Impact of Poor Tolerance and Discontinuation of the Dexamethasone during Treatment with Lenalidomide-Dexamethasone in Relapsed and Refractory Multiple Myeloma

Background. Lenalidomide plus Dexamethasone is approved at first relapse and beyond in Europe, and has transformed the prognosis of Myeloma in the relapse setting. Lenalidomide plus Dexamethasone is approved until progression, that could last for years, the median PFS in phase 3 studies being at 17 months at first relapse, but many patients eventually reach 5 to 7 years these days. Dexamethasone was showed to enhance lenalidomide-antitumor efficacy and to prolong the progression-free survival. However, long term exposure to dexamethasone is also known to be associated to an array of adverse events. Finally, IMiDs are known to act through immunomodulation a class-based mechanism. It is possible that lenalidomide might show efficacy on the long run without need to dexamethasone use, at least for some patients with myeloma. We sought to study the impact of dexamethasone discontinuation beyond six months and one year, and compare this analysis to patients treated on lenalidomide plus dexamethasone. Method. We have recruited 200 relapse refractory myeloma patients for this study from various IFM centers. The patients were to be older than 18 years old and treated with lenalidomide plus dexamethasone. We sought to study the impact of the various ways to use dexamethasone in the real life, and therefore dexamethasone was given according to physician decision. We identified groups according to dexamethasone given high dose (4 days 160mg total in a raw), given once a week at 40mg (considered standard dose), given at lower dose (considered low dose) and a group that had dexamethasone discontinued. Patients were not allowed to have other type of combination but lenalidomide plus dexamethasone. Result. A total of 200 patients were analyzed, median age of 57 years old (range 25-76). 17,5% patients had renal dysfunction at diagnosis. ISS was 2 for 20% and 3 for 20%. Approximately 10% had either del17p or t(4;14). 7% of patients had previous history of venous thrombosis before the treatment. Response rate, survival, including TTP, PFS, EFS and overall survival will be presented at ASH with updated follow-up. Conclusion. This study aims to investigate the importance of long run and exposure to Dexamethasone in the Lenalidomide-Dexamethasone regimen. We also wished to assess the optimal dose of dexamethasone that could be given to patients with prolonged exposure to lenalidomide plus dexamethasone. Disclosures Arnulf: Celgene: Membership on an entity's Board of Directors or advisory committees; Janssen: Membership on an entity's Board of Directors or advisory committees. MACRO:millenium: Membership on an entity's Board of Directors or advisory committees; jansen: Membership on an entity's Board of Directors or advisory committees; celgene: Membership on an entity's Board of Directors or advisory committees. Facon:Celgene: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Millenium: Membership on an entity's Board of Directors or advisory committees; BMS: Membership on an entity's Board of Directors or advisory committees; Onyx: Membership on an entity's Board of Directors or advisory committees; Janssen: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Novartis: Membership on an entity's Board of Directors or advisory committees; Amgen: Membership on an entity's Board of Directors or advisory committees; Pierre Fabre: Membership on an entity's Board of Directors or advisory committees. Leleu:LeoPharma: Honoraria; Pierre Fabre: Honoraria; BMS: Honoraria; Novartis: Honoraria; TEVA: Honoraria; Amgen: Honoraria; Takeda: Honoraria; Celgene: Honoraria; Janssen: Honoraria; Chugai: Honoraria.