Trial in progress: A randomized phase II study of pembrolizumab with or without defactinib, a focal adhesion kinase inhibitor, following chemotherapy as a neoadjuvant and adjuvant treatment for resectable pancreatic ductal adenocarcinoma (PDAC).
Authors: Davelaar John , Brown Zachariah , Linden Sheila , Rodriguez Christina , Elmadbouh Omer , Pachter Jonathan A. , Gong Jun , Hendifar Andrew Eugene , Lo Simon , Gaddam Srinivas , Nissen Nicholas , Burkhart Richard A. , Zheng Lei , Osipov Arsen 
Published: June 2022

TPS4192 Background: PDAC is an aggressive cancer. It remains refractory to checkpoint inhibition because of its significant desmoplastic and immunosuppressive tumor microenvironment (TME). Focal adhesion kinase (FAK), a non-receptor tyrosine kinase, is involved in tumor progression in many cancers and appears to be a targetable master regulator of the TME in PDAC. FAK inhibition combined with anti-PD1 antibody has been shown to modulate pancreatic stellate cells and decrease immunosuppressive myeloid and T-reg cells, leading to increased CD8 infiltration and improved survival in PDAC mouse models. A recent single arm phase I study of defactinib, a FAK inhibitor, combined with pembrolizumab, an anti-PD1 antibody, and chemotherapy was shown to be safe, and two confirmed partial responses were observed in patients with microsatellite-stable disease. Furthermore, increased CD8 T cell infiltration was observed in metastatic biopsies. Given the promising preclinical data and efficacy signals, as well as safety of the phase I clinical trial, our current study aims to assess the translational and clinical effects of sequentially combined defactinib and pembrolizumab following neoadjuvant and adjuvant chemotherapy in patients with high-risk resectable PDAC. Methods: This study is a multi-center, two-arm, randomized, open label, phase II clinical trial of neoadjuvant and adjuvant immunotherapy with defactinib and pembrolizumab, following neoadjuvant standard of care (SOC) gemcitabine and nab-paclitaxel in subjects with high-risk resectable PDAC. The primary objectives aim to assess changes in CD8 T cell intratumoral infiltration utilizing multiplex IHC and the pathologic complete response rate with defactinib and pembrolizumab or pembrolizumab alone, following neoadjuvant chemotherapy. Secondary objectives include assessment of disease-free survival, overall survival, and safety. Translational exploratory objectives include evaluating stromal and immune signatures among treatment groups via multiplex IHC and RNA/DNA sequencing. 36 subjects will be randomly assigned to receive 400 mg defactinib PO BID and 200 mg pembrolizumab IV every 3 weeks (Arm A) or 200 mg pembrolizumab IV alone every 3 weeks (Arm B). After enrollment, subjects will undergo 2 cycles (̃2 months) of standard neoadjuvant therapy of gemcitabine and nab-paclitaxel, followed by 2 cycles (6 weeks) of investigational treatment (Arm A or B) before surgical resection. Following surgery, subjects will receive SOC adjuvant chemotherapy followed by investigational treatment (Arm A or B) for 8 cycles (̃24 weeks). Key inclusion criteria include: resectable PDAC, CA 19-9>200, no prior systemic treatment for PDAC, and ECOG PS ≤1. As of February 2022, 14 patients have been enrolled. Clinical trial information: NCT03727880.