Lenalidomide/Dexamethasone Improves Response and Prolongs Time to Progression, Even in Patients with IgA Multiple Myeloma: A Sub-Analysis of the MM-009/010 Studies.

Background: Historically, patients with IgA multiple myeloma (MM) respond poorly to treatment. In 2 recent phase III trials, Lenalidomide (Len) in combination with Dexamethasone (Dex) led to an overall response (OR) rate of approximately 60% (61% in MM-009 and 60% in MM-010), a complete response (CR) rate of about 15% (14% and 16%, respectively), an overall survival (OS) of at least 29.5 months (29.5 and not yet reached), and a median time to progression (TTP) of at least 11.1 months (11.1 months and 11.3 months, respectively) in patients with relapsed/refractory MM. In both studies, OR, CR, OS and TTP were significantly better with Len/Dex than with Dex alone. Here, we assess the impact of IgA disease on the efficacy and tolerability of treatment with Len/Dex versus Dex alone.

Methods: Data were pooled from the MM-009 and MM-010 studies. Patients were randomized to receive Len (25 mg/day on days 1–21 of each 28-day cycle) or placebo. Both groups received Dex 40mg PO q.d. on days 1–4, 9–12, and 17–20 (for the first four cycles). After four cycles, Dex 40 mg/day was administered only on days 1–4. Response to therapy, TTP, OS, and adverse events were assessed. Response rate and TTP were based on data obtained before unblinding (June 2005 [MM-009] and August 2005 [MM-010]).

Results: Of 154 patients with IgA at baseline, 72 were treated with Len/Dex and 82 with Dex alone. Among those without IgA, 281 received Len/Dex and 269 received Dex alone. Baseline characteristics were balanced between treatment groups. Len/Dex was associated with a significantly higher OR and longer median TTP than Dex alone in patients with and without IgA (Table). In the non-IgA group, patients treated with Len/Dex had a significantly longer OS than those treated with Dex alone. Response, TTP and OS were comparable between IgA and non-IgA patient groups. There was no difference in the incidence of adverse events between patients with and without IgA. Among those with IgA, the most common grade 3–4 adverse events with Len/Dex and Dex alone were neutropenia (37.5% and 2.4%), thrombocytopenia (16.7% and 8.5%), and anemia (11.1% and 7.3%). The respective rates for patients without IgA were 46.5% and 14.5%, 12.1% and 5.7%, and 11.0% and 5.7%.

Conclusion: In patients with and in those without IgA MM, Len/Dex treatment induces a high response rate and a prolonged TTP compared with Dex.