Durvalumab Following Chemoradiotherapy for Stage III Non-small Cell Lung Cancer: Differences in Survival Based on Age and Post-Progression Systemic Therapy.

Background: Concurrent chemoradiotherapy (cCRT) followed by 1 year of the immune checkpoint inhibitor (ICI) durvalumab is standard of care for patients with unresectable stage III nonsmall cell lung cancer (NSCLC).

Objectives: The purpose of this study was to evaluate survival outcomes of (1) cCRT followed by durvalumab in patients older versus younger than 75 years of age and (2) post-progression treatment with ICI alone versus chemotherapy alone versus combined ICI and chemotherapy.

Patients and methods: Patients with unresectable stage III NSCLC treated between January 2018 and July 2023 with cCRT followed by durvalumab were identified retrospectively. Progression-free survival (PFS) and overall survival (OS) from ICI start were analyzed in three cohorts aged < 65, 65-74, and ≥ 75 years. Multivariable Cox proportional hazard regression modelling of factors associated with OS was undertaken. Logistic regression analysis identified risk factors of early durvalumab discontinuation for toxicity. Time from first salvage drug treatment to death (OS-2) was described.

Results: A total of 472 patients were analyzed: the proportions aged < 65, 65-74, and ≥ 75 years were 34.3%, 42.8%, and 22.9%, respectively. Odds of early durvalumab discontinuation was 2.2-fold greater in the oldest (versus youngest) cohort. Age associated differences in median PFS (26.7 months, 20.3 months, and 14.2 months; p < 0.001) and OS (60.8 months, 44.4 months, and 27.6 months; p < 0.001) were observed. On multivariable analysis, factors associated with shorter OS were age ≥ 75 years (versus < 65), performance status 2/3 (versus 0/1), stage IIIC (versus IIIA), neutrophil to lymphocyte ratio (per 7.43 unit increase), Charlson comorbidity index (per 1 unit increase), tumoral PD-L1 expression < 1% (versus ≥ 50%, 1-49%, or unknown), and squamous histology (versus non-squamous). Of 264 patients with disease progression, 48.5% received subsequent drug therapy. Median OS-2 was longer with ICI alone (9.9 months) or ICI-chemotherapy (11.8 months) than platinum doublet chemotherapy (6.7 months.) For recurrences < 6 months from the last durvalumab infusion, OS-2 were similar across treatment groups.

Conclusions: In the studied cohort, OS was significantly shorter for patients ≥ 75 years of age treated with cCRT followed by durvalumab compared to those < 65 years. Post-progression systemic therapy was associated with modest efficacy, underscoring the need for new therapies.