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Koichi Takayama



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    EP1.14 - Targeted Therapy (ID 204)

    • Event: WCLC 2019
    • Type: E-Poster Viewing in the Exhibit Hall
    • Track: Targeted Therapy
    • Presentations: 1
    • Now Available
    • Moderators:
    • Coordinates: 9/08/2019, 08:00 - 18:00, Exhibit Hall
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      EP1.14-05 - Clinical Characteristics of Osimertinib Responder in Non-Small Cell Lung Cancer Patients with EGFR-T790M Mutation (Now Available) (ID 207)

      08:00 - 18:00  |  Author(s): Koichi Takayama

      • Abstract
      • Slides

      Background

      Osimertinib is a mutant-selective EGFR inhibitor that is effective against non-small cell lung cancer (NSCLC) patients with the EGFR-T790M mutation, who are resistant to EGFR-tyrosine kinase inhibitors (EGFR-TKIs). However, the factors affecting response to osimertinib treatment are unknown.

      Method

      In this retrospective study, 27 NSCLC patients with the EGFR-T790M mutation were enrolled at 5 institutions in Japan.

      Result

      Among several parameters tested, the progression-free survival (PFS) associated with the initial EGFR-TKIs was positively correlated with the PFS after osimertinib treatment (p = 0.021). The median PFS following osimertinib treatment and the overall survival (OS) were longer in patients who responded to osimertinib than in those who did not (17.7 months versus 3.5 months, p = 0.009 and 24.2 months versus 13.5 months, p = 0.021, respectively). A multivariate analysis demonstrated that the PFS with initial EGFR-TKIs was significantly related to the PFS with osimertinib treatment (p = 0.035), whereas osimertinib response was significantly related to the PFS and OS with osimertinib treatment (p = 0.016 and p = 0.006, respectively).

      Conclusion

      Our retrospective observations indicate that PFS following the initial EGFR-TKI treatment and the response rate to osimertinib might be promising predictors for effective osimertinib treatment in NSCLC patients with the EGFR-T790M mutation.

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    P1.01 - Advanced NSCLC (ID 158)

    • Event: WCLC 2019
    • Type: Poster Viewing in the Exhibit Hall
    • Track: Advanced NSCLC
    • Presentations: 1
    • Now Available
    • Moderators:
    • Coordinates: 9/08/2019, 09:45 - 18:00, Exhibit Hall
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      P1.01-47 - Prospective Study for Usefulness of Plasma DNA on Prediction of Third Generation EGFR Tyrosine Kinase Inhibitors (S-PLAT Study) (Now Available) (ID 1112)

      09:45 - 18:00  |  Author(s): Koichi Takayama

      • Abstract
      • Slides

      Background

      The AURA and FLAURA studies have shown that EGFR T790M mutation detected in cfDNA is correlated with efficacy of osimertinib as measured via overall response rate (ORR), and progression-free survival (PFS). However, the following clinical-related questions have been raised: Can other different assay systems confirm the results mentioned above? Does T790M level affect osimertinib treatment efficacy? Do mutations at loci other than EGFR influence treatment efficacy?

      Method

      This is a prospective observational study, joining 27 Japanese hospitals. Plasma samples from patients with non-small cell lung cancer (NSCLC) who acquired resistance to EGFR-TKI (gefitinib, erlotinib, afatinib) were collected between Feb 2017 and Jan 2019. We tested T790M by MBP-QP method which has been newly developed using cfDNA and investigated the concordance with the result by cobas EGFR mutation Test v.2 (tissue and/or plasma) which is commercially available. We also checked the allele frequency (AF) of T790M in cfDNA by ddPCR and the mutational status of cancer related actionable genes by cfDNA specific NGS (Guardant360). The major objectives were ORR, disease control rate (DCR) to osimertinib and PFS in patients with T790M positive by MBP-QP method.

      Result

      Among 145 NSCLC patients who acquired resistance to 1st or 2nd EGFR-TKI, T790M was detected in 57 patients by cobas (tissue and/or plasma), and these patients received osimertinib (80mg daily). T790M was detected by cobas in 16 patients from plasma, 44 patients from tissue, 3 patients from both samples. Among assessable patients, ORR, DCR and PFS in patients with T790M positive by cobas from plasma were 66.7%, 86.7%, 194 days, those of tissue were 53.5%, 97.7%, 186 days, respectively. In these 57 patients, MBP-QP also could detect T790M from 10 patients from plasma, and ORR, DCR and PFS in patients with T790M positive by MBP-QP from plasma were 75.0%, 87.5%, 184 days, respectively. These results suggest that T790M detection from cfDNA not only by cobas but also MBP-QP is correlated with RR of osimertinib. Now, using ddPCR and Guardant360, we have been investigating about the relationship between T790M AF and RR to osimertinib, and the influence of mutations at loci other on efficacy of osimertinib.

      Conclusion

      cfDNA analysis can be predictive for osimertinib efficacy, just as re-biopsy. Whether comprehensive approach including AF and coexistence of other actionable genes is more precisely informative for drug efficacy has been continuously analyzed.

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