Phase III Intergroup Study of Lenalidomide (CC-5013) Versus Placebo Maintenance Therapy Following Single Autologous Stem Cell Transplant for Multiple Myeloma (CALGB 100104): Initial Report of Patient Accrual and Adverse Events.

Abstract 3416

Poster Board III-304

Relapse and/or progression of disease are the primary causes of treatment failure after autologous hematopoietic stem cell transplant (ASCT) for multiple myeloma (MM). The primary objective of CALGB 100104 was to investigate whether adding maintenance therapy would improve the time to progression (TTP). The study was powered to detect an improvement of 9.6 months (prolongation of TTP from 24 months to 33.6 months) in MM patients undergoing a single ASCT. Secondary objectives were the Complete Response conversion rate following maintenance initiation, the Overall Survival and the feasibility of long term lenalidomide maintenance therapy. Eligible MM patients were Durie-Salmon Stage I-III patients within 1 year of diagnosis, receiving at least 2 months of any induction therapy with response (Stable Disease (SD) or better) and ≤ 70 years of age. Patients with progressive disease prior to ASCT were not eligible for study. Patients underwent stem cell mobilization followed by Melphalan 200 mg/m² and ASCT with a minimum of 2 × 10⁶ CD34 cells/kg for stem cell infusion. Responding patients with SD or better were randomized at day 100 to 110 post ASCT to study drug versus placebo. Patients with progressive disease were not randomized. Randomized patients were stratified by elevated β2 microglobulin at diagnosis and prior thalidomide or lenalidomide use during induction therapy. The starting dose was 10 mg daily with an escalation at 3 months to 15 mg if tolerated. Study drug could be de-escalated by 5 mg daily if not tolerated. Patients could be maintained at 5, 10 or 15 mg as tolerated and were followed with monthly complete blood counts. Drug was held for neutropenia (Absolute Neutrophil Count (ANC) < 500/μl or thrombocytopenia (<30,000/ μl) and restarted after resolution of cytopenia(s). Patients were re-staged by blood and urine testing every 3 months, by skeletal survey and bone marrow testing yearly and remained on maintenance therapy until progression. A total of 568 pts were registered at centers from the following cooperative groups: CALGB (n=377), ECOG (n=132), and BMT-CTN (n=59). The study opened in 12/2004 with increasing annual accrual: 2005, n=33, (6%); 2006, n=62, (11%); 2007, n=137, (24%); 2008, n=214, (38%); 2009, n=122, (21%) and study closure on 07/03/09. The drop out rate before randomization at day 100 to 110 was projected to be 10-15% with an expected randomization of 462 patients. Among the 568 registered patients, 424 have been randomized, 81 have dropped out pre-randomization and 63 are pending randomization as of 08/06/09. Projected final randomization is approximately 475. Pooled Hematologic and Non-Hematologic Adverse Events (AEs) are available from 275 patients in both arms. Individual patients experiencing Hematologic AEs are as follows: Grade 3 (severe) n=43 (16%); Grade 4 (life-threatening) n=26 (9%); and no Grade 5 (lethal). Individual patients experiencing Non-Hematologic AEs are as follows: Grade 3 n=74 (27%); Grade 4 n=9 (3%); Grade 5 n=5 (2%). The most common Non-Hematologic AEs were infection, fever, rash and fatigue. The Data Safety and Monitoring Board (DSMB) will continue to monitor the study for AEs and determination of progression. This large Phase III study has successfully completed patient registration and is nearing completion of patient randomization at day 100 to 110 post ASCT through the cooperation of the Intergroup oncology and transplant clinical research groups. Further analysis will determine if maintenance therapy with lenalidomide (CC-5013) is of benefit for MM patients following single ASCT.