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Masayuki Takeda
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P2.14 - Targeted Therapy (ID 183)
- Event: WCLC 2019
- Type: Poster Viewing in the Exhibit Hall
- Track: Targeted Therapy
- Presentations: 1
- Moderators:
- Coordinates: 9/09/2019, 10:15 - 18:15, Exhibit Hall
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P2.14-15 - Impact of Coexisting Gene Mutations in EGFR-Mutated Non–Small Cell Lung Cancer Before Treatment on EGFR T790M Mutation Status After EGFR-TKIs (ID 1347)
10:15 - 18:15 | Presenting Author(s): Masayuki Takeda
- Abstract
Background
The T790M secondary mutation of epidermal growth factor receptor gene (EGFR) is the most common mechanism of acquired resistance to first- or second-generation EGFR tyrosine kinase inhibitors (TKIs). We investigated the association between gene mutation profile in EGFR mutation–positive non–small cell lung cancer (NSCLC) before EGFR-TKI treatment and T790M status after treatment.
Method
A total of 57 EGFR mutation–positive NSCLC patients who had undergone a repeat biopsy (tissue or liquid) after failure of treatment with a first- or second-generation EGFR-TKI and who had sufficient tumor tissue available from before treatment for genetic analysis was enrolled. The gene mutation profile of tumor tissue obtained before EGFR-TKI treatment was evaluated by next-generation sequencing with a comprehensive cancer gene panel (409 genes). The number of potentially damaging nonsynonymous mutations was predicted with PolyPhen-2 software.
Result
Progression-free survival during EGFR-TKI treatment did not differ significantly between patients who developed T790M-mediated resistance and those who developed T790M-independent resistance. The predicted number of damaging nonsynonymous mutations in pretreatment tumor tissue was significantly lower in patients who developed T790M-mediated resistance than in those with T790M-independent resistance (P = 0.024).
Conclusion
Coexisting mutations in tumor tissue before EGFR-TKI treatment may contribute to the emergence of cell clones responsible for development of T790M-dependent or T790M-independent TKI resistance in patients with EGFR-mutated NSCLC. Multiplex genomic testing of pretreatment tumor tissue may thus provide a means of identifying patients likely to develop T790M-mediated TKI resistance and therefore inform treatment selection.