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Real-World Effectiveness of Palbociclib in Combination With an Aromatase Inhibitor

Real-World Treatment Effectiveness of Palbociclib in Combination With an Aromatase Inhibitor as 1st Line Therapy in Metastatic Breast Cancer

Status
Completed
Phases
Unknown
Study type
Observational
Source
ClinicalTrials.gov
Registry ID
NCT05361655
Enrollment
2888
Registered
2022-05-05
Start date
2021-09-01
Completion date
2021-09-01
Last updated
2024-06-07

For informational purposes only — not medical advice. Sourced from public registries and may not reflect the latest updates. Terms

Conditions

Metastatic Breast Cancer

Keywords

cyclin-dependent kinase 4/6i (CDK4/6i)

Brief summary

A retrospective study of de-identified (to preserve patient privacy) patient information from the Flatiron Health Analytic Database to compare effectiveness (i.e., overall survival) of first line palbociclib + aromatase inhibitor (AI) versus AI alone treatment in postmenopausal women or men with hormone receptor positive/human epidermal growth factor receptor 2 negative (HR+/HER2-) metastatic breast cancer (MBC) in the United States clinical practices.

Interventions

Palbociclib + an aromatase inhibitor therapy

DRUGAromatase inhibitor

Aromatase inhibitor therapy

Sponsors

Pfizer
Lead SponsorINDUSTRY

Study design

Observational model
COHORT
Time perspective
RETROSPECTIVE

Eligibility

Sex/Gender
ALL
Age
18 Years to No maximum
Healthy volunteers
No

Inclusion criteria

* Confirmed HR+/HER2- status after MBC diagnosis. * Received palbociclib + AI or AI as first-line therapy

Exclusion criteria

* Evidence of prior treatment with other CDK4/6I, AI, tamoxifen, raloxifene, toremifene, or Fulvestrant for MBC * First structured activity greater than 90 days after MBC diagnostic date * Treatment with a CDK4/6 inhibitor as part of a clinical trial

Design outcomes

Primary

MeasureTime frameDescription
Overall Survival (OS) in Postmenopausal Female or Male Participants With Metastatic Breast CancerFrom index date to death due to any cause or censoring date of 30-Sep-2020 (approximately up to 68 months)OS was defined as the time from the index date (start of palbociclib + AI or AI alone) to death. Participants who did not die, were censored at the end of study date (30-Sep-2020). Kaplan-Meier method adjusted by stabilized inverse probability of treatment weighting (sIPTW) was used.

