N9986: a phase II trial of thalidomide in patients with relapsed chronic lymphocytic leukemia.

We enrolled 28 eligible patients with relapsed chronic lymphocytic leukemia (CLL) to a phase II study of single agent thalidomide (200 mg/d, with dose escalation up to 1000 mg/d over 60 days). The median age was 66 years and 71% were males. Study participants received a median of 2 (range 1-7) prior treatment regimens and 61% had Rai stage 3-4 disease at enrollment. Grade 3 or higher hematologic toxicity was observed in 13 (46%) and 16 (57%) had grade 3 or higher non-hematologic toxicity. Grade 3-4 tumor flare was observed in five (18%) patients. The overall response rate was 11% (3 of 28) with one (4%) complete remission and two (7%) partial remissions. Duration of response for these three responders was 3, 14 and 15 months. Fourteen (50%) patients had stabilisation of disease for a median duration of 8 months (95% CI: 7-16 months). Median time to progression for all 28 patients was 7.3 months. Although thalidomide appears to have modest clinical activity in pretreated/relapsed CLL primarily based on reduction of the absolute lymphocyte count, in our opinion the toxicity profile precludes it from more active investigation in CLL.