MCT1 is a predictive marker for lenalidomide maintenance therapy in multiple myeloma

Biomarkers that predict response to lenalidomide maintenance therapy in patients with multiple myeloma (MM) have remained elusive. We have shown that immunomodulatory drugs (IMiDs) exert anti-MM activity via destabilization of MCT1 and CD147. In this study, cell samples of 654 patients with MM who received lenalidomide (n = 455), thalidomide (n = 98), or bortezomib (n = 101) maintenance were assessed by gene expression profiling and RNA sequencing, followed by correlation of MCT1 and CD147 expression with data for progression-free survival (PFS) and overall survival (OS). Patients with high expression levels of MCT1 showed significantly reduced PFS (31.9 months vs 48.2 months in MCT1(high) vs MCT1(low); P = .03) and OS (75.9 months vs not reached [NR] in MCT1(high) vs MCT1(low); P = .001) in cases with lenalidomide maintenance, whereas MCT1 expression had no significant impact on PFS or OS in cases with bortezomib maintenance. We validated the predictive role of MCT1 for IMiD-based maintenance in an independent cohort of patients who received thalidomide (OS, 83.6 months vs NR in MCT1(high) vs MCT1(low); P = .03). Functional validation showed that MCT1 overexpression in human MM cell lines significantly reduced the efficacy of lenalidomide, whereas no change was observed with bortezomib treatment, either in vitro or in a MM xenograft model. Our findings have established MCT1 expression as a predictive marker for response to lenalidomide-based maintenance in patients with MM.