU (three times weekly) for six to 12 months with observation ranging from 3 months to 4 years. "A complete response (two consecutive normal blood ALT [alanine aminotransferase] levels at least 21 days apart) was observed in 43% (75 of 173) of patients who received 3 MIU Roferon-A 3 times per week for 12 months." However, this "complete response" was observed at some time during therapy and "only 23% had a complete response at the end of treatment." "In studies with long-term follow-up, 91% (39 of 43) of patients with normal ALT 6 months after discontinuation of therapy had persistently normal ALT during continuous follow-up of up to 4 years. This response corresponded with an improvement in liver condition, as measured by liver biopsy, and decreased levels of virus as measured by PCR (polymerase chain reaction). Responders to treatment were more likely to be younger than 35 and free of cirrhosis. Although ALT levels typically normalize immediately after interferon alfa therapy is begun, studies have shown that patients who are treated for 12 months with Roferon-A are more likely to maintain normal ALT levels after treatment is discontinued than those treated for 6 months. In addition, patients treated with higher doses are more likely to experience a complete response at the end of follow-up than those treated with lower doses."

    Normalization of abnormal liver function, particularly ALT, generally occurs within a few weeks in those patients who respond to therapy and about 90% of patients who respond to Roferon-A do so within the first three months of treatment. However, patients who respond with a reduction in ALT should complete a full 12 months of treatment for optimal results. About half of patients having received Roferon-A at the 3 MIU dose for 12 months who had a complete response at the end of treatment subsequently relapsed (recurrence of abnormal ALT) following cessation of therapy. For those who relapse, retreatment with either the 3 MIU dose or 6 MIU dose three times weekly for 6 to 12 months may be considered. Studies have shown that most relapsing patients will respond to this retreatment and often develop a sustained response.

    Regarding adverse effects, Roche reports, "In clinical trials, side effects were mild to moderate and included flu-like symptoms such as fatigue, muscle aches, headaches, fever/chills, nausea, vomiting, or diarrhea, and skin irritation at the injection site. Depression, irritability, insomnia, and anxiety were other side effects associated with interferon alfa therapy." In chronic hepatitis C clinical trials using the 3 MIU dose, fatigue occurred in 58%, myalgia/arthralgia in 51%, flu-like symptoms in 33%, headache in 52%, dizziness in 13%, nausea/vomiting in 33%, diarrhea in 20% and depression in 16%. Generally, there were fewer adverse events after the first six months of treatment. The side effects associated with Roferon-A are usually manageable and reversible upon discontinuation of therapy. The incidence of adverse events was higher in patients receiving higher dosages. Patients tolerant to initial therapy generally tolerate retreatment at the same dose, but tend to have more adverse reactions at higher dosages. A 50% dosage reduction is recommended in patients who cannot tolerate the prescribed dosage and the original dosage may be reinitiated if adverse effects resolve. Treatment should be halted in patients intolerant of the reduced dosage.

    Roferon-A offers "a longer dosing regimen with a physician support system to help optimize treatment." The recommended dosage for treatment of chronic hepatitis C is 3 million International Units (MIU) administered either subcutaneously or intramuscularly three times weekly for 12 months (48 to 52 weeks). Roferon-A is packaged as a sterile solution for injection in vials containing either 3, 6, 9, 18 or 36 MIU of recombinant E. coli-expressed interferon alpha-2a solution and in a vial containing 18 MIU of powder for reconstitution (solution) before use. Based on the specific activity of 2.7 x 108 IU/mg protein, a 3 MIU vial contains 11.1 µg/ml of active protein. The production process includes affinity chromatography purification using a specific murine monoclonal antibody. As part of its marketing strategy, Roche offers physicians guidelines for treating new and relapsing patients and offers the Roferon Patient Support System to educate patients about the side effects of Roferon-A. Physicians may call 1-800-LAROCHE for further information.

    Although there are surely differences, Roferon-A from Roche and Intron A from Schering-Plough are both interferon alpha variants with only partial efficacy for treatment of chronic hepatitis C and a relatively high incidence of adverse effects. Only a minority of U.S. patients treated with these interferon alpha preparations show long-term efficacy. More potent, effective and safer therapeutics for chronic hepatitis C are still very much needed. Therapeutics which have recently been reported to have shown promise for chronic hepatitis C include thymosin alpha 1 in combination with interferon alpha (November Bulletin, p. 291); natural leukocyte-derived alpha-interferon (August Bulletin, p. 200); amantadine, a drug used for influenza A (August Bulletin, p. 199); and interferon-alpha-2b (Intron A) in combination with ribavirin (August 1995 Bulletin, p. 234).

    Oral Ganciclovir Approved for Prevention of CMV Disease in Transplant Recipients

    The FDA has approved oral ganciclovir (Cytovene capsules; 9-[[2-hydroxy-1-(hydroxymethyl)-ethoxy]methyl]gaunine) from Hoffmann-La Roche Inc. (Nutley, NJ) for prevention of cytomegalovirus (CMV) disease in solid organ (e.g., liver) transplant recipients. CMV disease, including systemic infection, can be life-threatening in organ transplant recipients. Prior to this approval, intravenous ganciclovir (Cytovene-I.V.) also marketed by Roche was the only approved treatment for prevention of CMV disease in solid organ transplant recipients (and the i.v. formulation is also approved for treatment of CMV retinitis in immune compromised patients). Oral ganciclovir has been approved (see February 1995 Bulletin, p. 33) as an alternative to continued intravenous ganciclovir for treatment of CMV retinitis in immune compromised (e.g., AIDS) patients whose retinitis has stabilized following intravenous induction therapy with ganciclovir and for prevention of CMV retinitis in immune compromised patients (see November 1995 Bulletin, p. 324). Vitrasert Implant from Chiron Vision Corp. and co-promoted by Roche, containing controlled release ganciclovir for implantation into the eye, has been approved for treatment of CMV retinitis (as discussed in the March Bulletin, p. 66). Ganciclovir had originally been developed by Syntex (U.S.A.) Inc. which was acquired by Roche in 1994.

    This recent approval was primarily based on results from a multinational, double-blind study (GAN 040; discussed in the September Bulletin, p. 229) in 304 orthotic liver transplant (OLT) recipients who received either oral ganciclovir (1,000 mg three times daily for up to 14 weeks following transplantation) or matching placebo. After six months of follow-up, an overall 78% reduction in the incidence of CMV disease was observed in drug recipients (18.9% of placebo recipients vs. 4.8% of drug recipients). A 93% reduction was observed in the incidence of tissue invasive disease (8.4% of placebo recipients vs. one patient or 0.7% of drug recipients), the most serious type of CMV disease. Oral ganciclovir was effective even in those at highest risk for CMV diseaseÑthose who were CMV-seronegative at the time of the transplant who received an organ from a CMV-seropositive donor. The six-month incidence of CMV disease in this group was 44% in placebo patients and 14.8% in oral ganciclovir patients. Patients who received the most immune suppression drug treatments also benefited from oral ganciclovir prophylaxis. Among patients who received anti-lymphocyte antibodies for prevention of graft rejection or for treatment of refractory rejection, the incidence of CMV disease was 33% in placebo patients and 4.6% in the oral ganciclovir patients. Oral ganciclovir also reduced the incidence of herpes simplex virus (HSV) infection from 23.5% in the placebo patients to 3.5% in oral ganciclovir patients. However, oral ganciclovir is not approved for any HSV indication. Infection, fever and headache were among the more common side effects of oral ganciclovir treatment. Other adverse effects include granulocytopenia, anemia and thrombocytopenia. In animal studies, ganciclovir is carcinogenic, teratogenic and caused spermatogenesis.

    The market for oral ganciclovir now includes the over 20,000 persons in the U.S. annually receiving solid organ transplants, including liver, kidney, heart, lung and pancreas transplants. CMV disease generally occurs in about 15%-30% of all solid organ transplant recipients, primarily in the first three months post-transplantation when drug-induced immune suppression (to reduce rejection of transplanted tissue) is most intense. Dr. M. Pescovitz, a GAN 040 investigator, remarked, "The prevention of CMV is a critical step in helping patients achieve a full recovery after transplantation." CMV-infection in transplant recipients can cause debilitating CMV syndrome (fever, malaise) and life-threatening invasive tissue disease, including hepatitis and pneumonia, and further immune suppression with resulting secondary infection.

    Plant-Derived HIV Protein-Tyrosine Kinase Inhibitor Shows Indications of Efficacy

    Paracelsian, Inc. (Ithaca, NY) has reported that AndroVir, an oral plant-derived HIV protein-tyrosine kinase inhibitor drug, has shown safety and indications of efficacy in a nine-week Phase I trial. The trial was conducted by Bastyr Univ. (Seattle, WA), a "College of Natural Medicine (Naturopathy), in 16 HIV-infected patients. As discussed in the July 1995 Bulletin (p. 202), AndroVir (then called PN355), is an HIV protein-tyrosine kinase inhibitor isolated from a traditional Chinese and Indian herb, recently disclosed to be Andrographis paniculata. This appears to be the first tyrosine kinase inhibitor in clinical development for treatment of HIV-infection and the first to show indications of efficacy for treatment of HIV-infection. Tyrosine phosphorylation by the tyrosine kinase enzyme is important in intracellular signaling, including T-cell receptor mediated cell activation and proliferation. HIV-infection has been shown to induce signals leading to apoptosis in both infected and uninfected cells. Inhibition of tyrosine kinases involved in cellular signaling may halt the immune system destruction associated with advancement to AIDS.

    Paracelsian reports that AndroVir "appears to induce apoptosis," or programmed cell death in HIV-infected cells and that it has synergistic effects for inhibition of HIV in combination with reverse transcriptase inhibitors. In preclinical studies, AndroVir has been shown to have "extremely low acute and subchronic toxicity," with no toxicity observed in rats or rabbits fed 1 g/kg/day for seven days; has an in vitro IC50 against HIV in human lymphocytes of 640 ng/ml and exhibited synergistic effects in vitro with AZT. Historical use of several Andrographis paniculata extracts further supports safety and the potential for both oral and topical administration.

