Efficacy Of Lenalidomide Treatment In Multiple Myeloma (MM) Patients – a Report of Polish Myeloma Group

The aim of the multi-centre observational study was to evaluate the efficacy of lenalidomide (len) therapy in patients (pts) with resistant or relapsed MM as well in pts who continued treatment with len due to complications from the earlier lines of the therapy.

The study involved 306 pts, 153 women and 153 men, aged 26-89 years (mean 60,5); on the onset of lenalidomide therapy 115 pts (38,8 %, Cohort 1, C1) were diagnosed with resistant MM, 135 pts (44,1%, Cohort 2, C2) had relapse of the disease, and 56 (18,3 %, Cohort 3, C3 ) len was instituted as continuation therapy due to polyneuropathy. In Stage I, II and III according to Durie - Salmon staging system there were 36, 88 and 182 pts respectively; 23 pts developed renal failure. 179 pts had IgG myeloma, 78 – IgA, 31pts were diagnosed with light chain disease, 13 – with non-secretory myeloma, 3- IgM, 2 -IgD and 196 with kappa light chain disease. Prior to len therapy the pts received 1-9 treatment lines (mean:3); 83 pts underwent megachemiotherapy. Average time from diagnosis to start of len treatment was 47 months (1-230).

In 284 (92,8%) pts, len was administered at the dose of 25mg p.o , on days 1-21, in the remaining 22 (7,2%) pts (14, 3, 5 pts respectively) at the dose of 15mg, 10mg or 5 mg for 21 days, and dexamethasone (dx) at the dose of 20 mg on days 1-4, 8-11. 28 pts received only len at the dose of 25 mg for 21 days; individual pts were administered len with bortezomib or bendamustin and dexamethasone. The cycles were repeated every 28 days. All the pts were administered aspirin 75mg as 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 in all pts. At the time of the assessment 32 (10,45% ) pts have completed 1-2 cycles, 48 (15,7%) 3-4 cycles, the others 6 and more.

The response rate was highest in pts continuing treatment, significantly higher than in resistant and relapsed myeloma. The response rate in group 1 and 2 was comparable 68,7% i 85,7%.(tabl) respectively.

The percentage of all responses was significantly higher in pts without renal insufficiency compared to those with renal failure (224/283 vs. 11/23) p= 0,0006, and in the group of pts whose serum beta-2-microglobulin was <3.5 mg/L compared to those with beta-2-m > 3.5 mg/L 89/112 vs 45/68 p=0,0316.

There were no significant differences in response to len, depending on the number of previous lines of treatment 1 vs.> 1, stage ISS, and underwent or no megachemotherapy.

The median TTP was 14.0 months in pts who responded to treatment with len and dx (CR, nCR, VGPR, PR). The TTP in pts with disease stabilization, or disease progression was significantly shorter (p = 0.0000), median 5.0 months.

The median TTP was 9.0 months in pts with resistant MM, 8.0 months in pts with relapsed MM, and was significantly shorter (p = 0.00007) compared with median TTP in pts continuing treatment (16.50 months).

The median OS was 15.0 months in pts who responded to treatment with len and dx (CR, nCR, VGPR, PR), and it was significantly longer (p = 0.00000) than the median OS in pts with disease stabilization, or disease progression (median 8.0 months).

In pts with resistant MM median OS was 10.50 months, in pts with relapsed MM -11.0 months, and were significantly shorter (p = 0.00077) comparing to pts continuing treatment (18.0 months).