Manufacturing Development of SENTI-101, a Gene Circuit Modified Allogeneic Bone Marrow Derived Mesenchymal Stromal Cell (BM-MSC) Therapy for the Treatment of Solid Tumors

Abstract

Background & Aim Immunotherapies have shown success in activating endogenous immune responses against solid tumors. Many immunologically cold tumors do not respond to current immunotherapies such as checkpoint inhibitors, and present a major unmet clinical need. In prior clinical studies, allogeneic gene modified MSCs have been administered through intraperitoneal (IP) infusion to ovarian cancer patients, demonstrating safety and localization to tumor lesions.1 SENTI-101 is an allogeneic cell product consisting of MSCs engineered with a gene-circuit that expresses a potent combination of immunomodulatory cytokines: IL12 and IL21. Upon IP administration, SENTI-101 innately homes to peritoneal tumors, secretes IL12 and IL21 in a localized and sustained fashion, and induces a strong and durable anti-tumor immune response. Methods, Results & Conclusion The gene modification process for SENTI-101 includes packaging the gene circuit into a lentiviral vector, stable transduction of allogeneic BM-MSCs, expansion, and cryopreservation. The drug product is further expanded, formulated, and cryopreserved prior to clinical delivery. Key product attributes of SENTI-101 include: transduction efficiency, IL12 and IL21 secretion, cell doubling time, tumor homing, and vector copy number. A 2D culture manufacturing process was developed to maintain key product attributes over at least 14 population doublings, translating to over 10^12 final product cells per bone marrow collection. The product attributes were comparable between freshly cultured cells and those that underwent a freeze/thaw cycle and further expanded. They also showed similar localized cytokine production of IL12 and IL21 and in vivo efficacy in tumor models. Transduction efficiency was optimized by comparing different MSC donors, lentivirus titer, different chemical transduction enhancers, and other process variables. SENTI-101 was further evaluated for growth characteristics, immunomodulatory function, distribution and kinetics in mouse models, vector insertion site analysis, cell transformation assay, and karyotype. In addition, SENTI-101 was demonstrated to maintain equivalent product attributes in a 3D bioreactor process, enabling larger scale production for the allogeneic MSCs for commercial manufacturing. In conclusion, we have developed a GMP-ready process for the gene modification, expansion, and administration of SENTI-101 in preparation for upcoming human clinical studies in solid tumor indications.