Phase I Nab-Paclitaxel Plus Gemcitabine With Proton Therapy for Locally Advanced Pancreatic Cancer (LAPC)

The purpose of this study is to determine the maximum tolerated dose of the chemotherapy drugs nab-paclitaxel and gemcitabine when combined with hypofractionated ablative proton therapy for the treatment of locally advanced pancreatic cancer. You will receive proton therapy once a day (Monday - Friday) for 3 weeks. Participants will also receive chemotherapy on each Monday of those three weeks.

The investigators propose a phase I trial to determine the maximum tolerable dose (MTD) and the recommended dose for phase II (RP2D) of concurrent nab-paclitaxel + gemcitabine in combination with ablative IMPT delivered as a fixed dose of 67.5 Gy in 15 fractions daily fractions with 5 fractions per week. In contrast to prior pancreatic cancer studies of chemoradiotherapy which utilized photon RT to treat gross disease and elective lymph nodes (1,2) the proposed study is hypothesized to reduce toxicity risk by limiting highly conformal IMPT to the gross tumor volume. Furthermore, to increase the margin of safety in a manner similar to published data from MDACC (3), the high dose region will be limited to areas at least 5 mm from nearby GI structures (duodenum, small bowel, stomach, etc.). Regions within this area will be treated only to 37.5 Gy in 15 fractions. This dose limitation is also important given that paclitaxel, in addition to increasing systemic efficacy, is a known radiosensitizer (1).