    Sixteen HIV-infected patients (CD4+ T-cell counts 200-700, median 430) having stopped other antiretroviral therapy received AndroVir (5 mg/kg) three times daily for three weeks, followed by 10 mg/kg three times daily for another three weeks. Elevations in viral load observed in two subjects after three weeks of treatment resulted in the protocol being changed from planned administration of 20 mg/kg three times daily during the last three weeks of the study to a withdrawal or washout period during the final three weeks. However, after six weeks the elevations turned out to be transient and the viral load in these patients returned to the range of the others in the trial. A "very slight increase" in two liver enzymes, AST and ALT, were observed in two patients, suggesting lower tolerance for the herb in some individuals. Thirteen of 16 patients completed the study with two of the withdrawing patients reporting a bitter taste and one displaying severe allergic hypersensitivity.

    The company reports, "Oral administration of AndroVir for six weeks was otherwise well-tolerated and produced a median decrease in HIV-1 viral load of 38 percent as well as a median increase in CD4 cell counts of 31 percent. One subject experienced an 83 percent decrease in HIV-1 viral load and another exhibited a 90 percent increase in CD4 cells in six weeks...During the AndroVir withdrawal period, all these beneficial trends were reversed and approached pre-study values in all but one subject." Further clinical trials are planned. Based on current dose ranges, the company expects "the product cost will be less than $1000 per year." As reported in the December 1995 Bulletin (p. 366), Paracelsian is participating in a Collaborative Research and Development Agreement (CRADA) with the National Cancer Institute (NCI, NIH; Bethesda, MD) and the National Institute of Child Health and Human Development (NICHD, NIH) for study of the mechanism of action of AndroVir and related compounds and screening of the company's library of 2,800 extracts from traditional Chinese medicines for protein-tyrosine kinase inhibitor activity against HIV and cancer.

    HPV Vaccine Shows Indications of Efficacy for Genital Warts

    Cantab Pharmaceuticals PLC (Cambridge, U.K.) reported at the recent 15th International Papillomavirus Workshop, Brisbane, Australia, "promising Phase IIa data with TA-GW, its novel immunotherapeutic vaccine for genital warts" associated with human papillomavirus (HPV) infection. Dr. J. St. Clair Roberts, Medical Director, Cantab, reports, "These results are even better than we had expected. This is the first clinical trial of a therapeutic vaccine for genital warts, and it shows that TA-GW is very well-tolerated and is able to elicit a good immune response in patients with this disease. Also, the fact that during follow-up we did not observe wart recurrence in any patient is very encouraging. I believe that proof of principle has been clearly established and that the results of this trial provide an excellent foundation for the future development of TA-GW in partnership with SmithKline Beecham."

    Cantab and SmithKline Beecham Biologicals Manufacturing S.A. (SKB; Rixensart, Belgium) have formed a collaboration for the development and marketing of Cantab's TA-GW recombinant HPV vaccine for treatment and prevention of recurring genital warts, as discussed in the July Bulletin (p. 170). Cantab can receive up to $37 million in license and milestone payments, and will receive royalties from product sales. Two clinical trials with TA-GW are ongoingÑa trial studying TA-GW immunogenicity and safety in combination with cryotherapy; and a trial testing TA-GW in patients with laryngeal papillomatosis, another disease associated with the same strains of HPV as genital warts. Future clinical development will be primarily handled by SKB. As reported in the June Bulletin (p. 133), a similar vaccinia virus vector HPV vaccine (TA-HPV) from Cantab for immunotherapy of cervical cancer has induced immune responses in early trials.

    Dr. S. Thompson, Cantab, reported results from the first in a series of open-label Phase IIa trials at the Leeds General Infirmary (Leeds, U.K.) with TA-GW in patients with genital warts. Twenty-seven male patients were enrolled including 16 with a history of persistent or relapsing genital warts refractory to courses of conventional treatments and 11 patients with new warts. Patients received three intramuscular injections of TA-GW (300 µg) on days 0, 7 and 28. Safety, immunogenicity and wart status were followed for eight weeks. Eight of the new warts patients received podophyllotoxin (a conventional treatment) in combination with TA-GW. After eight weeks, all patients with persisting warts were treated with conventional therapy and their clinical outcome continued to be monitored.

    In addition to "an excellent safety profile, immunogenicity was demonstrated in all patients" with induction of IgG antibodies, primarily IgG1 subclass. "Of the total 15 patients followed after week eight, 13 have shown total wart clearance" and "No wart recurrence has been observed following clearance." Twenty-three of 25 (92%) patients had antigen-specific T-cell proliferative responses and produced both interferon-gamma and interleukin-5 in vitro. There were no significant adverse events and any reactions were transient and self-limiting. "Clinically 3/15 patients with persistent warts (given TA-GW alone) and 3/6 patients with newly presenting warts (given TA-GW + podophyllotoxin) showed total wart clearance at week 8. Wart recurrence has not been observed in any subject whose warts were cleared either by TA-GW alone or in conjunction with conventional therapy." Among the 36 persons vaccinated in a Phase I trial, specific dose-dependent immune responses included in vitro T-cell proliferative responses and interferon-gamma production that persisted for up to six months.

    TA-GW is formulated from two fused HPV-6 genes (L2 and E7) expressed in E. coli, with an alum (Alhydrogel) adjuvant. The purified L2E7 protein forms 0.2 µm filterable aggregates with an approximate size of 50 nm. The vaccine induces serum IgG (primarily IgG1) antibodies, cellular immune responses, including in vivo delayed-type hypersensitivity reactions and in vitro lymphocyte proliferation responses, and cytokine production. The vaccine is designed to stimulate natural spontaneous regression and preventative responses to genital warts observed in many HPV-infected persons, including increased expression of major histocompatibility (MHC) class II and ICAM-1 on keratinocytes (skin cells) along with a mononuclear cell infiltrate dominated by CD4+ T-cells and macrophages. TA-GW has so far been formulated with alum adjuvant, but Cantab plans to test it with other more potent adjuvants, including the broad range of adjuvants licensed by SKB, such as monophosphoryl lipid A (MPL) from Ribi ImmunoChem Research, Inc. (Hamilton, MT), also optioned by Cantab as reported in the February Bulletin (p. 45), and QS-21 Stimulon from Cambridge Biotech Corp. (Worcester, MA), now Aquila Biotech. Cantab has reported successful boosting of immune responses in mice, including in vitro interferon-gamma production and T-cell proliferative responses, using alum-adjuvanted TA-GW plus MPL.

    Genital warts treatments have considerable market potential. Genital warts, actually benign tumors caused by HPV (usually type 6 and, to a lesser extent, type 11), is the most common sexually transmitted disease. There are an estimated one million new cases of genital warts in the U.S. and Europe each year, and an estimated 1%-2% of sexually active adults have detectable genital warts. Between 20%-50% of patients experience recurrences following initial diagnosis and treatment. Current therapies include podophyllotoxin formulations, including purified, self-administered podophyllotoxin (Condylox) from Oclassen Pharmaceuticals Inc. (being acquired by Watson Pharmaceuticals Inc.) and physical removal methods including cryotherapy, topical trichloroacetic acid, electrocauterization and laser surgery. Many of these procedures are painful and costly, requiring repeated physician visits, and none of these act against the underlying human papillomavirus infection to prevent recurrences.

    Humanized Respiratory Syncytial Virus Antibody in Phase III Trial

    MedImmune, Inc. (Gaithersburg, MD) is conducting a randomized, double-blind, placebo-controlled Phase III clinical trial (IMpact-RSV) with MEDI-493 for prevention of serious respiratory syncytial virus (RSV) disease in high-risk infants. IMpact-RSV involves 130 centers in the U.S., Canada and U.K., and has enrolled over 1,500 premature infants and children with bronchopulmonary dysplasia (BPD). This is "the largest prospective clinical trial ever conducted in this patient population." Patient accrual has been completed and results should be available in the third quarter of 1997.

    The IMpact-RSV trial will evaluate the safety and efficacy of MEDI-493 for prevention of serious RSV disease in children under 24 months of age having BPD, or who were 35 weeks gestation or less at birth and are less than 6 months of age at time of enrollment. Children will be randomized in a 2:1 ratio to receive intramuscular injection of MEDI-493 (15 mg/kg) or placebo every 30 days from November 1996 through April 1997 for a total of up to five injections. The primary endpoint of the trial is reduction of the incidence of RSV hospitalization (confirmed by RSV antigen test).

    As reported in the November 1995 Bulletin (p. 327), MedImmune amended its licensing agreement with American Home Products Corp. (AHP; Madison, NJ) to regain full manufacturing and marketing rights to MEDI-493 (with AHP to receive some royalties based on sales). MedImmune, Inc. already markets Respiratory Syncytial Virus Immune Globulin Intravenous (Human), trade name RespiGam, approved early this year for prevention of respiratory syncytial virus (RSV) disease in infants less than 24 months old having BPD or a history of prematurity (² 35 weeks gestation) as discussed in the February Bulletin (p. 33). RespiGam, unlike MEDI-493, is a polyclonal antibody formulation purified from pooled immune globulin obtained from high RSV antibody titer donors. RespiGam was recently launched for this RSV season in the U.S. MedImmune and the Wyeth-Lederle Vaccines and Pediatrics subsidiary of American Home Products Corp. co-market it in the U.S. and Baxter Healthcare Corp. markets it outside of the U.S.

    MEDI-493 is a humanized RSV monoclonal antibody which binds to the RSV fusion (F) protein which is required for the virus to infect cells. It has been shown to neutralize RSV in vitro and to reduce RSV infection in an animal model. MEDI-493 has already been tested for both immunotherapeutic and prophylactic indications in about 300 patients in Phase I and II trials, and shown to be well tolerated with no significant adverse effects. MEDI-493 is administered by intramuscular injectionÑmuch easier than RespiGam which requires a two to four hour intravenous infusion. This "has the potential to enhance patient care, reduce costs associated with drug administration and improve convenience for parents, physicians and nurses." MEDI-493's increased ease of use and associated lower costs may allow it to reach a larger market than RespiGam.

