GEM+Nab-Paclitaxel Plus Losartan Followed by Stereotactic Radiotherapy for Locally Advanced Pancreatic Cancer

Pancreatic cancer (PC) is a malignant disease presenting high mortality rates, with a 5-year survival of about 11%, partly because of its known resistance to Chemotherapy (CHT) and Radiotherapy (RT). Radiation therapy in locally advanced and borderline resectable pancreatic cancer improves only local control as demonstrated by 5 studies published from 1980 to 2011 and confirmed by the more recent LAP-07 trial, which investigated conventional RT after induction CHT with the same results. Losartan was administered because it indirectly affects tumor microenvironment mechanisms of chemo- and radioresistance. PC cells, through transforming growth factor-β (TGF-β), platelet-derived growth factor (PDGF) and Angiotensin II activating signaling pathways lead to tumor microenvironment (TME) cells activation, like pancreatic stellate cells, which play a key role in chemoresistance. Angiotensin system and TGF-β increase and maintain the extracellular matrix, which acts as a barrier against drugs. Murphy et al. showed that Losartan administration during chemotherapy resulted in an effective decrease in plasma levels of TGF-β. Their unexpected successful results suggest that targeting not only tumor but also TME might be a novel treatment paradigm. The purpose of this study is to prospectively evaluate the safety and activity, in terms of resectability rate, of GEM-nab-paclitaxel chemotherapy with concurrent Losartan followed by SBRT in patients with LAPC. Secondary endpoints are margin-negative resection rate (R0), progression-free survival (PFS), overall survival (OS), blood biomarkers response, safety and quality of life. A Carbohydrate antigen-19.9 (CA19.9) reduction ≥15% from baseline to the end of induction therapy and Carcinoma embryonic antigen (CEA) are tested as a reliable prognostic factor.