Delayed Efficacy After Treatment With Lenalidomide or Thalidomide in Patients With Mucosa-Associated Lymphoid Tissue Lymphoma

The immunomodulatory drugs (IMiDs) thalidomide and lenalidomide have both been tested for treatment of mucosa-associated lymphoid tissue (MALT) lymphoma, with lenalidomide, in particular, showing promising activity. However, long-term results are missing. Because of the late-onset remissions registered in individual patients, we have systemically analyzed the patients treated with IMiDs at our institution for long-term results.Within the present retrospective analysis, we identified 25 patients who had been treated with lenalidomide (n = 18) or thalidomide (n = 7) and were available for long-term assessments of outcome. All patients were followed up according to a standardized follow-up protocol.Of the 25 patients, 7 (28%) experienced delayed-onset responses without further treatment (thalidomide, n = 2; lenalidomide, n = 5). In 4 patients (16%), the initial outcome switched to a better result (partial remission [PR] to complete remission [CR], n = 1; stable disease [SD] to PR, n = 1; SD to CR, n = 1; and PD to CR, n = 1) after a median time of 19.5 months (range, 10.9-32.0). Furthermore, 2 patients showed ongoing shrinkage of the target lesion for 47.4+ and 43.5+ months, respectively, and 1 patient had durable disease stabilization for 16.2+ months. The median time to the best response for all responding patients (13 of 25; 53%) was 7.3 months (interquartile range [IQR], 5.6-22.5). After a median follow-up of 46 months (IQR, 32.0-58.5), 23 of 25 patients (92%) were alive.Our findings suggest that late-onset remissions might be a common phenomenon in the use of IMiDs for the treatment of MALT lymphoma. Thus, sufficient follow-up time after treatment before the initiation of further therapy appears crucial to assess the full effect of therapy and avoid unnecessary overtreatment.The immunomodulatory drugs (IMiDs) thalidomide and lenalidomide have been tested for the treatment of mucosa-associated lymphoid tissue (MALT) lymphoma, with lenalidomide showing promising activity. However, long-term results are missing. The present findings suggest that late-onset remissions and delayed responses could be a common phenomenon with IMiD use for MALT lymphoma. Using a standardized restaging protocol to ensure concise follow-up data, these findings suggest it is of major importance to ensure a sufficient follow-up time after treatment with these compounds and before initiation of further treatment lines, because nearly one third of treated patients showed further improvement during prolonged follow-up.