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Lenalidomide, an immunomodulatory drug, was approved for treatment of relapse/refractory multiple myeloma (RR-MM). In Turkey, we have been used the combination of lenalidomide and dexamethasone (RD) for RR-MM patients after 2010. Therefore, we analyzed efficacy and safety of RD in Turkish patients with RR-MM.

We aimed to evaluate the outcome and the tolerability of the RD in patients with RR-MM who had been treated under the standard clinical practice between October 2010 and June 2016.

This is a retrospective, single center study. Patients’ clinical and laboratory data were collected from patient’ files. The overall and progression free survival (OS and PFS) were estimated by Kaplan–Meier methods. Log- rank test was used to evaluate the variables affecting OS and PFS (univariate analysis). Cox proportional hazards regression was used for multivariate analysis to analyze the independent variables affecting PFS and OS.

One-hundred and twenty patients (71 male and 49 female) enrolled in the study. The median age at the start of RD was 64 years (29- 84) and the median number of previous line of treatment was 1 (1- 4). Seventy-two patients (60 %) received RD as second-line therapy and 51 of patients (42.5%) treated with autologous stem cell transplantation (ASCT). With regard to the initial dose of lenalidomide, 82 (68.3 %) of the patients received the recommended dose of 25 mg per day for 21 days in a cycle of 28 days. Objective response (≥PR) was observed in 87 patients (72.5 %); 23 patients (19.2 %) achieved CR. The median follow-up was 14 months (range, 1– 72 months), and the median DOR was 19 months (range, 12.4- 25.6 months). Median OS and PFS were 32 months (95 % CI, 15.8–48.1 months) and 21 months (95 % CI, 15.8- 26.1 months), respectively. In the multivariate analysis, the independent prognostic factors for OS and PFS were treated with previous ASCT, patients who achieved at least PR, patients receiving RD for more than 12 cycles. Adverse events occurred in 69 of patients (57.5%). Hematological and non-hematological adverse events were found at the same rate (n= 47, 39.2%). The treatment discontinuation rate due to AEs was 11.7% (14 patients). The overall incidence rate (IR, events per 100 patient-years) of second primary malignancies (SPMs) was 0.93 (95% CI, 0.04- 4.60). Tha rate of anemia was 12.5% and thrombocytopenia was 9.2% in all grades. Penumania (15.8%), fatigue (14.2%) and herpes infections (0.8%) have been reported as most frequent non-hematological side effects.

RD is a safe, well tolerated and effective treatment in patients with RR-MM. Good response, previous ASCT and using more than 12 cycles are associated with better survival. Higher OS and PFS and ORR seem to be related to using RD in the first relapse. Adverse events are manageable and lower with prophylaxis.