    Herpes Simplex Virus Subunit Vaccine Development Halted by Chiron

    Chiron Corp. (Emeryville, CA) has announced that it has halted development of its bivalent recombinant herpes simplex virus type 2 (HSV-2) subunit vaccine after preliminary data from Phase III clinical trials for genital herpes prophylaxis failed to "indicate efficacy for this product." Chiron will not apply for approval of the vaccine. The HSV-2 vaccine contains recombinant HSV-2 glycoprotein B2 (gB2) and glycoprotein D2 (gD2) antigens with a novel adjuvantÑMF-59, a proprietary microfluidized formulation of squalane. Further analysis of the trials is underway and complete results are expected to be reported soon by the clinical investigators at scientific meetings.

    Chiron has also delayed the start of planned Phase III clinical trials with its cytomegalovirus (CMV) vaccine until final analysis of the HSV vaccine trial is complete (expected in mid-1997). Noting the close relationship between CMV and HSV and that they are both subunit vaccines, a company spokesman commented, "We need to fully digest the full situation before we can make decisions about proceeding with the CMV trial." Development of CMV immune globulin by NABI (formerly Univax Biologics; discussed in the September 1995 Bulletin, p. 260) is continuing using Chiron's CMV vaccine for immune stimulation.

    As reported in the September Bulletin (p. 227), a 202-patient, randomized, placebo-controlled Phase III trial conducted by NIAID using the same vaccine for treatment of genital herpes found it to be well tolerated with efficacy in some respects comparable to that of available drugs for treatment of recurrent genital herpes. The vaccine reduced the duration and severity of symptoms associated with the first postvaccination outbreak. However, no significant effects were observed for the primary endpointÑprevention of further outbreaks or delay in their occurrence. In other clinical studies, cervical IgG and IgA antibody titers were found to be comparable or higher in female HSV-negative and HSV-positive vaccine recipients than in patients with HSV-2 infections.

    The Phase III placebo-controlled prophylaxis trials involved testing the efficacy and safety of the HSV gB2/gD2 vaccine in 250 discordant couples (where one sex partner has recurrent genital herpes and the other does not) with one half of the couples receiving vaccine while the others received placebo. Chiron considers that the Phase III trials were "well designed and well-executed," the immunogenicity goals were achieved and "the immunogenicity was consistent with that previously reported in earlier trials." "We don't have an explanation for why it didn't work, but it didn't work. That was the clear-cut, unambiguous answer from the trials." Preliminary data from an ongoing trial involving 2,000 sexually active (high-risk) HSV-negative persons recruited at sexual disease clinics also contributed to the company's decision to halt further development. No significant efficacy has been observed in this trial with patients receiving the vaccine at 0, 1 and 6 months with 12 months of follow-up.

    Development of effective prophylactic and immunotherapeutic genital herpes vaccines remains an elusive goal. Chiron's HSV-2 vaccine had been the furthest along in clinical testing. Other genital herpes vaccines have been tested in efficacy trials and abandoned, including a solvent inactivated vaccine developed by Porton International PLC and a live intertypic (HSV-1 and HSV-2) vaccine from Institute Merieux. Companies developing genital herpes vaccines, mostly for prophylaxis, include SmithKline Beecham Corp., Virus Research Institute, CEL-SCI Corp., Apollon Inc. with American Home Products Corp. (discussed in a News Brief below), Paradigm Biosciences, Cantab Pharmaceuticals PLC, Vical Inc., Merck & Co. and Pasteur-Merieux Connaught. Among these, the recombinant HSV-2 truncated gD2t subunit vaccine from SmithKline Beecham (discussed in the November 1994 Bulletin, p. 327), now in Phase III trials, appears to be the furthest along in development.

    HIV NNRTI/Nucleosides Combination Shows Indications of Efficacy

    Dr. B. Conway, Canadian HIV Trials Network (Vancouver, BC, Canada), and collaborators with the Boehringer Ingelheim 1046 Study Team (INCAS trial) reported at the recent Third International Congress on Drug Therapy in HIV Infection, Birmingham, U.K., results from a one-year clinical trial indicating that a non-nucleoside reverse transcriptase inhibitor (NNRTI) in combination with two nucleoside analog reverse transcriptase inhibitors can have efficacy comparable to combinations of a HIV protease inhibitor plus nucleoside analogs, reducing HIV below detectable levels using the most sensitive assays available, with delayed development of resistant virus. While it is becoming increasingly common for clinical trials with combinations of a HIV protease inhibitor plus nucleoside analogs to result in reduction of HIV plasma viral load below detectable levels and HIV protease inhibitor/nucleoside analog combinations are among the most popular regimens where available for first-line treatment, this study indicates that NNRTIs, particularly nevirapine, in combination with multiple nucleoside analogs can provide comparable efficacy. This may further broaden the options for long-term suppression of HIV replication and treatment of HIV-infection to include another class of drugs, the NNRTIs (in combination with conventional nucleoside analogs).

    This double-blind, controlled, randomized trial compared combinations of nevirapine (Viramune; NVP), marketed in the U.S. by Roxane Laboratories, a subsidiary of Boehringer Ingelheim Corp. (Ridgefield, CT), AZT (Retrovir from Glaxo Wellcome), and DDI (Videx from Bristol-Myers Squibb). Nevirapine plus AZT plus DDI, nevirapine plus AZT or AZT plus DDI were administered for one year to 151 antiretroviral drug-naive HIV-infected patients with CD4+ T-cell counts 200-600. HIV plasma viral loads were measured using the Amplicor HIV Monitor polymerase chain reaction (PCR) assay from Hoffmann-La Roche Inc. Samples from Canadian patients with fewer than 500 copies/ml were further tested with the more sensitive Ultra-Direct PCR (UD-PCR) assay from Roche having a lower detection threshold of 20 copies/ml. The triple combination of nevirapine plus AZT plus DDI produced "a substantially greater virological and immunological effect than DDI + ZDV [AZT] which in turn was superior to NVP + ZDV after one year of follow up. The average plasma viral load at 40-52 weeks in patients evaluated by UD-PCR shows that all patients in dual therapy with < 500 copies/ml had detectable virus above threshold (> 20 copies/ml). In contrast, 8/12 patients treated with NVP + ZDV + DDI had levels below 20 copies/ml. Overall, the study regimens were well tolerated." As discussed in the November Bulletin (p. 292), decreases in lymph node HIV viral load, including decreases below detection level (using Chiron's bDNA assay) observed in this trial were found to parallel decreases in plasma HIV viral load, suggesting that HIV replication may be effectively suppressed in the lymph nodes, the major reservoir for HIV-infection. A mean increase in CD4+ T-cell count of 138 was observed at weeks 40-52 in the triple combination patients, compared to an increase of 81 in the AZT plus DDI group, and a decline of 6 in the nevirapine plus AZT group. The investigators concluded that the triple combination of nevirapine plus the two nucleoside analogs has "substantially greater virological and immunological" efficacy compared with the double combinations tested.

    Another presentation by Dr. M.A. Wainberg, McGill Univ. AIDS Centre (Montreal, Quebec, Canada), and the Boehringer Ingelheim 1046 Study Team examined the development of viral resistance in this trial. Peripheral blood mononuclear cell (PBMC)-derived HIV was assayed for sensitivity to nevirapine, AZT and DDI, and the reverse transcriptase gene was sequenced to explore relationships between viral resistance and suppression of replication. Among those patients for whom viral load data were available (generally, among those with higher viral loads allowing culture of HIV), after six months of treatment, resistance to nevirapine (IC50 > 20 µM) was observed in all seven nevirapine plus AZT patients with initial viral load decreases of 2 log copies/ml below baseline followed by return to 0.5 log copies/ml below baseline at six months. In contrast, "no marked phenotypic changes were observed" among those receiving AZT plus DDI. Among the triple combination recipients, development of resistant HIV was observed in three non-compliant patients, while two "patients developed decreased susceptibilty with IC50 of 1.2 µM and 2.5 µM, and 2 compliant patients remained fully susceptible." The latter two patients also had HIV plasma viral load below detectable levels. The investigators concluded, "Combination therapy with NVP + ZDV resulted in rapid, consistent emergence of resistance to NVP. By contrast, NVP + DDI + ZDV can produce profound sustained suppression of viral replication, delaying the emergence of NVP resistance."

    These findings of effective suppression of viral replication below detectable levels in blood and lymph nodes using an HIV NNRTI plus nucleoside analogs with delayed development of resistant virus indicate that nevirapine and other NNRTIs may be used comparably to HIV protease inhibitors in combination with nucleoside analog RT inhibitors. Combinations of an NNRTI, nucleoside analogs plus HIV protease inhibitor(s) may be even more effective. However, these results may not apply to all NNRTIs, just as the increasingly common suppression of HIV replication below detectable levels observed with HIV protease inhibitors plus nucleoside analogs does not universally apply to all protease inhibitors and combinations. Along these lines, the recent equivocal review of another NNRTI, delavirdine mesylate (Rescriptor) from Pharmacia & Upjohn, by the FDA Antiviral Drugs Advisory Committee is discussed in the "Federal Activities" section below.

    New Data Show Importance of AZT to Reduce Maternal Transmission of HIV

    Dr. R.S. Sperling, Mount Sinai School of Medicine, reported in the November 28 issue of the New England Journal of Medicine that new data analyses from ACTG 076, a clinical trial that tested AZT for prevention of maternal transmission of HIV-infection, further demonstrate the efficacy and importance of AZT prophylaxis, irrespective of the HIV-infected mother's immune status or HIV plasma viral load. AZT has been approved for treatment of HIV-infected pregnant women for prevention of maternal transmission of HIV-infection, largely based on ACTG 076 as reported in the August 1994 Bulletin (p. 227). Dr. A.S. Fauci, NIAID director, commented, "HIV transmission to the infant is most likely to occur when a woman has large quantities of virus in her bloodstream, but there appears to be no absolute threshold of maternal viral load below which HIV is not transmitted from mother to infant, nor a Ôsafe' maternal CD4+ T cell level above which transmission never occurs." The new analyses support providing AZT to all pregnant HIV-infected mothers, even those with low viral load and normal CD4+ T-cell counts.

