A Study of Palbociclib (PD-0332991) + Letrozole vs. Letrozole For 1st Line Treatment Of Postmenopausal Women With ER+/HER2- Advanced Breast Cancer (PALOMA-2)

A RANDOMIZED, MULTICENTER, DOUBLE-BLIND PHASE 3 STUDY OF PD-0332991 (ORAL CDK 4/6 INHIBITOR) PLUS LETROZOLE VERSUS PLACEBO PLUS LETROZOLE FOR THE TREATMENT OF POSTMENOPAUSAL WOMEN WITH ER (+), HER2 (-) BREAST CANCER WHO HAVE NOT RECEIVED ANY PRIOR SYSTEMIC ANTI CANCER TREATMENT FOR ADVANCED DISEASE

Status

Active, not recruiting

Phases

Phase 3

Study type

Interventional

Source

JPRN

Registry ID

JPRN-jRCT2080222282

Enrollment

666

Registered

2013-11-07

Start date

2013-11-25

Completion date

Unknown

Last updated

2026-06-29

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

Conditions

Postmenopausal Breast Cancer

Interventions

investigational material(s) Generic name etc : PD-0332991 INN of investigational material : - Therapeutic category code : 429 Other antitumor agents Dosage and Administration for Investigational mater

Eligibility

Sex/Gender

Female

Inclusion criteria

Inclusion criteria: Inclusion Criteria: *Adult women with locoregionally recurrent or metastatic disease not amenable to curative therapy. *Confirmed diagnosis of ER positive breast cancer *No prior systemic anti-cancer therapy for advanced ER+ disease. *Postmenopausal women *Measurable disease as per Response Evaluation Criterion in Solid Tumors [RECIST] or bone-only disease *Eastern Cooperative Oncology Group [ECOG] 0-2 *Adequate organ and marrow function *Patient must agree to provide tumor tissue

Exclusion criteria

Exclusion criteria: Exclusion Criteria: *Confirmed diagnosis of HER2 positive disease *Patients with advanced, symptomatic, visceral spread that are at risk of life threatening complication in the short term *Known uncontrolled or symptomatic CNS metastases *Prior (neo)adjuvant treatment with letrozole or anastrozole with DFI <= 12-months from completion of treatment. *Prior treatment with any CDK 4/6 inhibitor.

Design outcomes

Primary

Measure	Time frame
efficacy To demonstrate that the combination of PD-0332991 with letrozole is superior to placebo plus letrozole in prolonging PFS in postmenopausal women with ER(+)/HER2 (-) advanced breast cancer who have not received any prior systemic anti-cancer therapies for their advanced/metastatic disease.	—

Secondary

Measure	Time frame
pharmacodynamics - To compare measures of tumor control duration and overall survival between the treatment arms; - To compare safety and tolerability between the treatment arms; - To compare health related quality of life between the treatment arms; - To characterize the effects of PD-0332991 at therapeutic doses in combination with letrozole on QTc interval in this patient population; - To determine trough PD-0332991 plasma concentration in this patient population and explore correlations between exposure and response and/or safety findings; - To characterize alterations in genes, proteins, and RNAs relevant to the cell cycle (eg, CCND1 amplification, CDKN2A deletion), drug targets (eg, CDK 4/6), and tumor sensitivity and/or resistance (eg, Ki67, pRb) in tumor tissues.	—

Measure

Time frame

pharmacodynamics - To compare measures of tumor control duration and overall survival between the treatment arms; - To compare safety and tolerability between the treatment arms; - To compare health related quality of life between the treatment arms; - To characterize the effects of PD-0332991 at therapeutic doses in combination with letrozole on QTc interval in this patient population; - To determine trough PD-0332991 plasma concentration in this patient population and explore correlations between exposure and response and/or safety findings; - To characterize alterations in genes, proteins, and RNAs relevant to the cell cycle (eg, CCND1 amplification, CDKN2A deletion), drug targets (eg, CDK 4/6), and tumor sensitivity and/or resistance (eg, Ki67, pRb) in tumor tissues.

—

Countries

Asia except Japan, Europe, Japan, North America, Oceania

Contacts

Public ContactClinical Trials Information Desk

Pfizer R&D Japan G.K.

clinical-trials@pfizer.com+81-3-5309-7000

Outcome results

None listed

Source: JPRN (via WHO ICTRP) · Data processed: Jul 3, 2026