Markers for progression to acquired immune deficiency syndrome and zidovudine treatment of asymptomatic patients

Zidovudine update: 1990

Zidovudine (ZDV) is the only approved antiviral for the treatment of human immunodeficiency virus infection (HIV) in the U.S. Although newer antivirals have reached Phase II testing, ZDV is now the accepted therapy against which all other agents will be compared. Zidovudine 1500 mg/d was previously prescribed only to adult HIV-infected patients who had developed AIDS or AIDS-related complex (ARC). However, results obtained from recently completed studies indicate that a lower daily dose (500 mg) appears to be equivalent. In addition, ZDV therapy appears to be beneficial to asymptomatic HIV-infected patients with CD4+ counts less than 500/mm3. The toxicity profile of ZDV, previously obtained from patients receiving 1500 mg/d, consisted of either acute (e.g., fever, rash, headache) or chronic (e.g., anemia, neutropenia, myopathy) adverse effects. ZDV pharmacokinetics are variable within and between the different subpopulations of HIV-infected patients who have been studied. Bioavailability ranges from 50 to 70 percent, and values for half-life, total body clearance, and volume of distribution are 1-2 h, 20-40 mL/min/kg, and 1-2 L/kg, respectively. Drug interactions occur primarily between ZDV and other agents that undergo hepatic glucuronidation (e.g., probenecid, sulfamethoxazole) resulting in decreased ZDV clearance. ZDV is currently measured by HPLC, radioimmunoassay and FPIA; however, the role of therapeutic monitoring is currently under investigation. Studies of ZDV therapy in neonates, pediatric patients, patients with resistant isolates of HIV, and HIV-infected patients receiving combined treatment with other reverse transcriptase inhibitors or immunomodulators are ongoing.

Virological examinations of patients with AIDS-related complex/Walter-Reed 5 enrolled in a double-blind placebo-controlled study with intravenous gammaglobulin administration. Prognostic value of anti-p24 determination. The ARC-IVIG Study Group

Thirty patients with AIDS-related complex/Walter-Reed 5 enrolled in a placebo-controlled double-blind study with high-dose intravenous gammaglobulin administration were tested by quantitating HIV Western blot and other serological tests for viral antibodies. Furthermore, conventional virus isolation attempts were performed. Absence or loss of p24 antibodies during the study period was associated with progression to AIDS (p = 0.01) and thereby was an earlier prognostic parameter of a poor prognosis than T4 cell count. Neither changes in antibody patterns against other HIV polypeptides, HIV titers in the immunofluorescence test nor demonstration of HIV antigen were significantly associated with progression to AIDS. Cytomegalovirus (CMV) could be isolated from two duodenal biopsies of a patient who developed AIDS at the same time, but a concomitant serological diagnosis of CMV infection was not successful. Though signs in the serology of human herpesviruses (herpes simplex virus, CMV, Epstein-Barr virus), possibly indicating a reactivation of latent infections, could be observed in some instances, a correlation with clinical symptoms or the clinical outcome was not feasible, perhaps also because of a poor standardization of some of the test kits used. All patients were positive for IgG antibodies against the three herpesviruses when entering the study. High prevalence of hepatitis B virus (HBV) markers was found (83% anti-HBc positive), only 1 patient being chronically infected and highly infectious, as shown by HBV-DNA hybridization. No significant difference between treatment and placebo group was observed with the parameters tested in this study.

Disappearance of anti-p17 correlates with successful isolation of human immunodeficiency virus and deterioration in clinical status

Anti-p17 was examined as a human immunodeficiency virus (HIV) marker predicting the onset of the acquired immunodeficiency syndrome (AIDS). Two different comparisons were done: (1) anti-p17 negativity and successful HIV isolation; and (2) anti-p17 negativity and clinical status, using the Centers for Disease Control classification. Anti-p17 negativity was not only significantly correlated with deterioration in clinical status (P less than 0.01), but also with successful HIV isolation (P less than 0.05). HIV isolation was affected by several drugs, e.g. zidovudine. However, the results of the antibody test were not affected. It is significant that anti-p17 can compensate for the defects of virus isolation.

Current and future trials with zidovudine

The first placebo-controlled trial of zidovudine in the management of HIV infection involved patients with the acquired immune deficiency syndrome (AIDS) following their first episode of Pneumocystis carinii pneumonia and patients with severe AIDS-related complex (ARC). Zidovudine was shown to increase survival, and the trial was terminated early at the request of an independent review board. In order to obtain more information on the long-term efficacy and tolerance of the drug the study was continued on an open-label basis where all patients were offered zidovudine. Data from this ongoing open-label study are reviewed on a regular basis. Side-effects associated with zidovudine include anaemia and neutropenia both of which are more predominant in patients with more advanced disease. Two basic strategies have been adopted with the aim of improving the therapeutic index of the drug involving (i) dose modification and (ii) combination with other antiviral or immunomodulatory compounds. Although several phase I and II studies are proceeding it is likely that research in this area will continue to expand. AIDS patients with Kaposi's sarcoma (but without a history of AIDS-defining opportunistic infection) were precluded from the original phase II trial described above. The value of zidovudine in the treatment of the sarcoma per se has yet to be established. Trials are currently in progress in this indication evaluating the potential of zidovudine administered either alone or in combination with interferon. Possibly the largest area of research is concerned with defining the role of zidovudine earlier in the course of HIV infection.(ABSTRACT TRUNCATED AT 250 WORDS)