WEDNESDAY, Dec. 7, 2022 (HealthDay News) – Patients with hormone receptor (HR)-positive, HER2-negative advanced breast cancer treated with ribociclib plus endocrine therapy (ET) had fewer adverse events and significantly longer progression-free survival than those treated with combination chemotherapy, according to a study presented at the San Antonio Breast Cancer Symposium, held from Dec. 6 to 10.
Yen-Shen Lu, M.D., Ph.D., from National Taiwan University College of Medicine in Taipei, and colleagues compared the progression-free survival, time to treatment failure, and overall response rate of patients with aggressive breast cancer treated with ribociclib plus ET to those treated with combination chemotherapy, as part of the phase II RIGHT Choice trial.
“For HR-positive, HER2-negative advanced breast cancer patients with high tumor burden or aggressive disease features, many physicians prefer to use chemotherapy or even combination chemotherapy for a higher chance of tumor control rate,” Lu told Elsevier’s PracticeUpdate. “This study provides evidence that first-line ribociclib plus ET could be a better choice.”
For the trial, 222 premenopausal or perimenopausal patients with HR-positive, HER2-negative, aggressive breast cancer (visceral crisis, 52.3 percent) with no prior systemic therapy were recruited; 112 patients were randomly assigned to ribociclib (600 mg daily, three weeks on/one week off) plus an aromatase inhibitor – letrozole or anastrozole – and goserelin and 110 patients were assigned to a physicians’ choice combination chemotherapy regimen (docetaxel plus capecitabine, paclitaxel plus gemcitabine, or capecitabine plus vinorelbine). To balance the groups, randomization was further stratified by liver metastasis and whether the disease-free interval (duration from date of complete tumor resection for primary breast cancer lesion to the date of documented disease recurrence) was less than two years.
The researchers found that during a median follow-up of 24.1 months, 45.5 percent of patients remained on treatment in the ribociclib + ET group versus 23.6 percent in the chemotherapy group. Progression-free survival, the primary endpoint, was significantly longer in the ribociclib-plus-ET group (24.0 versus 12.3 months with chemotherapy; hazard ratio [HR], 0.54; P = 0.0007). The median time to treatment failure was also longer for ribociclib plus ET (18.6 versus 8.5 months, respectively; HR, 0.45). Overall survival data were not yet available at data cutoff. The overall response rate was similar for the groups (65.2 versus 60.0 percent).
“A biomarker study is ongoing, to see whether we can pick up which specific population may still need chemotherapy as front-line treatment in critical situations,” Lu told Elsevier’s PracticeUpdate. “Also, we excluded patients with estrogen receptor less than 10 percent and patients with bilirubin higher than 1.5-fold of the upper limit of normal. We need to know if the current conclusion could apply for these populations in future study.”
No new safety signals were seen with ribociclib. Further, ribociclib plus ET was associated with lower rates of treatment-related serious adverse events (AEs) compared with chemotherapy (1.8 versus 8.0 percent) and lower rates of discontinuation due to treatment-related AEs (7.1 versus 23.0 percent).
Lu disclosed financial ties to the pharmaceutical industry, including Novartis, which funded the study.