The effectiveness and safety of lenalidomide and dexamethasone in patients with relapsed/refractory multiple myeloma in real-world clinical practice: a study of the Korean Multiple Myeloma Working Party (KMMWP-151 study).

Although lenalidomide plus dexamethasone (RD) is a therapeutic option for relapsed/refractory multiple myeloma (RRMM), limited real-world clinical data exist. The purpose of this study was to estimate efficacy and safety of RD in RRMM patients of the clinical practice. Data from patients at 25 university hospitals in South Korea between October 2009 and December 2016 were collected retrospectively. We report the effectiveness and safety of RD in 546 RRMM patients in routine clinical practice in South Korea. Patients (median age, 65 years) typically received median 7 cycles of RD, and 184 (33.7%) patients were treated with 10 or more cycles of RD. Patients with renal impairment (CLCr < 40 mL/min; 10.4%), comorbid conditions (≥ 2; 12.0%), and poor performance status (≥ 2; 25.1%) were included. The overall response rate was 64.2%: complete response (13.1%), very good partial response (VGPR 19.9%). With median follow-up duration of 18.6 months, median PFS and OS were 11.2 months and 25.2 months, respectively. In multivariate analysis, less than 2 comorbid conditions, normal LDH, failed one chemotherapy prior to RD, and ≥ 10 cycles of RD therapy had significantly prolonged PFS (P = 0.007, P = 0.011, P = 0.007, and P < 0.001, respectively). Adverse events were acceptable. RD is effective and safe in real-life clinical practice, including patients with comorbidities. RD is an effective and safe treatment in a real clinical setting which includes patients with comorbidities. Early and continual use of RD treatment may improve RRMM survival outcomes.