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.