Efficacy and Safety of Lenalidomide in the Treatment of Multiple Myeloma (MM) Patients: a Preliminary Report of Polish Myeloma Group
Authors: Usnarska-Zubkiewicz Lidia , Debski Jakub , Butrym Aleksandra , Legiec Wojciech , Dmoszynska Anna , Stella-Holowiecka Beata , Zaucha Jan Maciej , Rymko Marcin , Torosian Tigran , Kuliczkowski Kazimierz 
Published: October 2019

Abstract
Abstract 5125
The aim of the multi-centre observational study was to evaluate the efficacy and safety of lenalidomide therapy in patients with resistant or relapsed multiple myeloma as well in maintenance treatment.
The study involved 84 patients, 47 women and 37 men, aged 38–84, mean age 57.8 years; in Stage I, II and III according to Durie - Salmon staging system there were 6, 28 and 50 patients respectively; 12 patients developed renal failure. Fourty-eight patients had IgG myeloma, 26 – IgA, 6 patients were diagnosed with light chain disease, 2 – with non-secretory myeloma and 56 with kappa light chain disease. Prior to lenalidomide therapy the patients had received 1–8 treatment lines (mean:3). In 19 patients (22.6%), who were in disease remission (including CR 2, VGPR 6 and PR 11) lenalidomide was instituted due to polyneuropathy (Cohort 1, C1), among the remaining patients, on the onset of lenalidomide therapy 27 patients (32.1%, Cohort 2, C2) were diagnosed with resistant multiple myeloma and 38 patients (45.3%, Cohort 3, C3) had relapse of the disease. Lenalidomide was administered at the dose of 25mg p.o, on days 1–21 (15 pts in C1 and 54 in C2 and C3), at the dose of 15mg, 10mg or 5 mg for 21 days (1 and 2 patients in C2 and 1, 2 and 1 patient in C3 respectively) and dexamethasone at the dose of 20 mg on days 1–4, 8–11 and 17–20. Four patients with C1 and 2 with C2 received only lenalidomide at the dose of 25 mg for 21 days; individual patients from group C2 were administered lenalidomide with bortezomib or bendamustin and dexamethasone. The cycles were repeated every 28 days. All the patients were administered aspirin 75mg in the prophylaxis of deep vein thrombosis.
Therapeutic response was evaluated on the basis of modified criteria of the European Group for Blood and Marrow Transplantation (EPMT) in patients who had completed at least 3 therapeutic cycles.
In patients who were administered lenalidomide as a maintenance therapy, there were no cases of disease progression, and the percentage of CR and VGPR increased (from 42% to 68.4%), in the group of resistant patients the percentage of therapeutic response was 44.4% and in the group of relapsed myeloma it was 44.7%. The analysis of response rates in patients with maintenance therapy, resistant and relapsed MM is shown in Table 1.Table 1.Response rate analyzed by disease status.C1 n=19 maintenance therapyC2, n=27 resistantC3, n=38 relapsedCR3 (15.7%)1 (2.6%)VGPR10 (52.6%)2 (7.4%)3 (7.8%)PR6 (31.5%)10 (37.0%)13 (34,2%)SD12 (44.4%)13 (34.2%)PD3 (11.1%)8 (20.9%)
During the observation period there were three deaths: 2 patients died due to disease progression, 1 patient due to pulmonary thrombosis. Other undesired effects included neutropenia and thrombocytopenia (II and III grade), and infections.

Summary:
Lenalidomide with dexamethasone is an effective and well tolerated both in maintenance therapy as well as in resistant and relapsed patients.

Disclosures:
No relevant conflicts of interest to declare.