    Reduction in risk of maternal transmission could only partially be explained by the mother's drug-related reduction of HIV plasma load (median reduction of 1.7-fold between study entry and delivery) and may be due to other still unknown AZT-related mechanisms. Dr. Sperling noted, "Even when antiretroviral drugs [e.g., HIV protease inhibitors and other multiple drug combinations] with a greater impact on reducing viral load are indicated for the health of a pregnant HIV-infected woman, she and her physician should strongly consider incorporating AZT into her treatment regimen, and should continue AZT during delivery and to the newborn, according to the ACTG 076 protocol." The U.S. Public Health Service issued guidelines in 1994 for the use of AZT to prevent perinatal HIV transmission and for HIV counseling and voluntary testing for pregnant women.

    A nationwide CDC study has found that rates for HIV maternal transmission fell from 21% before 1994 to 11% in 1995. On November 21, CDC released a study documenting a dramatic reduction in the number of U.S. perinatally-acquired AIDS cases in children. However, by late 1995, 1.5 million children worldwide are estimated to have become infected with HIV, and this is expected to grow to 10 million by the year 2000. Over 90% of HIV-infection in children is contracted from HIV-infected mothers. For most of the world's population, particularly those in lesser-developed countries, AZT, other antiretroviral drugs, HIV testing and quality medical care remain unaffordable or unavailable; and the new results are likely to have little impact on vertical transmission of HIV-infection.

    HIV Rev M10 Gene Therapy from SyStemix Enters Trials

    The FDA has accepted an Investigational New Drug (IND) application from SyStemix, Inc. (Palo Alto, CA) to conduct a 35-patient Phase I/II clinical trial with a gene therapy protocol for treatment of HIV-infection. This is the first clinical trial using hematopoietic stem cells (HSCs; CD34+Thy-1+ cells) as a delivery vehicle for a therapeutic gene against HIV-infection. A HIV-1 dominant defective Rev M10 gene will be inserted ex vivo into HSCs removed from patients and the cells will be returned to the same patient. Rev M10-transformed cells produce a defective or decoy version of HIV Rev protein that competes with and inhibits HIV Rev protein involvement in transport of HIV genetic material from the nucleus into the cytoplasm of infected cells. HSCs are precursor cells which have the ability to self-renew and mature into blood and immune cells. The Rev M10 gene prevents HIV from replicating within transformed cells, trapping virus and limiting further spread of HIV to uninfected, non-transformed cells. Thus, Rev M10-transformed HSCs may be able to reconstruct the immune system of HIV-infected patients with cells resistant to HIV-infection. Preclinical studies have shown that Rev M10-transformed HSCs pass on their Rev M10 gene to new stem cells and to "daughter" cells, including T-cells, macrophages and other cells that would otherwise be susceptible to HIV-infection. Dr. C. Juttner, V.P. Medical Affairs, SyStemix, stated, "Stem-cell-based gene therapy for HIV may be able to provide long-term therapeutic benefit from only a single treatment, and could be used alone or in combination with multi-drug anti-viral therapies." The trial is expected to continue through mid-1998.

    This approach is the result of a "50/50 collaboration with Sandoz Pharmaceuticals, and was initiated in 1993 to design and evaluate a series of anti-HIV gene therapies using the HSC, the common source of all cells in the blood and immune system." As discussed in the April Bulletin (p. 103), Sandoz AG (Basel, Switzerland), which has a controlling interest in SyStemix, is merging with Ciba-Geigy AG (Basel, Switzerland) to form Novartis. The HIV-1 Rev M10 gene construct is obtained from Sandoz which licensed it from Duke University (Durham, NC). SyStemix brings to the collaboration its proprietary hematopoietic stem cell technologies and expertise and its SCID-hu mouse model which mimics the human immune system. SyStemix has shown that Rev M10-transformed human stem/progenitor cells engrafted into SCID-hu mice properly differentiated, and the resulting cells retained the defective rev gene and expressed it at levels that should be sufficient for therapeutic efficacy. Preclinical goals which have been achieved include the isolation and gene-modification of HSCs from HIV-infected patients, development of a safe "packaging cell line" derived from human cells that enables high efficiency insertion of genes into the patient's HSCs; and demonstration that gene-modified stem cells produce gene-modified progeny, and that these cells also express the gene in sufficient quantities to prevent HIV replication.

    Human Hepatitis B Virus Antibody Enters Phase II Trials

    Protein Design Labs. (PDL; Mountain View, CA) announced that Boehringer Mannheim GmbH (Mannheim, Germany) has initiated a multinational Phase II clinical trial of Human Anti-Hepatitis B Antibody (OST 577) for treatment of chronic hepatitis B virus infection. Two hundred patients in the U.S., Europe (including France, Germany, Great Britain, Italy and the Netherlands) and Israel will receive this recombinant humanized antibody as monotherapy or in combination with alpha-2b-interferon (Intron A from Schering-Plough Corp.), the only approved treatment for chronic hepatitis B in the U.S. and Europe. The trial will include interferon-naive patients and patients having failed to respond to interferon. The safety and efficacy of Human Anti-Hepatitis B Antibody treatment will be studied for 24 weeks with an additional 24 weeks of follow-up. Boehringer Mannheim also plans to initiate a clinical program in Asia in 1997, and a Phase II/III trial is planned in early 1997 to study prevention of hepatitis B virus infection in patients having undergone a liver transplant due to end-stage chronic hepatitis B. A Phase II/III trial is planned for prevention of hepatitis B re-infection of hepatic transplants in HBsAb-positive patients.

    Human Anti-Hepatitis B Antibody is a human monoclonal antibody (MAb) derived from the peripheral blood leukocytes of a human volunteer immunized with a hepatitis B vaccine. This "IgG1 (lamda) MAb binds tightly (K = 4 x 109 M-1) to the common Ôa' group determinant of the hepatitis B surface antigen (HBsAg) that is associated with protective immunity. Based on comparative binding studies, OST 577 is 200-fold more potent than commercial preparations of hepatitis B immune globulin...Pharmacokinetic studies conducted with Rhesus monkeys (0.5 mg OST 577/kg body weight) showed peak plasma levels (approximately 11 µg/mL) and a long plasma half-life (approximately 2 weeks) characteristic of a human IgG (correlates to an approximate 3 week plasma half-life in humans)...In a single-animal, chimpanzee HBV-challenge study, one dose of OST 577 (5 mg/kg, iv) was able to delay onset of HBV infection for 41 weeks, approximately 5-fold longer than the historic median value of 8 weeks."

    In a multiple-dose Phase I/II trial conducted by PDL involving 12 patients with chronic hepatitis B treated with Human Anti-Hepatitis B Antibody for 5 weeks at three different dosage levels 7-9 times over a 35-37 day period, levels of key surrogate markers of efficacy (such as hepatitis B surface antigen, hepatitis B DNA and enzymes [e.g., ALT] released into the blood by damaged liver cells) declined by at least 50% temporarily during treatment in half or more of the patients having elevated levels at the start of the trial. "Reductions were seen in 5 of 10 patients with elevated liver enzyme levels; in 10 of 12 with elevated levels of hepatitis B surface antigen; and in 5 of 9 with elevated viral DNA levels." In a Phase I/II trial in five end-stage liver disease patients receiving multiple doses of the antibody before, during and after liver transplantation, all doses were tolerated even when treatment was continued for 18 months after transplantation; all five patients converted to HBsAg seronegativity; and none showed further symptoms of clinical hepatitis for the next four years. In a Phase I study conducted by Boehringer Mannheim in 33 patients, the in vivo half-life of Human Anti-Hepatitis B Antibody was about 20 days and the antibody was well tolerated. As discussed in the October Bulletin (p. 261), Protovir, a similar recombinant humanized cytomegalovirus (CMV) antibody from PDL, is currently in clinical trials.

    Corange Ltd. (Bermuda), the privately-held parent company of Boehringer Mannheim and DuPuy Pharmaceuticals, has licensed PDL products including its humanized hepatitis B virus and CMV antibody-based immunotherapeutics in a deal that could provide PDL with over $100 million in payments (discussed in the November 1993 Bulletin, p. 327). Corange acquired exclusive marketing rights for the Human Anti-Hepatitis B Antibody outside of North America, while PDL retains U.S. and North American development and marketing rights, subject to certain co-promotion rights held by Sandoz Pharmaceuticals Corp. (now being merged into Novartis). Boehringer Mannheim has manufactured clinical supplies of Human Anti-Hepatitis B Antibody and is currently improving and scaling-up production. The company has started construction of a manufacturing facility in Penzberg, Germany for potential commercial production of Human Anti-Hepatitis B Antibody and other biologics (probably including Protovir CMV antibody from PDL).

    Polio Vaccine Controversies Continue in the U.S.

    The 51,000 member American Academy of Pediatrics (AAP) and many other healthcare organizations are supporting recommendations for polio vaccination that differ from those recently issued by the Centers for Disease Control and Prevention (CDC). As discussed in September Bulletin (p. 235), CDC now recommends sequential universal use of inactivated poliovirus vaccine (IPV) followed by oral poliovirus vaccine (OPV). CDC's change was primarily related to concerns about live OPV-associated paralytic polio, a rare complication with an estimated 6-8 cases/year in the U.S. AAP, the American Academy of Family Physicians and other organizations are now recommending a choice of three options with no stated preference among the optionsÑall OPV, all IPV or sequential IPV/OPV. As discussed in the prior Bulletin article, a number of public health, economic, political and other factors are involved in the recommendations for polio vaccinations. Although CDC recognizes that the two other vaccination protocols, all IPV and all OPV, are valid and acceptable options, only the sequential IPV/OPV protocol is formally recommended.

    In related news, the National Vaccine Information Center (NVIC; Vienna, VA), primarily representing parents and others concerned with vaccine safety, has called for a halt in the use of monkey kidney tissues as hosts for culture of poliovirus used in current polio vaccines due to concerns about the presence of contaminating primate retroviruses, including SV40. NVIC notes, "There is evidence that vaccine manufacturers and government regulators knew in the late 1950's and early 1960's that the polio vaccines were contaminated with monkey viruses but chose to continue producing vaccines using monkey tissues rather than develop alternative ways to make both vaccines. All polio vaccines using monkeys for production should be removed from the market until there is a scientific investigation into the contamination problem." Lederle Labs., now merged with Wyeth-Ayerst Pharmaceuticals, a subsidiary of American Home Products Corp. (Madison, NJ), manufactures OPV in the U.S. and Pasteur Merieux Connaught manufactures IPV in the U.S. and OPV in France. Both companies use African green monkey kidney cells for culture of poliovirus used in their U.S. vaccines. Pasteur Merieux Connaught produces an IPV sold internationally that is produced using human lung cells.

