A large trial found that the synthetic peptide IM862 (a glutamine‑tryptophan dipeptide) does not improve Kaposi's sarcoma outcomes in HIV patients and may even speed disease progression, with no major side effects observed.

IM862 is a synthetic dipeptide (L-glutamine L-tryptophan) with in vitro and in vivo antiangiogenic properties. Phase I/II studies showed minimal toxicity and a response rate of 36% in AIDS-Kaposi's sarcoma. We report a 24-week, randomized, double-blinded, placebo-controlled phase III trial with the phase II dose, 5 mg intranasally every other day. Two hundred two HIV-positive patients were enrolled, 104 on IM862 and 98 on placebo. Baseline characteristics were comparable except current antiretroviral therapy: 88% versus 96% (IM862 v placebo group; P = .042). The median treatment durations were 19.5 versus 24 weeks (IM862 v placebo). No significant difference was detected in response rate (IM862, 23%; 95% CI, 15% to 32% v placebo, 21%; 95% CI, 14% to 31%; P = .46), time to response (8.5 weeks v 14 weeks; P = .024), or duration of response. However, IM862 was associated with both a shorter time to response (8.5 weeks v 14 weeks; P = .024) and shorter median time to progression (16 weeks, 95% CI, 13 to 27 weeks v 35 weeks, 95% CI, 26 to 114 weeks; P = .012). Despite promising phase I and phase II studies, IM862 5 mg every other day was not superior to placebo and may accelerate time to progression. Highly active antiretroviral therapy alone was associated with a substantial rate of sustained tumor response and may have contributed to prior estimates of IM862 response. Therapeutic trials for AIDS-Kaposi's sarcoma must account for ongoing immune reconstitution in the setting of concurrent highly active antiretroviral therapy that may confound estimates of therapeutic activity.