A phase 2 trial of durvalumab treatment following radiation monotherapy in patients with non-small cell lung cancer ineligible for stage III chemoradiotherapy: The SPIRAL-RT study

Background: Although concurrent chemoradiotherapy (CCRT) followed by durvalumab is the standard treatment for patients with stage III non-small cell lung cancer (NSCLC), only half of the patients are allowed to receive CCRT in real-world settings. We evaluated the efficacy and safety of durvalumab after radiation monotherapy for NSCLC patients who are ineligible for chemoradiotherapy. Methods: A single-arm, prospective, open-label, multicenter phase II trial was conducted in Japan. The patients received radiation (54–66 Gy) followed by durvalumab (10 mg/kg every 2 weeks for up to 12 months). The primary endpoint was the 1-year progression-free survival (PFS) rate. The secondary endpoints were the objective response rate (ORR), PFS, overall survival (OS), and safety. Results: Between September 2019 and April 2021, 33 patients were enroled from eight institutions. The median patient age was 79 years, and the majority of patients were male (78.8%). The 1-year PFS rate was 39.1% (90% confidence interval [CI]: 24.7–54.6%). Three patients (9.1%) had a performance status of 2. The ORR was 42.4% (95% CI: 27.2–59.2%). The median PFS and OS were 8.9 (95% CI: 7.4–19.4) and 20.8 (95% CI: 15.8–not estimable) months, respectively. The most common adverse event was radiation pneumonitis (51.5%). The median treatment duration was 6.4 (range: 0.50–12.0) months for durvalumab. At the endpoint, 30.3% (10/33) of the patients had completed 1 year of durvalumab therapy. Conclusions: Durvalumab is an effective treatment with tolerable toxicity following radiation monotherapy in stage III NSCLC patients who are ineligible for chemoradiotherapy. Trial registration: JMA-IIA00434 (jRCT).