Enhanced Tumor Rejection in Colorectal Cancer Mouse ModelCombined Synergistically with PD1 and PD-L1 Checkpoint Inhibitors DURHAM, N.C., Nov. 14, 2016 (GLOBE NEWSWIRE) -- Heat Biologics, Inc. (Nasdaq:HTBX), a leader in the development of gp96-based immunotherapies that are designed to activate a patient's immune system to fight cancer, announced that preclinical data from its ComPACT platform, a single product that combines Heat's ImPACT therapeutic vaccine with an immune co-stimulatory molecule, was presented at the Society for Immunotherapy of Cancer (SITC) Annual Meeting. In the poster, "Gp96-Ig/Costimulator (OX40L, ICOSL, or 4-IBBL) Combination Vaccine Improves T-cell Priming and Enhances Immunity, Memory and Tumor Elimination," researchers assessed ComPACT/OX40L in a third preclinical mouse tumor model: colorectal cancer (MC38). ComPACT/OX40L amplified antigen-specific CD8+ T cells and memory precursor effector cells (MPECs). It also blocked tumor growth, and increased both tumor rejection and animal survival, generating better results than an OX40 antibody, and without the broad systemic inflammation typically seen with OX40 antibody therapy. Furthermore, ComPACT/OX40L, combined with either PD1 or PD-L1 blocking antibodies, produced even greater antitumor immunity than either compound alone. The researchers concluded that ComPACT synergizes well with checkpoint inhibitors, which could provide an effective cancer treatment approach in humans. These studies expand on previous ComPACT studies, which demonstrated anti-tumor efficacy of ComPACT/OX40L in two mouse models: colon cancer and melanoma, where it was attributed to amplified antigen-specific CD8+ T cell expansion ( Fromm et. al. Cancer Immunology Research. 2016). "These data provide a compelling mechanistic rationale for combinations between ComPACT vaccines and PD-1/L1 blockade," said Taylor Schreiber, M.D., Ph.D., Heat's Chief Scientific Officer, and a study author. "The combination significantly increased the frequency of tumor-antigen specific CD8+ T cells, and increased the fraction of those cells that are most likely to become long-lived memory cells capable of providing durable tumor immunity."