“Treatment approaches for patients with visceral crises can sometimes be difficult for clinicians, as there is no precise guidance on treatment strategy,” Lu explained. While National Comprehensive Cancer Network (NCCN) guidelines recommend chemotherapy for this patient population, he added that patients with compromised organ function as a result of metastatic spread are often excluded from clinical trials, making it more difficult to determine new treatment regimens for them.
They recruited 222 premenopausal or perimenopausal patients with hormone receptor-positive, HER2-negative, aggressive breast cancer, more than 50 percent of whom had visceral crises, as determined by the investigators; 112 were randomly assigned to receive ribociclib plus an aromatase inhibitorletrozole or anastrozoleand goserelin, which decreases ovarian estrogen production. The other 110 patients were assigned to receive a physicians’-choice combination chemotherapy regimen.
Patients treated with ribociclib plus ET had a progression-free survival of 24 months, nearly one year more than that of patients treated with chemotherapy (12.3 months). The median time to treatment failure was also longer among patients treated with ribociclib plus ET18.6 months versus 8.5 months among patients treated with chemotherapy.
The overall response rate was similar between the two treatment arms (65.2 percent for ribociclib plus ET and 60 percent for chemotherapy). However, the rates of symptomatic adverse events, such as diarrhea and fatigue, were different: Serious, treatment-related adverse events emerged in 1.8 percent of patients receiving ribociclib plus ET and in 8 percent of patients receiving combination chemotherapy. Similarly, 7.1 percent of patients treated with ribociclib plus ET and 23 percent of patients treated with chemotherapy discontinued at least one component of study treatment due to treatment-related adverse events.
“To be able to extend lives, treatment compliance is key,” Lu said. “A treatment with improved tolerability will definitely enhance compliance and thus increase the chances of longer disease control.
“Compared with combination chemotherapy, ribociclib plus endocrine therapy may offer more durable antitumor efficacy with better tolerability and compliance,” Lu said. “Overall, these improvements in outcomes and tolerability should translate into an evolution of our standard of care for patients with hard-to-treat breast cancer, providing clinicians with guidance for treating this patient population.”
Lu hopes that forthcoming subgroup analyses will reveal clinical characteristics that may help physicians predict which patients will respond best to ribociclib plus ET versus those who may respond better to chemotherapy.
Limitations of this study include its relatively small sample size as a phase II trial, as well as the exclusive applicability of these findings to first-line treatment.
Funding for this study was provided by Novartis Pharma AG. Lu has received personal funding from Novartis, Roche, Merck Sharp & Dohme, Pfizer, AstraZeneca, Eisai, Eli Lilly, and Daiichi Sankyo.
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