Prediction Of Outcome In Li-Fraumeni Syndrome: Development Of An Integrative Function-Based Prognostic Model.

Abstract Li-Fraumeni Syndrome (LFS) is a highly penetrant familial cancer disorder caused by germline TP53 mutations. Hundreds of different germline TP53 mutations with a wide gradient of functional consequences have been found in association with LFS, which has a remarkably diverse clinical spectrum in terms of tumor type, age of onset, penetrance, and survival rates. Clinical tools for prognostication and risk stratification are needed to guide clinical decision making. We performed an integrated analysis combining five large-scale mutant p53 functional screens to identify three functionally distinct groups of mutations. Combined functional scores measuring multiple parameters (loss-of-function, dominant negative activity, growth inhibition, oligomeric status, and transcriptional activity) were used to classify mutations as high, intermediate, or low pathogenicity. Patients identified with germline TP53 mutations at The Hospital for Sick Children and other institutes (174 patients from 50 families) provided the discovery set. An external validation cohort included 1674 patients from 1522 families with germline TP53 mutations collected from the International Agency for Research on Cancer database. Our mutation classifications stratified carriers into three distinct risk groups with significantly different overall survival outcomes in the discovery (P=0.02) and validation cohorts (P<0.0001). In the discovery dataset, patients in the high-risk group had considerably shorter median life expectancy (28 years; n=21) compared to the intermediate-risk group (61 years; n=51) and low-risk group (median survival not reached; n=10). On average, 92% (24/26) of patients in the high-risk group developed tumors compared to only 63% (32/51) in the low-risk group (P=0.005). This model remained significant when applied to the validation cohort. In conclusion, patients at increased risk of cancer mortality can be identified to guide treatment and cancer surveillance strategies. Citation Format: Nicholas Fischer, David Malkin. Prediction of outcome in Li-Fraumeni Syndrome: Development of an integrative function-based prognostic model [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 886.