medwireNews: The monarchE investigators have identified baseline factors linked to an increased risk for discontinuation of abemaciclib in the trial comprising patients with hormone receptor-positive, HER2-negative early breast cancer.
The findings were presented in a poster by Sara Tolaney (Dana-Farber Cancer Institute, Boston, Massachusetts, USA) and co-researchers at the 2022 ASCO Annual Meeting, held in Chicago, Illinois, USA.
They explained that although the addition of abemaciclib to adjuvant endocrine therapy in the phase 3 study significantly improved the outcomes of patients with high-risk disease, 25.8% “discontinued abemaciclib before completing the 2-year treatment period due to reasons other than recurrence.”
The team therefore conducted exploratory analyses to evaluate the impact of baseline parameters on time to discontinuation of abemaciclib or all treatment among the participants who received the CDK4/6 inhibitor at a dose of 150 mg twice daily alongside endocrine therapy of physician’s choice.
Multivariate analysis showed that patients aged at least 65 years were significantly more likely than their younger counterparts to discontinue abemaciclib (hazard ratio [HR]=1.89). This was also the case for postmenopausal versus premenopausal patients (HR=1.52) and those with four or more comorbidities versus none (HR=1.53).
By contrast, the likelihood of discontinuation was significantly lower for participants with an ECOG performance status of 0 versus 1 (HR=0.80), those with four to nine or 10 or more positive nodes versus one to three nodes (HRs=0.80 and 0.63, respectively), and those recruited from Asia or other geographic regions versus North America or Europe (HR=0.67 for both comparisons).
Tolaney and colleagues noted that the differences “in discontinuation between subgroups within each factor started early on treatment and continued to separate during the 2-year treatment period.”
For instance, the rate of discontinuation at 6 months was 27.6% for the 65 years and older subgroup and 11.6% for those younger than 65 years, while the rates at 12 and 24 months were 36.4% versus 16.3% and 46.8% versus 22.9%, respectively.
Similarly, the 6-month discontinuation rates were 17.7% and 9.3% for postmenopausal and premenopausal participants, respectively, while the 12-month rates were 24.6% versus 12.8% and the 24-month rates were 33.0% versus 18.4%.
“These results illustrate the importance of close monitoring along with appropriate interventions such as dose adjustments, early on treatment, to retain patients on abemaciclib treatment,” concluded the team.
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2022 ASCO Annual Meeting; Chicago, Illinois, USA: 3–7 June
Abstract link https://meetings.asco.org/abstracts-presentations/211284
Author: Shreeya Nanda