Neoadjuvant Chemoradiotherapy With CRLX-101 and Capecitabine for Rectal Cancer

This is an open label, single-arm, multi-center, Phase Ib/II study designed to evaluate CRLX101, which is a NP formulation of camptothecin, dosed in combination with capecitabine and radiation therapy in patients with advanced rectal carcinoma. The purpose of the Phase Ib portion of this study is to identify the MTD of CRLX101 when added to standard neoadjuvant chemo-radiotherapy. The MTD will be based on the rate of dose-limiting toxicity (DLT) in Phase Ib, and will be assessed via NCI's CTCAE v4.0 toxicity criteria. The MTD will be assigned as the RP2D in this trial. If CRLX101 can be safely administered in combination with capecitabine and radiation at doses \>/= 9 mg/m\^2 IV in the Phase Ib study, then the trial will proceed to Phase II. Patients in the Phase Ib study will be included in the Phase II outcome analyses when applicable. The phase II study is designed to evaluate the efficacy of this regimen by assessing the rate of pathological complete response (pCR) while monitoring safety and tolerability. We anticipate accrual of up to 25 patients per year for the Phase II study, with a slightly faster accrual of 2-3 patients per month for Phase Ib given the broader inclusion criteria. During Phase Ib, we will evaluate the safety and determine the MTD/RP2D of CRLX101 + capecitabine (Cape) and radiation therapy (XRT) in patients with rectal cancer using the traditional 3+3 dose escalation design. Adverse events (AEs) will be evaluated via the CTCAE version 4.0. Patients in Phase Ib will also be followed for pathological response if they have resectable disease. If CRLX101 can be safely administered in combination with capecitabine and radiation at doses \>/=9 mg/m\^2 IV in the Phase Ib study, then the trial will proceed to Phase II with a primary objective of estimating the rate of pCR. Non-metastatic patients with resectable disease and treated at the MTD/RP2D in Phase Ib will be included in the Phase II study population. In Phase II, CRLX101 will be administered at the RP2D in combination with capecitabine and radiation in patients with locally advanced rectal cancer for a total of 5-6 weeks, depending on the total radiation dose. A total of 3 doses of CRLX101 will be administered every other week. Surgery will take place at least 6 weeks after the completion of chemoradiotherapy. For our non-metastatic Phase I patients and our Phase II population, postoperative adjuvant therapy is indicated regardless of whether a pCR is achieved or not. While there are a number of regimens used in the adjuvant setting, national guidelines do not specify one of these regimens over the other. Given the consistent application of adjuvant therapies in this population, we also plan to follow Phase II patients for both disease free survival (DFS) and overall survival (OS).