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P1.13 - Targeted Therapy (Not CME Accredited Session) (ID 945)
- Event: WCLC 2018
- Type: Poster Viewing in the Exhibit Hall
- Presentations: 1
- Coordinates: 9/24/2018, 16:45 - 18:00, Exhibit Hall
P1.13-17 - Multicentre Phase II Trial of First-Line Afatinib in Patients with Suspected/Confirmed EGFR Mutant NSCLC: ctDNA & Long-Term Efficacy (ID 11908)
16:45 - 18:00 | Author(s): Simon Roitt
Efficacy of afatinib in EGFR mutant patients with comorbidities or those with suspected EGFR mutations unfit for chemotherapy is poorly explored. We evaluated afatinib in this population, with serial plasma ctDNA to investigate the role of molecular EGFR genotyping and monitoring.a9ded1e5ce5d75814730bb4caaf49419 Method
Phase-II trial enrolled NSCLC patients with comorbidities precluding chemotherapy, and either (i) EGFR-mutation, PS 0-3, or (ii) suspected EGFR-mutation (tissue unavailable/failed genotyping), never/former-light smoker, adenocarcinoma, and PS 0-2. Afatinib (40mg daily) given until progression/toxicity. Blood samples obtained at baseline and 12-weekly until discontinuation; plasma ctDNA performed using InVisionSeq™ (amplicon-based NGS).4c3880bb027f159e801041b1021e88e8 Result
39 patients recruited (14 UK centres). Median age 72 years; 27 PS 0-1/12 PS 2-3. 21 patients (54%) had known tissue EGFR-mutations. Additional 8 patients with unknown tissue status (8/17;47%), were ctDNA EGFR-mutant, making 74% EGFR-mutant in total (29/39). Combined tissue and ctDNA data identified 21 patients with common mutations (exon 19/L858R), 8 with rare mutations (exon 18/20), and 10 suspected only. Corresponding median PFS of these cohorts were 10.2/3.9/5.3 months, with 6-month PFS of 71/38/50% all exceeding the 30% target; median OS were 24.8/5.7/11.4 months (p<0.001). Therefore, all patient groups benefitted; known EGFR-mutants having best outcomes. In April 2018, 5/39 patients survived >36 months, including 4/39 progression-free (median follow-up 33 months, maximum 55). Patients with ctDNA mutation clearance during afatinib treatment had substantially improved outcomes compared to those without clearance (Figure). 40% (4/10) of mutant cases who discontinued after 3 cycles because of progressive disease developed an exon 20 EGFR-mutation.
Patients unsuitable for chemotherapy with confirmed/suspected EGFR-mutations by tissue or ctDNA benefit from afatinib. Serial ctDNA is a potentially useful stratification and monitoring tool; amplicon-based ctDNA analysis can identify EGFR mutations when tissue is unavailable. Exon 20 mutations were observed at acquired resistance. ctDNA clearance during afatinib treatment is strongly associated with better PFS/OS.
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