Stereotactic Centralized Ablative Radiotherapy for Locally Advanced Pancreatic Cancer: A Single-Arm Phase I Safety and Feasibility Study

Overview

This is a single-arm, phase I clinical study designed to evaluate the safety and feasibility of SCART (Stereotactic Centralized Ablative Radiation Therapy) dose escalation in patients with locally advanced pancreatic cancer. Pancreatic cancer carries a dismal prognosis, and the majority of patients are not surgical candidates at diagnosis. Radiotherapy is an important local treatment modality, but conventional approaches have shown limited efficacy. SCART is intended to deliver higher ablative doses to the tumor core while minimizing toxicity to surrounding normal tissues. In this trial, eligible patients will receive SCART with escalating dose levels using a standard 3+3 design. The primary endpoints are to determine the dose-limiting toxicity (DLT) and the maximum tolerated dose (MTD). Secondary endpoints include overall survival (OS), local control rate (LCR), and objective response rate (ORR).

Pancreatic cancer is among the most aggressive malignancies and is associated with poor prognosis. The 5-year survival rate remains below 10%, and most patients present with unresectable disease at diagnosis. Radiotherapy plays a pivotal role in local disease control, yet conventional fractionated radiotherapy (CFRT) has demonstrated limited survival benefits. Stereotactic body radiotherapy (SBRT) allows delivery of higher biologically effective doses with improved local control, but further dose escalation is restricted by normal tissue tolerance. SCART (Stereotactic Centralized Ablative Radiation Therapy) is an innovative technique that delivers ablative radiation doses to selected intratumoral sub-volumes while maintaining lower doses at the tumor periphery. This spatial dose distribution has the potential to induce bystander effects and enhance biological efficacy beyond that achievable with uniform SBRT. This phase I study is designed to evaluate the safety and feasibility of SCART dose escalation in patients with locally advanced pancreatic cancer. Patients will be enrolled into sequential dose cohorts (10 Gy, 13 Gy, 16 Gy, and 19 Gy per fraction within the SCART region) using a standard 3+3 dose-escalation design. All patients will also receive background SBRT (25 Gy in 5 fractions) covering the gross tumor volume and margin. The primary objective is to determine dose-limiting toxicities (DLTs) and establish the maximum tolerated dose (MTD) of SCART. Secondary objectives include overall survival (OS), local control rate (LCR), objective response rate (ORR), and treatment-related adverse events (AEs). Exploratory analyses will investigate potential biomarkers and immune response modulation associated with SCART. The estimated enrollment is 12-24 patients, with an accrual period of 24 months and a minimum follow-up of 12 months.