ASCO 2017: Abemaciclib Plus Fulvestrant in Endocrine-Resistant Breast Cancer
For patients with endocrine-resistant hormone receptor–positive/HER2-negative breast cancer, the combination of the cyclin-dependent kinase (CDK) 4/6 inhibitor abemaciclib and the estrogen receptor–antagonist fulvestrant improved both progression-free survival and response rates. At the 2017 American Society of Clinical Oncology (ASCO) Annual Meeting, George W. Sledge, MD, of Stanford University Medical Center, presented the results of the double-blind, phase III MONARCH 2 trial and discussed them in further detail in a video recorded at the ASCO Meeting for JNCCN 360.
Of the 669 patients who participated in this trial, 446 received abemaciclib plus fulvestrant, and 223 received placebo plus fulvestrant. The investigators found that in the intent-to-treat population, median progression-free survival favored the group receiving abemaciclib over the one that did not (16.4 vs 9.3 months)—a difference that Dr. Sledge called “highly statistically significant.”
In addition, abemaciclib plus fulvestrant produced more than a doubling in the objective response rate compared with fulvestrant and placebo (48.1% vs 21.3%). However, the benefits of the combination therapy were accompanied by an increase in treatment-emergent adverse events, particularly diarrhea, neutropenia, and nausea.
“This trial brings abemaciclib forth as a contender in the space of CDK4/6 inhibitors and one that certainly will go forward in terms of adjuvant trials in the relatively near future,” stated Dr. Sledge in an interview.