    SRA Technologies Forms Collaboration for Drug Evaluation Methods

    SRA Technologies, Inc. (Falls Church, VA) and Albany Medical Center (Albany, NY) have formed a collaboration for research and development of in vitro and in vivo methods for improved antiviral and other drug screening and preclinical testing. SRA is a specialty laboratory providing contract research services for evaluation of drugs for infectious diseases and cancer, specializing in analysis of surrogate markers of drug efficacy and resistance based on molecular and cellular immunology. Albany Medical Center provides preclinical assessment and clinical trials of drugs for infectious diseases and cancer, with specialized expertise in pharmacokinetics and evaluation of combination therapies. The organizations will adapt proprietary SRA clinical evaluation assays to Albany Medical Center's "hollow fiber" system to offer drug testing services in which markers of efficacy, drug resistance, immune function and toxicity relevant to clinical trials are available in directly comparable form from preclinical studies. The two organizations will also collaborate to develop novel clinical markers and methods for drug evaluation based on research that each has been conducting independently, including quantitative methods for genotypic analysis of antiviral resistance and markers of HIV disease progression that are faster and cheaper than current methods such as viral burden; standardized in vitro and in vivo assays for assessing interactions among therapeutics for HIV and opportunistic infections; fluorescent differential display technologies for rapid, high throughput measurement of gene expression; and in vitro cellular immune assays for evaluating antiviral and other therapeutics. Both companies will continue to offer contract services to industry and Albany Medical Center is relocating its in vitro testing services to SRA laboratories in Rockville, MD.

    Herpes Simplex Virus DNA Vaccine Enters Trials

    Apollon, Inc. (Malvern, PA) has started Phase I clinical trials with its plasmid-based herpes simplex virus (HSV) "facilitated DNA injection" vaccine. One trial is administering the vaccine to 40 healthy volunteers to study safety and immune response, and another is enrolling patients with genital herpes. The vaccine involves a DNA plasmid vector carrying the HSV gD2 glycoprotein gene that is injected directly into muscle that has been pretreated with agents, such as the local anesthetic bupivacaine, that facilitate plasmid cellular uptake and muscle cell regeneration. The plasmid vectors enter muscle cell cytoplasm and the HSV gD2 gene (and/or other packaged genes) are expressed without the plasmid becoming integrated into cellular DNA. The resulting in vivo expression of HSV gD2 glycoprotein simulates natural infection presentation of HSV gD2 and is expected to induce potent cellular and humoral immune responses. The vaccine may have potential for both prevention and treatment of genital herpes and reduction of risk of transmission by infected persons. Apollon is continuing to study other potential HSV genes/antigens for DNA plasmid use. Apollon and the start of clinical trials with the company's multivalent immunotherapeutic GENEVAX-HIV vaccine were discussed in the August 1995 Bulletin (p. 231). As discussed in the December 1995 Bulletin (p. 361), Wyeth-Lederle Vaccines and Pediatrics, a subsidiary of American Home Products Corp. (Madison, NJ), is collaborating with Apollon on development of DNA plasmid-based vaccines for HSV, HIV and human papillomavirus (HPV). Apollon is also conducting a clinical trial with a DNA vaccine for treatment of T-cell lymphoma.

    Cuban HIV Vaccine to Enter Trials

    Cuban President F. Castro announced on December 21 that the Centre for Genetic Engineering and Biotechnology, a government-sponsored laboratory, has started clinical trials with a prophylactic HIV vaccine, and that "24 Cuban scientists" (presumably HIV-negative volunteers) have received the vaccine. Cuban scientists have already developed a meningococcal meningitis type B vaccine that is used in Latin America and other developing countries.

    LeukoSite and Warner-Lambert Link for CCR-5 HIV-Infection Blockers

    LeukoSite, Inc. (Cambridge, MA) and Warner-Lambert Co. (Ann Arbor, MI) have formed a collaboration for development of drugs that block the CCR-5 receptor. The companies will share rights to any drugs they discover. Financial terms were not disclosed. Besides drugs for treatment of HIV-infection, the collaboration will include CCR-5 blocking drugs for inflammatory disease indications. As discussed in the August Bulletin (p. 194), CCR-5 (cysteine-cysteine chemokine receptor-5; CC-CKR-5) is a cellular cofactor required (along with CD4) for fusion and entry of macrophage-tropic HIV virions into infection-susceptible CD4+ cells, and some individuals with defects in the CCR-5 gene appear to be resistant to HIV-infection. Researchers from LeukoSite and their collaborators described in the November 14 issue of Nature the two-step process that enables HIV to breech membranes of T-cells. HIV gp120 on the virus surface first binds to the CD4 receptor on T-cells, forming a complex which changes its configuration (refolds), revealing a second structure that binds to the CCR-5 chemokine receptor, enabling HIV to fuse and enter the cell. Neutralizing antibodies directed to CD4-induced or V3 epitopes on HIV gp120 were shown to block the interaction of gp120-CD4 with CCR-5 complexes. Dr. L. Wu, LeukoSite, reported, "Our research validates the Ôsecond structure' theory that had previously been postulated and builds on earlier work by Dr. Joseph Sodroski at Dana Farber [Cancer Inst; Boston, MA]. Now that we know a Ôsecond structure' exists, we can study the way the gp120 CD4 complex changes shape to bind to CCR5, and use the information to improve drug discovery assays and fine tune rational drug design efforts." Some forms of HIV may avoid neutralization by antibodies by keeping the "second structure" hidden until just before the virus enters the cell. The investigators suggest that, "This two-step viral entry strategy may explain the failure of some treatment strategies that targeted the CD4-viral envelope complex" (with such failed strategies including use of recombinant soluble CD4).

    Hepatitis B Immunotherapeutic Vaccine More Effective at Lower Viral Loads

    Cytel Corp. (San Diego, CA) has reported that Theradigm-HBV, its hepatitis B virus (HBV) immunotherapeutic vaccine, may be particularly useful in combination with nucleoside analogs or other drugs for treatment of chronic HBV. Theradigm-HBV (CY-1899) is a synthetic nine amino acid hepatitis B virus-derived peptide linked to a MHC class-I receptor peptide sequence. As reported in the June Bulletin (p. 132), Theradigm-HBV has shown indications of efficacy for treatment of chronic HBV with induction of cellular immune responses including cytotoxic T lymphocytes (CTL). Cytel now reports, "Recently available data suggests that the effectiveness of Theradigm in generating a cellular immune response may be stronger in patients with lower amounts of virus in their bodies. Since several newly developed anti-viral drugs are effective at quickly lowering viral load, this data points to the potential use of Theradigm in combination with these agents." Dr. R.L. Roe, Exec. V.P. and COO, Cytel, remarked, "The new generation of nucleotide compounds appears to be effective at temporarily lowering viral load, but the infection often recurs when treatment is stopped, and extended therapy introduces the risk of viral mutations leading to drug resistance. Since Theradigm seems to work best when viral loads are low, we have decided that our most likely chance of achieving a true cure will be to use a combination drug approach: combining a nucleotide to suppress viral activity that overwhelms the immune system, with Theradigm to activate a selective immune response that eradicates the infection. Thus, we plan to initiate clinical studies of Therdigm-HBV in combination with an anti-viral agent in early 1997, and we have no plans at present to conduct additional clinical studies of Theradigm-HBV as a monotherapy." Recently, several nucleoside analogs have shown strong indications of efficacy for treatment of chronic HBVÑlamivudine (3TC) from Glaxo Wellcome Co. (Research Triangle Park, NC) and BioChem Pharma Inc., and Famciclovir (Famvir) from SmithKline Beecham Corp., both discussed in last month's Bulletin, pages 290 and 289, respectively; and GS 840 (adefovir dipivoxil) from Gilead Sciences, Inc. as discussed in the September Bulletin (p. 226).

    Agouron Files for Approval of Nelfinavir for HIV-Infection

    Agouron Pharmaceuticals, Inc. (La Jolla, CA) submitted its New Drug Application (NDA) to FDA for approval of nelfinavir mesylate (AG1343; trade name Viracept) on December 23. Agouron's intention to file was discussed in last month's Bulletin (p. 295). This is the first NDA to seek simultaneous approval of a HIV protease inhibitor for use in both adults and children. This NDA was filed "just three years after first synthesizing the drug," and involved a dedicated effort by more than 100 Agouron employees, in collaboration with the company's development partner, Japan Tobacco Inc., and PAREXEL International Corp., a leading contract clinical research organization.

    VIMRx Acquiring Innovir, Consolidating Ribozyme Technologies

    VIMRx Pharmaceuticals Inc. (Wilmington, DE) is acquiring a controlling interest in Innovir Laboratories, Inc. (New York, NY), a company developing antiviral and other therapeutic ribozymes. VIMRx will provide Innovir with $7 million of operating capital with a commitment for an additional $2 million. As reported in the June Bulletin (p. 138), VIMRx has acquired Ribonetics GmbH (Gšttingen, Germany), a company developing oligonucleotide-based ribozymes (Rilons) targeted to mRNA. The combination of the two companies' technologies is expected to result in an improved "competitive position, critical mass and global reach...in the catalytically active oligomer field...because the EGS and RILON technologies are so synergistic." Innovir is developing External Guide Sequence (EGS) technology and the InnoPhor drug delivery system to facilitate entry of EGS drugs into liver cells. VIMRx will end up owning about 66% of Innovir, and the RILON and EGS technologies will be combined under the Innovir company name.

