Osimertinib for Lung Squamous Cell Carcinoma: A Case Report and Literature Review

Efficacy of osimertinib for lung squamous cell carcinoma with de novo EGFR T790M-positive: Case report and literature review

Among epidermal growth factor receptor (EGFR) mutation-positive non-small cell lung cancers, squamous cell carcinoma is less common and shows lower responsiveness to first-generation EGFR tyrosine kinase inhibitors (TKIs) compared to adenocarcinoma. However, the efficacy of osimertinib for squamous cell carcinoma with EGFR mutations is not well known. This study reports the case of a 57-year-old male diagnosed as having stage IIIC squamous cell lung cancer. Oncomine Dx Target Test identified EGFR exon19 deletion and de novo EGFR T790M mutation with variant allele frequencies (VAF) of 21.6% and 25.2%, respectively. The patient was treated with osimertinib after progression on chemoradiotherapy followed by durvalumab, and a partial response was maintained for more than 20 months. To predict EGFR-TKI efficacy, confirmation of gene mutations and VAF using next-generation sequencing is helpful.

Receptor tyrosine kinase inhibitors in cancer

Targeted therapy is a new cancer treatment approach, involving drugs that particularly target specific proteins in cancer cells, such as receptor tyrosine kinases (RTKs) which are involved in promoting growth and proliferation, Therefore inhibiting these proteins could impede cancer progression. An understanding of RTKs and the relevant signaling cascades, has enabled the development of many targeted drug therapies employing RTK inhibitors (RTKIs) some of which have entered clinical application. Here we discuss RTK structures, activation mechanisms and functions. Moreover, we cover the potential effects of combination drug therapy (including chemotherapy or immunotherapy agents with one RTKI or multiple RTKIs) especially for drug resistant cancers.

Efficacy of Osimertinib in Lung Squamous Cell Carcinoma Patients with EGFR Gene Mutation–Case Report and A Literature Review

Non-small cell lung cancer (NSCLC) is the most common type of lung cancer and the leading cause of cancer-related mortality worldwide. It is responsible for 80–85% of lung cancer cases. NSCLC can be divided into several groups, led by adenocarcinoma (ADC)–40–50% and squamous cell carcinoma (SCC)–20–30%. The development of new molecular therapies targeting particular abnormalities such as mutations in the EGFR (Epidermal Growth Factor Receptor) gene or ROS1 or ALK genes rearrangements resolved in novel strategies in advanced NSCLC management. EGFR mutation occurs mostly in patients with ADC and those patients are mostly females with no or light smoking history. The hereby presented patient fitted the ADC characteristics, while they were diagnosed with SCC. The unusual diagnosis implied further genetic testing, which established the occurrence of L858R substitution in exon 21 in the EGFR gene. A 63-year-old female was admitted to the unit due to a dry cough, pain in the right chest area and dyspnoea. When diagnosed, the patient had a peripheral mass in the right lung superior lobe (55 × 40 mm), satellite nodules in the apex of the same lung and packets of disintegrating lymph nodes. Positron Emission Tomography (PET-CT) confirmed a diffuse neoplastic process qualified as stage IV on the TNM scale. Due to EGFR gene mutation, the woman was administered osimertinib, however, the treatment did not succeed, and other therapeutic solutions were undertaken. The patient died 10 months after diagnosis. Patients with advanced ADC harboring EGFR mutation can receive osimertinib, a third-generation tyrosine kinase inhibitor (TKI), however, the use of TKIs in SCC remains controversial. In some published cases, osimertinib treatment led to success, in others, the therapy did not result in the expected final effect. Small sample groups and diverse molecular backgrounds indicate the need for further research in this field. Thus, the treatment decision-making process in those patients overall remains extremely demanding and ambiguous.