Lung adenocarcinoma with a novel SRBD1-ALK Fusion responding to crizotinib

Anaplastic lymphoma kinase (ALK) rearrangements account for approximately 3-5% in non-small-cell lung cancer (NSCLC) patients who tend to be young and never/light-smokers. Echinoderm microtubule-associated protein like 4 (EML4) is the most common partner for ALK fusion, while more than 90 other partners have been reported in NSCLC. Majority of the ALK actionable rearrangements were sensitive to crizotinib, yet some rare fusion types may less benefit than EML4-ALK. Here, we reported a case of lung adenocarcinoma harboring a novel S1 RNA binding domain 1 (SRBD1)-ALK fusion which the breakpoints was (S6,A20). To our knowledge, this case is the first report showed clinical evidence of SRBD1-ALK fusion responding to crizotinib.

Immunohistochemistry (IHC), fluorescence in situ hybridization (FISH) examination and next-generation sequencing (NGS) based on a 425-gene panel was performed on the biopsy sample.

The IHC analysis revealed positive expression of ALK and atypical FISH signals were detected. Further NGS detected a novel SRBD1-ALK fusion. The patient received crizotinib (250 mg, twice a day) as first-line treatment and partial response was observed. The progression-free survival (PFS) is already over than 10 months up to today.

To our knowledge, our case is the first case of SRBD1-ALK fusion with excellent response to crizotinib. This case merits further follow-up and provides valuable information on the response to crizotinib of NSCLC patients with SRBD1-ALK fusion.