medwireNews: Ribociclib plus endocrine therapy (ET) is associated with a significant progression-free survival (PFS) benefit relative to combination chemotherapy in treatment-naïve patients with hormone receptor-positive, HER2-negative, advanced breast cancer with aggressive features, suggest trial data.
The findings were presented at the 2022 San Antonio Breast Cancer Symposium in Texas, USA, by Yen-Shen Lu, from the National Taiwan University Hospital in Taipei.
Speaking at a press conference, Lu said that even though RIGHT Choice was a phase 2 trial, it provided “clear evidence” of the efficacy and tolerability of the CDK4/6 inhibitor–ET combination. He noted that it would be “quite difficult” to conduct a phase 3 study in this setting and therefore Lu believes that these data are “practice changing.”
Virginia Kaklamani, from UT Health San Antonio, who moderated the press conference, agreed that “this will change some of that standard of care.”
She continued: “We don’t use a lot of chemotherapy nowadays because of how well these CDK4/6 inhibitors work, but I think the little that we use is probably now dead.”
The study recruited 222 pre- or perimenopausal women (median age, 43–44 years) who had not received prior systemic treatment for hormone receptor-positive, HER2-negative advanced breast cancer defined as aggressive on the basis of one of the following features:
- symptomatic visceral metastases;
- rapid disease progression or impending visceral compromise; or
- markedly symptomatic non-visceral disease.
After a median follow-up of 24.1 months, the primary endpoint of investigator-assessed PFS was a median of 24.0 months for the participants who were randomly assigned to receive ribociclib 600 mg/day on a 3 weeks on, 1 week off schedule alongside letrozole or anastrozole plus goserelin.
This was nearly double the median PFS achieved by their counterparts who received investigator’s choice of docetaxel plus capecitabine, paclitaxel plus gemcitabine, or capecitabine plus vinorelbine, at 12.3 months, and equated to a significant 46% reduction in the risk for progression or death with ribociclib plus ET.
Treatment with ribociclib plus ET also significantly prolonged the median time to treatment failure compared with combination chemotherapy, at 18.6 versus 8.5 months, and reduced the risk for treatment failure by 55%.
But there was no significant difference between the ribociclib–ET and combination chemotherapy groups with respect to either the overall response rate (65.2 vs 60.0%) or clinical benefit rate (80.4 vs 72.7%).
Turning to the safety, Lu noted that the incidence of serious treatment-related adverse events (TRAEs) was lower with ribociclib plus ET than combination chemotherapy; any-grade events occurred in a respective 1.8% and 8.0% of patients, while events of grade 3 or 4 occurred in 0.9% and 7.0%.
Similarly, fewer patients in the ribociclib plus ET arm than those in the combination chemotherapy arm discontinued any component of the regimen due to any-grade TRAEs, at rates of 7.1% versus 23.0%. The rates of discontinuation due to TRAEs of grade 3–4 were comparable, however, at 6.3% and 7.0%, respectively.
The RIGHT Choice trial results suggest that “first-line ribociclib plus endocrine therapy can be an efficacious, clinically meaningful treatment option for patients with aggressive, advanced breast cancer, and help to avoid the need for combination chemotherapy and its associated toxicities,” concluded the presenter.
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