Response to First Cycle Is the Major Predictor of Long-Term Response to Lenalidomide and Dexamethasone Therapy in Relapsed and Refractory Multiple Myeloma: Can We Spare Patients the Toxicity and Costs of Additional Agents?

Background: Lenalidomide plus dexamethasone (Ld) is still considered an option of care for some selected patients with relapsed or refractory multiple myeloma (RRMM), despite the proven superiority of lenalidomide-based triplet therapy. Up to 20% of patients obtain long-term benefit from Ld alone. The aim of this multicenter retrospective study was to identify and characterize those with good response to Ld salvage therapy, defined as progression-free survival lasting more than 24 months.
Patients and Methods: Patients treated with Ld in a consortium of 3 tertiary-care hospitals (Institut Català d'Oncologia) between 2009 and 2016 were prospectively registered; 227 patients had evaluable data.
Results: In multivariate analysis, obtaining partial response after the first therapy cycle was the main independent factor associated with progression-free survival lasting more than 24 months. Together with standard risk cytogenetics, partial response after first cycle was also independently associated with a higher rate of complete response. Previous plasma-cell dyscrasia remained as the only baseline characteristic independently associated with long-lasting responses. High-risk cytogenetics and no history of monoclonal gammopathy of undetermined significance were the only statistically significant negative prognostic factors for overall survival. Patients who had received only one prior therapy showed a trend toward higher overall survival.
Conclusion: If Ld is to be considered a treatment choice, at least a partial response should be obtained after the first therapy cycle to maintain double-agent therapy safely.
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