SEVERE THROMBOCYTOPENIA IN PATIENTS TREATED WITH SURAMIN - EVIDENCE FOR AN IMMUNE MECHANISM IN ONE

Although suramin has long been used to treat human trypanosomiasis, re cent clinical trials have tested its efficacy against the acquired imm unodeficiency syndrome (AIDS) and various malignancies, Thrombocytopen ia was observed in early trials with suramin in AIDS, but has been unc ommon in patients treated for solid tumors. Here we describe 5 patient s out of a total of 67 (7%) who developed severe thrombocytopenia whil e receiving suramin as part of a phase II clinical trial for metastati c prostate carcinoma refractory to hormonal therapy. IgG purified from one patient's plasma caused suramin-dependent platelet aggregation, T here was also evidence of crossreactivity between suramin and heparin in this system, An immune mechanism, however, could not be documented in the other cases, suggesting that multiple mechanisms may he respons ible for severe thrombocytopenia in this patient population. (C) 1996 Wiley-Liss, Inc.