Secondary

MeasureTime frameDescription
Number of Participants According to Real-World Tumor Responses (rwTR): Postmenopausal Female or in Male Participants With Metastatic Breast CancerFrom 30 days after index treatment initiation until CR, PR, SD or PD (approximately 67 months)Real-world best responses were assessed based on treating clinician's assessment of radiological evidence for change in burden of disease over course of treatment after 1 month of index treatment initiation. Responses were classified as complete response (CR), partial response (PR), stable disease (SD), progressive disease (PD), indeterminate response (IR). CR=Complete resolution of all visible disease. PR=partial reduction in size of visible disease in some or all areas without any areas of increase in visible disease. SD=no change in overall size of visible disease. PD: an increase in visible disease; also included cases where some lesions increased in size and some lesions decreased in size; included cases where clinician indicated progressive disease; IR=study data not available for evaluation of efficacy for any reason, including participants lost to follow-up or assessment not undertaken or death. Analysis was performed using sIPTW method to balance participant characteristics.
Real-World Response Rate (rwTR) in Postmenopausal Female or in Male Participants With Metastatic Breast CancerFrom 30 days after index treatment initiation until disease progression or death due to any cause or censoring date (approximately up to 67 months)Real-world tumor response rate (rwTR) was defined as the percentage of participants with a real world complete response (rwCR) or real-world partial response (rwPR). CR: complete resolution of all visible disease. PR: partial reduction in size of visible disease in some or all areas without any areas of increase in visible disease. Analysis was performed using sIPTW method to balance participant characteristics.
Number of Participants According to Initial Dose of Palbociclib: Palbociclib + Aromatase Inhibitor Arm OnlyAt index (anytime between 03-Feb-2015 to 31-Mar-2020, approximately up to 62 months)Number of participants according to the initial dose of palbociclib (75 milligrams \[mg\]/day, 100mg/day, 125 mg/day or missing dose) are reported in this outcome measure.
Time to Dose Adjustment for Palbociclib- Palbociclib + Aromatase Inhibitor Arm OnlyAt index (anytime between 03-Feb-2015 to 30-Sep-2020, approximately up to 68 months)Time to dose adjustment for participants who received palbociclib 125 mg/day, 100 mg/day, or 75 mg/day as initial dose was presented in this outcome measure.
Real-World Progression Free Survival (rwPFS) in Postmenopausal Female or in Male Participants With Metastatic Breast CancerFrom index date until disease progression or death due to any cause or censoring date (approximately up to 68 months)Real-world PFS was defined as the number of months from start of palbociclib + AI or AI alone to death from any cause or disease progression (based on clinical assessment or by radiographic scan/tissue biopsy), whichever occurred first. Disease progression was defined as at least a 20 percentage (%) increase in the sum of diameters of target lesions, taking as reference the smallest sum on study (this includes the baseline sum if that was the smallest on study). Participants who did not die and did not have disease progression were censored at the date of initiation of next line of therapy for participants with 2 or more lines of therapy or at the date of their last visit during the study period (February 2015-September 2020) for participants with only 1 line of therapy. Kaplan-Meier method adjusted by stabilized IPTW was used.
Time to Next Line of TreatmentFrom start of study treatment to start of next line of therapy (up to 68 months)Time to next line of treatment represents the interval from commencement of one treatment to initiation of the next line of therapy. Analysis was performed using sIPTW method to balance participant characteristics among reporting groups.
Time to Subsequent ChemotherapyFrom start of study treatment to administration of different chemotherapeutic agent (up to 68 months)Time to subsequent chemotherapy represents the time interval to administration of a different chemotherapeutic agent after the first course of therapy was administered. Analysis was performed using sIPTW method to balance participant characteristics among reporting groups.
Real-World Progression Free Survival 2 (rwPFS2) in Postmenopausal Female or in Male Participants With Metastatic Breast CancerFrom start of study treatment until disease progression, or death from any cause following second line of therapy, whichever occurred first (approximately up to 68 months)rwPFS2 was defined as the time from the index date to the date of the first documentation of a rwPD or death due to any cause after starting second line of therapy, whichever occurs first. Disease progression was defined as at least a 20% increase in the sum of diameters of target lesions, taking as reference the smallest sum on study (this includes the baseline sum if that was the smallest on study). In addition to the relative increase of 20%, the sum must also demonstrate an absolute increase of at least 5 mm. Analysis was performed using sIPTW method to balance participant characteristics among reporting groups.
Duration of TreatmentFrom start of study treatment to end of treatment, start of subsequent line of therapy, or death from any cause, whichever occurred first (up to 68 months)Duration of treatment was defined as days from index prescription order date to end of treatment, start of subsequent line of therapy, or death from any cause, whichever occurred first. Kaplan-Meier method adjusted by stabilized IPTW was used.

Countries

United States

Participant flow

Recruitment details

Postmenopausal women or men with human epidermal growth factor receptor positive(HR+)/human epidermal growth factor receptor 2 negative(HER2-)metastatic breast cancer(MBC)who initiated first line treatment with palbociclib + aromatase inhibitor(AI)or AI alone from February 2015 through March 2020 and were registered in the Flatiron Health Analytic Database were included in the study. Participants were followed until death or study end (date of data cutoff, 30-Sep-2020), whichever occurred first.

Pre-assignment details

All participants who were eligible for the retrospective database analysis were included for the study (i.e., 2888).

Participants by arm

ArmCount
Palbociclib + Aromatase Inhibitor
Participants with HR+/HER2- MBC who initiated first line treatment with palbociclib + aromatase inhibitor between 03 Feb 2015 to 31 Mar 2020 were included and observed.
1,324
Aromatase Inhibitor
Participants with HR+/HER2- MBC who initiated first line treatment with aromatase inhibitor alone between 03 Feb 2015 to March 2020 were included and observed.
1,564
Total2,888

Baseline characteristics

CharacteristicPalbociclib + Aromatase InhibitorAromatase InhibitorTotal
Age, Categorical
<=18 years
0 Participants0 Participants0 Participants
Age, Categorical
>=65 years
808 Participants1148 Participants1956 Participants
Age, Categorical
Between 18 and 65 years
516 Participants416 Participants932 Participants
Race/Ethnicity, Customized
Black
107 Participants136 Participants243 Participants
Race/Ethnicity, Customized
Unknown
317 Participants369 Participants686 Participants
Race/Ethnicity, Customized
White
900 Participants1059 Participants1959 Participants
Sex: Female, Male
Female
1314 Participants1545 Participants2859 Participants
Sex: Female, Male
Male
10 Participants19 Participants29 Participants

Adverse events

Event typeEG000
affected / at risk
EG001
affected / at risk
deaths
Total, all-cause mortality
420 / 1,324736 / 1,564
other
Total, other adverse events
0 / 00 / 0
serious
Total, serious adverse events
0 / 00 / 0

Outcome results

Primary

Overall Survival (OS) in Postmenopausal Female or Male Participants With Metastatic Breast Cancer

OS was defined as the time from the index date (start of palbociclib + AI or AI alone) to death. Participants who did not die, were censored at the end of study date (30-Sep-2020). Kaplan-Meier method adjusted by stabilized inverse probability of treatment weighting (sIPTW) was used.

