This study aims to evaluate the efficacy and safety of branded palbociclib (Ibrance®) compared to available local generic formulations (Palbociclib-IPI) in Iraqi patients with hormone receptor-positive, human epidermal growth factor receptor 2-negative breast cancer (HR+ HER2- BC). This research aims to provide evidence

The main problem, though, is that there is no local study performed that evaluates the effectiveness, safety, and tolerability of palbociclib in Iraqi patients. Although conducted worldwide, the clinical benefit established with palbociclib may not apply to the outcomes in Iraq, due to the difference in patients, the health care system, and continuity of treatment, which do not resemble those present in countries of high income.

Another equally urgent problem is the absence of comparative studies performed on the branded palbociclib (Ibrance®) and the versions that are now entering the Iraqi market. The high cost of branded forms of palbociclib and the out-of-pocket payment in the bulk of them make it necessary for patients to resort to the generic forms, in view of the absence of comparative data showing clinical equivalence. The oncologists, at the same time, lack data that show whether substitution leads to any loss of efficacy or safety, and the information is lacking to determine the consequences of procurement and reimbursement policies.

Thus, the problem addressed in this thesis is two-fold in nature: (1) the absence of real-world data on the outcome of palbociclib therapy in Iraqi breast cancer patients and the absence of comparative studies on branded versus generic evaluations in Iraq. In the absence of local data, treatment will have to be based on result extrapolation from foreign studies instead of local data, which may lead to undesirable results in the way of results and efficiency of administration of limited health care resources.

Inclusion Criteria: 1. Females ≥ 18 years. 2. Histological or cytological confirmation of HR+/HER2- advanced or metastatic breast cancer according to international criteria for pathology.

3. Patients evaluated prior to treatment with letrozole or fulvestrant having had at least 1 cycle of palbociclib (retrospectively, Ibrance® or prospectively, Palbociclib-IPI) for HR+/HER2- advanced or metastatic breast cancer.

4. Availability of a complete history and physical examination, laboratory tests, and imaging studies of the patients, including baseline and follow-up tests and examinations.

5. For the prospective group, the patients had to be willing to give informed consent for evaluation of quality of life and for evaluation of medical data.

Exclusion Criteria: 1. Male breast cancer patients, due to a different biology and small population proportion in Iraq.

2. Patients with HER2-positive or triple-negative breast cancer, due to different algorithms for treatment and prognosis.

3. Patients previously receiving CDK4/6 inhibition apart from palbociclib (ribociclib or abemaciclib) so as to not have biased results.

4. Patients without complete medical history or follow-up sufficient to evaluate reliable outcomes.

5. Patients with other cancers or severe comorbidities which had a direct impact on survival results independent of breast cancer per criteria done in other real-world observational cohorts

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The study involved women who are adults with hormone receptor-positive (HR+) and negative (HER2-) advanced or metastatic breast cancer patients who received systemic therapy that comprised palbociclib combined with endocrine therapy (e.g., letrozole or fulvestrant).

De-identified individual participant data will be shared upon reasonable request."

start one year after publication

"Access to de-identified individual participant data will be granted to qualified researchers upon reasonable request, subject to approval by the study investigators and the University of Mustansiriyah ethics committee."