Safety And Efficacy Of Lenalidomide As Maintenance Therapy In Patients With Newly Diagnosed Multiple Myeloma Following A Tandem Autologous-Allogeneic Transplant

Rationale: We recently reported a study where overall and event free survivals in newly diagnosed myeloma patients receiving an autologous transplant followed by an allograft from an HLA-identical sibling were superior as compared to those undergoing a double autologous transplant. A larger multicenter study by the Gruppo Italiano Trapianti di Midollo (GITMO), co-ordinated by our group and recently closed, employing a tandem auto-allo approach in newly diagnosed patients confirmed the achievement of prolonged event free and overall survival. Importantly, the achievement of at least very good partial remission at the time of allografting conferred a significant advantage in both event-free-survival (HR 0,23, CI 0,11-0,48; p=0,0001) and overall survival (HR 0,26; CI 0,09-0,79; p=0,02). Moreover, recent advances in the understanding of the pathogenesis of multiple myeloma have identified specific signalling pathways that have become targets for biologically-based drugs such as thalidomide, bortezomib and lenalidomide and employed in several trials, including after allograft. The aim of the current proposal is to combine the post-transplant efficacy of graft-vs.-myeloma with the anti-myeloma effect of lenalidomide in newly diagnosed myeloma patients with an HLA-identical sibling treated with a tandem autograft-allograft approach. Maintenance/consolidation of the response may be a key factor to further improve rate of clinical and molecular (as a prelude to cure) remissions and prolong overall and event free survivals after allografting. We would like to investigate the safety and efficacy of lenalidomide as consolidation/maintenance therapy in patient undergoing tandem autologous-allogeneic transplant.

Objectives of study: To evaluate 1) toxicity and tolerability of lenalidomide after allografting; 2)To evaluate efficacy of lenalidomide in inducing complete remission, defined as negative immunofixation, 12 months after allografting; 3) overall-survival; 4) event-free survival; 5) molecular remission rate. Furthermore we plan to compare molecular remission rate in patients treated with lenalidomide after tandem auto-allo transplant and after double autologous transplant and to monitor minimal residual disease in patients achieving clinical CR with lenalidomide.

Patient Selection: Patients with newly diagnosed multiple myeloma with an HLA identical sibling suitable for PBSC donation will be included. Complete cytogenetic analysis at diagnosis will be required. The patient must have the capacity to give informed consent. Age >18 and < 65. Negative pregnancy test and willing to use contraceptive techniques during and for 12 months following treatment is required. Only very unfitted patients will be excluded.

Treatment plan: Lenalidomide will be started at 6 months post-allotransplant at the dose of 10 mg/day continuously in all patients (unless in molecular CR), if the following conditions are present:

• absolute neutrophil count > 1 x 109/L without the use of growth factors;
• platelet count > 75 x 109/L without transfusion support;
• calculated or measured creatinine clearance: ≥ 20 mL/minute;
• total bilirubin < 2 x the upper limit of normal,
• AST and ALT < 2.5 x upper limit of normal
• less than 1 mg/kg/day of prednisone, and no more than 2 immunosuppressive drugs other than steroid to control GVHD (if more immunosuppression is required to control GVHD, the maintenance therapy with lenalidomide will be held until this criteria will be satisfied) Treatment will be continued without interruption, unless not tolerated, until unacceptable adverse events are experienced or progressive disease occurs. Moreover, lenalidomide will be discontinued in patients who achieve and maintain molecular remission for 2 consecutive controls at least 6 weeks apart.

Safety section - dose modification plan: During the study patients will be monitored for the occurrence of side effects. Toxicity events will be graded according to the NCI toxicity criteria. In case of severe toxicity, the lenalidomide dose will be reduced or withheld as outlined in the protocols.

Statistical section: - Total patient sample size: 53. This is a phase 2 study designed according to a Simon's two-stage Minimax Design. An early stopping rule will be established to interrupt the study in case of futility (a non satisfactory response rate). In stage I 27 patients will be enrolled; if < 14 complete remissions will be observed, the trial will be stopped. In stage II 26 more patients will be enrolled. If ≥ 32 responses will be observed, it will be concluded that the lenalidomide maintenance is active in increasing the complete remission rate after auto-allograft.

Analysis plan: Toxicity monitoring will be incorporated into the study design by requiring that the trial be terminated after an initial stage if the number of observed toxicities (treatment related deaths) is excessive.