Durable Response to Osimertinib in a Chinese Patient with Metastatic Lung Adenocarcinoma Harboring a Rare EGFR L858R/D761Y Compound Mutation

De Novo mutation in Epidermal growth factor receptor (EGFR)-D761Y responding to third generation tyrosine kinase inhibitor Osimertinib: A case report

INTRODUCTION

Non-small cell lung cancer (NSCLC) is the most common type of lung cancer. Epidermal growth factor receptor (EGFR) mutations are the most common accurate gene targets. However, the lack of case reports or cohort studies on the exceptionally rare mutations limit the acquisition of deeper insights.

PATIENT CONCERNS

A 76-year-old female nonsmoker presented to our hospital with a one-week disease history of cough accompanied by shortness of breath.

DIAGNOSIS

Contrast-enhanced CT scan showed right pleural effusion with scattered inflammation and consolidation in the right upper lung. Tumor marker display showed obvious increased. Histopathology of the pulmonary mass combined with Immunohistochemical staining indicated lung adenocarcinoma. Contrast-enhanced magnetic resonance imaging suggested brain metastases. ECT scan showed bone metastasis. The patient was thus diagnosed as right lung adenocarcinoma of stage IV (cT3N3M1c). Next generation sequencing was performed to profile the mutation status of known oncogenic driver mutations, and only EGFR-D761Y in exon 19 (allelic frequency, AF: 0.53%) mutation was found.

INTERVENTIONS

The patient was accordingly treated with the third generation EGFR-Epidermal growth factor receptor tyrosine kinase inhibitor (TKI) Osimertinib (80 mg, qd). Accompanied with whole brain radiotherapy (DT3000c Gy/10f) for brain metastases, technetium methylene diphosphonate injection was performed for bone metastases.

OUTCOMES

The efficacy of the first-line Osimertinib treatment for 1 month was assessed as PR per RECIST version 1.1. The NSCLC patient harboring EGFR-D761Y mutation detected prior to the EGFR L858R mutation was benefited from the third-generation EGFR-TKI Osimertinib and had a worse prognosis than with other EGFR mutations according to data from previous case reports.

CONCLUSIONS

This case reported a NSCLC patient with de novo mutation of EGFR-D761Y responding to third generation TKI Osimertinib.

Osimertinib-Centered Therapy Against Uncommon Epidermal Growth Factor Receptor-Mutated Non-Small-Cell Lung Cancer- A Mini Review

Osimertinib is a third-generation, irreversible mutant epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor that is approved by the U.S. Food and Drug Administration (FDA) and European Medicines Agency (EMA). Osimertinib is currently the first line drug recommended by National Comprehensive Cancer Network (NCCN) guidelines against lung cancer harboring the EGFR TKI-sensitive mutation and acquired EGFR T790M resistance mutation. Osimertinib demonstrated some efficacy in clinical trials and case reports in patients bearing certain uncommon EGFR mutations, but it is not active in patients with other mutations such as C797S. This mini-review presents the mechanisms underlying the variations in patient responses, discusses the use of osimertinib against non-small-cell lung carcinomas with uncommon EGFR mutations, and addresses the future prospects of osimertinib-centered therapy.