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M. Iqbal
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P3.01 - Advanced NSCLC (ID 621)
- Event: WCLC 2017
- Type: Poster Session with Presenters Present
- Track: Advanced NSCLC
- Presentations: 2
- Moderators:
- Coordinates: 10/18/2017, 09:30 - 16:00, Exhibit Hall (Hall B + C)
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P3.01-019 - Canadian Multicentre Validation Study of Plasma Circulating Tumour DNA for Epidermal Growth Factor (EGFR) T790M Testing (ID 8878)
09:30 - 09:30 | Author(s): M. Iqbal
- Abstract
Background:
Plasma detection of EGFR T790M mutations in circulating tumour DNA (ctDNA) of advanced lung cancer patients with acquired resistance to EGFR tyrosine kinase inhibitor (TKI) has been proposed as alternative to tumor re-biopsy. This national validation study across Canadian centres aimed to establish the sensitivity and specificity of plasma detection of T790M as a clinical test using digital droplet (dd)PCR and next generation sequencing (NGS) assays.
Method:
Canadian patients at 7 centres undergoing screening for ASTRIS (NCT02474355) were invited to participate in this companion blood-based study. Patients with acquired resistance to EGFR TKI consented to collection of blood samples and demographic data. Samples were analysed using ddPCR and/or NGS platforms available at 4 molecular diagnostic laboratories across Canada. Concordance between the results of plasma T790M assayed in these 4 laboratories with reference tissue/plasma testing conducted for ASTRIS was assessed.
Result:
63 patients participated; the median age was 64 years (range 31-87), 69%(40/58) were Asian; 55%(33/60) were male. All patients received prior EGFR TKI, 17%(10/60) also received prior chemotherapy. Reference testing for EGFR T790M for ASTRIS eligibility identified positive T790M(+) results for 31(49%), negative(-) for 30(48%) and indeterminate(i) results for 2(3%) patients. One laboratory tested all 63 patient samples using both ddPCR and NGS (Oncomine Lung cfDNA assay), another laboratory tested 18 samples using ddPCR and NextSeq, a third tested 10 samples using ddPCR and COBAS EGFRv2, and a fourth tested 6 samples using Ion Torrent PGM. A total of 188 tests were performed including 91 by ddPCR, 87 NGS and 10 COBAS assays. Combining test results for each patient, 60%(38/63) of patient plasma samples were T790M+, 23(37%) were T790M-, and 2(3%) were inconclusive. Of 31 patients with reference T790M+ results from ASTRIS, 23(74%) had T790M detected in plasma, 6(19%) did not (T790M-), and 2(7%) had indeterminate (T790Mi) plasma results. For 30 patients with T790M- reference results from ASTRIS, 13(43%) had plasma T790M+ and 17 plasma T790M- results. The 2 patients with T790Mi by reference testing both had T790M+ results from plasma. Altogether, 47%(15/32) of patients deemed to have T790M-/i tumours by reference testing were found to have T790M+ results by plasma in this multicentre study. Combining results from both tissue and plasma testing, 73%(46/63) of study patients had T790M+ results.
Conclusion:
Plasma ctDNA testing in this multicentre Canadian study identified a significant number of additional patients eligible for osimertinib therapy beyond routine biopsy tissue testing for EGFR T790M.
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P3.01-062 - The Perceived Value of Avoiding Biopsy: Patients' Willingness to Pay for Circulating Tumour DNA T790M Testing (ID 10004)
09:30 - 09:30 | Author(s): M. Iqbal
- Abstract
Background:
Plasma detection of circulating tumour DNA (ctDNA) with T790M mutation in the context of EGFR tyrosine kinase resistance has been shown to have high concordance with tissue biopsy specimens. In a public healthcare system, patients’ perceived value of a test and willingness to pay can inform policy decisions regarding implementation and funding of a novel technology.
Method:
As part of screening for the ASTRIS clinical trial (NCT02474355), Canadian patients were invited to participate in a national validation study of blood-based ctDNA T790M testing. Eligible patients had acquired resistance to EGFR TKI and consented to collection of blood samples, demographic data, and completion of a structured interview measuring their perceived value of blood-based ctDNA testing as an alternative to tumour biopsy. They were asked about their willingness to pay for testing using both open-ended and iterative bidding approaches. The study was supported by a grant from AstraZeneca.
Result:
60 patients were accrued to the study. Median age of the cohort is 64 years (range 31-87); 69% are Asian (40/58); 55% (33/60) are male. All patients had received prior EGFR kinase inhibitor treatment, with 67% (45/60) receiving gefitinib. 17% of patients also received chemotherapy (10/60). A median of 1 prior line of therapy had been received (range 1-6). All patients preferred to have the blood test over repeat tumour biopsy. Patients estimated a mean reasonable price to pay for the test of $954; median $300 (range 0-10,000; IQR 150-800). Patients were personally willing to pay a mean of $281; median $100 (range 0-2500; IQR 33-350).
Conclusion:
In a public health system that covers the cost of standard diagnostic tests, Canadian patients indicated a willingness to pay out of pocket for peripheral blood detection of ctT790M. Patients have high perceived value of ctDNA and prefer it to tumor biopsy.
