Table 1.
Results from pivotal prospective randomized controlled trials investigating palbociclib, ribociclib and abemaciclib combined with an endocrine partner in the treatment of first-line patients with HR + MBC.
| Trial Details | PALOMA-213,26 | MONALEESA-212,15 | MONALEESA-320,22,24 | MONALEESA-718,25 | MONARCH-314,29 |
|---|---|---|---|---|---|
| CDK4/6 inhibitor | Palbociclib | Ribociclib | Ribociclib | Ribociclib | Abemaciclib |
| Endocrine therapy | Letrozole | Letrozole | Fulvestrant | Goserelin plus tamoxifen or NSAI | NSAI |
| Menopausal status | Post-menopausal | Post-menopausal | Post-menopausal | Pre/peri-menopausal | Post-menopausal |
| Sample size | 666 | 668 | 365 (1L therapy) | 672 | 493 |
| Median follow up (months) | 90 | 80 | 70.8 | 53.5 | 70.2 |
| mPFS combination arm (months) | 24.8 | 25.3 | 33.6 | 23.8 | 28.2 |
| mPFS control arm (months) | 14.5 | 16 | 19.2 | 13 | 14.8 |
| mPFS HR (95% CI) | 0.58 (0.46–0.72) | 0.57 (0.46–0.7) | 0.55 (0.42–0.72) | 0.55 (0.44–0.69) | 0.54 (0.42–0.69) |
| mPFS p value | <0.001 | <0.001 | n/a | <0.001 | <0.001 |
| mOS combination arm (months) | 53.9 | 63.9 | 67.6 | 58.7 | 67.1 |
| mOS control arm (months) | 51.2 | 51.4 | 51.8 | 48 | 54.5 |
| mOS HR (95% CI) | 0.956 (0.777–1.177) | 0.76 (0.63–0.93) | 0.67 (0.5–0.9) | 0.76 (0.61–0.96) | 0.754 (0.584–0.974) |
| mOS p value | 0.3378 | <0.001 | n/a | <0.001 | 0.0301a |
| % ≥1 dose reduction due to AE (combination arm) | 36% | 50.6% | n/a | 31% | 46.5% |
| % treatment discontinuation (combination arm) | 9.7% | 7.5% | n/a | 4% | 16.5% |
1L first-line, NSAI non-steroidal aromatase inhibitor, mPFS median progression-free survival, mOS median overall survival, AE adverse events.
aResults from preplanned interim analysis, the statistical significance threshold for abemaciclib superiority was not met.