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A Phase II Randomized Study Evaluating the Biological and Clinical Effects of the Combination of Palbociclib With Letrozole as Neoadjuvant Therapy in Post-Menopausal Women With Estrogen-Receptor Positive Primary Breast Cancer

A Phase II Randomized Study Evaluating the Biological and Clinical Effects of the Combination of Palbociclib With Letrozole as Neoadjuvant Therapy in Post-Menopausal Women With Estrogen-Receptor Positive Primary Breast Cancer

Status
Completed
Phases
Phase 2
Study type
Interventional
Source
ClinicalTrials.gov
Registry ID
NCT02296801
Acronym
PALLET
Enrollment
307
Registered
2014-11-20
Start date
2015-01-31
Completion date
2019-03-31
Last updated
2022-01-13

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

Conditions

Breast Cancer, Breast Carcinoma, Breast Tumors

Brief summary

This study will look at effects the combination of palbociclib and letrozole may have on estrogen receptor (ER)-positive/human epidermal growth factor receptor 2 (HER2)-negative breast cancer tumors which have not yet been treated. Letrozole is a type of endocrine therapy called an aromatase inhibitor (AI) and is standard treatment for post-menopausal women with ER-positive/HER2-negative breast cancer.

Detailed description

The FB-11 study is a Phase II, randomized, open label, four arm study to examine the biological and clinical effect of neoadjuvant letrozole with or without palbociclib in the first-line treatment of estrogen-receptor (ER) positive, HER2-negative early invasive breast cancer. The co-primary aims of this study are to to compare the changes in the proliferation marker Ki67, and to compare clinical response after 14 weeks of therapy with letrozole with or without palbociclib. The FB-11 study initiative is a joint partnership between the NSABP Foundation, Inc. (NSABP) Department of Site and Study Management (DSSM) and United Kingdom (UK) co-investigators at the Royal Marsden NHS Foundation Trust and the Institute of Cancer Research (ICR). Parallel protocols will be conducted in the US and Canada (FB-11), and the UK (PALLET) with joint analysis of interim and final data. Postmenopausal women, newly diagnosed with ER-positive/HER2-negative early breast cancer, who are suitable candidates for neoadjuvant endocrine therapy will be invited to join the FB-11/PALLET trial. Approximately 306 patients will be accrued to this study. Each collaborative group will recruit at least 1/3 and no more than 2/3 of the target accrual. Patients will be randomized to one of four treatment arms (3:2:2:2 ratio). Treatment in the first 14 weeks of neoadjuvant therapy will be:Arm A Letrozole alone; Arm B Letrozole for 2 weeks followed by letrozole + palbociclib to week 14; Arm C Palbociclib for 2 weeks followed by letrozole + palbociclib to week 14; Arm D Letrozole + palbociclib to week 14. Letrozole will be administered orally as a 2.5mg daily tablet. Palbociclib will be administered orally as 125mg capsules, daily on a schedule of 3 weeks (21 days) on, 1 week (7 days) off of a 4 week \[28 day\] cycle. The end of study therapy for patients in Arm A will be completion of week 14. Patients in Arms B, C, and D will complete study therapy following 14 days of palbociclib in the final treatment cycle past 14 weeks if treatment delays have occurred. Note: After week 14 (end of study therapy) all patients should continue letrozole until surgery. Letrozole is not considered study therapy beyond completion of week 14 for Arm A or after 14 days of palbociclib in the final treatment cycle for patients in Arms B, C, and D. Following completion of study therapy, surgery will be scheduled for 15-18 weeks post-randomization. Post-surgical treatment will be at discretion of treating clinician, following local protocols, and not influenced by allocation of treatment within the FB-11/PALLET study. Toxicity will be graded according to the National Cancer Institute (NCI) Common Terminology Criteria for Adverse Events version 4.0 (CTCAE v4.0).

Interventions

DRUGLetrozole
DRUGpalbociclib

Sponsors

Pfizer
CollaboratorINDUSTRY
Royal Marsden NHS Foundation Trust
CollaboratorOTHER
Institute of Cancer Research, United Kingdom
CollaboratorOTHER
NSABP Foundation Inc
Lead SponsorNETWORK

Study design

Allocation
RANDOMIZED
Intervention model
PARALLEL
Primary purpose
TREATMENT
Masking
NONE

