Multicenter, phase II study of response-adapted lenalidomide-based therapy for transplant-ineligible patients with newly diagnosed multiple myeloma without high-risk features.

Lenalidomide and low-dose dexamethasone (Rd) are a standard treatment for older adults with multiple myeloma (MM). Lenalidomide monotherapy has rarely been evaluated for newly diagnosed transplant-ineligible MM patients. This multicenter phase II trial evaluated a response-adapted strategy for elderly patients with newly diagnosed MM without high-risk features. Patients were administered single-agent lenalidomide for the first 21 days of two 28-day cycles. Patients with progressive disease received Rd. The primary endpoint was progression-free survival using the uniform response assessment from the International Myeloma Working Group . Of the 34 enrolled patients, 28 were included in the efficacy analysis. The overall response rate (ORR, ≥ partial response [PR]) to single-agent lenalidomide or lenalidomide plus prednisone was 64.3%. Ten patients received Rd after disease progression, with an Rd ORR of 70%. The ORR of response-adapted lenalidomide-based therapy was 75%. After the median follow-up of 35.6 months, the median progression-free survival was 33.5 months (95% confidence interval [CI], 16.9-50.2), and the median overall survival was 51.8 months (95% CI, 22.0-81.6). The most common adverse event was neutropenia (46.7%), and 17 patients (56.7%) experienced infection including pneumonia. Response-adapted lenalidomide-based therapy was feasible in newly diagnosed, transplant-ineligible MM patients without high-risk features.