Poor effect of osimertinib on EGFR exon 20 insertion-positive lung adenocarcinoma: A case report
Yuji Inagaki1, Akihiro Tamiya1, Yoshinobu Matsuda2
1Department of Internal Medicine.
Introduction:
The clinical efficacy of osimertinib for patients with lung adenocarcinoma harboring epidermal growth factor receptor (EGFR) exon 20 insertion mutations is unclear. Few case reports exist on the successful treatment of such tumors with osimertinib. We report a case wherein osimertinib administration had no effect in a patient with EGFR exon 20 insertion-positive lung adenocarcinoma.
Patient Concerns:
A 48-year-old never-smoking woman was referred to our hospital for chronic cough. Computed tomography (CT) and positron emission tomography-CT revealed a nodule in the right middle lobe, consolidation in the right upper lobe, multiple lymph node metastases, liver metastasis, and multiple bone metastases.
Diagnosis:
On the basis of further examination using transbronchial lung biopsy, the patient was diagnosed with cT1N3M1 stage IVB lung adenocarcinoma. An EGFR exon 20 insertion, without any additional mutations, was identified.
Interventions:
Daily oral administration of 80 mg osimertinib was initiated to treat the EGFR exon 20 insertion-positive lung adenocarcinoma.
Outcomes:
Although the disease appeared to be stable 2.5 months after the administration of osimertinib, the tumor started to grow 3 months after administration, and carcinoembryonic antigen levels became higher than those before treatment. Thus, osimertinib was discontinued, and treatment with carboplatin as well as pemetrexed and bevacizumab was started, which the patient responded to.
Conclusion:
EGFR exon 20 insertion mutations must be classified in more detail to assess the efficacy of EGFR tyrosine kinase inhibitors. Osimertinib doses that provide favorable therapeutic windows should be considered. Further clinical research is required to clarify the efficacy of osimertinib and other drugs for exon 20 insertion mutations.
Insights
Osimertinib showed no efficacy in a patient with EGFR exon 20 insertion-positive lung adenocarcinoma. Subsequent treatment with chemotherapy and bevacizumab was effective, highlighting the need for further research into targeted therapies for this mutation.
Area of Science:
- Oncology
- Molecular Biology
- Pharmacology
Background:
- Lung adenocarcinoma with EGFR exon 20 insertion mutations presents a treatment challenge.
- The clinical efficacy of osimertinib for this specific mutation remains unclear.
- Limited case reports exist on osimertinib's success in treating these tumors.
Observation:
- A 48-year-old non-smoker presented with advanced lung adenocarcinoma (stage IVB).
- The tumor harbored an EGFR exon 20 insertion mutation without other co-mutations.
- Initial CT and PET-CT revealed widespread metastases.
Findings:
- Osimertinib treatment initially showed stable disease for 2.5 months, followed by tumor progression.
- Tumor growth and rising carcinoembryonic antigen levels indicated treatment failure.
- Combination therapy with carboplatin, pemetrexed, and bevacizumab resulted in a positive patient response.
Implications:
- EGFR exon 20 insertion mutations require detailed classification for targeted therapy selection.
- Further investigation into optimal osimertinib dosing and alternative therapies is crucial.
- Clinical research is needed to establish effective treatment strategies for EGFR exon 20 insertion-positive lung adenocarcinoma.
