Case Report: Significant Clinical Benefit From Pemetrexed-Based Therapy in ROS1- and ALK-rearranged Lung Cancer With Adenosquamous Histology

Case Report: Response to ALK-TKIs in a metastatic lung cancer patient with morphological heterogeneity and consistent molecular features

Lung adenosquamous carcinoma (ASC) is a rare heterogeneous tumor containing two distinct components of adenocarcinoma (ADC) and squamous cell carcinoma (SQCC). The limited biopsy sampling of the primary tumor might have overlooked either the ADC component or the SQCC component, resulting in a misdiagnosis of pure histology. Genotyping for driver mutations is now routinely performed in clinical settings to identify actionable oncogenic mutations and gene arrangements. Additionally, somatic mutations can potentially serve as a marker of clonal relationships. We report a rare case of ASC lung cancer, in which metastases were identified as ADC, while the primary was initially diagnosed as SQCC based on a fibrobronchoscope brush biopsy. The primary and metastatic tumors shared ALK rearrangement and other mutations support they were derived from a single clone origin. Our hypothesis is that the primary tumor contained a minor component of ADC that was not present in the histologic sections of lung biopsy. After sequential ALK-tyrosine kinase inhibitor (TKI) targeted therapy, both the patient's primary lung tumor and the site of metastatic subcutaneous nodules decreased in size, with the metastatic sites demonstrating more noticeable shrinkage. However, after 11 months of targeted therapy, the patient was found to be resistant to ALK-TKIs. Subsequently, the patient's respiratory status deteriorated rapidly, and a cycle of immunotherapy and chemotherapy did not show efficacy. To the best of our knowledge, this is a very rare case of lung ASC, disseminated metastasizing, with distinct morphology between the primary and metastases. Different therapeutic effects of ALK-TKIs were observed in two different morphological sites, with the metastatic cutaneous lesions shrinking more significantly than the primary lung lesions, though they both harbor the same EML4-ALK rearrangement. This case may provide diagnostic and therapeutic insights into lung ASC.

Genomic landscape and actionable mutations of brain metastases derived from non-small cell lung cancer: A systematic review

Background

Brain metastases derived from non-small cell lung cancer (NSCLC) represent a significant clinical problem. We aim to characterize the genomic landscape of brain metastases derived from NSCLC and assess clinical actionability.

Methods

We searched Embase, MEDLINE, Web of Science, and BIOSIS from inception to 18/19 May 2022. We extracted information on patient demographics, smoking status, genomic data, matched primary NSCLC, and programmed cell death ligand 1 expression.

Results

We found 72 included papers and data on 2346 patients. The most frequently mutated genes from our data were EGFR (n = 559), TP53 (n = 331), KRAS (n = 328), CDKN2A (n = 97), and STK11 (n = 72). Common missense mutations included EGFR L858R (n = 80) and KRAS G12C (n = 17). Brain metastases of ever versus never smokers had differing missense mutations in TP53 and EGFR, except for L858R and T790M in EGFR, which were seen in both subgroups. Of the top 10 frequently mutated genes that had primary NSCLC data, we found 37% of the specific mutations assessed to be discordant between the primary NSCLC and brain metastases.

Conclusions

To our knowledge, this is the first systematic review to describe the genomic landscape of brain metastases derived from NSCLC. These results provide a comprehensive outline of frequently mutated genes and missense mutations that could be clinically actionable. These data also provide evidence of differing genomic landscapes between ever versus never smokers and primary NSCLC compared to the BM. This information could have important consequences for the selection and development of targeted drugs for these patients.