The content of this website has been produced in line with the IBRANCE® Summary of Product Characteristics for Great Britain and Northern Ireland. IBRANCE® (palbociclib) Prescribing Information for Great Britain and Northern Ireland click here. Adverse event reporting information can be found at the bottom of the page.
Confidence Through Experience1-9
There is a growing body of RWE for IBRANCE® in the UK and globally to complement PALOMA-2 and PALOMA-3 RCT data and to help support prescribing decisions for appropriate patients with HR+/HER2- ABC.2-12
Learn more about IBRANCE® Real World Evidence.
Baseline characteristics between the IBRANCE® plus letrozole and letrozole alone groups were generally balanced after sIPTW adjustment.4
Patients treated with IBRANCE® plus letrozole demonstrated significantly longer rwPFS (8 months) compared with patients receiving letrozole alone.4
In a real-world setting, IBRANCE® plus letrozole was more effective than letrozole alone: median OS was not reached for patients receiving IBRANCE® plus letrozole and was 43.1 months with letrozole alone.4
Benefit was consistent across heterogeneous population and various patient subgroups encountered in routine clinical practice, including patients over 70 years and bone-only and visceral disease patients.4
Study Design
Key Baseline Characteristics
Progression Free Survival
Overall Survival
Subsequent Treatment Lines Following First-Line Treatment with IBRANCE® plus Letrozole or Letrozole Alone
Limitations to RWE
IBRANCE® Safety Profile
This study was a retrospective analysis of EHRs of 1430 Patients with HR+/HER2- mBC enrolled in the Flatiron Health Analytic Database.4 The study aimed to describe patient characteristics and real-world effectiveness of IBRANCE® plus letrozole versus letrozole alone as first-line ET for HR+/HER2- mBC in routine clinical practice in the USA.4
* Real-world PFS in P-REALITY was defined as the time in months from the start of IBRANCE® plus letrozole or letrozole alone therapy to death or disease progression.
† The PSM method was used to analyse the robustness of the primary analysis results by matching patients based on baseline demographics and clinical characteristics.4
‡ sIPTW is a statistical approach used to minimise bias in retrospective real-world studies. It is calculated using the Propensity Score (PS), the probability of a subject being assigned to a particular treatment (e.g. Drug A vs Drug B) given a set of observed key covariates (e.g. patient age or performance status) that may impact this treatment decision.13,14
sIPTW is a statistical approach increasingly used to minimise bias in retrospective real-world studies, where randomisation is not possible.13,14
The sIPTW method was used as the primary analysis in the P-REALITY study.4
PSM is a statistical-matching technique that attempts to eliminate or reduce any bias in real-world studies that are caused by the lack of randomisation.13
The PS is the probability of a subject being assigned to a particular treatment (e.g. Drug A or Drug B) given a set of observed key covariates (e.g. age or performance status) that may impact on this treatment decision.13
Adapted from DeMichele A, et al. 2021.4
* Variable used in the PSM model; de novo versus not de novo were used as categories for initial diagnosis to metastatic diagnosis.
† Visceral disease was defined as metastatic disease in the lung and/or liver; patients could have had other sites of metastases. No visceral disease was defined as no lung or liver metastases.
‡ Bone-only disease was defined as metastatic disease in the bone only.
IBRANCE® plus letrozole significantly prolonged rwPFS by 8 months compared with letrozole alone (median 20.0 vs 11.9 months; HR=0.58; [95% CI: 0.49–0.69]; p<0.0001) in a heterogeneous population of patients with HR+/HER2− mBC, with consistent PFS improvements observed across the majority of patient subgroups examined.4
Figure adapted from DeMichele A, et al. 2021.4
Figure adapted from DeMichele A, et al. 2021.4
Adapted from DeMichele A, et al. 2021.4
* Race by Cohort interaction and Metastatic Sites by Cohort interaction were the only subgroup variable-by-treatment cohort interaction that were significant (p<0.0001 and p=0.0050, respectively); however, race data were not known in the “not documented” race group.
† Bone-only disease was defined as metastatic disease in the bone only
‡ Visceral disease was defined as metastatic disease in the lung and/or liver; patients could have had other sites of metastases. No visceral disease was defined as no lung or liver metastases.
The total patient population for different subgroups varied due to the application of sIPTW. Therefore, the total n number for each subgroup may not have always equalled the N number of the treatment arm (due to rounding error and categorisation differences).
In a real-world setting, IBRANCE® plus letrozole was more effective than letrozole alone: median OS was not reached for patients receiving IBRANCE® plus letrozole and was 43.1 months with letrozole alone.4
Figure adapted from DeMichele A, et al. 2021.4
Figure adapted from DeMichele A, et al. 2021.4
Adapted from DeMichele A, et al. 2021 and Pfizer Ltd. Data on file. 20214,15
* Table does not include all patients receiving CDK4/6 inhibitors (clinical study drugs are excluded). In the UK a CDK4/6 inhibitor is not permitted after progression on a CDK4/6 inhibitor.
† Patient percentages have been calculated as a percentage of patients receiving any CDK4/6 inhibitor in the second-line.
‡ Data for the rationale of switching from letrozole to fulvestrant (i.e. due to intolerance or progression) are unavailable.
§ Data on the timing of palbociclib addition to the patient’s treatment regimen, or whether patients switched treatment due to intolerance are unavailable.
There are inherent limitations of real-world analyses due to the lack of random treatment assignment, the variations in follow-up and the lack of uniform assessment of disease progression; missing data or erroneous data entry, and incomplete capture of comorbid conditions and performance status are also limiting factors.4
1L : First-line, ALT : Alanine Aminotransferase, AST : Aspartate Aminotransferase, CDK4/6 : Cyclin-Dependent Kinase 4/6, CI : Confidence Interval, ECOG PS : Eastern Cooperative Oncology Group performance status, EHR : Electronic Health Record, ET : Endocrine Therapy, HR+/HER2- : Hormone Receptor‑Positive/Human Epidermal Growth Factor Receptor 2-Negative, HR : Hazard Ratio, LHRH : Luteinising Hormone-Releasing Hormone, mBC : metastatic Breast Cancer, ND : Not Documented, NE : Not Estimable, NR : Not Reached, OS : Overall Survival, PFS : Progression-Free Survival, PS : Propensity Score, PSM : Propensity Score Matching, RCT : Randomised Controlled Trial, RWE : Real World Evidence, rwPFS : real-world Progression-Free Survival, sIPTW : stabilised inverse Probability of Treatment Weighting
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