Sacituzumab govitecan boosts pretreated metastatic TNBC outcomes
medwireNews: Previously treated patients with metastatic triple-negative breast cancer (TNBC) derive a significant survival benefit from treatment with sacituzumab govitecan (SG) versus standard single-agent chemotherapy, show phase 3 study data.
Reporting the findings at the ESMO Virtual Congress 2020, Aditya Bardia (Massachusetts General Hospital, Boston, USA) explained that SG is a first-in-class Trop-2-directed antibody–drug conjugate that received accelerated approval for metastatic TNBC in the USA earlier this year on the basis of promising efficacy and manageable safety in a phase 1/2 basket trial.
He said that the ASCENT study was initiated to confirm these results and recruited 529 metastatic TNBC patients (primarily women) who had received at least two lines of chemotherapy, randomly assigning them to receive either intravenous SG 10 mg/kg on days 1 and 8 of every 3-week cycle or physician’s choice of capecitabine, eribulin, vinorelbine, or gemcitabine.
The primary endpoint of progression-free survival in the brain metastases-free population (n=468) was significantly improved with SG versus chemotherapy, at a median of 5.6 and 1.7 months, respectively, giving a hazard ratio (HR) for progression or death of 0.41.
Median overall survival was also significantly longer in the SG than chemotherapy group, at 12.1 versus 6.7 months, and an HR for death of 0.48, and the objective response rate was significantly higher, at 35% versus 5%.
These improvements in survival outcomes and response rate were observed “across all prespecified subgroups,” including those defined by age, prior immune checkpoint inhibitor use, and liver metastases status, Bardia reported.
He added that “SG was well tolerated, with a manageable safety profile consistent with prior reports.”
The key treatment-related adverse events (TRAEs) of at least grade 3 that occurred more commonly in the SG than chemotherapy arm were neutropenia (51 vs 33%), diarrhea (10 vs <1%), leukopenia (10 vs 5%), anemia (8 vs 5%), and febrile neutropenia (6 vs 2%).
A comparable proportion of patients in the SG and chemotherapy groups required a dose reduction due to TRAEs (22.0 vs 26.0%) and the rate of discontinuation due to AEs was also similar (4.7 vs 5.4%). There were no treatment-related deaths among SG-treated patients.
Noting that the trial was stopped early “due to compelling evidence of efficacy,” Bardia concluded that the observed clinical benefit in a randomized phase 3 setting confirms that “SG should be considered as a new standard of care” for this patient population.
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