    EGS technology involves small, modified, stabilized RNA oligonucleotides that bind to targeted RNA to form a structure that directs cleavage of the bound RNA by RNase P, a ribozyme occurring in all cells which naturally targets a tRNA precursor. The EGS oligonucleotide is "catalytic" in nature, in the sense that it is not broken down in the process and can interact with additional target sequences. EGS oligonucleotides are composed of a constant core domain and two variable hybridizing arms which direct the EGS to bind to targeted mRNA. The variable arms can be designed to direct the EGS to different targets. EGS oligonucleotides are much smaller and simpler than most ribozymes, can be produced synthetically rather than by recombinant methods, and may be administered parenterally. EGS oligonucleotides have been developed with an in vivo half-life of up to 18 hours. EGS technology was developed by Dr. S. Altman, Yale Univ., and has been exclusively licensed by Innovir. Innovir is collaborating with The Scripps Research Institute (La Jolla, CA) for evaluation of candidate hepatitis B virus drug candidates in specialized animal models as reported in the August Bulletin (p. 201).

    Reticulose Anti-HIV Trial Results

    Advanced Viral Research Corp. (New York, NY) has reported preliminary results from a double-blind efficacy trial at the Univ. of the West Indies School of Medicine with Reticulose, a peptide nucleic acid formulation, for treatment of HIV-infection. As discussed in the June Bulletin (p. 138), reticulose is also being tested for treatment of human papillomavirus (HPV) genital warts, has a long history of use, but continues to experience difficulties with regulatory authorities in developed countries due to its complex, largely undocumented structure and concerns about its manufacture in the Bahamas. Data were reported for 43 retroviral drug-naive patients having received Reticulose or placebo daily every other week for a 60-day period with 60-days follow-up. There was a 37% increase in the mean CD4+ T-cell count in Reticulose patients vs. a 7% reduction among placebo patients; and there was a 21% average decrease in HIV plasma viral load (Roche quantitative HIV RNA PCR assay) in Reticulose patients vs. a 33% increase in placebo patients. After the follow-up period, the mean HIV viral load in treated patients was less than half (42%) of the placebo patients. Also, 83% of Reticulose patients had a rise in blood hemoglobin with 61% having a rise in hemoglobin ³ 1 g/dl; compared with a hemoglobin rise in 44% of placebo patients with only 25% having a rise of ³ 1 g/dl. "There was zero toxicity and no side effects were observed by physicians or reported by patients as a result of Reticulose therapy."

    Hepatitis A/B Vaccine Approved in Europe

    The European Union's new centralized drug registration system has granted approval to Twinrix, a combination hepatitis A/B vaccine, from SmithKline Beecham Biologicals (SKB; Rixensart, Belgium). Twinrix combines SKB's Hepatitis A Vaccine, Inactivated (trade name Havrix) with SKB's Engerix B recombinant hepatitis B vaccine. The combination vaccine is expected to offer convenience and cost savings for adult travelers to lesser developed countries and other areas where hepatitis A and B are more common and, in the long-term, will facilitate the universal vaccination of children and adolescents against hepatitis A and B as a growing proportion of this population is susceptible to hepatitis A (and universal vaccination for hepatitis B is recommended).

    Hepatitis G Virus Diagnostics Available

    Genelabs Technologies, Inc. (Redwood City, CA) has received a $1 million milestone payment from Boehringer Mannheim GmbH (Mannheim, Germany) upon commercialization of the first hepatitis G virus (formerly hepatitis X virus) diagnostic kits. Boehringer Mannheim is marketing two kits, an oligonucleotide probe-based kit which can be used experimentally for detection and diagnosis of hepatitis B [should be G] virus infection and an antibody-based kit for detection of hepatitis B [should be G] virus E2 envelope antigen, which may be useful as a marker for clearance of the virus and patient recovery. Genelabs has nonexclusive licensing and collaborative development agreements with Boehringer Mannheim (discussed in the June 1993 Bulletin, p. 171) and Ortho Diagnostic Systems (subsidiary of Johnson & Johnson) for HGV diagnostics and blood screening tests; and has cross-licensed its hepatitis G patents with hepatitis C patents from Chiron Corp. (as discussed in the March 1995 Bulletin, p. 77).

    Cimetidine Lacks Efficacy for HIV-Infection

    Dr. C.J. Cohen, Community Research Initiative of New England (Brookline, MA), and collaborators have reported in Clinical Infectious Diseases (vol. 23, p. 1045-54) the results from a 182-patient, placebo-controlled, community-based clinical trial demonstrating that cimetidine (Tagamet) from SmithKline Beecham Corp. (Philadelphia, PA) lacks efficacy for treatment of HIV-infection. Although cimetidine (1,200 mg/day for 8-16 weeks) was found safe in HIV-infected patients, an overall decline in CD4+ T-cell counts was observed in both the treated and placebo groups and there were no improvements in HIV p24 antigen levels in any subjects after cimetidine treatment. A German uncontrolled study in the late 1980s had reported a correlation between cimetidine use and significant increases in CD4+ T-cell counts in HIV-infected patients. Cimetidine is a guanine derivative histamine H2 antagonist used for treatment of ulcers and gastric distress and is one of the most commonly used drugs. H2 receptors are present on various immune cells, including T-helper and T-suppressor cells, B-cells and monocytes/macrophages.

    Influenza Vaccine from Warner-Lambert Recalled

    The Parke-Davis Div., Warner-Lambert Co. (Ann Arbor, MI), has voluntarily recalled eleven lots of its influenza vaccine (Fluogen) because of insufficient potency for one of the vaccine's three viral antigens. Already into the influenza season, the recalled doses had been administered to an estimated 5%-7% of persons in the U.S. having received influenza (flu) vaccines for this 1996-1997 influenza season, with the recalled vaccine lots distributed throughout the U.S. The recalled vaccine lots had decreased levels of influenza A/Nanchang antigen but still enough to generate immune responses, which the authorities presume to be sufficiently protective (enough not to warrant recommended wholesale revaccination) in immune competent recipients.

    The company, the Food and Drug Administration (FDA) and the Centers for Disease Control and Prevention (CDC) issued advisory notices to U.S. health professionals and the media recommending "that the first priority for use of the remaining supplies of vaccine are high-risk individuals who have not yet received any doses of the 1996-1997 flu vaccine." Those at high risk (e.g., having chronic, debilitating conditions or immune deficiency) having received vaccine from defective lots should consider reimmunization. The FDA and CDC recommend that all unvaccinated high-risk persons receive influenza vaccine since the vaccine provides protection in about two weeks and the peak of the influenza season typically occurs in January and February. However, the FDA and CDC consider, "It is very difficult to estimate clinical and public health benefits, if any, that reimmunization might provide regardless of which vaccine was previously administered." The agencies make no specific recommendations about revaccination of those having received recalled vaccine, leaving this up to the patient and physician on a case-by-case basis.

    Eleven lots of vaccine were voluntarily recalled by Parke-Davis in November. According to FDA, "At that time, based on available information, neither the FDA nor CDC recommended that anyone who had received this influenza vaccine be reimmunized." The CDC subsequently compared blood samples from 86 elderly nursing home residents who had received recalled Fluogen to blood samples from 86 other nursing home recipients who had received vaccine from another manufacturer. Those having received recalled Fluogen "had moderately lower levels" of influenza A/Nanchang antibodies that "may place those receiving the recalled vaccine at a somewhat higher risk of becoming ill from the A/Nanchang strain of influenza. In contrast, a study of generally young, healthy health-care workers receiving Fluogen from recalled versus non-recalled lots did not show significant differences in levels of antibodies." Thus, healthy persons having received recalled vaccine are presumed to have sufficiently protective levels of influenza A/Nanchang antibodies. Adequate supplies of influenza vaccine are available. Three other companies (not affected by the recall) market influenza vaccines in the U.S.ÑConnaught Labs., Inc. (Fluzone); Evans Medical Ltd. (Fluvirin); and Wyeth Labs., Inc. (Flushield).

    FDA Antiviral Advisory Committee Fails to Recommend Delavirdine Approval

    The Antiviral Drugs Advisory Committee, FDA, tied 4-4 and failed to provide FDA with a recommendation to grant accelerated approval to delavirdine mesylate (Rescriptor), a non-nucleoside reverse transcriptase inhibitor (NNRTI), from Pharmacia & Upjohn, Inc. (Kalamazoo, MI) for use in combination with other drugs for treatment of HIV-infection. This leaves the decision entirely up to FDA. Preliminary, partially unblinded results from two randomized, double-blind North American Phase II/III clinical trials with delavirdine were reported in the February Bulletin (p. 38). At the meeting, Pharmacia & Upjohn representatives presented data generally showing some improvements in early stage patients but not in advanced patients. Data from some trials showed improvements while other trials failed to replicate these results. Some positive effects on CD4+ T-cell counts were reported from ACTG 261 but viral load data from this trial will not be available until mid-January, and data from two company studies, 0017 and 0021, were not considered convincing or consistent. Because of the design of the studies, involving multiple combinations, it was difficult to determine delavirdine's contribution to efficacy, with triple drug combinations showing the most improvements.

    Delavirdine has an HIV resistance mutation profile different than that of other anti-HIV drugs and is synergistic in vitro with other antiretroviral drugs, suggesting it should be particularly useful in multi-drug combinations. The company reported that delavirdine appeared to reduce development of AZT resistance. The adverse effect most associated with delavirdine was skin rash that occurred with twice the frequency in delavirdine recipients than in other trial arms. The rash cleared in 85% of patients after two weeks of antihistamine treatment, but 20% of patients in one trial dropped out due to rash. The committee generally agreed that delavirdine is at least as safe and effective as other marketed HIV therapeutics but was largely unpersuaded by available results from clinical trials. Another NNRTI, nevirapine (Viramune) from Boehringer Ingelheim Corp., has already received accelerated approval from FDA.

