Comparative Effectiveness of Palbociclib Plus AI Versus Fulvestrant for HR+/HER2- ABC

Study Overview
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Brief Summary
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A retrospective cohort study conducted at the Cancer Hospital Chinese Academy of Medical Sciences to compare the effectiveness of palbociclib plus AI therapy and fulvestrant monotherapy as initial endocrine therapy in the patients with HR+/HER2- advanced breast cancer.

Detailed Description
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This study is designed to be a retrospective cohort study conducted at the Cancer Hospital Chinese Academy of Medical Sciences. The target populations of this study are patients with HR+/HER2- advanced breast cancer who received the initial endocrine therapy of palbociclib plus AI or fulvestrant monotherapy from August 1, 2018 to December 31, 2020. It is expected to enroll 600 subjects in this study. The subjects' data such as demographics and other baseline characteristics, medications, prognosis, will be collected retrospectively, and statistical analysis of data will be conducted to compare the effectiveness outcome measures.

Official Title
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Comparative Effectiveness of Palbociclib Plus Aromatase Inhibitor Versus Fulvestrant Alone as Initial Endocrine Therapy for HR+/HER2- Advanced Breast Cancer in Chinese Clinical Practice: a Real-world Study

Conditions
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Hormone Receptor Positive Advanced Breast Cancer

Intervention / Treatment
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* Drug: palbociclib + aromatase inhibitor
* Drug: fulvestrant


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Chinese women ≥18 years old; Diagnosed with locally advanced (stage IIIb/IIIc) or metastatic (stage IV) breast cancer; The molecular classification is pathologically confirmed as HR+/HER2-; Palbociclib plus AI or fulvestrant monotherapy as initial endocrine therapy for advanced breast cancer for at least 1 cycle; The follow-up time should be not less than 3 months after the start of palbociclib plus AI therapy or fulvestrant monotherapy. Exclusion Criteria: 1. Subjects who have previously received chemotherapy, other CDK4/6 inhibitors or other endocrine monotherapy for advanced breast cancer.

Ages Eligible for Study
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Minimum Age: 18 Years

Sexes Eligible for Study
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Female

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| palbociclib + aromatase inhibitor<br>Adult patients with HR+/HER2- advanced breast cancer who received the initial endocrine therapy of palbociclib plus aromatase inhibitor at the Cancer Hospital Chinese Academy of Medical Sciences from August 1, 2018 to December 31, 2020. | Drug: palbociclib + aromatase inhibitor<br>* palbociclib + aromatase inhibitor therapy<br>|
| fulvestrant<br>Adult patients with HR+/HER2- advanced breast cancer who received the initial endocrine therapy of fulvestrant monotherapy at the Cancer Hospital Chinese Academy of Medical Sciences from August 1, 2018 to December 31, 2020. | Drug: fulvestrant<br>* fulvestrant monotherapy<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Real-world progression-free survival (rwPFS) | It is defined as the time (months) from the start of palbociclib+AI or fulvestrant monotherapy to progressive disease or all-cause mortality. The progressive disease is determined by clinicians based on the results of clinical evaluation, laboratory tests, imaging or pathological examinations. Patients who have not died or have not experienced progressive disease will be censored at the beginning of next-line treatment or at the last visit during the study period. | From date of index treatment to death, disease progression, or end of study, whichever came first, assessed up to 36 months. | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Overall survival | It is defined as the time (months) from the start of palbociclib+AI or fulvestrant monotherapy to all-cause mortality. Patients who have not died are censored on the study deadline. | From date of index treatment until date of death from any acuse or date of end of study, whichever came first, assessed up to 36 months. | 
| Real-world tumor response (rwTR) | Real world ORR is defined as the proportion of patients with complete response (CR) or partial response (PR) reported by doctors among all patients with response data available.Real world CBR is defined as the proportion of patients who have reached CR, PR, or stable disease (SD) for at least 24 weeks reported by the doctors among all patients with response data available. | From date of index treatment to death, disease progression, or end of study, whichever came first, assessed up to 36 months. |