Coexisting RET/PTC and TERT Promoter Mutation Predict Poor Prognosis but Effective RET and MEK Targets in Thyroid Cancer.

ABSTRACT

PURPOSE: To investigate the role of coexisting RET/PTC rearrangement and TERT promoter mutation in the prognosis and therapeutic targeting in papillary thyroid cancer (PTC). METHODS: A total of 669 PTC patients with complete clinical follow-up and genetic data were pooled from thyroid cancer datasets TCGA, MSK MetTropism, and MSK-IMPACT, from whom 163 patients (112 women and 47 men, 4 unknown) with wild-type BRAF/RAS were identified, with median age (IQR) of 46.00 (33.00, 61.00) years and median follow-up time (IQR) of 16.13 (8.09, 27.91) months for comparative genotype cohort analysis of mortality. RESULTS: There was a significant concurrence index between RET/PTC and TERT promoter mutations, being 2.040 (95% CI 1.110-3.747, P = 0.023). Mortality occurred in 5/100 (5%) patients harboring neither mutation, 2/18 (11.1%) patients harboring TERT promoter mutation alone, 0/31 (0%) patients harboring RET/PTC alone, and 7/14 (50%) patients harboring both genetic alterations, corresponding to HRs (95% CI) of 1 (Reference), 2.469 (0.405-14.02), 3.296e-09 (0-inf), and 9.019 (2.635-30.87), respectively, which remained essentially unchanged after adjustment for patient race, sex, and age. Similar results were observed with BRAF/RAS and TERT promoter mutations. Mechanistically, RET/PTC used the MAP kinase pathway to upregulate the mutated TERT, but not the wild-type TERT, and, correspondingly, targeting RET and MEK could suppress mutated TERT but not the wild-type TERT. CONCLUSION: Coexisting RET/PTC and TERT promoter mutation identify PTC as a unique clinical entity with high mortality, providing new implications for genetic-based prognostication and potential therapeutic targeting of RET and MEK guided by RET/PTC and TERT status.