Time frame: From index date to death due to any cause or censoring date of 30-Sep-2020 (approximately up to 68 months)

Population: FAS population comprised of all eligible participants enrolled in the study. Analysis was performed using sIPTW method to balance participant characteristics among reporting groups. sIPTW method created balanced virtual groups and hence overall number of participants analyzed was different from numbers in participant flow (not balanced).

ArmMeasureValue (MEDIAN)
Palbociclib + Aromatase InhibitorOverall Survival (OS) in Postmenopausal Female or Male Participants With Metastatic Breast Cancer49.1 Months
Aromatase InhibitorOverall Survival (OS) in Postmenopausal Female or Male Participants With Metastatic Breast Cancer43.2 Months
p-value: <0.000195% CI: [0.65, 0.87]Cox proportional hazard model
Secondary

Duration of Treatment

Duration of treatment was defined as days from index prescription order date to end of treatment, start of subsequent line of therapy, or death from any cause, whichever occurred first. Kaplan-Meier method adjusted by stabilized IPTW was used.

Time frame: From start of study treatment to end of treatment, start of subsequent line of therapy, or death from any cause, whichever occurred first (up to 68 months)

Population: FAS population comprised of all eligible participants enrolled in the study. sIPTW method created balanced virtual groups and hence overall number of participants analyzed was different from numbers in participant flow (not balanced).

ArmMeasureValue (MEDIAN)
Palbociclib + Aromatase InhibitorDuration of Treatment12.3 Months
Aromatase InhibitorDuration of Treatment5.5 Months
p-value: <0.000195% CI: [0.6, 0.72]Cox proportional hazard model
Secondary

Number of Participants According to Initial Dose of Palbociclib: Palbociclib + Aromatase Inhibitor Arm Only

Number of participants according to the initial dose of palbociclib (75 milligrams \[mg\]/day, 100mg/day, 125 mg/day or missing dose) are reported in this outcome measure.

Time frame: At index (anytime between 03-Feb-2015 to 31-Mar-2020, approximately up to 62 months)

Population: FAS population comprised of all eligible participants enrolled in the study.

ArmMeasureCategoryValue (COUNT_OF_PARTICIPANTS)
Palbociclib + Aromatase InhibitorNumber of Participants According to Initial Dose of Palbociclib: Palbociclib + Aromatase Inhibitor Arm OnlyPalbociclib 75 mg/day48 Participants
Palbociclib + Aromatase InhibitorNumber of Participants According to Initial Dose of Palbociclib: Palbociclib + Aromatase Inhibitor Arm OnlyPalbociclib 125 mg/day1110 Participants
Palbociclib + Aromatase InhibitorNumber of Participants According to Initial Dose of Palbociclib: Palbociclib + Aromatase Inhibitor Arm OnlyPalbociclib 100 mg/day144 Participants
Palbociclib + Aromatase InhibitorNumber of Participants According to Initial Dose of Palbociclib: Palbociclib + Aromatase Inhibitor Arm OnlyMissing22 Participants
Secondary

Number of Participants According to Real-World Tumor Responses (rwTR): Postmenopausal Female or in Male Participants With Metastatic Breast Cancer

Real-world best responses were assessed based on treating clinician's assessment of radiological evidence for change in burden of disease over course of treatment after 1 month of index treatment initiation. Responses were classified as complete response (CR), partial response (PR), stable disease (SD), progressive disease (PD), indeterminate response (IR). CR=Complete resolution of all visible disease. PR=partial reduction in size of visible disease in some or all areas without any areas of increase in visible disease. SD=no change in overall size of visible disease. PD: an increase in visible disease; also included cases where some lesions increased in size and some lesions decreased in size; included cases where clinician indicated progressive disease; IR=study data not available for evaluation of efficacy for any reason, including participants lost to follow-up or assessment not undertaken or death. Analysis was performed using sIPTW method to balance participant characteristics.

Time frame: From 30 days after index treatment initiation until CR, PR, SD or PD (approximately 67 months)

Population: FAS population comprised of all eligible participants enrolled in the study. Here, 'Overall Number of Participants Analyzed' signifies participants evaluable for this outcome measure.

