SQZ Biotechnologies presented new SQZ? AAC and eAPC preclinical research describing the robust potential of these platforms to treat cancer, including data demonstrating synergistic activity when combined with chemotherapy. The company also presented new research on the development of enhanced tumor infiltrating lymphocytes (TILs) that show increased potency in the absence of exogenous cytokine (IL-2) support. The data was presented at the 36th Annual Meeting of the Society for Immunotherapy of Cancer (SITC) being held November 10-14, 2021, in Washington, D.C. and virtually. Major Findings from Preclinical Research; Poster #156: RBC-Derived, Activating Antigen Carriers (SQZ? AACs) Prime Potent T Cell Responses and Drive Tumor Regression In Vivo. SQZ? Activating Antigen Carriers (AAC) were derived from red blood cells (RBCs) and engineered to direct tumor-specific antigens and adjuvant to endogenous professional APCs, which subsequently activated T cell responses in vivo. In TC-1 tumor bearing mice, a model of HPV16+ cancers, AACs demonstrated a synergistic therapeutic effect in combination with cisplatin, a common chemotherapy used in many clinical settings. Median survival of mice increased in all combination treatment cohorts compared to single agent cisplatin or ACC treatment. Poster #211: SQZ? eAPCs Generated from PBMCs by Delivery of Multiple mRNAs Encoding for Antigens, Costimulatory Proteins, and Engineered Cytokines. SQZ? Enhanced Antigen Presenting Cells (eAPC) derived from peripheral blood mononuclear cells (PBMCs) and engineered with various mRNA encoding for multiple target antigens and immuno-stimulation signals, including CD86 and membrane bound IL-2 and IL-12, generated robust T cell responses in human in-vitro models. HPV16-encoding mRNA delivery to PBMCs stimulated CD8+ T cells across a range of HLA haplotypes, supporting future eAPC clinical development in broad HPV16+ patient populations. eAPC data highlights the potential to expand the therapeutic impact across tumor types by changing the antigen-encoding mRNA. Poster #165: Generating Enhanced Tumor Infiltrating Lymphocytes through Microfluidic Cell Squeezing. Cell Squeeze? delivery of mRNA encoding membrane bound IL-2 (mbIL2) and IL-12 (mbIL12) into expanded tumor reactive CD8 human tumor infiltrating lymphocytes (TILs) from AgonOx (AGX-148) demonstrated high levels of membrane-bound cytokine expression in vitro. Enhanced TILs proliferated independent of exogenous IL-2 and demonstrated improved granzyme B levels, illustrating the potential to eliminate systemic IL-2 administration in the clinical setting. In an in vitro co-culture model with matched human melanoma cells, enhanced TILs demonstrated increased tumor killing as compared to un-modified TILs. AgonOx Inc. is a biotechnology company with a close alignment with the Earle A. Chiles Research Institute at the Providence Cancer Institute in Portland, OR.