Long-term follow-up of symptomatic patients with lymphoplasmacytic lymphoma/Waldenström macroglobulinemia treated with the anti-CD52 monoclonal antibody alemtuzumab.

CD52 is expressed on malignant cells in lymphoplasmacytic lymphoma (LPL), including IgM-secreting Waldenström macroglobulinemia (WM). We examined the activity of alemtuzumab in 28 symptomatic LPL (27 IgM and 1 IgA) patients. The median prior number of therapies for these patients was 2 (range, 0-5) and 43% had refractory disease. Patients received alemtuzumab at 30 mg IV 3 times weekly for up to 12 weeks after test dosing, and also received hydrocortisone, acyclovir, and Bactrim or equivalent prophylaxis. Patients had a complete response (n = 1), a partial response (n = 9), or a MR (n = 11) for an overall and major response rate of 75% and 36%, respectively. Median serum Ig decreased from 3510 to 1460 mg/dL (P < .001 at best response). With a median follow-up of 64 months, the median time to progression was 14.5 months. Hematologic and infectious complications, including CMV reactivation, were more common in previously treated patients and were indirectly associated with 3 deaths. Long-term follow-up revealed late-onset autoimmune thrombocytopenia (AITP) in 4 patients at a median of 13.6 months after therapy, which contributed to 1 death. Alemtuzumab is an active therapy in patients with LPL, but short- and long-term toxicities need to be carefully weighed against other available treatment options. Late AITP is a newly recognized complication of alemtuzumab in this patient population. This study is registered at www.clinicaltrials.gov as NCT00142181.