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Since the results of PACIFIC trial, consolidation treatment with durvalumab has become the standard of care for patients with stage III unresectable non-small cell lung cancer (NSCLC) with response to chemoradiotherapy (CRT). First reports show comparable efficacy and toxicity of this treatment strategy in the real-life setting. The data on factors predicting survival of these patients is however scarce. 

In this retrospective analysis we reviewed patients with stage III NSCLC and disease control after CRT who were included in durvalumab early access programme in Slovenia. Survival curves were estimated using the Kaplan-Meier method. Cox regression model was used for multivariate analysis to evaluate the effect of different prognostic factors including radiotherapy parameters.

A total of 59 patients were included, median age 62 years (36-73), 71.2% were male, 78.0% in stage IIIB or IIIC and 96.6% had ECOG 0-1. 66.1% had squamous-cell carcinoma and 30.5% adenocarcinoma. PD-L1 expression was 0% in 22.0%, ≥1% in 66% and unknown in 11.9% of patients. Concurrent chemotherapy was given to 59.3% of patients, sequential to 40.7%. Majority of patients (86.4%) received a total dose of at least 60Gy. Median follow up period was 28 months. Median post-CRT progression-free survival (PFS) for the entire cohort was 22.6 months and not reached for overall survival (OS). Estimated 12 and 18-month PFS rate were 67.8% and 55.9%, estimated 12 and 18-month OS rate were 84.7% and 72.8%. No patient experienced ≥G3 immune related (IO) toxicity, whereas 47.5% patients experienced G2 or less IO toxicity. Pneumonitis was observed in 9 patients (15.3%). There was no significant difference in PFS or OS in patients with 0% vs ≥1% PD-L1 expression and patients who received concurrent vs. sequential CRT. In the univariate analysis mean heart dose (MHD) was correlated with significantly improved PFS (p=0.023) and PTV volume showed trend toward significance (p=0.076). In the multivariate analysis MHD remained significant with HR 2.11 (95% CI 1.02-4.37), p=0.045. Estimated 12-month PFS rate for patients receiving MHD≤8.5Gy and >8.5Gy was 80.6% and 53.6%.

Outcomes of patients in real-life setting are aligned with PACIFIC trial. There might be an association between radiotherapy dose to the heart and survival of patients treated with this combined therapy that warrants further investigation.