Ribociclib/Letrozole in UK Subgroup of Phase IIIb Trial of Advanced Breast Cancer
Posted: Thursday, February 4, 2021
In the multicenter phase IIIb CompLEEment-1 trial, first-line treatment with ribociclib plus letrozole seemed to be safe and active in patients in the UK cohort with hormone receptor–positive, HER2-negative advanced breast cancer, according to Mark Tuthill, MBBS, BSc, PhD, of the Oxford University Hospitals NHS Foundation Trust, London, and colleagues. The final results from this cohort, which were presented during the virtual 2020 San Antonio Breast Cancer Symposium (SABCS; Abstract PS10-49), seem to be consistent with the overall intention-to-treat population and other ribociclib registration studies.
“Ribociclib is an oral selective CDK4/6 inhibitor approved for use in combination with an aromatase inhibitor or fulvestrant in women with hormone receptor–positive, HER2-negative advanced breast cancer in several countries, including the United Kingdom,” the investigators commented.
A total of 139 patients were administered ribociclib plus letrozole. The median duration of exposure to treatment was 18.4 months, and the median time to disease progression was 27.6 months. The overall response and clinical benefit rates were 25.9% and 74.1%, respectively.
A total of 86 patients discontinued treatment due to disease progression (30.9%), adverse events (24.5%), physician or subject/guardian decision (both 2.9%), and protocol deviation (0.7%). Overall, the adverse-event profile appeared to be congruent with previous reports. Neutropenia (68.3%), nausea (59.7%), fatigue (54.0%), and neutropenia (48.9%) were among the most frequently reported adverse events. According to the investigators, the most common adverse event leading to dose reduction (12.2%) or interruption (33.8%) was neutropenia. The most common cause of treatment discontinuation (10.1%) was elevated levels of alanine transaminase. QT prolongation resulted in dose interruptions (2.2%) and reductions (1.4%), but no treatment discontinuations.
Disclosure: For full disclosures of the study authors, visit sabcs.org.