Eligibility

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

Inclusion criteria

* Patients must be postmenopausal women defined as: Age 56 or older with no spontaneous menses for at least 12 months prior to study entry; or Age 55 or younger with no menses for at least 12 months prior to study entry (e.g., spontaneous or secondary to hysterectomy) and with a documented estradiol level in the postmenopausal range according to local institutional/laboratory standard; or Age greater than or equal to 18 with documented bilateral oophorectomy. * Operable ER-positive/HER2- negative, invasive early breast cancer, suitable for neoadjuvant AI treatment. HER2-negative as determined by American Society of Clinical Oncology - College of American Pathologists (ASCO-CAP) guidelines. * No known severe hypersensitivity reactions to compounds similar to palbociclib or palbociclib excipients or to endocrine treatments. * A breast tumor with an ultrasound size of at least 2.0 cm. * Patients must have the ability to swallow oral medication. * Eastern Cooperative Oncology Group (ECOG) performance status of 0 or 1. * At the time of randomization, blood counts performed within 4 weeks prior to randomization must meet the following criteria: absolute neutrophil count (ANC) must be greater than or equal to 1500/mm3; Platelet count must be greater than or equal to 100,000/mm3; Hemoglobin must be greater than or equal to 10 g/dL. * international normalized ratio (INR) must be within normal limits of the local laboratory ranges. * The following criteria for evidence of adequate hepatic function performed within 4 weeks prior to study entry must be met: total bilirubin must be less than or equal to upper limit of normal (ULN) for the lab unless the patient has a bilirubin elevation greater than ULN to 1.5 x ULN due to Gilbert's disease or similar syndrome involving slow conjugation of bilirubin; and alkaline phosphatase must be must be less than or equal to 1.5 x ULN for the lab; and aspartate aminotransferase (AST) and alanine aminotransferase (ALT) must be less than or equal to 1.5 x ULN for the lab. * Serum creatinine performed within 4 weeks prior to study entry must be less than or equal to 1.25 x ULN or estimated creatinine clearance less than 60 mL/min (as calculated using the method standard for the institutions).

Exclusion criteria

* Active hepatitis B or hepatitis C with abnormal liver function tests. * HIV positive patients receiving antivirals. * Premenopausal or peri-menopausal women. * Inflammatory/inoperable breast cancer. * HER2-positive as determined using ASCO-CAP Guidelines. * Concurrent use (defined as use within 4 weeks prior to baseline tissue sample being taken) of hormone replacement therapy (HRT) or any other estrogen-containing medication (including vaginal estrogens) * Prior endocrine therapy for breast cancer. * Any invasive malignancy within previous 5 years (other than basal cell carcinoma or cervical carcinoma in situ). * Other nonmalignant systemic disease that would preclude the patient from receiving study treatment or would prevent required follow up such as: Active infection or chronic infection requiring chronic suppressive antibiotics; Malabsorption syndrome, ulcerative colitis, inflammatory bowel disease, resection of the stomach or small bowel, or other disease or condition significantly affecting gastrointestinal function; Chronic daily treatment with corticosteroids with a dose of greater than or equal to 10 mg/day methylprednisolone equivalent (excluding inhaled steroids); Seizure disorders requiring medication. * Diagnosis by fine needle aspiration (FNA) alone or excisional biopsy or lumpectomy performed prior to study entry. * Surgical axillary staging procedure prior to study procedure (with exception of FNA or core biopsy). * Definitive clinical or radiologic evidence of metastatic disease. * History of ipsilateral invasive breast cancer regardless of treatment or ipsilateral ductal carcinoma in situ (DCIS) treated with radiotherapy or contralateral invasive breast cancer at any time. * Any treatment, including radiotherapy, chemotherapy, and/or targeted therapy, administered for the currently diagnosed breast cancer prior to study entry. * Use of any medication or substances that are strong inhibitors or inducers of CYP3A isoenzymes. * Class III or Class IV myocardial disease as described by the New York Heart Association; a recent history (within 6 months) of myocardial infarction, or symptomatic arrhythmia at the time of randomization. Class III: Patients with cardiac disease resulting in marked limitation of physical activity. Such patients are comfortable at rest. Less than ordinary physical activity that causes fatigue, palpitation, dyspnea, or anginal pain. Class IV: Patients with cardiac disease resulting in inability to perform any physical activity without discomfort. Symptoms of cardiac insufficiency or anginal syndrome may be present even at rest. * QTc greater than 480 msec or a family or personal history of long or short QT syndrome, Brugada syndrome or know history of QTc prolongation, or Torsade de Pointes (TdP). * The investigator should assess the patient to determine if she has any psychiatric or addictive disorder or other condition that, in the opinion of the investigator, would preclude her from meeting the study requirements.

Design outcomes

Primary

MeasureTime frameDescription
Measurement of the Proliferation Marker Ki67 (% Positive Tumor Cells)Baseline and at 14 weeksThe change in Ki67 from baseline to 14 weeks.
Clinical Response : Number of Patients Who Have Resolution of Measurable Lesions or no New Lesions or Other Signs of Disease Progression Compared to Baseline.Baseline and at 14 weeksClinical Response is assessed by ultrasound at the end of the treatment (week 14) according to ECOG response criteria defined in Appendix A1 of the protocol. Number of participants with clinical complete response.

