FROM BLOOD
Swapping lenalidomide for thalidomide in a standard regimen for transplant-ineligible patients with untreated multiple myeloma did not improve efficacy, but the toxicity profile may favor the use of lenalidomide in a maintenance regimen, results of a randomized trial suggest.
Among patients with previously untreated multiple myeloma who were not eligible for autologous stem cell transplant, neither median progression-free survival (PFS) nor overall survival (OS) were significantly different for patients treated with either melphalan, prednisone, and thalidomide (MPT-T) followed by thalidomide maintenance, or with the same regimen with lenalidomide (Revlimid) substituted for thalidomide (MPR-R), reported Dr. Sonja Zweegman of Vrije University Medical Center in Amsterdam.
“MPR-R has no advantage over MPT-T with respect to response rate, PFS, and OS. However, the use of thalidomide as maintenance therapy was associated with a high rate of clinically significant neuropathy and is therefore not preferred for maintenance strategies,” they wrote ( Blood 2016;127[9];1109-16 ).
The investigators randomly assigned 637 transplant-ineligible patients with newly-diagnosed multiple myeloma to receive nine 4-week cycles of either MPT-T (318 patients) or MPR-R (319 patients). At 36 months’ median follow-up, median PFS, the primary endpoint, was 20 months for patients treated with MPT-T, compared with 23 months for those treated with MPR-R. This translated into a hazard ratio (HR) of 0.87, P = .12).
The overall response rates were 81% for MPT-T and 84% for MPR-R. Very good partial responses or better were seen in 47% and 45%, of patients, respectively. The complete response rate with MPT-T was 10%, compared with 13% for MPR-R. Median time to response and time to maximum response were similar between the arms.
OS at 2, 3, and 4 years in the MPT-T and MPR-R arms was 73% vs. 84%, 64% vs 69%, and 52% vs. 56%, respectively. These differences were not statistically significant.
The proportion of patients with one or more grade 3 or 4 adverse events was 81% with thalidomide and 86% with lenalidomide.
The investigators noted, however, that there was a high rate of discontinuation during induction therapy in each arm, with 49% of those starting on MPT-T and 41% of those starting on MPR-R halting therapy. Most of the patients who discontinued were older than age 75. Early treatment deaths (within three cycles) occurred in 13 patients on MPT-T, and 8 on MPR-R.
Among patients who started on maintenance therapy, significantly more patients on thalidomide had to discontinue thalidomide than did patients who started on lenalidomide maintenance (60% vs, 17%, P = .017).
The primary reason for the higher rate of discontinuation of MPT-T maintenance was neuropathy, which occurred in 87% of the discontinuations in this study arm, compared with 3% of those in the lenalidomide arm. Neuropathy of at least grade 3 was 16% in the MPT-T arm vs. 2% in MPR-R, resulting in a significantly shorter duration of maintenance therapy (5 vs. 17 months in MPR-R), irrespective of age.
Hematologic toxicities were higher in the MPR-R group, especially grades 3 and 4 neutropenia (64% vs 27%), but this did not translate into a higher clinical infection rate, and the toxicities were manageable in older patients, the investigators reported.
