TP53 Signature Can Predict Pathological Response From Neoadjuvant Chemotherapy and Is a Prognostic Factor in Patients With Residual Disease

BACKGROUND: The TP53 signature that predicts the mutation status of TP53 has been shown to be a prognostic factor and predictor of neoadjuvant chemotherapy (NAC) response. OBJECTIVES: The current study sought to investigate the utility of the TP53 signature for predicting pathological complete response (pCR) and its prognostic significance among patients with residual disease (RD). DESIGN: The study followed a retrospective cohort study design. METHODS: Patients with T1-3/N0-1 from a cohort of those with HER2-negative breast cancer who received NAC were selected. Ability to predict pCR was evaluated using odds ratio, positive and negative predictive values, sensitivity, and specificity. Prognostic factors in the RD group were explored using the Cox proportional hazards model with distant recurrence-free survival (DRFS). Four independent cohorts were used for validation. RESULTS: A total of 333 eligible patients were classified into the TP53 mutant signature (n = 154) and wild-type signature (n = 179). Among the molecular and pathological factors, the TP53 signature had the highest predictive power for pCR. In 4 independent cohorts (n = 151, 85, 104, and 67, respectively), pCR rate in TP53 mutant signature group was significantly higher than that in the wild-type group. Univariate and multivariate analyses on DRFS in the RD group identified the TP53 signature and nodal status as independent prognostic factors, with the former having a better hazard ratio than the latter. After comparing DRFS between 3 groups (pCR, RD/TP53 wild-type signature, and RD/TP53 mutant signature groups), the RD/TP53 mutant signature group showed significantly worse prognosis compared with others. The RD/TP53 wild-type signature group did not exhibit inferior DRFS compared with the pCR group. CONCLUSION: Our results showed that the TP53 mutant signature can predict pCR and that combining pathological response and TP53 mutant signature allows for the identification of subgroups with truly poor prognosis.