CD4 Polarized T cells Reduce the Expansion of Tumor Infiltrating Lymphocytes in Melanoma Patients Treated with Adoptive Cell Therapy [ChIP-seq]

Background: Adoptive cell therapy (ACT) with tumor infiltrating lymphocytes (TIL) is effective in treating PD-1 refractory melanoma, but requires adequate ex vivo expansion of TIL. Methods: CD4+ and CD8+ TIL from metastatic melanoma patients treated with TIL ACT were analyzed by RNA-seq (n=12) and ChIP-seq of acetylated histone 3 (n=19). Patients were grouped into “TIL high” and “TIL low” based on division at the median number of TIL infused. The number of TIL infused and CD4+ TIL frequency were correlated with overall survival (OS). Results: The number of TIL infused correlated with longer OS (R2=0.57, p=0.00076), and the percent of CD4+ infused was negatively correlated with the total number of TIL infused (R2=0.64, p=0.00047). RNA-seq analysis of CD4+ TIL showed increases in Th2/Th17/Treg transcripts and pathways in the TIL low group. ChIP-seq analysis of CD8+ TIL showed decreased acetylation in the TIL low group in genes upregulated during CD8+ activation. Conclusion: The numbers of TIL infused were associated with increased overall survival, while RNA-seq suggested that polarized CD4+ cells in the transferred TIL were associated with decreased overall expansion. These data suggest that improper CD4+ TIL polarization may reduce expansion and treatment efficacy. Multi-omic analysis of tumor infiltrating lymphocytes expanded from melanoma patients enrolled in clinical trials NCT01005745, NCT01659151 and NCT01701674 for the treatment of melanoma. Anlyses include RNA-seq, panH3ac ChIP-seq and DNA methylation microarray. No healthy controls are included in the study design. Experimental design involved comparison of patients with high TIL expansion vs those with low TIL expansion.