Cristiano Ferrario

BACKGROUND: Patients with metastatic triple-negative breast cancer have a poor prognosis. Sacituzumab govitecan is an antibody-drug conjugate composed of an antibody targeting the human trophoblast cell-surface antigen 2 (Trop-2), which is expressed in the majority of breast cancers, coupled to SN-38 (topoisomerase I inhibitor) through a proprietary hydrolyzable linker. METHODS: In this randomized, phase 3 trial, we evaluated sacituzumab govitecan as compared with single-agent chemotherapy of the physician's choice (eribulin, vinorelbine, capecitabine, or gemcitabine) in patients with relapsed or refractory metastatic triple-negative breast cancer. The primary end point was progression-free survival (as determined by blinded independent central review) among patients without brain metastases. RESULTS: A total of 468 patients without brain metastases were randomly assigned to receive sacituzumab govitecan (235 patients) or chemotherapy (233 patients). The median age was 54 years; all the patients had previous use of taxanes. The median progression-free survival was 5.6 months (95% confidence interval [CI], 4.3 to 6.3; 166 events) with sacituzumab govitecan and 1.7 months (95% CI, 1.5 to 2.6; 150 events) with chemotherapy (hazard ratio for disease progression or death, 0.41; 95% CI, 0.32 to 0.52; P<0.001). The median overall survival was 12.1 months (95% CI, 10.7 to 14.0) with sacituzumab govitecan and 6.7 months (95% CI, 5.8 to 7.7) with chemotherapy (hazard ratio for death, 0.48; 95% CI, 0.38 to 0.59; P<0.001). The percentage of patients with an objective response was 35% with sacituzumab govitecan and 5% with chemotherapy. The incidences of key treatment-related adverse events of grade 3 or higher were neutropenia (51% with sacituzumab govitecan and 33% with chemotherapy), leukopenia (10% and 5%), diarrhea (10% and <1%), anemia (8% and 5%), and febrile neutropenia (6% and 2%). There were three deaths owing to adverse events in each group; no deaths were considered to be related to sacituzumab govitecan treatment. CONCLUSIONS: Progression-free and overall survival were significantly longer with sacituzumab govitecan than with single-agent chemotherapy among patients with metastatic triple-negative breast cancer. Myelosuppression and diarrhea were more frequent with sacituzumab govitecan. (Funded by Immunomedics; ASCENT ClinicalTrials.gov number, NCT02574455; EudraCT number, 2017-003019-21.).

Importance: Treatment options for patients with disease progression after treatment with trastuzumab, pertuzumab, and ado-trastuzumab emtansine (T-DM1) are limited. Tucatinib is an oral, potent, human epidermal growth factor receptor 2 (HER2)-specific tyrosine kinase inhibitor (TKI) being developed as a novel treatment for ERBB2/HER2-positive breast cancer. Objective: To determine the maximum tolerated dosage of tucatinib in combination with T-DM1 in the treatment of patients with ERBB2/HER2-positive metastatic breast cancer with and without brain metastases. Design, Setting, and Participants: In this phase 1b open-label, multicenter, clinical trial, 57 participants enrolled between January 22, 2014, and June 22, 2015, were 18 years of age or older with ERBB2/HER2-positive metastatic breast cancer previously treated with trastuzumab and a taxane. Data were analyzed between January and March 2018. Interventions: Tucatinib 300 mg or 350 mg administered orally twice per day for 21 days and T-DM1 3.6 mg/kg administered intravenously once every 21 days. Main Outcomes and Measures: Safety assessments, pharmacokinetics, and response were assessed using RECIST 1.1 every 2 cycles for 6 cycles, followed by every 3 cycles. Results: Fifty-seven T-DM1-naive patients (median [IQR] 51 [44.0-63.0] years of age) who had undergone a median of 2 earlier HER2 therapies (range, 1-3) were treated. The tucatinib maximum tolerated dosage was determined to be 300 mg administered twice per day with dose-limiting toxic reactions seen at 350 mg twice per day. Pharmacokinetic analysis showed that there was no drug-drug interaction with T-DM1. Adverse events seen among the 50 patients treated at the maximum tolerated dosage regardless of causality included nausea (36 patients; 72%), diarrhea (30 patients; 60%), fatigue (28 patients; 56%), epistaxis (22 patients; 44%), headache (22 patients; 44%), vomiting (21 patients; 42%), constipation (21 patients; 42%), and decreased appetite (20 patients; 40%); the majority of adverse events were grade 1 or 2. Tucatinib-related toxic reactions that were grade 3 and above included thrombocytopenia (7 patients; 14%) and hepatic transaminitis (6 patients; 12%). Conclusions and Relevance: In this study, tucatinib in combination with T-DM1 appeared to have acceptable toxicity and to show preliminary antitumor activity among heavily pretreated patients with ERBB2/HER2-positive metastatic breast cancer with and without brain metastases. Trial Registration: ClinicalTrials.gov Identifier: NCT01983501.