Incidence of second primary malignancies (SPM) after 6-years follow-up of continuous lenalidomide in first-line treatment of multiple myeloma (MM).

Abstract

8008 Background: Lenalidomide (Rev) has markedly improved survival in patients (pts) with MM. As we gain insight into the long-term effects of this agent, concern has arisen for the possibility of SPM including MDS/AML. Clarithromycin (Biaxin), lenalidomide and dexamethasone (BiRD) was shown to be an effective regimen in symptomatic, newly diagnosed MM. Of 72 patients enrolled, 90.3% had an objective response, 38.9% a complete response (sCR/CR), and 73.6% at least a very good partial response (VGPR). This experience has been compounded by the observation of deepening responses to prolongation of Rev-based therapy beyond induction. All pts have continued to be followed. Methods: Review of all pts charts from the original study with focus on overall survival, progression of disease, time to progression, and development of SPM was completed. Pts were maintained on BiRD until progression of disease, stem cell transplant, or development of intolerable side effects. Results: Long-term follow up demonstrates an overall survival of 82.2% (95% CI 70.7, 89.5) after 4 years. Eleven pts remain on study, while 47 have received second line therapy. Evaluation of SPM in the 68 evaluable pts revealed 11 new diagnoses (incidence of 16%) after an average of 31 cycles (range 3-68) of lenalidomide (BiRd). Six were skin cancers (4 BCC, 2 SCC), 2 colon, 1 prostate, 1 pancreas and 1 metastatic melanoma. Notably, none developed MDS/AML. Mean time to SPM diagnosis was 35 months (range 5-64). Only 7/11 subjects were still on active lenalidomide therapy. Conclusions: BiRD is a highly effective regimen in newly diagnosed MM. In these treatment-naïve pts, no cases of secondary MDS/AML were seen, in contrast to reports in relapse/refractory pts who received Rev as third or fourth line therapy (Reece, Goswami ) or as post-transplant maintenance (Attal , McCarthy). Frequency of SPM is similar to 2010 SEER data for non-MM individuals of similar age. As survival in pts with MM continues to improve, so will our understanding of the long-term effects of novel agents. Design of regular cancer screening programs (derm and GI) of MM pts should be regularly implemented.