<i>TP53</i> multihit mutations in 142 patients with MPN or AML: Comparative analysis of survival and risk factors.

e18590 Background: TP53 mutations ( TP53 MUT ) are known to be associated with adverse prognosis in acute myeloid leukemia (AML) and multihit TP53 MUT in myelodysplastic syndromes (MDS). The prognostic relevance of multihit TP53 MUT in myeloproliferative neoplasms (MPN) was recently highlighted. The current study illustrates survival comparisons in multihit TP53- mutated MPN vs. AML and analysis of associated risk factors. Methods: A Mayo Clinic enterprise-wide database search identified 61 MPN and 81 AML cases with multihit TP53 MUT . Conventional statistical methods were used for analyses. Results: 142 patients with multihit TP53 MUT were included: i) chronic phase MPN (MPN-CP; N=19), ii) accelerated phase MPN (MPN-AP; N=14), iii) blast phase MPN (MPN-BP; N=28) and iv) AML, not including MPN-BP (N=81). Concomitant ASXL1 MUT , EZH2 MUT , IDH1 MUT and IDH2 MUT were more common in MPN-BP, compared to AML. At a median follow up of 0.6 years, 124 (87%) deaths and 19 (13%) allogeneic stem cell transplantations (ASCT) were documented. Overall survival (OS), calculated from time of TP53 MUT detection was similar between MPN-BP (median 4.6 months) and MPN-AP (5.6 months; p=0.5). OS in MPN-BP/AP (median 4.8 months) was inferior to that of AML (median 7.4 months; p=0.04) while that of MPN-CP (median 11.6 months) was similar to AML (0.07) but superior to that of MPN-BP/AP (p&lt;0.01). Age-adjusted multivariable analysis (MVA) confirmed the independent prognostic significance of undergoing ASCT (HR 0.4, p=0.03), MPN-CP or achieving response to pre-transplant therapy (HR 0.2, p&lt;0.01), and concurrent TET2 MUT or DNMT3A MUT (HR 2.7, p&lt;0.01) on OS. Based on these risk factors, a 3-tiered risk model was constructed: low (no risk factors; N=18; median OS 23.8 months); intermediate (1 risk factor; N=44; median 11.1 months); and high (2 or more risk factors; N=80; median 4 months; p&lt;0.01). Comparative analysis of risk factors among distinct diseases confirmed the prognostic significance of ASCT (HR 0.3, p=0.03), achieving response to pre-transplant therapy (0.4, p&lt;0.01) and concurrent TET2 MUT or DNMT3A MUT (HR 5.0, p&lt;0.01) in AML. In MPN AP/BP, OS was influenced by having received chemotherapy vs. supportive care (HR 0.1; p&lt;0.01) and achieving response to pre-transplant therapy (0.2, p&lt;0.01). No significant risk factors for OS were identified in MPN-CP. In MVA, ASCT did not appear to influence OS in MPN AP/BP (p=0.7) and MPN-CP (p=0.4) but the number of informative cases was too low to make definitive conclusions. Conclusions: The current study highlights the equally detrimental impact of multihit TP53 MUT in securing long-term survival in MPN and AML. Short-term survival was positively influenced by ASCT, at least in AML, and disease stage or remission status at time of mutation detection and ASCT, respectively.