CTIM-31. IMMUNOLOGIC MONITORING AFTER ADOPTIVE CELL THERAPY IN PEDIATRIC PATIENTS WITH RECURRENT MEDULLOBLASTOMA USING IMMUNOGENOMICS APPROACH

Abstract BACKGROUND Adoptive cellular therapy (ACT) using transfer of tumor-specific lymphocytes has emerged as a potent strategy for treatment advanced and refractory malignancies. We have employed the use total tumor RNA (TTRNA)-pulsed DCs in ex vivo expansion adoptive targeting pediatric malignant brain tumors. METHODS Total was isolated from patient PBMC samples collected prior to after 2-weeks 4-weeks following immunotherapy 18 patients (Re-MATCH protocol, FDA IND BB-14058). applied bulk RNA-Seq high-throughput T cell receptor sequencing monitor changes blood draws ACT. RESULTS observed an increase expression level genes responsible activation therapy. found that these were involved signaling pathways, proliferative signals, cytokine production. The data revealed certain T-cells clonally expanded ACT, with increasing number “hyper-expanded” TCR clones (comprising > 1% all beta or alpha sequences) These established new balance peripheral stable over month completion immunotherapy. Hyper-expanded increased diversity ACT associated radiographic response prolonged progression-free overall survival. Limited short CONCLUSIONS results emphasize importance gene profiling achieve higher resolution monitoring immune responses receiving immunotherapeutic treatment. Also, findings support further study suggest clonal may be positive clinical responses.