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Chang Lu
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P76 - Targeted Therapy - Clinically Focused - EGFR (ID 253)
- Event: WCLC 2020
- Type: Posters
- Track: Targeted Therapy - Clinically Focused
- Presentations: 1
- Moderators:
- Coordinates: 1/28/2021, 00:00 - 00:00, ePoster Hall
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P76.19 - Clinical Outcomes of Lung Cancer Patients Who Acquired EGFR T790M/in trans-C797S Mutations After Resistance to Osimertinib (ID 1260)
00:00 - 00:00 | Presenting Author(s): Chang Lu
- Abstract
Introduction
EGFR C797S is a well-established mechanism of resistance to osimertinib. Previous studies have documented whether C797S occurred in cis (on the same allele) or trans (on a different allele) with T790M affects the efficacy of subsequent therapies, and in trans C797S/T790M remain sensitive to a combination of first- and third-generation EGFR TKIs. To date, no standard treatment is available for patients with lung cancers harboring EGFRT790M/in trans-C797S mutations. We set out to characterize the clinical outcomes in this subset of patients.
Methods
Patients with a pathologically confirmed diagnosis of stage IV lung cancer harboring EGFR T790M/in trans-C797S mutations were analyzed. EGFR mutation was identified by DNA-based next-generation sequencing. A retrospective review of clinicopathologic and treatment information was performed. Response to subsequent therapy was determined (RECIST v1.1). Progression-free survival (PFS) in patients were determined using Kaplan-Meier estimates. Survival was measured from the date of the first subsequent treatment start.
Results
29 patients with EGFR T790M/in trans C797S-mutant lung cancers were identified. The median age was 55 (range 31-71 years), 69% were women. All had adenocarcinoma. Accurate information of previous and subsequent treatment were available for 16 patients. All patients had previous osimertinib administration, mostly at the 2nd line (n = 7) or 3rd line (n = 5). The majority (88%, 14/16) received subsequent therapy, of whom under half (n = 6) were treated with a combination of first- and third-generation EGFR TKIs (gefitinib or erlotinib+ osimertinib); the median PFS was 3.7 months (95%CI 3.3-4.1 months). The median PFS of patients who underwent other therapies (platinum-based chemotherapy, osimertinib+cabozantinib, osimertinib+brigatinib, or osimertinib+cetuximab) was 3.2 months (95%CI 1.7-4.7 months). At the time of reporting, overall survival data were not mature.
Conclusion
The clinical outcomes of patients who acquired EGFR T790M/in trans-C797S mutations after resistance to osimertinib were relatively poor. Further researches are required to investigate the biology of these compond mutations and to establish the optimal therapeutic option.
