Author(s): Dorff TB, Goldman B, Pinski JK, Mack PC, Lara PN Jr, , Dorff TB, Goldman B, Pinski JK, Mack PC, Lara PN Jr,
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Abstract PURPOSE: Interleukin-6 (IL-6) facilitates cancer cell survival via pleotrophic effects. We conducted a multicenter phase II study of CNTO328 (siltuximab) as second-line therapy for men with castration-resistant prostate cancer. EXPERIMENTAL DESIGN: Eligible men had castration-resistant prostate cancer treated with one prior chemotherapy. Subjects were treated with 6 mg/kg CNTO328 i.v. every 2 weeks for 12 cycles. Response was assessed after every three cycles. Primary end point was prostate-specific antigen (PSA) response rate defined as a 50\% reduction. Accrual was planned in two stages, with 20 eligible patients in the first stage and 40 overall. Plasma cytokines and growth factors were measured by Luminex. RESULTS: Fifty-three eligible subjects had all received prior taxane therapy. Two (3.8\%; 95\% CI, 0.5-13.0\%) had PSA response. None of the 31 patients with measurable disease had a RECIST (Response Evaluation Criteria in Solid Tumors) response but 7 (23\%) had stable disease. With median follow-up of 14.8 months, median progression-free survival was 1.6 months (95\% CI, 1.6-1.7) and median overall survival was 11.6 months (95\% CI, 7.5-19.0). Grade 3/4 toxicities included disseminated intravascular coagulation (1), central nervous system ischemia (1), elevated aspartate aminotransferase (1), gastritis/esophagitis (2), thrombocytopenia (2), pain (2), leukopenia (1), and neuropathy (2). Median baseline IL-6 levels were 12.5 pg/mL (interquartile range, 2.5-41.5). Patients with IL-6 >12.5 pg/mL had worse survival than those with levels <12.5 pg/mL (53\% versus 94\%; P = 0.02). After treatment, IL-6 levels were >250-fold higher. Thirty-two of 38 patients had a decline in C-reactive protein plasma levels at 6 weeks. CONCLUSIONS: CNTO328 resulted in a PSA response rate of 3.8\% and a RECIST stable disease rate of 23\%. Declining C-reactive protein levels during treatment may reflect biological activity. Despite evidence of CNTO-mediated IL-6 inhibition, elevated baseline IL-6 levels portended a poor prognosis. Copyright 2010 AACR.
This article was published in Clin Cancer Res
and referenced in Immunome Research