The efficacy of abemaciclib and endocrine therapy against chemotherapy in advanced breast cancer is tested

The ABIGAIL study, promoted by MEDSIR, will compare the efficacy of abemaciclib in combination with endocrine therapy (letrozole or fulvestrant), with a short course of chemotherapy as first-line treatment in patients with hormone receptor (HR) positive and negative breast cancer. for HER2 protein, locally advanced and inoperable or metastatic with criteria for aggressive disease.

Abemaciclib, a cyclin-dependent kinase (CDK) inhibitor drug, is indicated for the treatment of patients with these subtypes of breast cancer. These types of drugs block the activity of two proteins, CDK4 and CDK6, which help control cell division.

In the trial, called ABIGAIL, a total of 160 patients will be randomized 1:1 to treatment arm A, receiving abemaciclib with endocrine therapy, or arm B, receiving 3 cycles (12 weeks) of chemotherapy with paclitaxel. Once the chemotherapy cycles are completed and according to the investigator’s criteria, the patient could start treatment with abemaciclib plus endocrine therapy, or continue with the paclitaxel regimen.

The main objective of this trial is to evaluate the efficacy, measured by the objective response rate at 12 weeks, of abemaciclib in combination with endocrine therapy versus paclitaxel in this type of patient.

“Samples of primary tumor and metastatic lesions will be collected before the start of treatment in both arms, as well as blood samples at 15 days and in progression. with these samples Different parameters will be analyzed, such as the presence of mutations or genetic variations, to try to associate the results of the clinical study with different markers.“explains Dr. Elizabeth White, principal investigator of the Hospital San Cecilio.

Researchers from the hospital in Granada

They hope that this study will provide consistent evidence that the combination of abemaciclib with endocrine therapy as a first-line regimen is not inferior to the optimal first-line with chemotherapy, consisting of weekly paclitaxel, in terms of objective response rate after the first 12 weeks. weeks of treatment in patients with HR-positive and HER2-negative metastatic breast cancer with poor prognosis.

According to a recent patient subgroup analysis using data from the phase III MONARCH 2 and MONARCH 3 clinical trials, patients with aggressive disease and poor prognostic features (in terms of presence of liver metastases, progesterone receptor (PgR) -negative, high-grade tumors, or short treatment-free interval) had the greatest benefit from the addition of abemaciclib to endocrine therapy. These data suggest that patients with more aggressive disease and less sensitive tumor-endocrine profile could obtain considerable benefit from this combination in the context of advanced disease.

ABIGAIL is an international study – currently in the patient recruitment phase – which is being carried out in a total of 26 hospitals in Spain, France, Portugal and Italy under the scientific direction of Dr. Antonio Llombart.