Leflunomide, Pomalidomide, and Dexamethasone for the Treatment of Relapsed or Refractory Multiple Myeloma

This phase II trial studies how well leflunomide, pomalidomide, and dexamethasone work for the treatment of multiple myeloma that has come back (relapsed) or does not respond to treatment (refractory). Leflunomide may stop the growth of cancer cells by blocking some of the enzymes needed for cell growth. Immunotherapy with pomalidomide, may induce changes in body's immune system and may interfere with the ability of tumor cells to grow and spread. Chemotherapy drugs, such as dexamethasone, work in different ways to stop the growth of cancer cells, either by killing the cells, by stopping them from dividing, or by stopping them from spreading. Giving leflunomide with pomalidomide and dexamethasone may work better in treating multiple myeloma compared to pomalidomide and dexamethasone alone.

PRIMARY OBJECTIVE: I. To estimate the response rate and to evaluate the antitumor activity of the three-drug combination, leflunomide, pomalidomide, and dexamethasone, in patients with relapsed/refractory multiple myeloma. SECONDARY OBJECTIVES: I. To characterize and evaluate toxicities, including type, frequency, severity, attribution, time course, and duration. II. To obtain estimates of response duration, depth of response, clinical benefit, and survival (overall and progression-free). OUTLINE: Patients receive leflunomide orally (PO) on days 1-28, pomalidomide PO on days 1-21, and dexamethasone PO on days 1, 8, 15, and 22. Cycles repeat every 28 days in the absence of disease progression or unacceptable toxicity. After completion of study treatment, patients are followed up at 30 days and then every 3 months thereafter.