    Some advisory committee members were concerned about the lack of sufficient data and modest efficacy reported from clinical trials. For example, Dr. F. Valentine, a voting committee consultant, stated, "I do feel that there is a need for this drug...[but] I don't think the data support accelerated approval." He attributed some of the lack of dramatic efficacy with delavirdine to the continually improving combination treatments available for HIV-infection, stating, "As the standard of care becomes more effective, drug companies are going to have a harder time proving the effectiveness of their individual drug, particularly when used in combination with others." Committee member Dr. M.D. Murphy, who voted to recommend approval but had reservations about the quality of available clinical data, stated, "The problem is the inconsistency. We don't know where to use it, how to use it." Others who voted for approval noted that the drug's adverse effect and safety profiles were generally better than other currently available HIV drugs. Committee member Dr. W. Greaves commented, "We're in a tough position. There are still patients who need additional drugs." Another member, Dr. C. Mathews, remarked about his difficulties in recommending delavirdine approval after reviewing and recommending approval for several HIV protease inhibitors within the past yearÑ"A year ago, I would have viewed this very differently." Committee Chairman, Dr. S. Hammer (who refrained from voting) generally supported approval but agreed that available data could be much better.

    Company officials stated that they were disappointed with the lack of recommendation for approval and expected to subsequently meet with FDA to address agency concerns. Some meeting observers report that FDA staff appeared to favor approval. Many expect FDA to approve the drug but to wait until early next year when viral load data from an ongoing clinical trial (ACTG 261) are expected to become available. However, legal technicalities may complicate FDA actions. The company filed its New Drug Application in July and FDA user fee-related regulations require that the agency issue a decision about NDA approval within six months of filing. Delavirdine has obvious effects against HIV in some patients with relative safety. Even though this is not yet clearly demonstrated in clinical trials, the drug would be welcomed and probably approved as a new option for patients failing on or intolerant to other HIV drugs. Several AIDS treatment activist groups spoke in favor of delavirdine approval, citing its need by patients lacking other options. As discussed in last month's Bulletin (p. 300), Pharmacia & Upjohn has issued a warning to all physicians using delavirdine (currently available through its expanded access program) in certain combinations with HIV protease inhibitors.

    Dr. D. Baltimore to Head NIH HIV Vaccine Efforts

    Dr. D. Baltimore, a noted virologist and Nobel Prize winner currently with the Massachusetts Inst. of Technology, has been appointed to lead the National Institutes of Health (NIH; Bethesda, MD) prophylactic HIV vaccine research and development efforts. Many hope that appointment of such a respected figure will help revitalize NIH's HIV vaccine efforts. Although about 15 HIV vaccines have been or are currently in active development, none has demonstrated sufficient indications of efficacy to enter government-funded large-scale testing. Such large-scale trials will require U.S. and international government support because of their size and cost, potential for legal liability, the need to conduct trials in multiple countries, and the lack of private sector financial and other backing. One of Dr. Baltimore's main tasks will be to try and revive private sector interest in developing prophylactic HIV vaccines, a goal which is considered rather elusive based on our current limited knowledge of HIV and correlates of immunity, and is considered too costly and risky by most companies to warrant the required long-term commitment of scientific, managerial and monetary resources. Dr. Baltimore is no stranger to controversy, having been involved for almost ten years in a controversy involving alleged scientific fraud by a colleague, Dr. T. Imanishi-Kari (who only recently has been exonerated).

    FDA Approves Lymphocyte Adhesion Antibody Trials for HIV-Infection

    Cytolin, a murine monoclonal antibody directed against LFA-1, an adhesion molecule found on the surface of S6F1 CD8+ lymphocytes, from CytoDyn, Inc. (Los Angeles, CA) has entered an FDA-approved Phase I/II clinical trial in 16 patients for treatment of HIV-infection. CytoDyn is somewhat unique in that it is a nonprofit biotechnology company organized largely by HIV-infected patients and local AIDS community-based and activist groups. So far, the company has succeeded in developing its monoclonal antibody product, conducting preliminary studies and obtaining an IND from FDA "on a tight budget of only $1.25 millionÑa small sum by pharmaceutical standards. Most of that amount was raised from HIV-positive, gay male professionals and businessmen with a personal stake in fighting AIDS." As discussed in the October 1995 Bulletin (p. 297), clinical trials with Cytolin injection have been conducted in California, although under the authority of State regulatory authorities rather than FDA, and preliminary studies and anecdotal reports indicate safety and potential efficacy.

    CytoDyn now reports that records obtained from four physicians having treated 188 patients (under State physician experimental drug use regulatory exemptions) with 700 treatments over a period of up to two years found the main side effect to be allergic reaction in about 5% of the infusions (which take about 15 minutes), with only 1% resulting in serious adverse effects which were successfully managed with standard treatments. These results indicate that induction of human anti-mouse antibodies (HAMA) against this murine antibody is not a problem with LFA-1. The premise of Cytolin therapy is that CD8+ lymphocytes mediate the destruction of the immune system as HIV-infection advances. CD8+ lymphocytes exposed to LFA-1 antibodies lose their CD8+ killer cell function and LFA-1 monoclonal antibodies administered to animals result in a decrease in cellular immune responses. CytoDyn postulates that its LFA-1 monoclonal antibody blocks CD8+ lymphocyte adhesion receptors so that CD8+ lymphocytes cannot bind to and destroy monocytes and CD4+ lymphocytes as HIV-infection advances, while antiretroviral drugs inhibit HIV replication. This approach does have critics and a number of potential reasons why it may be ineffective or even exacerbate HIV-infection.

    New Meetings

    Foundations of HIV Therapy, March 13-16, 1997, Palm Springs, CA. Contact: Ms. Nita Driscoll, Cancer Research Inst., Univ. of California, Irvine, Biological Sciences II, Room 3221, Irvine, CA 92697-3905; Phone: 714-824-5886; Fax: 714-824-4023; E-mail: nrdrisco@uci.edu.

    Management of HIV, CMV and Hepatitis Infections, March 14-16, 1997, New York, NY. Sponsors include the International Society for Antiviral Research. Contact: The Macrae Group, 230 East 79th Street, Suite 8E, New York, NY 10021; Phone: 212-988-7732; Fax: 212-717-1222.

    Compliance Conference, April 7, 1997, Harrisburg, PA. The conference will "examine the State-of-the-Art for therapeutic compliance in HIV disease." Contact: Dr. W.C. Woodward, Director, HIV Primary Care Clinic, Saint Joseph Medical Center, 200 North 13th Street, Suite 200, Reading, PA 19604; E-mail: wcwood@ptd.net.

    Current Aspects of Vaccinology and Molecular Virology, April 9-11, 1997, Dana Point, CA. Contact. Drug Information Association, P.O. Box 7777-W8405, Philadelphia, PA 19175; Fax: 215-641-1229.

    The American Society for Virology, 16th Annual Meeting, July 19-23, 1997, Bozeman, MT. Contact: Conference Services, Montana State Univ., SUB, Room 402, Bozeman, MT 59717; Phone: 406-994-3333.

    New Books

    The E6 and E7 Onocproteins of Human Papillomaviruses, edited by M. Tommasino, Chapman & Hall, New York, April 1997, 250 pages, $79.95.

    Clinical Applications of the Interferons, edited by R. Stuart-Harris and R. Penny, Chapman & Hall, New York, December 1996, 424 pages, $145.50.

    The TH1-TH2 Paradigm in Disease, edited by S. Romagnani, Chapman & Hall, New York, December 1996, 196 pages, $79.95.

    The AIDS Cult: Essays on the Gay Health Crisis, edited by J. Lauritsen and I. Young, Pagan Press, Provincetown, MA, February 1997. [The contributors to this book are all "skeptical of the hypothesis that dubiously defined ÔAIDS' is caused by a virus"].

    New Internet Web Sites

    CafŽ HerpŽ

    SmithKline Beecham Corp. (SKB; Philadelphia, PA) has opened CafŽ HerpŽ at http://www.cafeherpe.com. SKB reports this is "the first web site to provide medical information on genital herpes and to address important issues of patient concern in a cafŽ-style environment that's fun to use...CafŽ HerpŽ creates a virtual Ôcoffee shop' experience for visitors where they can explore and learn how to live with genital herpes." Designed primarily for a general U.S. audience (largely ignorant about genital herpes), the Web site provides an overview of genital herpes, links to some support groups and online resources, a site search engine, information to help patients discuss sensitive issues with their partners, tips for dealing with genital herpes outbreaks, and information about Famciclovir (Famvir), an oral drug from SKB approved for treatment of recurrent genital herpes. Although 1% penciclovir cream (Denavir) from SKB was recently approved by FDA, as discussed in the October Bulletin (p. 270), the site does not yet provide information about this topical treatment for genital herpes.

    WWW.DUESBERG.COM

    Dr. P. Duesberg, Univ. of California (Berkeley, CA), the most prominent scientist critic of HIV being the etiologic agent for AIDS, has established a Web site at http://www.duesberg.com. Dr. Duesberg has proposed that long-term recreational drug use and treatment with AZT are the main cause for AIDS-related symptoms. Besides information supporting these views, the Web site offers users the opportunity to join an E-mail discussion list and search Dr. Duesberg's papers.

    EpiMatrix/HIV

    The TB/HIV Research Lab., Interational Health Inst., Brown Univ. (Providence, RI) has established a Web site at http://www.epimatrix.com which includes a free algorithm for predicting T-cell epitopes, useful for development of HIV vaccines.

    Schering Charges Amgen with Interferon Patent Infringement

    Schering Corp., a subsidiary of Schering-Plough Corp. (Madison, NJ), has filed suit against Amgen, Inc. (Thousand Oaks, CA) charging Amgen with infringement of U.S. Patent No. 4,530,901 concerning recombinant alpha interferons assigned to Biogen Inc. (Cambridge, MA) and exclusively licensed to Schering. The company charges that patent no. 4,530,901 covers aspects of consensus interferon (Infergen) for which Amgen has filed for approval for treatment of hepatitis C (as reported in the June Bulletin, p. 141). Amgen has not commented, but "fully anticipated" the suit. As discussed in the August 1995 Bulletin (p. 233), consensus interferon, a recombinant E. coli-expressed non-naturally occurring type one interferon, has shown efficacy for treatment of chronic hepatitis C virus (HCV) infection comparable to currently marketed interferon preparations, including Intron A (alpha-2b-interferon from Schering-Plough Corp.). Amgen has licensed rights to its consensus interferon outside of the U.S. and Canada to Yamanouchi Pharmaceutical Co., Ltd. (Tokyo, Japan) and received a licensing fee of $15 million. U.S. patent 4,530,901 licensed to Schering provides protection for Intron A. Biogen filed a related patent infringement suit against Amgen in Japan in 1994.

