Efficacy of immune checkpoint inhibitors plus platinum-based chemotherapy as 1st line treatment for patients with non-small cell lung cancer harboring HER2 mutations: Results from LC-SCRUM-Asia

Abstract

Introduction: HER2 mutations are reported to occur in 2%-5% of all cases of non-small cell lung cancer (NSCLC). The clinical outcomes in patients with HER2-mutant NSCLC treated with immune checkpoint inhibitors (ICIs) plus platinum-based chemotherapy as 1st line treatment still remain unclear.

Methods: Using the large-scale clinico-genomic database of LC-SCRUM-Asia, the clinico-genomic characteristics and therapeutic outcomes of patients with HER2-mutant NSCLC were investigated.

Results: Of the 15,251 patients with NSCLC enrolled in the LC-SCRUM-Asia database, tumor HER2 mutations were detected in 402 patients (2.6 %). The most common subtype of HER2 mutations was exon 20 in-frame insertions (79 %), followed in frequency by mutations in the tyrosine kinase domain other than Exon20ins (10 %) and mutations in extracellular domains (7 %). NSCLCs harboring HER2 mutations showed a higher tumor mutation burden (TMB) as compared with NSCLCs harboring EGFR mutations or ALK fusions (median: 4.22 vs. 2.54 and 2.52 mutation per megabase, respectively). Of the 402 patients, 268 patients had received platinum-based chemotherapy with ICIs (Chemo-ICI, n = 95) or without ICI (Chemo-alone, n = 173) as 1st line treatment. The progression-free survival (PFS) was significantly longer in the Chemo-ICI group as compared with the Chemo-alone group (median 8.5 vs. 6.3 months; HR [95 %CI]: 0.66 [0.50-0.88]; P < 0.005). Multivariate analysis identified use of ICIs in addition to platinum-based chemotherapy as an independent favorable prognostic factor for PFS. There was no significant difference in the overall survival between the patients of the Chemo-ICI and Chemo-alone groups (median 31.1 vs. 23.3 months; HR [95 %CI]: 0.80 [0.57-1.12], P = 0.20).

Conclusions: Addition of ICIs to platinum-based chemotherapy in 1st line treatment may improve the PFS in patients with HER2-mutant NSCLC. The relatively high TMB might be involved in the prolongation of the PFS in patients with HER2-mutant NSCLC receiving platinum-based chemotherapy with ICIs.

Keywords: HER2 mutations; Immune checkpoint inhibitors; LC-SCRUM-Asia; Non-small cell lung cancer; Tumor mutation burden.