Indian lung cancer patients with EGFR mutations: clinical response to TKI
Clinical collaborator: Dr. Kumar Prabhash (TMH)Non-small-cell lung cancer (NSCLC) studies have shown a significant higher prevalence of EGFR mutations in East Asian populations versus Caucasian populations of European descent (~30% in the Japan and ~10% in USA). However, frequency of EGFR mutations and their clinical response in most other ethnic populations, including India, remains to be explored. This study utilize Taqman based approach to genotype EGFR mutations in exon 18, 19 and 21 and establishes a correlation between the underlying mutation and the clinical response of the patients to the EGFR tyrosine kinase inhibitor.
In this study, we present the first report for correlation between EGFR mutation and clinical response to oral EGFR tyrosine kinase inhibitor among 119 non small cell lung cancer patients of Indian ethnicity. In our study, 39 out of 111 patients, i.e. 35% of the patients were found to harbor an EGFR mutation. The previous study from India found that the mutation rate was 51.8%. It is likely that both our study and the prior Indian report overestimated the incidence of EGFR mutation, because of a small sample size and clinically selected patients. The overall response to oral TKI therapy was 30%. Patients with an activating mutation of EGFR had a response rate of 74%, while the response rate in patients with wildtype EGFR was 5%, which was a statistically significant difference, p<0.001. This is very similar to what has been reported in the literature, with a response rate of 72% in mutant positive patients, and a response rate of 1.1% in mutant negative patients.
Survival by EGFR mutation status
(A) Progression-free survival (PFS) for the EGFR mutant patients was 10 months (95% CI: 8-11.9 months), while the estimated median PFS for EGFR mutation negative patients was 2 months (95% CI: 1.5-2.5 months), p=0.000 by log rank test (Mantel Cox).
(B) Overall survival (OS) for EGFR mutant patients was 21 months (95% CI: 12.4-25.6 months), while the estimated median OS for EGFR mutantion negative patients was 10 months (95% CI: 7.4-12.6 months), p=0.001 by log rank test (Mantel Cox).