Pro-inflammatory responses play an important role in controlling the development and progression of cancer. Contrary to the radiotherapy/chemotherapy that cause off-target bystander injuries, immunotherapies activate the patient’s immune responses for cancer elimination. Consequent to the critical role T lymphocytes play in the anti-cancer response, substantial pharmacologic efforts have been made to activate the endogenous T cell response. Unfortunately, many of these approaches have shown noteworthy toxicity due to their pan T cell activation. In contrast, the less robust T cell alloresponse has demonstrated a synergistic effect on the anti-cancer response but poses an inherent risk of Graft versus Host Disease. To overcome this risk, an acellular, allorecognition-derived, secretome-based, inflammatory agent (IA1) has been developed. To assess IA1’s immunomodulatory activity, T cell proliferation and differentiation were determined in vitro. The acellular effectors of the secretome were soluble and exosome-encapsulated microRNA and, due to the conserved nature of microRNA, demonstrated cross-species efficacy. The proliferation induced by IA1 was approximately 50% that of the allogeneic response and dramatically less than that induced by mitogen/mitogen-like stimulations suggesting that bystander cell injury, relative to these agents, could be substantially reduced. IA1 exerted no direct leukocyte toxicity but induced a significant proliferation of resting CD3⁺ (CD4⁺ and CD8⁺) T cells and skewed the response towards a pro-inflammatory state as evidenced by an increased ratio of effector versus regulatory T cells. In assessing the in vitro efficacy of IA1-activated leukocytes on cancer cell proliferation, we showed that IA1-treatment of resting leukocytes resulted in an enhanced anti-proliferative effect on cancer cells relative to untreated or sham-treated donor-matched leukocytes. The inhibition of HeLa cell proliferation by IA1-activated leukocytes was noted by ~12 hours versus 4-5 days for resting cells. Importantly, no toxicity of IA1-activated leukocytes to non-cancerous cells was noticed. A second biomanufactured therapeutic (IA2; produced using HeLa cells) surprisingly demonstrated broad direct toxicities to cancer cells but was less effective than IA1 in inducing a leukocyte-mediated response. Successful development of this secretome therapeutic approach may prove useful in enhancing the endogenous immune response to cancer, and consequent to enhanced immunosurveillance, in reducing the metastatic potential of existing cancers.Medicine, Faculty ofPathology and Laboratory Medicine, Department ofGraduat
