853 ACTM-838: a microbial-based immunotherapy that delivers combination IL-15 + engineered STING to tumor-resident APCs after IV dosing in T-cell excluded solid tumors by Laura Glickman, Michele Ardolino, Haixing Kehoe, Alexandre Iannello, Keith Cheung, Bret Peterson, Marie Marotel, Sara Tribble, Hailey He, Jonathan Hodgins, Christopher Rae, Christopher Thanos