Abemaciclib demonstrates ‘potential’ for advanced breast cancer
Monotherapy with abemaciclib induced objective tumor responses and was well tolerated among patients with HR-positive, HER-2–negative metastatic breast cancer, which may allow for prolonged treatment exposure, according to study results presented at the ASCO Annual Meeting.
“Abemaciclib is a CDK 4/6 inhibitor,” said Adam M. Brufsky, MD, PhD, professor of medicine, associate chief of hematology/oncology and co-director of the comprehensive breast cancer center at the University of Pittsburgh. “It differs from palbociclib in that it really, predominately, inhibits CDK 4 and not 6.”
Adam M. Brufsky
Brufsky spoke with HemOnc Today about the results of MONARCH1, a trial to evaluate the safety and efficacy of abemaciclib monotherapy. In this phase 2, single-arm study, Maura N. Dickler, MD, a medical oncologist at Memorial Sloan Kettering Cancer Center, and colleagues assigned 132 patients to treatment with 200 mg abemaciclib, administered orally on a continuous schedule every 12 hours until disease progression.
“MONARCH 1 included women with HR-positive, metastatic breast cancer who had been treated with multiple prior therapies,” Brufsky said.
The researchers evaluated objective response rate with RECIST v1.1 criteria. Interim and final analyses were performed 8 and 12 months after the last patient began treatment.
The median age of patients was 58 years (range, 36 to 89). ECOG performance status of 1 was noted in 44.7% of patients. Most women (90.2%) had visceral disease; 85.6% had 2 or more metastatic sites.
“What was dramatic in this population was that the median PFS was 5.7 months,” Brufsky said. “More importantly, the confirmed objective response rate was 17.4%. When you look at historical controls in this population, that is about 3 or 4 months longer than we would expect. This is a really interesting finding.”
The results of MONARCH1 demonstrate that abemaciclib “has potential as a single-agent CDK 4/6 inhibitor in later lines of disease,” Brufsky said. – by Julia Ernst, MS
Dickler MN, et al. Abstract 510. Presented at: ASCO Annual Meeting; June 3-7, 2016; Chicago.
Disclosures: Dickler reports consulting/advisory roles with AstraZeneca, Bristol-Myers Squibb, Eisai, Genentech/Roche, Merrimack, Novartis, Pfizer and Syndax and research funding through her institution from Genentech/Roche, Lilly and Novartis. Brufsky reports no relevant financial disclosures.