Efficacy and safety of lenalidomide treatment in multiple myeloma (MM) patients—Report of the Polish Myeloma Group

Abstract The aim of the multi-centre retrospective study was to evaluate the efficacy and safety of lenalidomide (LEN) therapy in patients with resistant or relapsed multiple myeloma (MM) as well as in patients with stable disease (LEN used due to neurological complications). The primary endpoint of this study was an overall response rate (ORR). The secondary endpoints were as follows: time to progression (TTP), overall survival (OS) and the safety of drug use. Data were collected in 19 centres of the Polish Multiple Myeloma Study Group. The study group consisted of 306 subjects: 153 females and 153 males. In 115 patients (38.8%, group A), a resistant myeloma was diagnosed; in 135 (44.1%, group B) a relapse, and in 56 (18.3%, group C) a stable disease were stated. In 92.8% of patients, LEN + DEX combination was used; in remaining group, LEN monotherapy or a combination therapy LEN + bortezomib or LEN + bendamustine and other were used. In the entire study group, ORR was 75.5% (including 12.4% patients achieving complete remission [CR] or stringent CR [sCR]). Median time to progression (TTP) was 20 months. Median overall survival (OS) was 33.3 months. The regression model for “treatment response” was on the borderline of statistical significance ( p  = 0.07), however the number of LEN treatment cycles ≥6 ( R 2  = 17.2%), baseline LDH level ( R 2  = 1.1%) and no ASCT use ( R 2  = 1.7%) where the factors most affecting treatment response achievement. The regression model for dependant variable – “overall survival” – was statistically significant ( p  = 0.0000004). Factors with the most impact on OS were as follows: number of LEN cycles treatment ≥6 ( R 2  = 16.7%), treatment response achievement ( R 2  = 6.9%), β-2-microglobulin (β-2-M) level ( R 2  = 4.8%), renal function ( R 2  = 3.0%) and lack of 3/4 grade adverse events ( R 2  = 1.4%). Summary: LEN is an effective and safe therapeutic option, even in intensively treated resistant and relapsed MM patients, as well as in patients with stable disease and previous treatment-induced neurological complications. In particular, the number of LEN treatment cycles ≥6 was the factor which affected treatment response achievement the most, together with an important impact on OS.