CDK4/6 inhibitors plus endocrine therapy benefit subset of breast cancer patients
Compared with endocrine therapy alone, CDK4/6 inhibitors plus endocrine therapy improved subsequent progression-free survival and time to subsequent chemotherapy in patients with HR-positive, HER2-negative advanced breast cancer, according to research presented at ASCO 2021.
“CDK4/6 inhibitors combined with endocrine therapy deeply transformed the treatment landscape of HR-positive HER2-negative advanced breast cancer,” Elisabetta Munzone, MD, deputy director at the Institute of European Oncology in the division of medical oncology, said during the presentation.
She added data from randomized clinical trials have suggested that progression-free survival (PFS2) was not compromised by using CDK4/6 inhibitors plus endocrine therapy, and that the time to subsequent chemotherapy may be delayed with this treatment.
Munzone and colleagues conduced a systematic review and meta-analyses to evaluate these benefits in patients with HR-positive/HER2-negative advanced breast cancer.
They searched PubMed and reviewed abstracts and presentation from major conferences to identify randomized clinical trials that evaluated CDK4/6 inhibitors and endocrine therapy that had data available on subsequent progression-free survival and time to subsequent chemotherapy.
Munzone and colleagues’ analyses included seven studies comprising 3,912 patients: PALOMA 1,2 and 3, MONALEESA 3 and 7, and MONARCH 2 and 3.
The researchers identified a benefit to PFS2 among patients who received CDK 4/6 inhibitors plus endocrine therapy (pooled HR = 0.67; 95% CI, 0.61-0.74).
They also observed a delay in time to subsequent chemotherapy in patients who received CDK4/6 inhibitors (pooled HR = 0.63; 95% CI, 0.58-0.7).
Additionally, investigators confirmed benefits in progression-free survival (pooled HR = 0.54; 95% CI, 0.5-0.59) and overall survival (pooled HR = 0.77; 95% CI, 0.68-0.86).
“Based on these results, we can conclude that CDK4/6 plus endocrine therapy compared with endocrine therapy alone improved PFS2 and time to chemotherapy,” Munzone said.
“The delay of chemotherapy can spare the patient toxicity, potentially improving their quality of life,” she added. “The observed benefit is PFS2 may postpone the onset of endocrine resistance and might also offer an additional therapeutic advantage in this setting.”
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