Hypermetabolic activity by FDG-PET after immunogenic chemotherapy and multi-peptide immunotherapy in ovarian cancer.

Abstract

e17079 Background: There are several reports of increased of SUV in the lymph nodes of cancer patients after immune manipulation such as the administration of vaccines and checkpoint inhibitors. However the clinical importance of these phenomena is poorly understood. The administration of two immunogenic drugs and eight peptides in HGSOC induced atypical bright zones in multiple lymph nodes and, in areas with microscopic disease where potentially we can have cancer stem cells (CSC’s). Methods: We enrolled N = 10 HGSOC after the local IRB ethic committee approval. All the patients had 3 recurrences with mPFS = 8 months of the third relapse. The last FDG-PET scan was used as basal image for the study. Blood was collected for cellular and humoral immunology analysis such as Granzyme B ELISPOT and ELISA. Tissue was used for IHC analysis for the evaluation of CD8, FOXP3, Th1, and proteins related with CSC’s. The patients received 50 mg of oxaliplatin and 30 mg of doxorubicin total dose every week four times simultaneously with multi peptide immunotherapy. A second FDG-PET scan was performed after the termination of the treatment. Results: After the treatment 100% of the patients showed intense atypical bright uptake areas in lymph nodes and in the peritoneum. There was a correlation between the brightness intensity (SUV), and the Granzyme B production (p = 0.001). We found multiple bright small lesions in the peritoneum that were not visible before treatment. We demonstrated the presence of proteins related with CSC’s in the original tumor tissue and an antibody immune response against EGFR (P = 0.005), Ape-1 (p = 0.003) and Bcl-2 (p = 0.05). Conclusions: Immunotherapy may produce hypermetabolic activity that could lead to overtreatment when evaluated by FDG-PET in HGSOC. Vaccination may activate lymph nodes and anti-cancer immune interventions may also activate CD8 and Th1 cells able to accumulate in CSC’s clusters and increased notably the SUV, which may lead to false relapse interpretation by the radiologists and oncologists.