Objective response of first-line chemotherapy of triple-negative breast cancer translates into survival benefit: an analysis in an independent, prospective clinical trial and a real-world setting

T LI, Y-H ZHU, J ZHANG, B-Y WANG, S ZHANG, L-P WANG, J CAO, Z-H TAO, J XIE,  X-C HU

Abstract:

This study sought to assess whether the objective response (OR, including complete response and partial response) of first-line chemotherapy can predict overall survival (OS) for patients with metastatic triple-negative breast cancer (mTNBC) in both clinical trial and a real-world setting. The survival predictable parameters were assessed in two independent cohorts, the training cohort of 236 patients as part of a phase 3 trial (CBCSG006, Trial registration number NCT0128762) and the validation cohort of 360 patients from the real-world setting. Univariable and multivariable Cox proportional hazard models were applied to explore associations with progression-free survival and OS in the training cohort and then in the validation cohort. OR (OR vs non-OR, HR, 0.438, p<0.001) together with Eastern Cooperative Oncology Group (ECOG) performance status, disease-free survival, number of metastatic organ sites and platinum-based chemotherapy used as first-line chemotherapy were observed to be independent prognostic factors for progression-free survival (PFS), and OR (OR vs non-OR, HR, 0.602, p=0.002) together with ECOG score, disease-free survival, number of metastatic organ sites and previous anthracycline and/or taxane treatment were observed to be independent predictive factors for OS in the training cohort. These predictors were confirmed in the validation cohort. For OR and non-OR group, median OS was 23.72 and 13.83 months in the training cohort (HR, 0.637, p=0.002), and 21.95 and 13.80 months in the validation cohort (HR, 0.608, p<0.001), respectively. By adding OR in the OS predictors, the concordance index (C-index) improved from 0.622 to 0.645 in the training cohort and 0.653 to 0.675 in the validation cohort. PFS and OS of mTNBC can be predicted by OR status with any regimen of first-line chemotherapy in an independent prospective clinical trial and a real-world setting. Therefore, TNBC, not like other subtypes of breast cancer, may be in need of combination chemotherapy or intense chemotherapy to achieve a high response rate for survival.