TROPION-Breast01: Datopotamab deruxtecan vs chemotherapy in pre-treated inoperable or metastatic HR+/HER2- breast cancer.

Improving the prognosis for patients with metastatic HR+/HER2- breast cancer remains an unmet need. Patients with tumors that have progressed on endocrine therapy and/or are not eligible for endocrine therapy had limited treatment options beyond chemotherapy. Antibody-drug conjugates are a novel and promising treatment class in this setting. Datopotamab deruxtecan (Dato-DXd) consists of a TROP2-directed humanized IgG1 monoclonal antibody attached via a serum-stable cleavable linker to a topoisomerase I inhibitor payload. TROPION-Breast01 is an ongoing phase III study that is evaluating the efficacy and safety of Dato-DXd compared with investigator's choice of standard-of-care chemotherapy in patients with inoperable or metastatic HR+/HER2- breast cancer who have received one or two prior lines of systemic chemotherapy in the inoperable or metastatic setting. Clinical Trial Registration: NCT05104866 (ClinicalTrials.gov).

Antibody-drug conjugates are a type of drug with two parts: an antibody that directs the drug to the cancer cells and a cancer-cell killing toxic payload. By binding to cancer cells before releasing the payload, treatment is directed to the site of action so there are fewer side effects in the rest of the body. Datopotamab deruxtecan (Dato-DXd) is an antibody-drug conjugates made up of datopotamab (antibody) and DXd (payload) which are joined together via a stable linker. Datopotamab binds to a protein found on cancer cells called TROP2; it then goes inside and releases the DXd payload to kill the tumor cells. DXd may leak out to surrounding cancer cells and kill those as well. The TROPION-Breast01 study is comparing Dato-DXd with standard-of-care chemotherapy. Around 700 patients will take part, who have: Tumors that cannot be surgically removed. Tumors that are hormone receptor-positive and do not have HER2 overexpression. Had one or two lines of previous chemotherapy (after the tumor could not be surgically removed, or had spread). Had tumor growth despite hormonal therapy or are ineligible for hormonal therapy. Patients who meet the entry criteria will be randomly assigned to a treatment group in equal numbers to either Dato-DXd or an appropriate chemotherapy, out of four options chosen by the treating doctor. At the end of the study, researchers will look at whether the patients who receive Dato-DXd live longer without their breast cancer getting worse, compared with patients who receive chemotherapy. This study is also looking at how the treatment affects patients' quality of life.

Genomic predictor of residual risk of recurrence after adjuvant chemotherapy and endocrine therapy in high risk estrogen receptor-positive breast cancers.

A subset of early stage estrogen receptor (ER)-positive breast cancers considered "high risk" for recurrence with endocrine therapy alone by current genomic prognostic predictors, such as Oncotype DX, is no longer high risk after receiving adjuvant chemotherapy. We hypothesized that a recently described gene expression-based outcome predictor adjuvant chemotherapy and endocrine therapy sensitivity (ACES) could re-stratify these patients into high and low risk groups for relapse when treated with both chemo- and endocrine therapies. ACES involves four separate modules (endocrine sensitivity, chemotherapy sensitivity, chemotherapy resistance, and survival prediction) that yield a prediction for good or poor outcome with current standard of care multimodality therapy. ACES was applied to Affymetrix gene expression data from 2 retrospectively collected ER-positive and HER2-negative patient cohorts that were uniformly treated with adjuvant endocrine and chemotherapy (n = 250). Each sample was first risk stratified by a genomic surrogate of Oncotype DX, and the high risk patients (n = 76) were re-stratified by ACES. Recurrence-free survival (RFS) was evaluated with ACES risk categories. The Oncotype DX high risk but ACES good prognosis patients (n = 24, 32%) had an RFS of 95% compared to 76% in the poor prognosis group (n = 52; log-rank p = 0.033) at 5 years. ACES risk category remained an independent predictor in multivariate analysis after adjusting for age, T-stage, and lymph node involvement at diagnosis (hazard ratio 0.15; p = 0.072). Tertiary risk prediction that takes into account chemotherapy and endocrine sensitivity, and baseline prognosis may help identify high risk ER-positive patients who have excellent survival after chemotherapy.