Progression free survival (PFS) in Asian vs non-Asian patients (pts) with EGFR mutant non-small cell lung cancer (NSCLC) receiving osimertinib.

Abstract

e21679 Background: Third generation EGFR tyrosine kinase inhibitor (TKI) osimertinib demonstrated superior PFS and OS compared to earlier generation TKIs in pts with EGFR+ NSCLC. These pts are disproportionately Asian, female, and never-smokers. Contradictory data has been reported regarding the PFS and OS to osimertinib in Asian pts as compared to 1st and 2nd generation EGFR TKI. These inconsistencies warrant further investigation. The purpose of this study is to evaluate the PFS in Asian vs non-Asian pts with EGFR+ NSCLC receiving osimertinib. Methods: We conducted a single institution IRB approved retrospective study of pts with EGFR+ NSCLC. PFS was evaluated in pts treated from 1/2013 – 12/2019. Disease and treatment characteristics were summarized using frequency distributions and Kaplan-Meier curves for comparison of subgroups. Results: Of 190 EGFR+ pts: 52 (27%) Asian, 108 (57%) Caucasian, 125 (66%) female, 172 (91%) advanced disease, 107 (56%) never-smokers. Baseline characteristics in Asian and non-Asian pts were similar in regards to de-novo stage IV disease (71% vs 65%, p = 0.80), brain metastases (42% vs 54%, p = 0.48), and differed with regards to ever-smoking (29% vs 56%, p = 0.04). Treatment: 126/172 (73%) pts with advanced disease received TKI across all lines of therapy; 92/126 received osimertinib (22 (24%) 1st line; 45 (49%) 2nd line; 18 (19%) 3rd line; 7 (8%) ≥4th line). There were insufficient number of pts who received osimertinib in the 1st line to comment on differences in PFS between Asian and non-Asian pts. In the 2nd line, 19 Asian pts and 26 non-Asian pts received osimertinib, with no observed difference in PFS (median 15.4 v 13.8 months, p = 0.20). Moreover, Asian pts who received osimertinib as second line therapy had superior PFS (median 15.4 vs 9.6 months, p < 0.01) compared to Asian pts who received earlier generation TKIs, likely due to T790M resistance. Conclusions: Among second line advanced EGFR+ NSCLC, we did not observe a difference in PFS between Asian and non-Asian pts treated with osimertinib. Median PFS in Asian pts treated with osimertinib was longer compared to those treated with 1st or 2nd generation TKIs in the 2nd line setting. Our study highlights the the role of ethnic background in response to EGFR therapies and may warrant further study.