Phase II Study of CC-5013 (Revlimid) and Rituximab in Waldenström’s Macroglobulinemia: Preliminary Safety and Efficacy Results.

INTRODUCTION: In previous studies, we observed that CC-5013 enhanced rituximab mediated ADCC killing of lymphoplasmacytic cells (

METHODS: Twelve patients were enrolled, 10 of whom were previously untreated with a median age of 65 (range 53–76 yrs), along with baseline BM involvement of 50 (range 5–90%), serum IgM of 4175 (range 1180–7130 mg/dL), hematocrit of 31.9% (range 24–36.6%), and B₂M of 3.5 (range 1.8–6.0 mg/L).

RESULTS: Four patients were taken off study due to intolerance to therapy (3 to CC-5013, 1 to CC-5013 and Rituximab) and were non-evaluable. Unexpected acute decreases in hematocrit occurred in 10/12 (85%) patients within the first 2 weeks of therapy, resulting in hospitalization for 4 patients. The median decrease in hematocrit, which coincided with CC-5013 administration was 4.2% (range 1.7-7.5%), and was not associated with blood loss, hemolysis, or generalized myelosuppression. Other grade 3/4 toxicities attributed to CC-5013 therapy were expected and included neutropenia (n=4); tinnitus (n=2); thrombocytopenia (1); myositis (n=1); and rash (n=1). Five patients had a spike in serum IgM levels following rituximab, accompanied with epistaxis (n=1), headaches and blurry vision (n=2) requiring plasmapheresis. Toxicities led to the discontinuation and dose reduction of CC-5013 for 8 and 4 patients, respectively, and discontinuation of rituximab in 1 patient due to recurring allergic reactions. Discontinuation of CC-5013 within the first 28 days of therapy occurred in 6 out of 8 patients. Responses among the 8 evaluable patients: PR (n=3); MR (n=4); SD (n=1); ORR 88% among evaluable patients. In two patients with bulky adenopathy and splenomegaly, a significant reduction in the node/spleen size was noted by week 12. Both of these pts have subsequently achieved a PR. With a median follow-up of 7+ months, no patient who received at least 2 months of CC-5013 have progressed.

CONCLUSION: The response data achieved with CC-5013 and rituximab in this study is encouraging, though the dose and schedule of CC-5013 administration, and mechanism for the unexpected acute drops in hematocrit observed in WM patients warrants further investigation. Such studies are in progress in our laboratory.