Alectinib treatment for 2 non-small cell lung carcinoma patients carrying different novel ALK fusions

The genomic fusions of the anaplastic lymphoma kinase (ALK) gene have been widely recognized as effective therapeutic targets for non-small cell lung carcinoma (NSCLC). The Second Xiangya Hospital of Central South University has treated 2 NSCLC patients with 2 distinct novel ALK gene fusions. Case 1 was a 55-year-old male with a solid nodule located in the right hilar lobe on enhanced CT scan. Case 2 was a 47-year-old female with enhanced CT showing involvement of the left upper lobe of lung. Histopathological examination of tumor tissues confirmed lung adenocarcinoma in both cases. Immunohistochemical (IHC) staining demonstrated positivity for thyroid transcription factor-1 (TTF-1) and ALK-D5F3 in tumor cells, while negativity for P40. The next-generation sequencing (NGS) tests identified a PNPT1-ALK (Exon22:Exon20) fusion variant in case 1 and a TCEAL2-ALK (Exon3:Exon19) fusion variant in case 2. The TCEAL2-ALK fusion was further confirmed by amplification refractory mutation system (ARMS)-PCR at the mRNA level. Both patients were treated with oral alectinib at a dosage of 600 mg twice daily. The tumors in both patients were significantly decreased after alectinib treatment, achieving partial response. At the time of submission, there was an absence of disease progression and the progression-free survival (PFS) had surpassed 1 year. It offered compelling evidences that the individuals with NSCLC and harboring either a PNPT1-ALK (Exon22:Exon20) fusion or a TCEAL2-ALK (Exon3:Exon19) fusion, experience favorable therapeutic outcomes through the administration of alectinib. This study expands the known ALK fusion variants database and supports the precision treatment of NSCLC using ALK tyrosine kinase inhibitors (TKIs).