OTHR-02. Engineered “of the shelf” allogeneic cellular therapies for metastatic brain tumors

Brain metastatic patients have multiple metastatic lesions or diagnostically challenging asymptomatic lesions, making surgery an inadequate therapeutic option. Given the challenges related to systemic delivery of a majority of therapeutic agents across the BBB, engineered cell based therapies offer an excellent platform to target metastatic tumors in the brain. We have established the use tumor cell surface receptor targeted allogeneic “off the shelf” gene engineered cellular therapies and developed two different approaches to treat brain metastases. In one approach, we have armed allogenic stem cells (SC) with oncolytic herpes virus (oHSV) variants and tested them in different mouse models of brain metastatic (BM) tumor derived from brain seeking metastatic melanoma tumor cells from patients. We show that intracarotid artery administration of SC-oHSV effectively tracks metastatic tumor lesions and significantly prolongs the survival of brain tumor bearing mice. We also show that a combination of SC-oHSV and PD-L1 blockade increases IFNγ-producing CD8+ tumor-infiltrating T lymphocytes and results in a profound extension of the median survival in syngeneic brain metastatic melanoma mouse models. In another approach, we have explored the versatility of cell mediated bi-functional EGFR and DR4/5-targeted treatment in basal like breast cancer (BLBC) mouse models featuring different patterns of brain metastasis. Most BLBC lines demonstrated a high sensitivity to EGFR and DR4/5 bi-targeting therapeutic protein, EVDRL [anti-EGFR VHH (EV) fused to DR ligand (DRL)]. Functional analyses using inhibitors and CRISPR-Cas9 knockouts revealed that the EV domain facilitated in augmenting DR4/5-DRL binding and enhancing DRL-induced apoptosis. EVDRL releasing allogeneic SCs alleviated tumor-burden and significantly increased survival in mouse models of residual-tumor after macrometastasis resection, perivascular niche micrometastasis, and leptomeningeal metastasis. These findings provide a clinically applicable therapeutic platform to target disseminated metastatic lesions in the brain and define a new paradigm for treatment of brain metastases.