Ribociclib improves survival in advanced breast cancer

Ribociclib combined with letrozole or fulvestrant demonstrates robust progression-free (PFS) and overall survival (OS), with modest objective response rates in heavily pretreated patients with advanced breast cancer, according to a real-world study.

Sixty-eight female patients who received >1 cycle of ribociclib between December 2018 and March 2022 were included in the analysis. The rates of adverse events (AEs) related to dose reduction and discontinuation of ribociclib were used as a surrogate marker for intolerance.

Ribociclib combined with letrozole or fulvestrant was administered in the first-, second-, third-, and fourth-line palliative hormonal therapy settings in 29 (42.6 percent), 26 (38.2 percent), 12 (17.6 percent), and 1 (1.5 percent) patients, respectively.

Thirty (44 percent) patients experienced AEs associated with dose reduction. Forty-two of 68 (61.8 percent) patients discontinued ribociclib permanently (disease progression: 33/68, 48.5 percent; AEs: 9, 13.2 percent). Ten of 61 (16.4 percent) patients had objective response.

The median PFS was 18 months (95 percent confidence interval, 11.7‒24.3), while the median OS was not reached. Most patients (84 percent) were alive at 3 years.

“AEs related treatment discontinuation rate is higher than that reported in clinical trials with stringent inclusion criteria,” the authors said.

“CDK 4/6 inhibitors, such as ribociclib, are recommended in combination with hormonal therapy to treat advanced/metastatic hormone receptor-positive, HER2-negative breast cancer,” they said.