Utility of decreased FDG SUV as a response and prognostic indicator in multiple myeloma therapy with BiRD

Abstract

8607 Background: To assess the utility of post-treatment [Rx] FDG SUV decrease from pre-Rx SUV as an indicator of response and prognosis [RPI] in Multiple Myeloma [MM] patients [pts] receiving BiRD therapy. Methods: 11 pts [6 M; 5 F] with active clinical and serologic MM [Salmon-Dury Class IIa (4), IIIa (6), III (1)] had FDG PET/CT pre and post BiRD Rx. Iliac crest [IC] and Index Lesion [IL] SUV obtained from images 60 min post 12–15 mCi FDG pre & post BiRD [Biaxin, lenalidomide (R) & Dexamethasone [D], 40 mg on day 1, 2,3,8,15 and 22]. BiRD is an innovative 23 day immunomodulator regimen in clinical trials for MM treatment. Pre and post Rx interval varied from 3–12 months depending upon pts ability to tolerate protocol. Results: 4 pts had CR; 4 PR; 3 minimal Respnse [mR]. Mean pre Rx SUV for CR: Rt IC/Lt IC/IL =3.9, 3.9, 6.7; PR = 5.1, 3.9, 9.3; mR = 3.5, 3.7, 3.6. Mean Post-Rx SUV: CR = 2.1, 2.2, 2.5; PR = 2.2, 2.1, 5.2; mR = 2.9, 2.4, 1.7. % Change SUV for CR = 46, 41, 44; PR = 50, 46, 54; mR = 0, 37, 49. Zero value due to 1 outlier; otherwise average 36%. Conclusions: Whereas post Rx SUV change is a promising RPI in many tumors, it was not useful in MM pts Rx with BiRD. 41–54% SUV decrease was seen regardless of clinical response. BiRD involves high doses of D which inhibits tumor glucose utilization. Effect of D dose and interval to FDG PET is undetermined in MM. Steroid administration may be another variable affecting FDG SUV. Author Disclosure Employment or Leadership Consultant or Advisory Role Stock Ownership Honoraria Research Expert Testimony Other Remuneration Celgene Celgene Celgene