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Brett Carter



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    MA09 - EGFR & MET (ID 128)

    • Event: WCLC 2019
    • Type: Mini Oral Session
    • Track: Targeted Therapy
    • Presentations: 1
    • Now Available
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      MA09.03 - Identification of Mechanisms of Acquired Resistance to Poziotinib in EGFR Exon 20 Mutant Non-Small Cell Lung Cancer (NSCLC) (Now Available) (ID 2904)

      15:15 - 16:45  |  Author(s): Brett Carter

      • Abstract
      • Presentation
      • Slides

      Background

      Insertions/mutations in exon 20 of EGFR occur in ~2% Insertions/mutations in exon 20 of EGFR occur in ~2% of all lung adenocarcinomas. These alterations are characterized by primary resistance to approved tyrosine kinase inhibitors (TKIs) with response rates of <12%. We have shown that exon 20 insertions restrict the size of the drug-binding pocket, limiting binding of large inhibitors. However, poziotinib can circumvent these steric changes and is a potent inhibitor of EGFR exon 20 mutants. In our investigator-initiated phase 2 trial of EGFR exon 20 mutant NSCLC, poziotinib was associated with a best objective response rate of 55% (Heymach et al, 19th WCLC). Herein, we use preclinical models and clinical samples from our phase 2 study to identify mechanisms of acquired poziotinib resistance (NCT03066206).

      Method

      EGFR exon 20 insertion (D770insNPG) genetically engineered mice (GEM) were treated with poziotinib until progression. Upon progression, tumor DNA and protein were analyzed using whole exome sequencing (WES) and reverse phase protein assay (RPPA). Mandatory and optional biopsies were obtained at baseline and progression, respectively, from patients treated in our phase 2 trial of poziotinib in EGFR exon 20 mutant NSCLC. Serial cfDNA was collected at baseline, 8 weeks of therapy, and on progression. Patient samples were analyzed using targeted next generation sequencing or WES.

      Result

      Poziotinib acquired-resistance GEM tumors acquired mutations in ErbB4, KRAS, and other genes which represent potential targetable bypass pathways. Resistant GEM tumors displayed increased activation of MAPK, AKT, ERK and MEK compared to sensitive tumors, suggesting that poziotinib acquired resistance is associated with reactivation of the MAPK/PI3K pathways. We enrolled 50 EGFR exon 20 mutant patients in our phase 2 trial. Analysis of matched pre-poziotinib and on-progression samples from 20 responding patients revealed acquired EGFR tyrosine kinase domain point mutations in 4 patients (T790M (2), V774A (1), D770A, (1)). Ba/F3 cells co-expressing EGFR exon 20 insertion (S768supSVD) and T790M were resistant to poziotinib, suggesting that T790M is a poziotinib resistance driver. Potential acquired EGFR-independent resistance mechanisms identified in patients to date include PIK3CA E545K (1), MAP2K2 S94L (1), MET amplification (1), EGFR amplification (2), and CDK6 amplification (2).

      Conclusion

      Parallel to acquired resistance mechanisms seen in classical EGFR mutation, acquired resistance to poziotinib can be mediated through EGFR-dependent mechanisms, notably T790M and other EGFR tyrosine kinase domain point mutations. EGFR-independent resistance mechanisms include activation of bypass pathways. Preclinical validation of resistance mechanisms and additional analysis of patient samples will be presented at the meeting.

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    MA11 - Immunotherapy in Special Populations and Predictive Markers (ID 135)

    • Event: WCLC 2019
    • Type: Mini Oral Session
    • Track: Immuno-oncology
    • Presentations: 1
    • Now Available
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      MA11.11 - STK11/LKB1 Genomic Alterations Are Associated with Inferior Clinical Outcomes with Chemo-Immunotherapy in Non-Squamous NSCLC (Now Available) (ID 2898)

      14:00 - 15:30  |  Author(s): Brett Carter

      • Abstract
      • Presentation
      • Slides

      Background

      Addition of pembrolizumab (P) to platinum-doublet chemotherapy [carboplatin (or cisplatin) and pemetrexed (CP)] prolongs overall survival and is a standard of care (SOC) for the 1st line treatment of metastatic EGFR/ALK wild-type (wt) non-squamous non-small cell lung cancer (mnsNSCLC). Despite widespread use of the CPP regimen, molecular determinants of clinical benefit from the addition of P to CP remain poorly defined. We previously identified genomic alterations in STK11/LKB1 as a major driver of primary resistance to PD-1/PD-L1 blockade in mnsNSCLC. Here, we present updated data on the impact of STK11/LKB1 alterations on clinical outcomes with CPP chemo-immunotherapy from a large retrospective multi-institution international study.

