Serum ProGRP and NSE levels predicting small cell lung cancer transformation in a patient with ALK rearrangement‑positive non‑small cell lung cancer: A case report

The resistance mechanisms to anaplastic lymphoma kinase (ALK) inhibitors comprise ALK gene variations, such as ALK point mutations and copy-number gains, the activation of bypass signaling through the activation of other oncogenes and small cell lung cancer (SCLC) transformation. To date, few studies have investigated whether tumor markers for SCLC correlate with the SCLC transformation in EGFR-mutant NSCLC and ALK-positive non-SCLC (NSCLC). The present case study reported a patient with SCLC transformation after alectinib treatment. The patient exhibited elevation of pro-gastrin-releasing peptide precursor and neuron-specific enolase levels, which may be predictive of SCLC transformation during the resistance to ALK-tyrosine kinase inhibitors.