4127 Background: Borderline resectable pancreatic cancer (BRPC) is frequently associated with positive surgical margins and a poor prognosis when treated with upfront surgery. This study was designed to assess whether neoadjuvant chemoradiotherapy (CRT) with S-1 increases the R0 resection rate. Methods: This was a multicenter, single-arm, phase II study. Patients with BRPC received S-1 (40 mg/m2 bid) and concurrent radiotherapy (50.4 Gy in 28 fractions) before surgery if they fulfilled any of the following: (1) bilateral impingement of the superior mesenteric vein or portal vein; and (2) tumor contact ≤180° with the superior mesenteric artery, common hepatic artery, or celiac axis. The primary endpoint was the R0 resection rate in BRPC confirmed by central review. Secondary endpoints were overall survival (OS), progression-free survival (PFS), response rate (RECISTv1.1), pathological response rate, surgical morbidity (Clavien–Dindo classification), and toxicity (CTCAEv4.0). At least 40 patients were required, with one-sided α = 0.05 and β = 0.05, with an expected and threshold value for the primary endpoint of 30% and 10%. Results: Fifty-two patients were eligible, of whom 41 had BRPC by central review. CRT was completed in 50 (96%) patients and was well tolerated. The rate of grade 3/4 toxicity with CRT was 43%. The R0 resection rate was 52% (95% CI, 37.6%–66.0%) in 52 eligible patients and 63% (95% CI, 46.9%–77.9%) in 41 patients with BRPC. The radiological response rate was 5.8%, while destruction of > 50% of tumor cells was shown microscopically in 32% of patients. Postoperative grade III/IV adverse events were observed in 7.5% of operated patients. Among the 52 eligible patients, the 2-year OS rate, median OS, and median PFS were 51%, 25.8 mo, and 6.7 mo. Of the 41 patients with BRPC, the 2-year OS rate, median OS, and median PFS were 58%, 30.8 mo, and 10.4 mo. Conclusions: S-1 and concurrent radiotherapy appear to be feasible and effective at increasing the R0 resection rate with encouraging survival rates in BRPC. A phase II/III trial evaluating this treatment is ongoing. Clinical trial information: NCT02459652.
Phase II trial of neoadjuvant S-1 and concurrent radiotherapy for borderline resectable pancreatic cancer (JASPAC05)
