Abstract CT220: A randomized multicenter phase Ib/II study to assess the safety and the immunological effect of chemoradiation therapy (CRT) in combination with Pembrolizumab (anti-PD1) to CRT alone in patients with resectable or borderline resectable pancreatic canc

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Abstract Background: Immunotherapy has recently emerged as a promising modality in cancer treatment, but little is known about the application of this modality in pancreatic cancer (PC). Tumor-infiltrating lymphocytes (TILs) play a major role in anti-tumor immune responses, and their presence is correlated with survival in a variety of tumors. These TILs do not reach the PC cells in significant numbers due to the presence of stroma and a suppressive microenvironment. One of the leading causes for immune suppression is elevated expression of PD-L1 either by the tumor cells or the surrounding regulatory cells, resulting in dysfunction of TILs. Neoadjuvant chemoradiation therapy (CRT) has been advocated as a potential way to improve outcomes of patients with resectable or borderline resectable PC. More importantly, there is recent evidence to suggest that CRT can increase the presence of TILs in the PC microenvironment (PCME), leading to production of interferon-γ (IFN-γ), which could increase the expression of PD-L1 through a negative feedback loop. Accordingly, we hypothesize that blocking the PD-1 receptor will synergize with CRT to increase the density and activation of TILs in the PCME. Methods: This is a prospective multicenter randomized trial which will accrue subjects with resectable or borderline resectable pancreatic cancer who had not received prior treatment for PC. The primary objectives of the study are: (1) to determine the safety of neoadjuvant CRT in combination with Pembrolizumab. (2) To estimate the difference in the number of TILs in pancreatic cancer subjects receiving neoadjuvant CRT in combination with Pembrolizumab to the number of TILs in subjects receiving neoadjuvant CRT alone. This study will also investigate the effect of CRT+/-anti-PD-1 on the other effector and suppressive immune cells and immune checkpoints in PCME. Eligible subjects will be randomized 2:1 to the investigational treatment (Arm A) to receive Pembrolizumab administered IV every 3 weeks on days 1, 22, and 43 during concurrent CRT with capecitabine (825 mg/m2 orally twice daily, Monday through Friday, on days of radiation only) and radiation (50.4 Gy in 28 fractions over 28 days) or Arm B to receive only concurrent CRT with capecitabine. In all subjects, restaging CT scan or MRI will be performed at 4-6 weeks after completion of neoadjuvant treatment to determine resectability. Patients without local or distant disease progression will be taken to the operative room for planned surgery (within 2 weeks of imaging). Postoperatively, resected patients will receive off study standard of care adjuvant gemcitabine (1000mg/kg IV weekly for 3 out of 4 weeks for 6 months). Post operatively resected patients will be followed for up for PFS and OS for up to 2 years. Citation Format: Matthew H.G Katz, Todd W. Bauer, Gauri Rajani Varadhachary, Reid B. Adams, Amy R. Lankford, Gina Petroni, Timothy N. Bullock, Craig L. Slingluff, Osama E. Rahma. A randomized multicenter phase Ib/II study to assess the safety and the immunological effect of chemoradiation therapy (CRT) in combination with Pembrolizumab (anti-PD1) to CRT alone in patients with resectable or borderline resectable pancreatic canc [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr CT220. doi:10.1158/1538-7445.AM2015-CT220