Analysis of the efficacy of thalidomide plus dexamethasone-based regimens in patients with relapsed/refractory multiple myeloma who received prior chemotherapy, including bortezomib and lenalidomide: KMM-166 study

Abstract Background For patients with multiple myeloma (MM) who relapsed after treatment with bortezomib- and lenalidomide-based regimens, there were no other treatment options in Korea until 2016. We aimed to determine the efficacy of thalidomide plus dexamethasone-based regimens in patients with relapsed or refractory MM (RRMM). Patients and Methods We conducted a multi-center retrospective analysis in Korea for patients with RRMM treated with thalidomide-based regimens, who previously received bortezomib and immunomodulatory agents (IMiDs), including thalidomide and lenalidomide. Results In 47 patients with RRMM, the median age was 64 years and the median number of previous treatment lines, including bortezomib and IMiDs, was three. Primary resistance to bortezomib and lenalidomide was observed in 12 (26 %) and 8 (17 %) patients, respectively. The most common regimen was a combination of thalidomide, cyclophosphamide, and dexamethasone. The overall response rate (ORR) was 38 %; 2 patients (4 %) achieved a complete response, and 2 patients (4 %) achieved a very good partial response. The ORR of patients who were previously exposed to thalidomide was 53 %. The median progression-free survival (PFS) was 5.9 months, and overall survival was 9.2 months. Patients who responded to the thalidomide-based regimen had better PFS compared to those who did not (median 8.8 vs. 2.5 months; P = 0.008). The most common adverse events were anemia (51 %) for hematologic and peripheral neuropathy (30 %) for non-hematologic toxicities. Conclusion Thalidomide-based regimens are potential salvage treatment options for patients with RRMM, even with prior resistance to IMiDs.