Tolerability and activity of a new recombinant interferon-alpha B/D hybrid in patients with HIV-1 infection

The maximum tolerated dose (MTD) and toxicity profile of a new recombinant interferon-alpha B/D hybrid (IFN-alpha B/D) in HlV-1-infected patients were determined in an outpatient, dose-escalating study with dose groups of three patients: 16, 32, 48, 64, 96 and 112 million international units (MIU) three times weekly subcutaneously during 12 weeks. The MTD was the last dose level just below the dose level at which more than one patient experienced > or = grade 3 toxicity. The study also searched for preliminary evidence of efficacy of IFN-alpha B/D. Sixteen HIV-1-infected patients with CD4 cell counts > or = 200/mm3 were enrolled: eight were asymptomatic and eight had symptomatic disease. Two patients were excluded as a result of protocol violations. Five patients (36 per cent; one at each tested dose level) discontinued prematurely due to side effects. One patient was lost to follow-up. Twelve patients (87 per cent) experienced > or = grade 2 toxicity. Toxicity > or = grade 3 occurred in none of three patients assigned to 16 MIU, one of five assigned to 32 MIU (fatigue), one of three assigned to 48 MIU (haemorrhagic colitis) and two of three assigned to 64 MIU (fatigue). One patient (48 MIU) had reversible cardiomegaly. Progressive weight loss was experienced by 12 of 14 participants. Serum HIV-1 p24 antigen declined in nine of 11 antigenaemic patients (seven persistently > 50 per cent) without a clear dose-response relationship. CD4 percentages showed no consistent pattern and T cell reactivity diminished. The tolerability and toxicity profile of IFN-alpha B/D appear to be fairly similar to that of other types of IFN-alpha.