CTIM-29. PHASE 2 STUDY OF A NOVEL IMMUNOTHERAPY SL-701 IN ADULTS WITH RECURRENT GBM: IDENTIFICATION OF TREATMENT-INDUCED CD8+CD107A+ CD57+ PD-1- MEMORY T-CELLS THAT ARE ASSOCIATED WITH INCREASED SURVIVAL

Abstract Recurrent glioblastoma (GBM) is an aggressive disease with poor survival and limited treatment options. SL-701 a novel immunotherapy comprised of synthetic peptides designed to elicit anti-tumor immune response against GBM antigens IL-13Rα2, ephrinA2, survivin. Here we describe 18-color flow cytometry analysis from stage 2 Ph2 clinical trial SL-701+poly-ICLC+bevacizumab (NCT02078648), in which 12-month overall (OS) was 50%. Of the 27 patients 2, 24 (89%) developed heterogeneous T-cell responses 1, or 3 CD8 peptides. Magnitude kinetics peptide were variable among these no clear relationship OS. Therefore, phenotypic all conducted using terraFlow, unique data approach utilizing machine learning identify phenotypes associated possible combinations markers. In total, 10,184 induced measured, including 223 (P < 0.05) 16 core that uniquely represent differences between OS above below 12 months 0.05). 50% CD8+ CD57+ CD107a+ PD-1- SL-701-specific T-cells, are highly-differentiated memory T-cells primed for cytotoxicity. The frequency (8%-18%) enhanced 1.6- 2.3-fold > Similarly, identified cytotoxic CD4+ T cells, 1.9- 2.5-fold >12 months. final 6 activated CD154+ (5%-19%) 0.3- 0.5-fold 0.05), suggesting helper absence Deep sequencing whole transcriptome-based molecular planned.