Introduction: The all stages combined five-year survival rate for pancreatic adenocarcinoma (PDA) is 11%; however, the five-year survival rate for localized PDA is 42%. These statistics highlight the importance of early prevention strategies to prevent disease progression and metastatic dissemination. Through the NCI PREVENT program, this research program explores immunoprevention strategies for PDA by targeting CD73, a gatekeeper ectoenzyme responsible for production of extracellular adenosine. We have recently shown aggressive subtypes of pancreatic intraepithelial neoplasia (PanIN) and PDA arising in ductal pancreatic epithelium have elevated CD73 and intrapancreatic adenosine indicating adenosine generation may be an early trigger of immunosuppression. We hypothesize inhibition of CD73 and adenosine generation will promote a more robust anti-tumor immune response and prevent PanIN and PDA progression. Methods: We tested three small molecule CD73 inhibitors (APCP, OP-5244, and AB680) in a syngeneic PDA mouse model by injecting 100-200k murine PDA cells derived from KrasG12D;Trp53R172H/+;Pdx:Cre (KPC) mice in the flanks of C57BL/6 female mice.

Tumor sizes were measured weekly and tumor volume and mass were recorded at time of death. Dosage: APCP oral gavage (3x/week at 20mg/kg) and intraperitoneal (IP) (3x/week at 20 mg/kg). OP-5244 oral (3x/week at 25mg/kg and 10mg/kg). AB680 oral gavage (3x/week at 10mg/kg). HPLC analysis was performed for each inhibitor to quantify adenosine levels.

Results: IP delivery of APCP significantly reduced tumor growth and intratumoral adenosine levels; however oral gavage delivery did not reduce tumor growth. Similarly, oral gavage delivery of OP-5244 did not reduce tumor growth. AB680 significantly reduced tumor volume and intratumoral adenosine levels and CyTOF immunoprofiling showed activated CD8+ T cells, dendritic cells, and macrophages were significantly increased in the tumors from AB680 treated mice. Conclusion: APCP IP delivery is more effective than oral gavage delivery and OP-5244 oral gavage delivery does not significantly decrease tumor growth. AB680 oral gavage delivery significantly decreases tumor growth and tumor adenosine concentrations. We observed a significant increase in infiltration of activated CD8+ T cells. AB680 shows high translational potential for preclinical testing in spontaneous GEM models.

Citation Format: Lincoln Ballew, Kanchan Singh, Vidhi Chandra, Tingting Mills, Erika Y. Faraoni, Victoria Mota, Trent Clark, Lana Vornik, Michelle I. Savage, Shizuko Sei, Altaf Mohammed, Holger K. Eltzschig, Powel H. Brown, Florencia McAllister, Jennifer M. Bailey-Lundberg. Preclinical testing of CD73 inhibitors for pancreatic cancer immunoprevention [abstract]. In: Proceedings of the Second Biennial NCI Meeting: Translational Advances in Cancer Prevention Agent Development (TACPAD); 2022 Sep 7-9. Philadelphia (PA): AACR; Can Prev Res 2022;15(12 Suppl_2): Abstract nr IA013.