Administration of Tadalafil in Conjunction With Lenalidomide and Dexamethasone in Patients With Multiple Myeloma

This is an early phase study to evaluate the safety and efficacy of the combination of tadalafil with lenalidomide and dexamethasone (Rd) or BiRd. 19 patients on Rd or BiRd will be treated with tadalafil for a minimum of 6 months. The investigational drug will be discontinued if there is evidence of disease progression as defined by the International Uniform Response criteria \[1\]. For responding patients (patients who have a CR, VGPR, PR or SD), the therapy will be continued until progression or intolerable adverse effects. Blood and bone marrow will be collected for various studies as detailed in section 14.10. Clinical response will be monitored every month during the study.