Prognostic Significance of Tracking Dynamic Changes in Positron Emission Tomography (PET) Scan Pre and Post Autologous Stem Cell Transplant (ASCT)

BACKGROUND: Multiple Myeloma (MM) is a heterogenous disease with variable outcomes based on both disease biology and burden. The revised international staging system (R-ISS) can distinguish 5-year overall survival (OS) however, it does not incorporate novel imaging that provide more accurate disease burden assessment (e.g., PET-CT). Previous studies (Usmani SZ et al Blood 2013) showed that the presence of more than 3 focal lesions (FL)s detected on PET-CT scan at baseline in newly diagnosed MM patients, or the persistence of any FL post induction therapy or post- autologous stem cell transplantation (ASCT), were associated with shorter progression free survival (PFS) and overall survival (OS) in Total Therapy trials. There is limited information available on the prognostic significance of PET-CT in the context of current standard 3-drug induction followed by ASCT in clinical practice. Herein, the investigators examined the prognostic implications of post-therapy PET-CT positivity in routine clinical practice. PATIENTS AND METHODS: The LCI MM database was interrogated (3/2014-5/2018) for NDMM patients who had undergone upfront ASCT and had PET-CT data available. Continuous variables were summarized with descriptive statistics, while categorical variables were summarized with frequencies and proportions. Survival distributions were estimated with Kaplan Meier techniques and compared using a log rank test PET-CT scan results were reported as negative or positive (defined as one FL having higher 18F-FDG uptake relative to uptake in mediastinum or surrounding background, with no similar activity seen on the contralateral side, or increased activity at any location incompatible with normal physiological distribution). RESULTS: A total of 198 MM patients were identified, 62 had pre-ASCT PET-CT scans and 80 patients had post-ASCT PET-CT. Median age at transplant was 62 years (range 25 - 77), 52.0% were female. R-ISS stage I (17.2%), stage II (41.4%), stage III (1.7%). The 3 years overall survival (OS) in patients with negative PET-CT post-ASCT vs. positive PET-CT post-ASCT was 96.6% vs. 74.2% (p-value 0.002) and median progression free survival (PFS) was 35 months vs. 13 months (p-value