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S. Gadgeel



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    MO21 - Prognostic and Predictive Biomarkers V - EGFR (ID 98)

    • Event: WCLC 2013
    • Type: Mini Oral Abstract Session
    • Track: Medical Oncology
    • Presentations: 1
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      MO21.10 - Serial monitoring of plasma EGFR T790M levels and evaluation of EGFR mutational status in matched tissue and plasma from NSCLC patients treated with CO-1686 (ID 2498)

      11:25 - 11:30  |  Author(s): S. Gadgeel

      • Abstract
      • Presentation
      • Slides

      Background
      Background: We explored the minimally-invasive detection of EGFR mutations in circulating free DNA from plasma and studied the concordance of EGFR mutation status between matched plasma and tumor tissue in a cohort of newly diagnosed or relapsed patients with advanced NSCLC. CO-1686 is an oral, potent, small-molecule irreversible tyrosine kinase inhibitor that selectively targets mutant forms of EGFR, including T790M and the common initial activating mutations, while sparing wild-type EGFR. Promising clinical activity has recently been reported from an on-going Phase I/II trial.

      Methods
      Methods: Matched tumor tissue and blood from 80 Stage IIIB/IV NSCLC patients, 41 treated with CO-1686, were tested using two allele-specific PCR assays, the cobas® EGFR FFPET and cobas® EGFR blood tests. Each test detects 41 mutations in EGFR, including the T790M resistance mutation, exon 19 deletions and L858R. We also used BEAMing, a highly quantitative and sensitive technology based on digital PCR, to assess a subset of 18 patients treated with CO-1686. BEAMing was compared to cobas analysis at baseline, and also used to serially monitor plasma EGFR mutation levels in response to CO-1686.

      Results
      Results: Using tissue as reference, the positive percent agreement between tissue and plasma was 76% (44/58) for activating mutations and 63% (17/27) for T790M. The cobas® EGFR blood test identified two patients with T790M mutations in plasma that were not detected in the corresponding tumor biopsy—likely because of tumor heterogeneity. The M1a/M1b status was known for 63 EGFR mutation-positive patients. Of the 44 with extrathoracic metastatic disease (M1b), 38 were found to have an activating mutation in plasma (86%). Conversely, only 53% (10/19) of EGFR mutation-positive patients with intrathoracic metastatic disease (M1a) had detectable activating mutations in plasma (p = 0.0081). For the 18 patients profiled by BEAMing, the overall percent agreement between BEAMing and the cobas® EGFR blood test was 94% (17/18) for T790M and 83% (15/18) for activating mutations. Nine of the 18 patients had detectable baseline plasma T790M levels, and several patients treated with CO-1686 had an initial decrease in plasma T790M by BEAMing.

      Conclusion
      Conclusions: Using the cobas® EGFR blood test, a high proportion of EGFR mutations identified in tissue were also detected in plasma. Mutations were more readily detectable in the plasma of patients with M1b rather than M1a disease. These findings suggest that the cobas® EGFR blood test and BEAMing can be useful tools for the non-invasive assessment and monitoring of EGFR mutations in NSCLC patients.

      EGFR mutation Evaluable patients Patients with tissue mutations* Patients with plasma mutations** Patients with same mutation detected in tissue and plasma Positive Percent Agreement***
      L858R, del19, S768I, G719X, or ex20ins 80 58 44 44 76%
      T790M 80 27 19 17 63%
      * identified by the cobas® EGFR tissue test
      ** identified by the cobas® EGFR blood test
      ***agreement of blood and tissue mutation-positive results with tissue as reference; although tissue is reference, some mutations may be missed due to tumor heterogeneity

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    O16 - NSCLC - Targeted Therapies III (ID 115)

    • Event: WCLC 2013
    • Type: Oral Abstract Session
    • Track: Medical Oncology
    • Presentations: 1
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      O16.06 - A phase 1 dose escalation study of a new ALK inhibitor, CH5424802/RO5424802, in ALK+ Non-Small Cell Lung Cancer (NSCLC) patients who have failed crizotinib (AF-002JG/NP28761, NCT01588028). (ID 1661)

      11:25 - 11:35  |  Author(s): S. Gadgeel

      • Abstract
      • Presentation
      • Slides

      Background
      Anaplastic lymphoma kinase (ALK) is a tyrosine kinase constitutively activated following chromosomal translocation in 3-7% of non-small cell lung cancer (NSCLC). These patients usually respond to the ALK inhibitor crizotinib with a median duration of response around 10 months. CH5424802 is a more potent and specific ALK inhibitor that is being studied as a treatment for NSCLC patients with ALK gene rearrangement.

      Methods
      A phase 1 dose escalation study of CH5424802 was performed using 3+3 study design in NSCLC patients who failed crizotinib. The primary endpoint was dose limiting toxicity, and the secondary endpoints were efficacy, safety and pharmacokinetic (PK) analyses. Key eligibility criteria include prior progression on crizotinib, ECOG 0-2, adequate organ functions, confirmed ALK-rearrangement by an FDA approved test. Patients with symptomatic CNS metastases required treatment before participating. CH5424802 was administered orally at doses of 300, 460, 600, 760 and 900 mg BID until lack of clinical benefits. Intensive PK sampling was performed. Efficacy was assessed by RECIST criteria v1.1. Toxicities were evaluated by CTCAE v4.0.

      Results
      37 NSCLC patients who have failed crizotinib and chemotherapy were enrolled in the study from 6 US sites from May 2012 to May 2013. No DLTs were observed up to the highest dose tested (900 mg BID). Only 1 patient required dose modification due to grade 2 fatigue. The most common AEs were fatigue, CPK increase, myalgia, cough, ALT increased, peripheral edema and rash. Grade 3/4 AEs include GGT increase (n=3), neutrophil decrease (n=2), hypophosphatemia, hyperglycemia, syncope, renal failure and pericardial effusion (n=1 each), but no grade 3 nausea, vomit, diarrhea, edema were reported. Preliminary efficacy was observed with PR 48% and SD 34% by investigator assessment amongst the 30 evaluable patients (See Figure of Waterfall plot). Median progression-free survival has not been reached with 27 patients (73%) remaining on study as of June 10, 2013 (median duration 85 days, range 39-347+ days). CNS activity was observed and described in the companion abstract by Ou et al. CH5424802 single dose half-life was approximately 22 hr, AUC was dose-dependent from 300 to 600 mg BID following multiple doses with a potential plateau at doses higher than 600 mg BID based on available data.Figure 1

      Conclusion
      CH5424802 is a well-tolerated ALK inhibitor with no DLTs observed up to the highest dose tested in this study. Promising anti-tumor activity was observed in patients who have failed crizotinib.

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