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J Clin Oncol. 2016 Oct 1;34(28):3375-82. doi: 10.1200/JCO.2016.66.7162. Epub 2016 Jun 27.

Association Between Plasma Genotyping and Outcomes of Treatment With Osimertinib (AZD9291) in Advanced Non-Small-Cell Lung Cancer.

Author information

1
Geoffrey R. Oxnard, Ryan S. Alden, Cloud P. Paweletz, and Pasi A. Jänne, Dana-Farber Cancer Institute, Boston; Kenneth S. Thress and J. Carl Barrett, AstraZeneca, Waltham, MA; Rachael Lawrance and Mireille Cantarini, AstraZeneca, Macclesfield, United Kingdom; and James Chih-Hsin Yang, National Taiwan University and National Taiwan University Hospital, Taipei, Taiwan. geoffrey_oxnard@dfci.harvard.edu.
2
Geoffrey R. Oxnard, Ryan S. Alden, Cloud P. Paweletz, and Pasi A. Jänne, Dana-Farber Cancer Institute, Boston; Kenneth S. Thress and J. Carl Barrett, AstraZeneca, Waltham, MA; Rachael Lawrance and Mireille Cantarini, AstraZeneca, Macclesfield, United Kingdom; and James Chih-Hsin Yang, National Taiwan University and National Taiwan University Hospital, Taipei, Taiwan.

Abstract

PURPOSE:

Third-generation epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs) have demonstrated potent activity against TKI resistance mediated by EGFR T790M. We studied whether noninvasive genotyping of cell-free plasma DNA (cfDNA) is a useful biomarker for prediction of outcome from a third-generation EGFR-TKI, osimertinib.

METHODS:

Plasma was collected from all patients in the first-in-man study of osimertinib. Patients who were included had acquired EGFR-TKI resistance and evidence of a common EGFR-sensitizing mutation. Genotyping of cell-free plasma DNA was performed by using BEAMing. Plasma genotyping accuracy was assessed by using tumor genotyping from a central laboratory as reference. Objective response rate (ORR) and progression-free survival (PFS) were analyzed in all T790M-positive or T790M-negative patients.

RESULTS:

Sensitivity of plasma genotyping for detection of T790M was 70%. Of 58 patients with T790M-negative tumors, T790M was detected in plasma of 18 (31%). ORR and median PFS were similar in patients with T790M-positive plasma (ORR, 63%; PFS, 9.7 months) or T790M-positive tumor (ORR, 62%; PFS, 9.7 months) results. Although patients with T790M-negative plasma had overall favorable outcomes (ORR, 46%; median PFS, 8.2 months), tumor genotyping distinguished a subset of patients positive for T790M who had better outcomes (ORR, 69%; PFS, 16.5 months) as well as a subset of patients negative for T790M with poor outcomes (ORR, 25%; PFS, 2.8 months).

CONCLUSION:

In this retrospective analysis, patients positive for T790M in plasma have outcomes with osimertinib that are equivalent to patients positive by a tissue-based assay. This study suggests that, upon availability of validated plasma T790M assays, some patients could avoid a tumor biopsy for T790M genotyping. As a result of the 30% false-negative rate of plasma genotyping, those with T790M-negative plasma results still need a tumor biopsy to determine presence or absence of T790M.

TRIAL REGISTRATION:

ClinicalTrials.gov NCT01802632.

PMID:
27354477
PMCID:
PMC5035123
DOI:
10.1200/JCO.2016.66.7162
[Indexed for MEDLINE]
Free PMC Article

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