ALK-EML4 Fusion in Small Cell Lung Cancer: Clinical and Molecular Insights From a Rare Case

Small cell lung cancer (SCLC) is a rare and aggressive malignancy with a poor prognosis and limited therapeutic options. While anaplastic lymphoma kinase (ALK) rearrangements are commonly observed in non-small cell lung cancer (NSCLC), their occurrence in SCLC is exceedingly rare. This report presents a unique case of SCLC harboring the ALK-EML4 fusion gene, identified through next-generation sequencing (NGS), contributing to a deeper understanding of potential targeted therapies for SCLC patients.

A 35-year-old male with a 45-pack-year smoking history presented with hyponatremia, dyspnea, and weight loss. Imaging revealed a left hilar mass with mediastinal lymphadenopathy, and a CT-guided biopsy confirmed the diagnosis of SCLC. The patient underwent initial treatment with chemotherapy and radiation. Despite an initial positive response, disease progression occurred, leading to a change in treatment with dual immunotherapy and palliative reirradiation. Subsequent NGS testing identified an EML4-ALK fusion gene. The patient was readmitted later with worsening symptoms and new metastatic lesions. Due to disease progression, immunotherapy was discontinued, and chemotherapy with carboplatin and irinotecan, along with alectinib, was initiated. Follow-up imaging revealed a partial response in the primary tumor.

This case highlights the rare occurrence of ALK fusion in SCLC, which may offer insights into potential targeted treatments. The patient's progression despite standard therapies suggests the need for further investigation into ALK inhibitors for SCLC patients with such mutations. Clinicians should consider NGS testing as a valuable diagnostic tool for identifying genetic alterations in SCLC, which could guide personalized treatment strategies and improve outcomes.