HER2 Amplification in Advanced NSCLC Patients After Progression on EGFR-TKI and Clinical Response to EGFR-TKI Plus Pyrotinib Combination Therapy

Background: HER2 (or ERBB2) amplification is an important mechanism for acquired resistance to EGFR tyrosine kinase inhibitors (TKI). The benefits of HER2-targeted therapy have been limited. Herein, we investigated the molecular and clinical patterns of HER2 amplification in non-small cell lung cancer (NSCLC) patients during progression on EGFR-TKIs and the potential of combining EGFR-TKI and pyrotinib to overcome resistance. Methods: In this study, 1,637 NSCLC cases from Geneseeq after progression of EGFR-TKIs were screened and analyzed by next generation sequencing (NGS), in which 48 patients with HER2 amplification were eligible and enrolled. A total of 403 patients from Sun Yat-sen University Cancer Center (SYSUCC) were screened and five patients with concomitant EGFR mutations and HER2 amplification were retrospectively collected to assess the effect of afatinib or combination of EGFR-TKI and pyrotinib. Results: In the 48 patients from the Geneseeq cohort, 27 (56.2%) patients suffered from resistance of 1st/2nd generation EGFR-TKI, and 21 (43.8%) patients from 3rd generation. As for the five patients forming the SYSUCC cohort, three patients were treated with afatinib, one achieved partial response (PR) with progression-free survival (PFS) of 6 months and two quickly developed disease progression. Two patients were treated with EGFR-TKIs plus pyrotinib, one receiving gefitinib plus pyrotinib achieved PR with PFS of 8 months and benefited from osimertinib plus pyrotinib for 3 months till data-off; one receiving osimertinib plus pyrotinib achieved SD for 4 months till data-off. The most common co-occurring alteration was TP53 (91.7%) in the mutation profile of the 48 patients from the Geneseeq cohort, and four patients had TP53 co-mutations of the five patients from the SYSUCC cohort. Conclusion: In this study, we detected 7% HER2 amplification present in EGFR-TKIs resistance. Patients with concomitant EGFR mutation and HER2 amplification may derive clinical benefit from therapies that target both EGFR and HER2.

Automated summary

In this study, HER2 amplification was found in 7% of cases with acquired resistance to EGFR-TKIs. Patients with concomitant EGFR mutation and HER2 amplification may benefit from therapies targeting both EGFR and HER2.