Ribociclib add-on to NSAI + goserelin prolongs PFS in HR+, HER2- advanced breast cancer
Adding ribociclib, a CDK*4/6 inhibitor, to NSAI** and goserelin improves progression-free survival (PFS) in premenopausal women with hormone receptor-positive (HR+), human epidermal growth factor receptor 2-negative (HER2-) advanced breast cancer (ABC), according to the MONALEESA-7*** study presented at ESMO Asia 2018.
“Consistent treatment benefit with ribociclib + NSAI + goserelin was observed in Asian and non-Asian patients,” said study lead author Dr Seock-Ah Im from the Department of Internal Medicine at Seoul National University Hospital in Seoul, Republic of Korea.
The phase III, double-blind trial involved 495 premenopausal women with HR+, HER2- ABC (Asian, n=166 and non-Asian, n=329) who were randomized to receive either oral ribociclib (600 mg/day on a 3-week-on, 1-week-off schedule) or placebo, both in addition to NSAI (either letrozole or anastrozole)/tamoxifen (TAM) and goserelin (GOS, 3.6 mg subcutaneously every 4 weeks). [ESMO Asia 2018, abstract 39O]
At data cut-off, PFS was significantly longer in the ribociclib arm compared with the placebo arm, regardless of race (median PFS, not evaluable vs 11 months, hazard ratio [HR], 0.418; log-rank p=0.000113 in Asians and 23.8 vs 16.5 months, HR, 0.603; log-rank p=0.001 in non-Asians).
Similarly, women in the ribociclib group achieved a higher overall response rate than those in the placebo group (Asians, 58.5 percent vs 34.2 percent and non-Asians, 46.5 percent vs 37.4 percent).
The clinical benefit rate was also higher among women who received ribociclib compared with those on placebo (Asians, 86.2 percent vs 63.2 percent and non-Asians, 79.5 percent vs 64.2 percent).
Haematological adverse events (AEs) such as neutropenia of any grade occurred more frequently among Asians than non-Asians treated with ribociclib (84 percent vs 75 percent), although a lower incidence of grade 3 febrile neutropenia was observed in Asians compared with non-Asians (1 vs 3 events).
A lower incidence of non-haematological AEs, such as diarrhoea (17 percent vs 21 percent), fatigue (17 percent vs 27 percent), hot flush (22 percent vs 36 percent), and arthralgia (28 percent vs 36 percent), were also observed among Asians compared with non-Asians who received ribociclib.
Of note, no Asian patients in the ribociclib arm experienced treatment discontinuation due to AEs, while 5 percent of non-Asian patients on ribociclib reported treatment discontinuation.
“Ribociclib + NSAI + goserelin may be a treatment option for Asian premenopausal women with HR+, HER2- ABC ... The safety profile was manageable, irrespective of race, and was consistent with that observed in the full population,” said Im.
*CDK: Cyclin-dependent kinase
**NSAI: Non-steroidal aromatase inhibitor
**MONALEESA-7: Study of efficacy and safety in premenopausal women with hormone receptor positive, HER2-negative advanced breast cancer