Phase III Evaluation of Concurrent Versus Sequential Chemotherapy and Aromatase Inhibitors (Exemestane, Letrozole, Anastrozole) in Endocrine-Responsive Early Breast Cancer

The primary objective of this phase III study is to evaluate the relative efficacy of **sequential** compared to concurrent administration of chemotherapy and aromatase inhibitors in post-menopausal patients with endocrine-responsive early breast cancer, specifically in the prevention of disease recurrence. This is clinically relevant as the optimal timing for integrating these treatments has not been clearly defined, and determining the most effective strategy could significantly impact patient outcomes by reducing recurrence rates.

Secondary objectives include evaluating the relative efficacy of the two treatment strategies on overall mortality, local relapses, and distant relapses, as well as comparing their toxicity profiles. These objectives are crucial for understanding the broader implications of treatment strategies on patient survival and quality of life, as well as for identifying potential adverse effects associated with each approach.

The clinical trial focuses on evaluating the efficacy of sequential versus concurrent administration of chemotherapy and aromatase inhibitors in patients with early **breast cancer**. The study population consists exclusively of **female** participants, as the trial is not open to male subjects. Participants are postmenopausal women with a histological diagnosis of invasive breast cancer that has been completely removed by surgery. The age range of the participants includes those aged 45 and above, with specific criteria for defining postmenopausal status. The trial does not include a vulnerable population. Participants are required to have primary tumors positive for estrogen receptor (ER) and/or progesterone receptor (PgR) and must be prescribed five years of endocrine therapy with an aromatase inhibitor. Additionally, patients with HER-2 positive tumors are eligible if they are prescribed trastuzumab according to the registered schedule. The sponsor has not provided information regarding the total number of participants in the trial. Lifestyle considerations such as diet, physical activity, or habits are not specified in the available data.

The clinical trial is designed to evaluate the relative efficacy of **sequential** versus concurrent administration of chemotherapy and **aromatase inhibitors** in post-menopausal patients with endocrine-responsive early **breast cancer**. This is a phase III, randomized, double-blind, controlled study. The trial aims to prevent disease recurrence by comparing these two treatment strategies. The study is expected to run from November 2013 to November 2034, with a maximum treatment period of 120 weeks for each participant.

Participants will undergo a series of study visits, beginning with an inclusion (screening) visit to confirm eligibility based on criteria such as histological diagnosis of invasive breast cancer, postmenopausal status, and primary tumor positivity for ER and/or PgR. Following randomization, participants will attend regular follow-up visits to monitor treatment efficacy and safety, with clinical and laboratory toxicities graded according to NCI criteria CTCAE. The primary endpoint is disease-free survival (DFS), defined as the time from randomization to the first occurrence of local, regional, or distant recurrence, contralateral breast cancer, second primary malignancy, or death from any cause. Secondary endpoints include overall survival (OS) and other outcomes as defined by the STEEP system.

The expected length of participant involvement is up to 120 weeks, with conditions for early termination including significant adverse events or withdrawal of consent. Participants will be administered one of the following **aromatase inhibitors**: **exemestane**, **letrozole**, or **anastrozole**, all in film-coated tablet form and taken orally. The study will ensure that all participants receive the appropriate dosage as per the trial protocol, with **exemestane** at a maximum daily dose of 25 mg, **letrozole** at 2.5 mg, and **anastrozole** at 1 mg. The end-of-study visit will conclude the participant's involvement, where final assessments will be conducted to evaluate the overall outcomes of the treatment strategies.

The clinical trial involves the administration of three **aromatase inhibitors** as part of the treatment regimen for post-menopausal patients with endocrine-responsive early breast cancer. The first experimental medication is **Exemestane**, which is provided in the form of a film-coated tablet. The active substance, exemestane, is a chemical compound classified as an irreversible steroidal aromatase inhibitor. The medication is administered orally with a maximum daily dose of 25 mg. The total maximum dose over the treatment period is 91,250 mg, with a treatment duration of up to 120 days. Compliance with the dosing schedule is monitored throughout the trial.

The second experimental medication is **Letrozole**, also available as a film-coated tablet. Letrozole is a chemical compound that functions as an aromatase inhibitor. It is administered orally with a maximum daily dose of 2.5 mg. The total maximum dose for the treatment period is 9,125 mg, and the treatment duration is also up to 120 days. Participant adherence to the dosing regimen is closely monitored to ensure compliance.

The third experimental medication is **Anastrozole**, which is provided in the form of a film-coated tablet. Anastrozole is a potent and highly selective non-steroidal aromatase inhibitor. The medication is administered orally with a maximum daily dose of 1 mg. The total maximum dose over the treatment period is 3,650 mg, with a treatment duration of up to 120 days. Monitoring of participant compliance with the dosing schedule is an integral part of the trial protocol.

In this study, no non-experimental treatments such as standard-of-care therapy, placebo, or comparator treatments are specified. The focus is on evaluating the efficacy of the sequential versus concurrent administration of these aromatase inhibitors in preventing disease recurrence in the specified patient population.

Efficacy in this clinical trial will be assessed primarily through the measurement of **Disease-Free Survival (DFS)**. DFS is defined as the time from randomization to the occurrence of any of the following events: local recurrence of disease, regional recurrence of disease, distant recurrence of disease, contralateral invasive or intraductal breast cancer, second primary malignancy other than breast cancer, or death from any cause. This endpoint is evaluated according to the STEEP system, as outlined by Hudis et al. in the Journal of Clinical Oncology.

Secondary efficacy endpoints include **Overall Survival (OS)**, which is defined as the time from randomization to death from any cause. Additional outcomes will be assessed as defined within the STEEP system. Safety assessments will also be conducted, with clinical and laboratory toxicities graded according to the NCI criteria CTCAE. The trial aims to evaluate the relative efficacy of sequential versus concurrent administration of chemotherapy and aromatase inhibitors in preventing disease recurrence in post-menopausal patients with endocrine-responsive early breast cancer.