ArmMeasureGroupValue (COUNT_OF_PARTICIPANTS)
Palbociclib + Aromatase InhibitorNumber of Participants According to Real-World Tumor Responses (rwTR): Postmenopausal Female or in Male Participants With Metastatic Breast CancerPartial response569 Participants
Palbociclib + Aromatase InhibitorNumber of Participants According to Real-World Tumor Responses (rwTR): Postmenopausal Female or in Male Participants With Metastatic Breast CancerProgressive disease155 Participants
Palbociclib + Aromatase InhibitorNumber of Participants According to Real-World Tumor Responses (rwTR): Postmenopausal Female or in Male Participants With Metastatic Breast CancerStable disease350 Participants
Palbociclib + Aromatase InhibitorNumber of Participants According to Real-World Tumor Responses (rwTR): Postmenopausal Female or in Male Participants With Metastatic Breast CancerIndeterminate response26 Participants
Palbociclib + Aromatase InhibitorNumber of Participants According to Real-World Tumor Responses (rwTR): Postmenopausal Female or in Male Participants With Metastatic Breast CancerComplete response163 Participants
Aromatase InhibitorNumber of Participants According to Real-World Tumor Responses (rwTR): Postmenopausal Female or in Male Participants With Metastatic Breast CancerIndeterminate response69 Participants
Aromatase InhibitorNumber of Participants According to Real-World Tumor Responses (rwTR): Postmenopausal Female or in Male Participants With Metastatic Breast CancerComplete response86 Participants
Aromatase InhibitorNumber of Participants According to Real-World Tumor Responses (rwTR): Postmenopausal Female or in Male Participants With Metastatic Breast CancerPartial response300 Participants
Aromatase InhibitorNumber of Participants According to Real-World Tumor Responses (rwTR): Postmenopausal Female or in Male Participants With Metastatic Breast CancerStable disease273 Participants
Aromatase InhibitorNumber of Participants According to Real-World Tumor Responses (rwTR): Postmenopausal Female or in Male Participants With Metastatic Breast CancerProgressive disease260 Participants
Secondary

Real-World Progression Free Survival 2 (rwPFS2) in Postmenopausal Female or in Male Participants With Metastatic Breast Cancer

rwPFS2 was defined as the time from the index date to the date of the first documentation of a rwPD or death due to any cause after starting second line of therapy, whichever occurs first. Disease progression was defined as at least a 20% increase in the sum of diameters of target lesions, taking as reference the smallest sum on study (this includes the baseline sum if that was the smallest on study). In addition to the relative increase of 20%, the sum must also demonstrate an absolute increase of at least 5 mm. Analysis was performed using sIPTW method to balance participant characteristics among reporting groups.

Time frame: From start of study treatment until disease progression, or death from any cause following second line of therapy, whichever occurred first (approximately up to 68 months)

Population: FAS population comprised of all eligible participants enrolled in the study. sIPTW method created balanced virtual groups and hence overall number of participants analyzed was different from numbers in participant flow (not balanced).

ArmMeasureValue (MEDIAN)
Palbociclib + Aromatase InhibitorReal-World Progression Free Survival 2 (rwPFS2) in Postmenopausal Female or in Male Participants With Metastatic Breast Cancer32.6 Months
Aromatase InhibitorReal-World Progression Free Survival 2 (rwPFS2) in Postmenopausal Female or in Male Participants With Metastatic Breast Cancer20.7 Months
p-value: <0.000195% CI: [0.54, 0.7]Cox proportional hazards model
Secondary

Real-World Progression Free Survival (rwPFS) in Postmenopausal Female or in Male Participants With Metastatic Breast Cancer

Real-world PFS was defined as the number of months from start of palbociclib + AI or AI alone to death from any cause or disease progression (based on clinical assessment or by radiographic scan/tissue biopsy), whichever occurred first. Disease progression was defined as at least a 20 percentage (%) increase in the sum of diameters of target lesions, taking as reference the smallest sum on study (this includes the baseline sum if that was the smallest on study). Participants who did not die and did not have disease progression were censored at the date of initiation of next line of therapy for participants with 2 or more lines of therapy or at the date of their last visit during the study period (February 2015-September 2020) for participants with only 1 line of therapy. Kaplan-Meier method adjusted by stabilized IPTW was used.

Time frame: From index date until disease progression or death due to any cause or censoring date (approximately up to 68 months)

Population: FAS population comprised of all eligible participants enrolled in the study. Analysis was performed using sIPTW method to balance participant characteristics among reporting groups. sIPTW method created balanced virtual groups and hence overall number of participants analyzed was different from numbers in participant flow(not balanced).

