308P - Phase II study of S-1 and cisplatin with concurrent thoracic radiotherapy followed by durvalumab for unresectable, locally advanced non-small cell lung cancer in Japan (SAMURAI study)

Background

The standard of treatment for patients with unresectable, locally advanced NSCLC (LA-NSCLC) is chemoradiotherapy (CRT) followed by durvalumab. Although phase II studies in Japan have shown high efficacy and good tolerability of CRT with cisplatin + S-1 (SP), no prospective study using durvalumab after SP-based CRT has been reported. Thus, we conducted a phase II study using durvalumab after SP-based CRT for LA-NSCLC. The primary analysis was already presented in IASLC Asia 2022. Here, we report the additional results.

Methods

This study was a single arm, prospective, multicenter, phase II trial. Eligibility criteria included patients with unresectable stage III LA-NSCLC, PS 0-1, aged over 20. Patients with EGFR mutation or ALK rearrangement were allowed. Cisplatin (60 mg/m2, day1) and S-1 (80-120 mg/body, day1-14) were administered with two 4-week cycles with concurrent thoracic radiotherapy (60Gy) followed by durvalumab (10 mg/kg) every two weeks for up to one year. The primary endpoint was 12-month PFS rate from first registration assessed by the investigators. The planned sample size was calculated to be 58 patients at α = 0.10 (one-sided) and β = 0.8, with a threshold value of 47% calculated from TORG1018 study in Japan, an expected value of 63% calculated from PACIFIC trial.

Results

From December 2019 to August 2020, 59 patients were enrolled. The transition rate from first registration to durvalumab was 86.4% (51/59). The median follow-up time was 21.9 months. The 12-month PFS rate from first registration was 72.5% (80% CI: 64.2–79.2, 95% CI: 59.1–82.2), which met the primary endpoint. Both median PFS and OS were not reached. The 12-month PFS and OS rate from second registration were 70.1% and 96.1%, respectively. The 12-month PFS and OS rate from second registration who received durvalumab after CRT in <14 days were not better than those received in ≥14 days (PFS; 54.2 vs 75.7%, p=0.6636, OS; 92.9 vs 97.3%, p=0.5486). The PD-L1 expression was not a significant factor in multivariate analysis for PFS (HR 1.454, p=0.381) and OS (HR 1.324, p=0.693) in ITT population.

Conclusions

SP-based CRT could be a candidate for the further evaluation. Further follow up are needed.

Clinical trial identification

jRCTs031190127.

Editorial acknowledgement

Legal entity responsible for the study

Shigeru Tanzawa.

Funding

AstraZeneca.

Disclosure

S. Tanzawa: Financial Interests, Personal and Institutional, Research Grant: AstraZeneca. K. Shibata: Financial Interests, Personal, Invited Speaker: AstraZeneca, Boehringer Ingelheim. N. Seki: Financial Interests, Personal, Invited Speaker: AstraZeneca, Taiho Pharmaceutical, Ono Pharmaceutical, Chugai Pharmaceutical, Eli Lilly, MSD, Daiichi Sankyo, Boehringer Ingelheim. All other authors have declared no conflicts of interest.