OBJECTIVES: Selpercatinib is an oral agent that targets the rearranged during transfection (RET) proto-oncogene that is currently being studied in patients diagnosed with RET-altered solid tumors including non-small cell lung cancer (NSCLC), medullary thyroid cancer (MTC) and other tumors with RET activation (NCT03157128, LIBRETTO-001). This study was designed to estimate the population potentially eligible for RET-targeted therapy per million per year in the United States (U.S.).

METHODS: Surveillance, Epidemiology, and End Results (SEER) data were used to estimate rates of cancer incidence and metastatic disease. The literature was reviewed to estimate the prevalence of RET alterations and rates of disease progression by tumor type.

RESULTS: The annual incidence of NSCLC is estimated at 48.8 per 100,000 in the U.S. population. Of those, 57.3% are diagnosed with metastatic disease and 34.2% are diagnosed with earlier stage disease that progresses to an advanced stage. Only 1-2% of these patients have an activating RET fusion, of which the majority have tumors of non-squamous histology. There are 15.8 patients in the U.S. diagnosed with thyroid cancer, and approximately 1.6% have MTC. Of those with MTC, 14.4% are diagnosed with metastatic disease and 42.8% have earlier stage disease that progresses. The proportion of MTC patients with RET mutations varies by family history (50% without hereditary disease versus 95% with hereditary MTC). Based on these data, it is estimated that 4 patients per million per year will have RET fusion-positive NSCLC and 1 patient will have RET mutation-positive MTC in the U.S. These patients may be eligible for RET-targeted therapy for their disease.

CONCLUSIONS: These findings provide a specific quantification of the anticipated number of patients potentially eligible for treatment with novel agents targeting RET, which are small relative to the overall population of patients with NSCLC or MTC.