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

backgroundThe 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.

methodsWithin 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.

resultsOf 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.

conclusionOur 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. IMPLICATIONS FOR PRACTICE: 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.