Clinical Outcomes of Maintenance Durvalumab After Definitive Concurrent Chemoradiotherapy in Unresectable Locally Advanced Stage III NSCLC According to EGFR and ALK Status: Korean Cancer Study Group LU-22-18

Introduction

The role of maintenance durvalumab after definitive concurrent chemoradiotherapy (CCRT) in unresectable locally advanced NSCLC with EGFR mutation or ALK translocation remains unclear. We compared the effectiveness of durvalumab maintenance therapy in groups with EGFR and ALK wild-type versus those with EGFR or ALK mutations.

Methods

In this retrospective multicenter observational study, patients with locally advanced NSCLC without progression after CCRT followed by maintenance durvalumab and available molecular test results (EGFR and ALK) were eligible. The primary objective was to compare progression-free survival (PFS) between EGFR and ALK wild-type and EGFR or ALK mutant NSCLC. Secondary objectives include overall survival according to EGFR or ALK mutation and programmed death-ligand 1 (PD-L1) expression.

Results

Among 339 patients, 279 had wild-type EGFR/ALK, 41 had EGFR mutations and 19 had ALK translocations. The median age was 68 years with 276 male individuals (81.4%) and 63 female individuals (18.6%), 165 (49.3%) had adenocarcinoma, 149 (44.5%) had squamous cell carcinoma, and 21 (6.3%) had other histologic types, 120 (35.4%) had stage IIIA, 168 (49.6%) stage IIIB, and 51 (15.0%) had stage IIIC. Most of the patients (n = 288, 85%) achieved partial response to CCRT, two (0.6%) had a complete response, and 49 patients (14.4%) had stable disease. Excluding four patients with unknown PD-L1 tumor proportion score (TPS), 16 (4.8%) had a PD-L1 TPS of 0, 168 (50.1%) had 1 to 49, and 151 (45.1%) had 50 or higher. The median PFS was 21.4 months (95% confidence interval [CI]: 17.3–25.3) for the EGFR/ALK wild-type group and 21.0 months (95% CI: 15.7–not available [NA]) for the EGFR or ALK mutant group with no difference (p = 0.74). Significant differences occurred in PFS on the basis of PD-L1 expression with values of 13.6 (95% CI: 10.5–NA), 18.7 (95% CI: 15.1–26.9), and 24.7 (95% CI: 20.7–NA) months for TPS of 0, 1–49, and 50 or higher, respectively (p = 0.02).

Conclusions

Durvalumab maintenance therapy after definitive CCRT in unresectable locally advanced NSCLC patients with EGFR or ALK mutation demonstrates comparable clinical outcomes to those with wild-type EGFR/ALK when PD-L1 expression is present.