2396 - The Effect of Adding Consolidation Durvalumab to Hypofractionated Involved-Field Radiotherapy with Concurrent Chemotherapy for Locally Advanced Non-Small Cell Lung Cancer: Does Durvalumab Consolidation Therapy Bring Survival Benefits?

Purpose/Objective(s): Since 2010, we have been performing definitive chemoradiotherapy (CCRT) using hypofractionated involved-field radiotherapy (Hypofx-IFRT) in 2.5 Gy fractions for locally advanced non-small cell lung cancer (LA-NSCLC). In 2018, with the aim of improving survival, we started consolidation durvalumab after CCRT. We herein report a retrospective analysis of the additional value of consolidation durvalumab for Hypofx-IFRT in LA-NSCLC patients.

Materials/Methods: Between 2010 and 2021, 70 patients of =80 years of age with treatment-naïve confirmed LA-NSCLC and an Eastern Cooperative Oncology Group (ECOG) performance status of 0–2 were treated, including 36 patients who were treated without durvalumab between 2010 and 2016 and 34 who received consolidation treatment with durvalumab between 2018 and 2021. Hypofx-IFRT was delivered at a median dose of 67.5 Gy (range, 60-70) in a single fraction (2.5 Gy) in both groups. Concurrent platinum-based chemotherapy was administered. Overall survival and progression-free survival were calculated from the date of treatment initiation to the date of progression and the date of death or the last follow-up examination, respectively.

Results: All patients were assessed for response and toxicity. The median age was 68 years (range, 42-80 years); 47 patients were male and 23 were female. The histological types included adenocarcinoma (n=40), squamous cell carcinoma (n=26), and other types of NSCLC (n=4). The disease stages were as follows: stage IIA (n=1), stage IIB (n=5), stage IIIA (n=26), IIIB (n=33), and IIIC (n=5). A comparison between the durvalumab+ and durvalumab- groups at three years showed that the overall survival rate was 61.8% vs. 61.1% (p = 0.238), respectively, while progression-free survival was 35.3% vs. 38.9% (p = 0.989). The time for first failure was 9.2 months in the durvalumab+ group and 9.6 months in the durvalumab– group. Distant metastasis alone was the first failure pattern to develop in 32.3% of patients in the durvalumab+ group and 44.4% of the patients in the durvalumab– group. The 3-year cumulative incidence of infield recurrence was 32.4% in the durvalumab+ group and 30.6% in the durvalumab– group (p = 0.842). The 3-year cumulative incidence of distant metastasis was 35.3% in the durvalumab+ group and 56.9% in the durvalumab- group. The incidence rates of grade 3 pneumonitis were 14.7% in the durvalumab+ group and 8.3% in the durvalumab– group. Grade 5 esophageal perforation was reported in the durvalumab+ groups.

Conclusion: In this retrospective analysis, consolidation durvalumab after HypoFx-IFRT with chemotherapy did not result in a significant survival benefit in patients with LA-NSCLC. Further investigations are needed to assess the role of durvalumab consolidation therapy after HypoFx-IFRT with chemotherapy in the treatment of LA-NSCLC.