RESUMEN
Aims: To investigate the safety profile, dose-limiting toxicity and antitumor activity of PEP503 (NBTXR3) nanoparticles with radiotherapy and concurrent chemotherapy in patients with locally advanced or unresectable rectal cancer. Methods: Patients will receive a single intratumoral injection of the nanoparticles, followed by radiotherapy and intravenous infusion of fluorouracil or oral capecitabine concurrently. In phase Ib (escalation phase, 3 + 3 design), volume escalation is based on the tumor volume of 5, 10, 15 and 22% of total baseline tumor volume. In phase II (expansion phase), 18 additional patients will be enrolled. Discussion: This study will be the first prospective, open-label, single-arm, nonrandomized study to investigate the efficacy and safety profile of PEP503 (NBTXR3) nanoparticles with radiotherapy and chemotherapy in these patients. Trial registration number: NCT02465593 (ClinicalTrials.gov).
Preoperative concurrent chemoradiotherapy is the standard treatment for patients with locally advanced rectal cancer. PEP503 (NBTXR3) has radioenhancement properties. Therefore, the dose per fraction during radiotherapy could be reduced, and the same therapeutic efficacy could be retained when PEP503 (NBTXR3) nanoparticles are used during radiotherapy. This study reveals the protocol of a phase Ib/II study to investigate the safety profile, dose-limiting toxicity and antitumor activity of PEP503 (NBTXR3) nanoparticles with radiotherapy combined with concurrent chemotherapy in patients with locally advanced or unresectable rectal cancer.