This retrospective observational cohort study emulates a target trial to compare the effectiveness and safety of two first-line treatment strategies for women with HER2-positive unresectable locally advanced, recurrent, or metastatic breast cancer in routine clinical practice: pertuzumab plus trastuzumab and docetaxel versus trastuzumab and docetaxel. Data were obtained from electronic health records held by the National Health and Medical Big Data (Eastern) Center and linked with the Jiangsu Provincial Mortality Registry. Eligible patients initiated one of the two treatment strategies between January 1, 2020, and December 31, 2024. Time zero was defined as the date of the first administration of the qualifying first-line regimen. No minimum number of treatment cycles was required. The primary outcome was overall survival. Secondary outcomes included progression-free survival and prespecified adverse events.
Patients were classified according to the first-line regimen initiated on the index date. Time zero was defined as the date of first administration of pertuzumab plus trastuzumab and chemotherapy or trastuzumab and chemotherapy. Eligibility criteria were assessed using information available on or before time zero. Patients were not required to complete a minimum number of treatment cycles and were followed from treatment initiation regardless of subsequent treatment discontinuation or modification.
Study Type
OBSERVATIONAL
Enrollment
2,250
Pertuzumab administered as part of first-line dual HER2-targeted therapy with trastuzumab and docetaxel. Exposure was identified from electronic prescriptions, medication orders, and administration records.
Trastuzumab administered as part of first-line HER2-targeted therapy with docetaxel, with or without pertuzumab. Exposure was identified from electronic prescriptions, medication orders, and administration records.
Docetaxel administered as first-line chemotherapy in combination with HER2-targeted therapy. Exposure was identified from electronic prescriptions, medication orders, and administration records.
Nanjing Medical University
Nanjing, Jiangsu, China
Overall Survival (OS)
Overall survival was defined as the time from the first administration of the index first-line treatment regimen to death from any cause.
Time frame: From the index date until death, last known follow-up, or December 31, 2024, whichever occurred first (up to 60 months)
Real-World Progression-Free Survival (rwPFS)
Real-world progression-free survival was defined as the time from the index date, defined as the first administration of the qualifying first-line treatment regimen, to the first documented real-world disease progression or death from any cause, whichever occurred first.
Time frame: From the index date until documented real-world disease progression, death, last known progression-free follow-up, or December 31, 2024, whichever occurred first (up to 60 months)
Proportion of Participants With Prespecified Grade 3 or Higher Adverse Events
Adverse-event severity was determined according to the severity grade documented in the electronic health record.
Time frame: From the index date through the documented end of first-line treatment (up to 60 months)
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