A pilot study of intratumoral SD-101 (toll-like receptor 9 agonist), nivolumab, and radiotherapy for treatment of chemotherapy-refractory metastatic pancreatic adenocarcinoma.

TPS782 Background: Pancreatic adenocarcinoma is an aggressive disease projected to be the second leading cause of cancer-related death. A majority of patients have advanced disease on diagnosis. Combination chemotherapy is first-line for advanced disease but limited by toxicity and median survival under 1 year. SD-101 is a toll-like receptor 9 agonist that is injected intratumorally to increase immunogenicity in the tumor microenvironment. Localized radiation can further enhance this via antigen release and potential abscopal effects. Immunotherapy has revolutionized care for various solid organ malignancies but not yet for pancreatic cancer. Therefore, the combination of SD-101, localized radiation, and checkpoint inhibitor is a promising therapeutic strategy for metastatic pancreatic adenocarcinoma. Methods: Six patients with chemotherapy-refractory, liver-metastatic pancreatic adenocarcinoma will be evaluated for combination SD-101, radiation, and nivolumab. SD-101 is injected intratumorally into a liver metastasis on days 1, 8, 15, 29 with optional dosing days 43 and 57. Localized radiation (6-10 Gy per fraction) to the injected lesion will be given on days 1, 3, 5, 8, and 10. Nivolumab will be given at 240 mg every 2 weeks starting day 2 until progression or unacceptable toxicity. Blood samples will be collected at baseline and at regular intervals while on treatment. Biopsies will be obtained at baseline and on day 29. Primary objectives are to evaluate safety and tolerability, defined so if ≥5 patients reach day 29 without experiencing grade ≥3 treatment-related toxicity. Secondary objectives include preliminary efficacy as defined by disease control rate, duration of response, progression-free survival, and overall survival. Exploratory objectives include objective response rate and biomarker correlatives (T-cell clonality, tumor mutational burden, tumor infiltrative immune cell subsets, and immune-related gene expression profile). Blood and biopsy specimens will be analyzed using flow cytometry, qRT-PCR, RNA sequencing, and whole exome sequencing including immunohistochemistry on biopsy specimens. Clinical trial information: NCT04050085.