    Lidak Reacquires Rights to Lidakol Cream

    Lidak Pharmaceuticals Inc. (La Jolla, CA) has reacquired certain foreign rights for manufacture and marketing of 10% n-docosanol cream (Lidakol) from Bristol-Myers Squibb Co. (BMS; New York, NY). As part of this agreement, Lidak had to return 20% of an undisclosed licensing fee to BMS. Lidakol cream has entered new Phase III trials for topical treatment of oral herpes simplex virus type 1 (HSV-1) infection as reported in the August Bulletin (p. 200). Preliminary results from two North American Phase III trials failed to show significant efficacy for the primary endpoint (because the placebo formulation showed efficacy), as discussed in the April Bulletin (p. 104), while a European Phase III trial found Lidakol cream to have efficacy comparable to 5% acyclovir (Zovirax) cream for treatment of recurrent oral herpes, as discussed in the October 1995 Bulletin (p. 293). Lidak has now reacquired rights (and will likely find new licensees) in China, South and Central America, Australia, India and parts of Asia. BMS will retain exclusive rights to manufacture and market Lidakol as a topical treatment for oral herpes in the U.S., Canada and Mexico. Lidak will retain all rights to Lidakol in these countries for treatment of genital herpes and other indications for which BMS retains right-of-first offer. The new agreement does not affect rights for Europe, Africa and the Middle East held by Yamanouchi Europe B.V.; rights in Japan held by Grelan Pharmaceutical Co.; rights in Korea held by Boryung Pharmaceutical Co., Ltd.; and rights in Israel held by CTS Chemical Industries, Ltd.

    Novartis Merger Opens Access to HSV tk Gene Therapy Technologies

    The merger between Ciba-Geigy AG and Sandoz AG (both based in Basel, Switzerland) is proceeding with the Federal Trade Commission (FTC) granting approval in the U.S., but requiring that the new company, Novartis AG, improve access by competitors to some of its more promising proprietary gene therapy technologies, including use of the herpes simplex virus (HSV) thymidine kinase (tk) gene for gene therapy. This is the first major antitrust action taken in the U.S. based on companies' technologies and pharmaceutical products in research and development rather than just on what products are already on the market. The merger between the two companies was discussed in the April Bulletin (p. 103). There were no forced divestitures of products or technologies, just requirements for improving access through licensing by competitors. The FTC will require Novartis to license use of the herpes simplex virus (HSV) thymidine kinase (tk) gene for gene therapy to other companies including its largest competitor, Rhone-Poulenc Rorer. The HSV tk gene is being used in a numb er of cancer and other gene therapies in development. Targeted cells transformed with HSV tk gain the ability to metabolize certain nucleosides, such as ganciclovir, to active phosphorylated forms which then kill the transformed cells. Novartis will pay Chiron Corp. (Emeryville, CA; 49.9% owned by Ciba-Geigy) $60 million over the next five years to allow nonexclusive licensing of HSV tk technology and will provide Chiron with cross-licenses for certain Novartis gene therapy technologies and other considerations. Other Novartis gene therapy technologies to become more available for licensing will include those from Sandoz, probably including patents held by Genetic Therapy Inc. (GTI; Gaithersburg, MD) which has been acquired by Sandoz, and SyStemix, Inc. (Palo Alto, CA) in which Sandoz owns majority interest. In related news, Novartis plans to reduce its work force by about 10% worldwide, eliminating 12,000 employees including about 1,400 in the U.S., although U.S.-based research and development is expected to remain largely untouched.

    Highlights of U.S. Patents

    Highlights of recently issued U.S. patents for which abstracts and/or exemplary claims are presented below include:

    Antiviral Agents
    - A method for preparation of 1-(2'-deoxy-2',2'-difluoro-D-ribo-pentofuranosyl)-cytosine patented by Eli Lilly & Co. (5,559,222).
    - 2',5'-Phosphorothioate oligoadenylates with antiviral activity patented by Temple University (5,556,840).
    - A method of inactivating enveloped viruses (such as orthomyxoviruses, paramyxoviruses, coronaviruses, and retroviruses) using paucilamellar lipid vesicles patented by Micro-Pak, Inc. (5,561,062).
    - Photoinactivation of biological fluid clinical specimens using aminopsoralens patented by Steritech, Inc. (5,556,958).
    - Use of 5-[N,N-bis(2-chloroethyl)amino]methyl-8-methoxypsoralen for inactivation of red blood cells patented by Steritech, Inc. (5,559,250).
    - Compounds for the photoinactivation of pathogens in blood patented by Steritech, Inc. (5,556,993).
    - Orally active antiviral drugs patented by Schering Corp. (5,559,133).
    - Use of organogermanium compounds for treating warts patented by Sanwa K.K. Co., Ltd. (5,560,925).
    - Lignin-derived compounds for treatment of viral infections (5,554,596).
    - Use of the anti-herpesvirus drugs acyclovir, penciclovir and famciclovir for treatment of autoimmune diseases (5,559,114).
    - Compositions derived from an Aspergillus fungi fermentation extract for topical prevention and treatment of viral-induced tumors patented by Solvay Enzymes, Inc. (5,562,900).
    Anti-HIV and Anti-Retroviral Agents
    - Conjugates of lipids or other membrane-targeting and membrane-anchoring molecules with HIV protease inhibitor peptides patented by NeXstar Pharmaceuticals, Inc. (5,554,728).
    - Mammalian cell lines transformed with a chimeric toxin gene under the control of HIV cis-acting sequences and HIV trans-acting factors that express diphtheria toxins within HIV-infected cells patented by the University of Colorado (5,554,528).
    - Cysteamine, cystamine, and phosphocysteamine for the treatment of HIV-infection patented by J.G. Thoene (5,554,655).
    - Formulations of cyclic urea compounds for treatment of HIV-infection patented by DuPont Merck Pharmaceutical Co. (5,559,110).
    - Benzeneacetamide derivatives for treatment of HIV-infection patented by Janssen Pharmaceutica N.V. (5,556,886).
    - HIV protease inhibitors patented by Eli Lilly & Co. (5,554,653).
    - Formulation of solid dosage forms of HIV protease inhibitors patented by Abbott Laboratories (5,559,158).
    - Diamine intermediates for the synthesis of HIV protease inhibitors patented by DuPont Merck Pharmaceutical Co. (5,559,252).
    Anti-Hepatitis B Virus Agents
    - L-2',3'-Didehydro-dideoxy-5-fluorocytidine patented by Yale University (5,561,120). [This patent has been licensed to VION Pharmaceuticals, formerly OncoRx, Inc.].
    - Compounds for treatment of hepatitis B patented by Glaxo Wellcome Inc. (5,559,100).
    Anti-Herpesvirus Agents
    - Low levels of neuraminidase protein for treatment of herpes simplex virus and varicella-zoster virus infections patented by Molecular Rx, Inc. (5,558,863).
    Viral Vaccines, Vectors and Adjuvants
    - Interleukin-2/viral antigen fusion protein vaccines patented by Takeda Chemical Industries, Ltd. (5,556,946).
    - HIV-1 gp120 protein and precursor gp160 protein monoclonal antibodies for passive immunization treatment of HIV-infection patented by Nissin Shokuhin K.K. (5,558,865).
    - Cytomegalovirus vaccine vectors which express anti-sense mRNA or other antigens patented by Syntro Corp. (5,561,063).
    - A chemically synthesized 15 amino acid HIV envelope peptide vaccine patented by E.I. Du Pont de Nemours & Co. (5,562,905).
    - Hepatitis E virus (HEV) genes and polypeptides patented by the U.S. Department of Health & Human Services/NIH (5,563,032).
    - Cloned DNA from Norwalk virus for vaccines and diagnostics patented by the Baylor College of Medicine (5,559,014).
    - Polyclonal and monoclonal antibodies for treatment and diagnosis of astrovirus gastroenteritis patented by the Univ. of Massachusetts Medical Center (5,556,746).
    - A meningitis related homologous antigenic sequence (MRHAS) common to viral and bacterial meningitis pathogens patented by Insight Biotek, Inc. (5,556,757).
    - Human parainfluenza virus type 4A (PIV-4A) gene and fusion protein patented by Fujikura Kasei Co., Ltd. (5,554,526).
    - Chicken anemia virus vaccines and diagnostics patented by Akzo Nobel N.V. (5,554,525).
    - Complex type retroviral vectors having mixed type LTR patented by the Wisconsin Alumni Research Foundation (5,554,524).
    - Recombinant attenuated Marek's disease virus vaccines patented by the Juridical Foundation and Chemo-Sero-Therapeutic Research Institute (5,558,867).
    - Herpes virus of turkeys vector vaccines against Marek's disease patented by Rhone Merieux S.A. (5,558,860).
    Immune Stimulators and Modulators
    - Recombinant human interferon-beta2a and interferon-beta2b patented by Yeda Research & Development Co. Ltd. (5,554,513 and 5,554,514).
    - Gene therapy transformation of cells for expression of the lytic peptide cecropin B to boost immunity to viral infections patented by the Louisiana State University (5,556,782).
    - An immune stimulant derived from Lactobacillus brevis patented by the Institut Pasteur de Kyoto, Shinwa Pharmaceutical Co., Ltd. and Nitto Pharmaceutical Industries Ltd. (5,556,785).
    Antisense Agents, Nucleosides and Nucleotides
    - Texaphyrins covalently coupled to a site-directed oligonucleotide for targeted phosphate ester hydrolysis patented by the University of Texas and Pharmacyclics, Inc. (5,559,207).
    - Polynucleotide analogs containing sulfonate and sulfonamide linkages patented by Southern Research Institute (5,561,225).
    Viral Diagnostics
    - A panel of HIV peptides useful for determining whether or not a mother will transmit HIV-1 to her fetus patented by the University of Pennsylvania and Wistar Institute of Anatomy & Biology (5,556,744).
    - DNA fragments derived from human papillomavirus type 33 (HPV-33) patented by Institut Pasteur (5,554,538).