Only SETBP1 hotspot mutations are associated with refractory disease in myeloid malignancies

Introduction: SETBP1 mutations have been established as a diagnostic marker in myeloid malignancies and are associated with inferior survival. Since there is limited data on their clinical impact and stability during disease progression, we sought to investigate the relationship between SETBP1 mutations and disease evolution.

Methods: Bidirectional Sanger sequencing of the SETBP1 gene was performed for 442 unselected patients with World Health Organization (WHO) defined myeloid disorders. Follow-up analysis was performed on samples from 123/442 patients to investigate SETBP1 mutation dynamics. Targeted deep next-generation sequencing for a panel of 30 leukemia-associated genes was established to study SETBP1 cooperating mutations.

Results: 10/442 patients (2.3%) had SETBP1 hotspot mutations (MDS/MPN, n = 7, sAML, n = 3), whereas four patients (1%) had SETBP1 non-hotspot mutations (MPN, n = 1; MDS, n = 2; sAML, n = 1). The median overall survival for patients with SETBP1 hotspot mutations, SETBP1 non-hotspot mutations, and SETBP1 wild type was 14 (range 0-31), 50 (range 0-71), and 47 months (range 0-402), respectively. In Kaplan-Meier analysis, SETBP1 hotspot mutations were significantly associated with reduced overall survival compared to SETBP1 non-hotspot mutations and the SETBP1 wild type (p < 0.001). All 10 patients with SETBP1 hotspot mutations died from relapse or disease progression. Three of four patients with SETBP1 non-hotspot mutations are alive with stable disease. Cooperating CSF3R and TET2 mutations were most frequently observed in patients with SETBP1 hotspot mutations.

Conclusions: Patients with SETBP1 hotspot mutations suffered from aggressive disease with rapid evolution and inferior overall survival. Patients with SETBP1 non-hotspot mutations had less aggressive disease and a more favorable prognosis. Diagnostic screens for SETBP1 hotspot mutations may help identifying this dismal patient group and treat them in multicenter clinical studies.