ArmMeasureValue (MEDIAN)
Palbociclib + Aromatase InhibitorReal-World Progression Free Survival (rwPFS) in Postmenopausal Female or in Male Participants With Metastatic Breast Cancer19.3 Months
Aromatase InhibitorReal-World Progression Free Survival (rwPFS) in Postmenopausal Female or in Male Participants With Metastatic Breast Cancer13.9 Months
p-value: <0.000195% CI: [0.62, 0.76]Cox proportional hazards model
Secondary

Real-World Response Rate (rwTR) in Postmenopausal Female or in Male Participants With Metastatic Breast Cancer

Real-world tumor response rate (rwTR) was defined as the percentage of participants with a real world complete response (rwCR) or real-world partial response (rwPR). CR: complete resolution of all visible disease. PR: partial reduction in size of visible disease in some or all areas without any areas of increase in visible disease. Analysis was performed using sIPTW method to balance participant characteristics.

Time frame: From 30 days after index treatment initiation until disease progression or death due to any cause or censoring date (approximately up to 67 months)

Population: FAS population comprised of all eligible participants enrolled in the study. Here, 'Overall Number of Participants Analyzed' signifies participants evaluable for this outcome measure.

ArmMeasureValue (NUMBER)
Palbociclib + Aromatase InhibitorReal-World Response Rate (rwTR) in Postmenopausal Female or in Male Participants With Metastatic Breast Cancer57.98 Percentage of participants
Aromatase InhibitorReal-World Response Rate (rwTR) in Postmenopausal Female or in Male Participants With Metastatic Breast Cancer39.04 Percentage of participants
p-value: <0.0001score test
Secondary

Time to Dose Adjustment for Palbociclib- Palbociclib + Aromatase Inhibitor Arm Only

Time to dose adjustment for participants who received palbociclib 125 mg/day, 100 mg/day, or 75 mg/day as initial dose was presented in this outcome measure.

Time frame: At index (anytime between 03-Feb-2015 to 30-Sep-2020, approximately up to 68 months)

Population: FAS population comprised of all eligible participants enrolled in the study. Here 'Overall Number of Participants Analyzed' signifies the total number of participants evaluable for this outcome measure.

ArmMeasureGroupValue (MEDIAN)
Palbociclib + Aromatase InhibitorTime to Dose Adjustment for Palbociclib- Palbociclib + Aromatase Inhibitor Arm OnlyInitial dose of 125mg/day85 Days
Palbociclib + Aromatase InhibitorTime to Dose Adjustment for Palbociclib- Palbociclib + Aromatase Inhibitor Arm OnlyInitial dose of 100mg/day95 Days
Palbociclib + Aromatase InhibitorTime to Dose Adjustment for Palbociclib- Palbociclib + Aromatase Inhibitor Arm OnlyInitial dose of 75mg/day112 Days
Secondary

Time to Next Line of Treatment

Time to next line of treatment represents the interval from commencement of one treatment to initiation of the next line of therapy. Analysis was performed using sIPTW method to balance participant characteristics among reporting groups.

Time frame: From start of study treatment to start of next line of therapy (up to 68 months)

Population: FAS population comprised of all eligible participants enrolled in the study. sIPTW method created balanced virtual groups and hence overall number of participants analyzed was different from numbers in participant flow (not balanced).

ArmMeasureValue (MEDIAN)
Palbociclib + Aromatase InhibitorTime to Next Line of Treatment18.4 Months
Aromatase InhibitorTime to Next Line of Treatment8.3 Months
p-value: <0.000195% CI: [0.51, 0.62]Cox proportional hazard model
Secondary

Time to Subsequent Chemotherapy

Time to subsequent chemotherapy represents the time interval to administration of a different chemotherapeutic agent after the first course of therapy was administered. Analysis was performed using sIPTW method to balance participant characteristics among reporting groups.

Time frame: From start of study treatment to administration of different chemotherapeutic agent (up to 68 months)

Population: FAS population comprised of all eligible participants enrolled in the study. sIPTW method created balanced virtual groups and hence overall number of participants analyzed was different from numbers in participant flow (not balanced).

ArmMeasureValue (MEDIAN)
Palbociclib + Aromatase InhibitorTime to Subsequent Chemotherapy37.4 Months
Aromatase InhibitorTime to Subsequent Chemotherapy29.2 Months
p-value: <0.000195% CI: [0.69, 0.86]Cox proportional hazard model

Source: ClinicalTrials.gov · Data processed: Feb 13, 2026