      Method

      620 pts with mnsNSCLC and tumor genomic profiling encompassing STK11/LKB1 from 21 academic institutions in the US and Europe were included in this study. Clinical outcomes were collected for two distinct patient cohorts: a) 468 pts treated with first-line CPP (or >1st line following FDA-approved TKIs) that were alive for 14 days thereafter and b) 152 STK11/LKB1-mt pts that received CP prior to regulatory approval of CPP.

      Result

      Among 468 CPP-treated pts, STK11/LKB1 genomic alterations (N=118) were associated with significantly shorter PFS (mPFS 5.0m vs 6.8m, HR 1.45, 95% CI 1.11 to 1.91; P=0.007) and shorter OS (mOS 10.6m vs 16.7m, HR 1.46, 95% CI 1.04 to 2.07; P=0.031) compared with STK11/LKB1-wt tumors (N=350). The likelihood of disease progression as BOR to CPP differed significantly between the two groups (29.5% vs 17%, P= 0.006). Similar results were obtained when limiting the analysis to EGFR and ALK-wt tumors (N=435) (mPFS 5.0m vs 6.9m, HR 1.48, 95% CI 1.12-1.95, P=0.006 and mOS 10.6m vs 16.7m, HR 1.45, 95% CI 1.02-2.05, P=0.036). Importantly, in pts with STK11/LKB1-mt mnsNSCLC, addition of pembrolizumab to CP did not result in significant improvement of PFS (mPFS 5.0m vs 3.9m, HR 0.82, 95% CI 0.63 to 1.07, P=0.14) or OS (mOS 10.6m vs 9.1m, HR 0.93, 95% CI 0.67 to 1.30, P=0.69) compared to CP alone.

      Conclusion

      In mnsNSCLC, STK11/LKB1 alterations define a subgroup of pts with inferior clinical outcomes with CPP and lack of benefit from the addition of pembrolizumab to CP chemotherapy. Novel therapeutic strategies are required to establish effective antitumor immunity in STK11/LKB1-mutant NSCLC.

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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
    • Moderators:
    • Coordinates: 9/08/2019, 09:45 - 18:00, Exhibit Hall
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      P1.01-98 - Outcomes in Advanced NSCLC Patients Treated with 1st Line EGFR-TKI Based on Mutation Detection from Tissue or cfDNA-Based Genomic Sequencing (ID 1861)

      09:45 - 18:00  |  Author(s): Brett Carter

      • Abstract

      Background

      Tumor genomic information from tissue has been the standard of practice for identifying actionable molecular alterations. The same genomic profiling is also widely available by a non-invasive blood test (cfDNA). We hypothesized that treatment naïve patients with advanced non-small cell lung cancer (NSCLC) and actionable oncogenic driver mutations identified by tumor and cfDNA would have similar clinical outcomes after treatment with targeted therapies.

      Method

      Patients with any EGFR-TKI sensitive mutation and received FDA-approved EGFR-TKI as first line therapy for their advanced NSCLC were included in this retrospective analysis. Consecutive patients were identified from our GEMINI database with therapy initiated that was based solely from either the tissue or cfDNA report were divided into each cohort, respectively. Assessment of PFS was from date of therapy initiation until disease progression. Tissue genomic profiling was performed on our institution’s CLIA-certified hotspot NGS assay covering 40-50 genes. For blood based genomic profiling, blood was sent for NGS of cfDNA with a panel of up to 70 cancer-related genes at a CLIA-certified lab (Guardant360, Guardant Health, Redwood City, CA). Kaplan–Meier methodology was used to calculate median PFS with Log-rank (Mantel-Cox) test assessment at significance level 5%.

      Result

      Forty patients for each group were identified between 2014-2016. The results as summarized in table and PFS graph below:

      table.jpgpfs graph.jpg

      Conclusion

      There was no progression-free survival difference in patients treated with FDA-approved front-line EGFR-TKI directed by genomic profiling from tissue vs blood -based testing. These results indicate that similar treatment outcomes with targeted therapy based on tissue or blood-based NGS profiling are both viable options for patient with newly diagnosed, advanced NSCLC.