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O03 - NSCLC - Targeted Therapies I (ID 113)
- Event: WCLC 2013
- Type: Oral Abstract Session
- Track: Medical Oncology
- Presentations: 1
O03.05 - Activity of afatinib in uncommon epidermal growth factor receptor (EGFR) mutations: Findings from three trials of afatinib in EGFR mutation-positive lung cancer (ID 1114)
10:30 - 12:00 | Author(s): J.C. Yang
EGFR (ErbB1) mutations define a lung cancer subtype with exquisite sensitivity to EGFR tyrosine kinase inhibitors (TKIs). While in-frame deletion in exon 19 (Del19) and a point mutation (L858R) in exon 21 are the two most common sensitizing EGFR mutations in non-small cell lung cancer (NSCLC), approximately 10% of EGFR mutation-positive tumours harbour uncommon mutations. These mutations represent a heterogeneous group of rare molecular alterations (or combinations) within exons 18–21, whose oncogenicity and sensitivity to EGFR TKIs may vary and has not been prospectively studied. Here we present the first prospective data series on activity of afatinib, the irreversible ErbB Family Blocker, in patients with tumours harbouring uncommon EGFR mutations.
This analysis is based on data from EGFR mutation-positive patients included in the LUX-Lung 2 (Phase II), LUX-Lung 3 and LUX-Lung 6 (both Phase III) studies. EGFR mutations were identified prospectively by direct sequencing in LUX-Lung 2 and by central testing with TheraScreen EGFR RGQ PCR kit (TheraScreen29) in LUX-Lung 3 and 6. Patients were classified as having common (Del19 or L858R) or uncommon (all other single or complex) mutations. Uncommon mutations were categorized into three groups: de novo T790M (alone or in combination with other mutations); exon 20 insertions; and other. Objective response rate (ORR), disease control (DCR), duration of response and progression-free survival (PFS) were assessed by independent review.
Seventy-five patients (LUX-Lung 2: n=23; LUX-Lung 3: n=26; and LUX-Lung 6: n=26) had uncommon mutations, accounting for 12.5% of all afatinib patients in these studies. The majority of patients received afatinib first line; 13 patients from LUX-Lung 2 received afatinib after chemotherapy. Breakdown into the three groups was T790M: n=14; Exon 20 insertions: n=23; other: n=38 (most frequent types were L861Q: n=12; G719X: n=8; G719X+S768I: n= 5; G719X+L861Q: n=3). Efficacy results for each group are shown below. Further details by mutation status will be presented.
Mutation ORR, % (n=) Median duration of response, months (95% confidence interval) DCR (ORR + stable disease), % (n) Median PFS, months (95% confidence interval) Median survival, months (95% confidence interval) De novo T790M alone or in combination with other mutations (n=14) 14.3 (2) Individual response durations: 4.1, 12.4 64.2 (9) 2.9 (1.2−8.3) 14.9 (8.1−24.9) Exon 20 insertions (n=23) 8.7 (2) Individual response durations: 4.2, 10.1 65.2 (15) 2.7 (1.8−4.2) 9.4 (4.1−21.0) Other (n=38) 71.1 (27) 11.1 (4.1, 15.2) 84.2 (32) 10.7 (5.6−14.7) 18.6 (16.4−not estimable)
Afatinib was active in lung tumours harbouring uncommon EGFR mutations, such as G719X, L861Q, S768I. Rate and duration of response was comparable with that previously observed in patients with common mutations in these trials. The response rate was low in tumours with de novo T790M mutations and insertions in exon 20 but durable tumour control was achieved in some patients. To date this is the largest analysis of data for prospectively identified patients with uncommon EGFR mutations; treatment options in this heterogeneous group of tumours will be discussed.
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