A novel PIBF1-RET gene fusion identified from a stage IA lung adenocarcinoma: A case report

Rearranged during transfection (RET) gene fusions occur in 0.7% to 2% in lung cancer and 1% to 2% in non-small cell lung cancer. Systemic therapies for RET fusion-positive non-small cell lung cancer consist mostly of targeted therapy with RET inhibitors such as selpercatinib and pralsetinib. To date, approximately 40 fusion partners have been reported. Herein, we report a novel progesterone immunomodulatory binding factor 1 (PIBF1)-RET gene fusion identified from a stage IA lung adenocarcinoma and was further validated by RNA sequencing analysis. PATIENT CONCERNS: A 55-year-old male smoker was found by chest computed tomography to have a solid nodule in the right lower lobe of the lung and enlarged mediastinal lymph nodes. DIAGNOSES: The patient was then diagnosed with stage IA lung adenocarcinoma (T1N0M0). INTERVENTION: The patient then underwent thoracoscopic lobectomy of the right lower lobe and mediastinal lymph node dissection. Molecular testing with a targeted panel of 8 lung cancer-associated driver genes detected a novel PIBF1-RET (P16:R12) fusion, which putatively encodes a gene in which the first 16 exons of PIBF1 was concatenated to RET exon 13 and its downstream sequence, retaining the RET kinase domain. The genomic translocation was further validated by RNA sequencing with a panel of 115 cancer-associated genes, which found no other aberrations. OUTCOMES: The patient was discharged 3 days after surgery. CONCLUSION: We report a novel PIBF1-RET fusion in early-stage lung adenocarcinoma. This finding expands the spectrum of RET fusion partners and warrants further studies in characterizing the oncogenic role of this genomic aberration and response to RET-targeted therapies.