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Dong Shen
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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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P76.06 - A Novel EGFR G724S and R776H Rare Co-Mutation Response to Afatinib in a Patient With Lung Adenocarcinoma (ID 888)
00:00 - 00:00 | Presenting Author(s): Dong Shen
- Abstract
Introduction
Epidermal growth factor receptor (EGFR) represents the first identified targetable oncogenic driver discovered in NSCLC. Approximately 40% of Asian patients with newly diagnosed metastatic NSCLC harbor a somatic mutation in the EGFR gene. The most common EGFR mutations are in-frame deletions in exon 19 and the L858R point mutation in exon. However, rare mutations were found in nearly 10-15% of EGFR-positive NSCLC. Although it has reported that afatinib is more effective against rare EGFR mutations, there are significant differences in PFS and OS. Herein, we described a rare case of EGFR G724S/R776H mutations in a NSCLC responding to afatinib.
Methods
Next-generation sequencing (NGS) and cinoembryonic antigen (CEA) on the liquid biopsy were performed.
Results
A 64-year-old non-smoking woman came to our hospital on April 26, 2019 for further treatment because the patient couldn’t tolerate the side effects of previous chemotherapy, including myelosuppression, cardiac and renal insufficiency. Chest computed tomography (CT) shows bone metastases in the thoracolumbar spine and bilateral local ribs, nodules in both lungs, pericardium and left pleural effusion. The previous pathological diagnosis was lung adenocarcinoma. To seek potential therapeutic regimens, the whole blood was subjected to NGS analysis, and an EGFR G724S (mutant allele frequency [MAF]: 67.59%) and R776H (MAF: 40.54%) rare co-mutation was identified. Based on these findings, the patient was administered with afatinib (a dose of 30 mg/d) combined with bevacizumab. After treatment, CT and NGS were reexamined. The left pleural effusion and pericardial effusion were significantly reduced before targeted therapy. And the allele frequencies for both EGFR R776H and G724S were decreased (R776H from 40.54% to 0.16% and G724S from 67.59% to undetected). In addition, during treatment, CEA continued to decrease. Several follow-up visits were conducted, and the last visit was in Mar. 2020, which showed tumor lesion in the left lung still kept stable and the OS already exceeded 11 months.
Conclusion
This is the first report of co-mutation of EGFR R776H/G724S in a patient with lung adenocarcinoma. Afatinib may be a beneficial therapeutic option for a subset of NSCLC with rare EGFR co-mutation.
