To determine the efficacy and safety of zidovudine ( AZT ) versus didanosine ( ddI ), AZT plus ddI, and AZT plus zalcitabine ( ddC ) in preventing disease progression in HIV-infected patients with CD4 counts of 200-500 cells/mm3.

Patients are randomized to receive AZT alone, AZT and ddI, AZT and ddC, or ddI alone for at least 2 years. Patients who develop AIDS or whose CD4 count falls to 50 percent or less of baseline are crossed over to another treatment arm.

PER AMENDMENT 4/5/95: Study treatment will be available until 10/31/95 at the latest for patients still taking study medications on 4/30/95, so that follow-up trials may be completed and approved.

• Drug: Zidovudine
• Drug: Zalcitabine
• Drug: Didanosine

• Havlir DV, Richman DD. Viral dynamics of HIV: implications for drug development and therapeutic strategies. Ann Intern Med. 1996 Jun 1;124(11):984-94. Review.
• Hammer SM, Katzenstein DA, Hughes MD, Gundacker H, Schooley RT, Haubrich RH, Henry WK, Lederman MM, Phair JP, Niu M, Hirsch MS, Merigan TC. A trial comparing nucleoside monotherapy with combination therapy in HIV-infected adults with CD4 cell counts from 200 to 500 per cubic millimeter. AIDS Clinical Trials Group Study 175 Study Team. N Engl J Med. 1996 Oct 10;335(15):1081-90.
• Simpson DM, Katzenstein DA, Hughes MD, Hammer SM, Williamson DL, Jiang Q, Pi JT. Neuromuscular function in HIV infection: analysis of a placebo-controlled combination antiretroviral trial. AIDS Clinical Group 175/801 Study Team. AIDS. 1998 Dec 24;12(18):2425-32.
• [No authors listed] Zidovudine, didanosine, and zalcitabine in the treatment of HIV infection: meta-analyses of the randomised evidence. HIV Trialists' Collaborative Group. Lancet. 1999 Jun 12;353(9169):2014-25.
• Katzenstein DA, Hughes MD, Albrecht M, Liou SH, Murphy R, Balfour H, Para M, Hammer S. Virologic and CD4 cell response to zidovudine or zidovudine and lamivudine following didanosine treatment of human immunodeficiency virus infection. AIDS Res Hum Retroviruses. 2001 Feb 10;17(3):203-10.
• Justice AC, Holmes W, Gifford AL, Rabeneck L, Zackin R, Sinclair G, Weissman S, Neidig J, Marcus C, Chesney M, Cohn SE, Wu AW. Development and validation of a self-completed HIV symptom index. J Clin Epidemiol. 2001 Dec;54 Suppl 1:S77-90.
• Katzenstein DA, Hammer SM, Hughes MD, Gundacker H, Jackson JB, Fiscus S, Rasheed S, Elbeik T, Reichman R, Japour A, Merigan TC, Hirsch MS. The relation of virologic and immunologic markers to clinical outcomes after nucleoside therapy in HIV-infected adults with 200 to 500 CD4 cells per cubic millimeter. AIDS Clinical Trials Group Study 175 Virology Study Team. N Engl J Med. 1996 Oct 10;335(15):1091-8.
• Fiscus SA, Hughes MD, Lathey JL, Pi T, Jackson B, Rasheed S, Elbeik T, Reichman R, Japour A, Byington R, Scott W, Griffith BP, Katzenstein DA, Hammer SM. Changes in virologic markers as predictors of CD4 cell decline and progression of disease in human immunodeficiency virus type 1-infected adults treated with nucleosides. AIDS Clinical Trials Group Protocol 175 Team. J Infect Dis. 1998 Mar;177(3):625-33.
• Currier JS, Spino C, Grimes J, Wofsy CB, Katzenstein DA, Hughes MD, Hammer SM, Cotton DJ. Differences between women and men in adverse events and CD4+ responses to nucleoside analogue therapy for HIV infection. The Aids Clinical Trials Group 175 Team. J Acquir Immune Defic Syndr. 2000 Aug 1;24(4):316-24.
• Kastrissios H, Suarez JR, Katzenstein D, Girard P, Sheiner LB, Blaschke TF. Characterizing patterns of drug-taking behavior with a multiple drug regimen in an AIDS clinical trial. AIDS. 1998 Dec 3;12(17):2295-303.
• Lathey JL, Hughes MD, Fiscus SA, Pi T, Jackson JB, Rasheed S, Elbeik T, Reichman R, Japour A, D'Aquila RT, Scott W, Griffith BP, Hammer SM, Katzenstein DA. Variability and prognostic values of virologic and CD4 cell measures in human immunodeficiency virus type 1-infected patients with 200-500 CD4 cells/mm(3) (ACTG 175). AIDS Clinical Trials Group Protocol 175 Team. J Infect Dis. 1998 Mar;177(3):617-24.

Inclusion Criteria

Concurrent Medication:

Allowed:

• PCP prophylaxis, M. tuberculosis prophylaxis, short courses of acyclovir, chronic suppressive acyclovir, pneumovax or Hib vaccine, antibiotics, rEPO and G-CSF for grade 3 or worse anemia and neutropenia, systemic corticosteroids for < 21 days, regularly prescribed medications, and vitamins or herbal therapies.

Patients must have:

• HIV infection without AIDS with CD4 200-500 cells/mm3.

PER AMENDMENT 4/5/95:

• Patients must have remained on ACTG 175 study treatment through 4/30/95 and meet toxicity management criteria for continuing treatment. Subjects taking ACTG 175 crossover treatment are eligible.

Exclusion Criteria

Co-existing Condition:

Patients with the following conditions are excluded:

• Current AIDS-related condition other than minimal KS, grade 2 or worse peripheral neuropathy, and malignancy requiring systemic therapy.

Concurrent Medication:

Excluded:

• Other anti-HIV drugs, biologic response modifiers other than rEPO and G-CSF, systemic cytotoxic chemotherapy, chronic systemic corticosteroids, or any drug that affects AZT glucuronidation or clearance.

Concurrent Treatment:

Excluded:

• Radiotherapy other than limited local therapy to skin.

Patients with the following prior conditions are excluded:

• AIDS-related condition other than minimal KS; intolerance to AZT, ddI, or ddC at study doses; and acute or chronic pancreatitis.

Prior Medication:

Excluded:

• Acute therapy for an infection or other medical illness within the past 14 days.

Current alcohol abuse.

• Bristol-Myers Squibb
• Glaxo Wellcome