RW Treatment Patterns and Outcomes in Postmenopausal HR+/HER2- mBC Patients Treated With Palbociclib Plus Letrozole as Initial Endocrine Therapy at Community Oncology Practices in the U.S.

Study Overview
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Brief Summary
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This is a retrospective, observational study that will document treatment patterns and clinical outcomes of postmenopausal patients diagnosed with HR+/HER2- mBC who received Palbociclib plus Letrozole as initial endocrine-based therapy in US community oncology network settings.

Official Title
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Real-World Treatment Patterns and Outcomes in Postmenopausal, Hormone-Receptor Positive, Human Epidermal Growth Factor Receptor 2 Negative, Metastatic Breast Cancer Patients Treated With Palbociclib Plus an Letrozole as Initial Endocrine Therapy at Community Oncology Practices in the U.S.

Conditions
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Breast Cancer

Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Patients must meet all of the following inclusion criteria to be eligible for inclusion in the study: Diagnosed with locoregional recurrent or metastatic female breast cancer. Pathologically confirmed HR-positive/HER2-negative diagnosis. Received treatment with palbociclib in combination with letrozole as initial endocrine-based therapy for advanced/metastatic breast cancer: Initiated treatment with palbociclib at least 3 months following the provider's first use of palbociclib following its FDA approval. At least 1 month of follow-up (at least one visit with the provider) after initiation of palbociclib. Postmenopausal (or receiving surgical or medical treatment to induce menopause) at the time of initiation of palbociclib. ≥18 year old at initiation of palbociclib. Exclusion Criteria: No exclusion criteria will be imposed for the selection of patients.
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 |
| --- | --- |
| Breast Cancer Patients<br>HR+/HER2- metastatic breast cancer patients in the US. | |

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Progression Free Survival (PFS) |  | mBC diagnosis through end of study (assessed up to 24 months) | 
| Tumor response |  | mBC diagnosis through end of study (assessed up to 24 months) | 
| Proportion of patients receiving various cancer treatment regimens |  | mBC diagnosis through end of study (assessed up to 24 months) | 
| Proportion of patients receiving each therapy sequence across lines |  | mBC diagnosis through end of study (assessed up to 24 months) | 
| Proportion of patients receiving each starting dose and end dose for those on palbociclib combination therapy |  | mBC diagnosis through end of study (assessed up to 24 months) | 
| Proportion of patients that experienced dose adjustment |  | mBC diagnosis through end of study (assessed up to 24 months) | 
| Proportion of patients that discontinued therapy |  | mBC diagnosis through end of study (assessed up to 24 months) |