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M. Poh
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P3.01 - Advanced NSCLC (ID 621)
- Event: WCLC 2017
- Type: Poster Session with Presenters Present
- Track: Advanced NSCLC
- Presentations: 1
- Moderators:
- Coordinates: 10/18/2017, 09:30 - 16:00, Exhibit Hall (Hall B + C)
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P3.01-088h - Resistance Mechanisms Causing First-line Epidermal Growth Factor Receptor-Tyrosine Kinase Inhibitor Treatment Failure (ID 9990)
09:30 - 09:30 | Author(s): M. Poh
- Abstract
Background:
Patients with epidermal growth factor receptor (EGFR) mutant advanced non-small cell lung cancer receiving first-line EGFR-tyrosine kinase inhibitor (TKI) inevitably developed disease progression after 9-13 months.
Method:
Before 1[st] January 2017, patients were investigated for resistance mechanisms upon failure of first-line EGFR-TKI by tissue re-biopsy. Liquid biopsy to detect secondary T790M mutation in plasma cell free tumor-DNA (cfDNA) was only performed if tissue re-biopsy was not feasible. Starting 2017, liquid biopsy was the first-choice of investigation. Tumor re-biopsy was only perfomed when cfDNA was negative for T790M mutation or if the patients had rapidly enlarging tumors.
Result:
Of 45 patients who were tested, 31(68.9%) underwent tissue re-biopsy and 14 (31.1%) underwent liquid biopsy as the first investigation to determine the presence of T790M mutation. For the latter group, 4 (8.9%) patients subsequently also had tumor re-biopsy. T790M mutation was detected in 30 (66.7%) of the 45 patients. C-Met amplification was tested in 7 T790M mutation-negative patients for possible recruitment into a clinical trial with 4 of them showing c-Met amplification. Small cell lung cancer transformation and ALK rearrangement were detected in 2 (5.7%) and in 1 (2.9%) of the re-biopsy tissue specimens, respectively. The resistance mechanisms in 8 patients (17.8%) was unknown. In short, two-third (66.7%) of our patients had T790M mutation upon first-line EGFR-TKI failure; while another one-third (33.3%) failed first-line EGFR-TKI due to other resistance mechanisms. The demographic, clinical and treatment characteristics were equally distributed among these 2 groups of patients. (Table 1)Table 1. Demographic, clinical and treatment characteristics of 45 patients with first-line EGFR-TKI treatment failure
Characteristic Total patients (n = 45) T790M mutation (n = 30) Other resistance mechanims (n =15) p value of univariate analysis Gender, No (%). Male Female 18 (40.0) 27 (60.0) 13 (43.3) 17 (56.7) 5 (33.3) 10 (66.7) 0.780 Smoking history, No (%). Never Ex or current smoker 36 (80.0%) 9 (20.0%) 22 (73.3) 8 (26.7) 14(93..3) 1 (6.7) 0.963 EGFR mutation subtype, No (%) Exon 19 deletion Exon 21 L858R Others Unknown 26 (57.8) 16(35.6) 2 (4.4) 1(2.2) 17 (56.7) 12 (40.0) 1 (3.3) 0 9 (60.0) 4 (26.7) 1 (6.7) 1 (6.7) 0.999 Treatment received, No (%) EGFR-TKI EGFR-TKI followed by chemotherapy 34 (75.5) 11 (24.5) 22 (73.3) 8 (26.7) 12 (80.0) 3 (20.0) 0.484 Best tumor response, No (%) Partial response Stable disease Disease progression 38 (84.4) 6 (13.3) 1 (2.2) 27 (90.0) 2 (6.7) 1 (3.3) 11 (73.3) 4 (26.7) 0 0.419 Initial progression free survival, months Median 13.0 13.0 11.7 0.538
Conclusion:
T790M mutation is the commonest acquired resistance mechanism causing first-line EGFR-TKI treatment failure. There was no difference in the clinical and treatment characteristics between patients with and without acquired T790M mutation as causes of resistance to first-line EGFR-TKI treatment.
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P3.15 - SCLC/Neuroendocrine Tumors (ID 731)
- Event: WCLC 2017
- Type: Poster Session with Presenters Present
- Track: SCLC/Neuroendocrine Tumors
- Presentations: 1
- Moderators:
- Coordinates: 10/18/2017, 09:30 - 16:00, Exhibit Hall (Hall B + C)
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P3.15-014 - Case Series of Small Cell Lung Cancer Transformation as Resistance Mechanism to Epidermal Growth Factor Receptor-Tyrosine Kinase Inhibitor (ID 9940)
09:30 - 09:30 | Author(s): M. Poh
- Abstract
Background:
Patients with epidermal growth factor receptor (EGFR) mutant advanced non-small cell lung cancer (NSCLC) developed resistance to first- or second-generation EGFR-tyrosine kinase inhibitor (TKI) after 9-13 months and third-generation EGFR-TKI after 10 months, respectively. Small cell lung cancer (SCLC) transformation is a rare resistance mechanism in these patients.
Method:
Tissue re-biopsy was performed in 35 patients with EGFR mutant advanced NSCLC who failed first-line EGFR-TKI; and 4 patients with acquired T790M mutant advanced NSCLC who failed third-generation EGFR-TKI, to look for SCLC transformation
Result:
SCLC transformation was identified in 2 out of 35 (5.7%) patients who failed first-line EGFR-TKI and 1 out of 4 (25.0%) patients who failed third-generation EGFR-TKI. The first patient was a 70-year-old never-smoker male who was diagnosed with stage IV lung adenocarcinoma harboring exon 19 deletion mutation in April 2014. He had partial response (PR) to gefitinib 250 mg daily but developed symptomatic progressive disease (PD) after 26 months. Re-biopsy of his enlarging primary lung lesion showed SCLC transformation. The second patient was a 43-year-old never-smoker male who was diagnosed with stage IV lung adenocarcinoma harboring exon 19 deletion mutation in November 2015. He had PR to gefitinib 250 mg daily but developed symptomatic PD after 15 months. Re-biopsy of his rapidly enlarging primary lung lesion showed SCLC transformation. His plasma cell-free tumour DNA (cftDNA) was positive for T790M mutation. The third patient was a 62-year-old never-smoker female who was diagnosed with stage IV lung adenocarcinoma harboring exon 21 L858R mutation in November 2015. She had PR to gefitinib 250 mg daily but experienced symptomatic PD after 8 months’ of gefitinib therapy. Re-biopsy of her primary lung tumor revealed the presence of T790M mutation and her treatment was switched to osimertinib 80 mg daily. After an initial PR, she developed PR in the 12[th] month of osimertinib treatment. Biopsy from a metastatic inguinal lymph node showed SCLC. The first and second patients were given standard SCLC chemotherapy with carboplatin and etoposide but did not respond. The third patient sought treatment in another hospital.
Conclusion:
Re-biopsy is recommended in all patients with symptomatic PD while on EGFR-TKI treatment. SCLC transformation under the pressure of first, second and third-generation EGFR-TKI is an emerging challenge to the management of advanced NSCLC. Other than conventional carboplatin and etoposide chemotherapy, new treatment strategies should be explored to improve the outcome of patients who develop SCLC transformation.
