# First‐Line Osimertinib for EGFR‐Mutated Squamous Cell Lung Carcinoma: A Case Report

## TL;DR

A rare case of EGFR-mutated squamous cell lung cancer responded well to osimertinib, suggesting it could be a treatment option for similar cases.

## Contribution

This case report presents a rare response to osimertinib in EGFR-mutated squamous cell lung carcinoma.

## Key findings

- The patient showed tumor shrinkage after 9 months of osimertinib treatment.
- EGFR mutation (exon 21 L858R) was confirmed via genomic analysis.
- PD-L1 tumor proportion score was 95% in the patient.

## Abstract

Epidermal growth factor receptor (EGFR) mutations in squamous cell lung carcinoma are rare. EGFR‐tyrosine kinase inhibitors are generally less effective for EGFR‐mutated squamous cell lung carcinoma. We herein present a case of EGFR‐mutated squamous cell lung carcinoma that responded to osimertinib.

A 75‐year‐old woman with bloody sputum and left back pain was referred to NHO Kochi Hospital. A mass was observed in the left lower lobe on chest CT. Squamous cell lung carcinoma, cT4N1M1b (adrenal metastasis) stage IVA, was diagnosed based on the findings of a CT‐guided percutaneous lung biopsy and a CT scan revealing right adrenal metastasis. The primary tumor was subjected to a genomic analysis with the AmoyDx Pan Lung Cancer PCR panel, which revealed an EGFR mutation (exon 21 L858R). The PD‐L1 tumor proportion score was 95%. Osimertinib was initiated as first‐line targeted therapy. Tumor shrinkage was observed and maintained over 9 months of treatment.

We encountered a rare EGFR‐mutated squamous cell lung carcinoma that responded well to osimertinib. Osimertinib may be an option for the treatment of patients with EGFR‐mutated squamous cell lung carcinoma.