The phase III MONALEESA-3 trial investigated Ribociclib, a cyclin-dependent kinase 4/6 ( CDK4/6 ) inhibitor, plus Fulvestrant as first-line ( 1L ) or second-line ( 2L ) treatment for postmenopausal patients with HR+/HER2− advanced breast cancer.
Researchers have reported overall survival ( OS ) and 1L progression-free survival ( PFS ) results.
Postmenopausal patients with HR+/HER2− advanced breast cancer were randomized 2:1 to receive Ribociclib + Fulvestrant or Placebo + Fulvestrant in 1L and 2L settings.
This is the 2nd of 3 protocol-specified OS analyses.
At the data cutoff ( 3 Jun 2019 ), 153 patients were still on treatment ( Ribociclib, n = 121 [ 25.0% ]; PBO, n = 32 [ 13.2% ] ); overall survival was evaluated after 275 deaths ( Ribociclib, 167 [ 34.5% ]; PBO, 108 [ 44.6% ] ).
Median follow-up was 39.4 months.
Ribociclib + Fulvestrant demonstrated a statistically significant overall survival prolongation over Placebo + Fulvestrant ( median, NR vs 40.0 months; hazard ratio, HR, 0.724, 95% CI, 0.568-0.924, P = 0.00455 ).
The result crossed the prespecified Lan DeMets ( O’Brien Fleming ) stopping boundary ( P = 0.01129 ) for superior efficacy.
Per protocol, these overall survival results are considered final.
Overall survival benefit with Ribociclib vs Placebo was consistent across all subgroups, including the 1L subgroup ( median, NR vs 45.1 months; HR, 0.700 [ 95% CI, 0.479-1.021 ] ) and the early-relapse / 2L subgroup ( median, 40.2 vs 32.5 months; HR, 0.730 [ 95% CI, 0.530-1.004 ] ).
In patients receiving 1L treatment, the median progression-free survival ( descriptive analysis ) with Ribociclib + Fulvestrant versus Placebo + Fulvestrant was 33.6 vs 19.2 months ( HR, 0.546 [ 95% CI, 0.415-0.718 ] ).
Time to progression on next-line therapy or death ( PFS2 ) was also longer with Ribociclib vs Placebo ( median, 39.8 vs 29.4 months; HR, 0.670 [ 95% CI, 0.542-0.830 ] ).
The safety profile was consistent with previously published analyses.
In conclusion, there was a statistically significant overall survival prolongation with Ribociclib over Placebo, which was consistent across all subgroups.
The median progression-free survival with Ribociclib in the 1L setting is the longest reported in a phase III trial in HR+/HER2− advanced breast cancer.
These data, combined with results from MONALEESA-7, have confirmed Ribociclib benefit with multiple combination partners in pre- and postmenopausal patients, and support Ribociclib as a recommended CDK4/6 inhibitor as 1L and 2L treatment in patients with HR+/HER2- advanced breast cancer. ( Xagena )
Source: ESMO ( European Society of Medical Oncology ) Meeting, 2019