Secondary

MeasureTime frameDescription
Number and Severity of Adverse EventsBaseline and weekly through 12 months after randomizationTo evaluate the overall safety and tolerability for the combination of letrozole and palbociclib. The number of patients experiencing at least one adverse event. Refer to Adverse Events section for more details.
Pathological Complete Response (pCR): Number of Patients With no Lesions in Breast and Nodes at Time of Surgery14 weeksPathologic complete response in the breast (pCR breast) is defined as no histologic evidence of invasive tumour cells in the surgical breast specimen. Pathologic complete response in breast and axillary lymph nodes as well as non-axillary SN (pCR breast & nodes) is defined as no histologic evidence of invasive tumour cells in the surgical breast specimen, axillary nodes, or SNs identified after neoadjuvant treatment. Data shows the pCR rates by randomised group.
Comparison of Surgical Intent (Mastectomy; Breast Conservation)Time frame between baseline and surgery date. (Note-surgical intent happened before randomization).To compare changes between surgical intent at baseline; surgical intent after 14 weeks; and actual surgery received after treatment with letrozole with or without palbociclib. Percentage of patients change to receiving breast conservation and receiving breast conservation.
Measurement of Ki67 MarkerWeek 2 and week 14To compare Ki67 results after 2 weeks and 14 weeks of study therapy. Log fold change in Ki67 from week 2-week 14.
Preoperative Endocrine Prognostic Index (PEPI) Score:14 weeksThe PEPI score estimates the risk of cancer recurrence after treatment. Analysis of the PEPI score were pre-specified in the protocol and statistical analysis plan. However, pathological/biomarker characteristics which comprise this score such as the Allred score for ER status were not collected during the trial so cannot be calculated at this stage. PEPI Scale range is 0-16 for RFS. Higher score represents worse outcome. No combination of subscales.

Countries

Canada, United Kingdom, United States

Participant flow

Participants by arm

ArmCount
A: Letrozole
letrozole 2.5 mg tablet orally daily for 14 weeks Letrozole
103
B: Letrozole Then Letrozole + Palbociclib
letrozole 2.5 mg orally daily plus beginning 2 weeks after starting letrozole, palbociclib 125 mg capsule orally daily for 1 week then 1 week off, then a 3 weeks on and 1 week off cycle for a total of 14 weeks from start of letrozole therapy Letrozole palbociclib
68
C: Palbociclib Then Letrozole + Palbociclib
palbociclib 125 mg capsule orally daily (for a 3 weeks on and 1 week off cycle for a total of 14 weeks from start of palbociclib) plus beginning 2 weeks after starting palbociclib, letrozole 2.5 mg tablet orally daily for a total of 12 weeks from start of letrozole therapy Letrozole palbociclib
69
D: Letrozole + Palbociclib
letrozole 2.5 mg tablet orally daily for a total of 14 weeks plus palbociclib 125 mg capsule orally daily for a 3 weeks on and 1 week off cycle, for a total of 14 weeks from start of therapy Letrozole palbociclib
67
Total307

Baseline characteristics

CharacteristicA: LetrozoleB: Letrozole Then Letrozole + PalbociclibC: Palbociclib Then Letrozole + PalbociclibD: Letrozole + PalbociclibTotal
Age, Customized
Age 40-49
0 Participants0 Participants1 Participants0 Participants1 Participants
Age, Customized
Age 50-59
32 Participants15 Participants19 Participants22 Participants88 Participants
Age, Customized
Age 60-69
34 Participants31 Participants29 Participants30 Participants124 Participants
Age, Customized
Age 70-79
30 Participants14 Participants17 Participants12 Participants73 Participants
Age, Customized
Greater than or equal to 80
7 Participants8 Participants3 Participants3 Participants21 Participants
Race/Ethnicity, Customized
Asian-patient-NA patient
1 Participants1 Participants1 Participants1 Participants4 Participants
Race/Ethnicity, Customized
Black or African American-NA patient
1 Participants2 Participants1 Participants0 Participants4 Participants
Race/Ethnicity, Customized
Caribbean-UK patients
1 Participants1 Participants0 Participants1 Participants3 Participants
Race/Ethnicity, Customized
Data not received-NA patient
1 Participants1 Participants0 Participants1 Participants3 Participants
Race/Ethnicity, Customized
Data not received-UK patients
0 Participants1 Participants0 Participants1 Participants2 Participants
Race/Ethnicity, Customized
Indian-UK patients
0 Participants0 Participants2 Participants1 Participants3 Participants
Race/Ethnicity, Customized
Other Asian background-UK patients
0 Participants2 Participants0 Participants1 Participants3 Participants
Race/Ethnicity, Customized
Other Black backgroud-UK patients
1 Participants0 Participants0 Participants0 Participants1 Participants
Race/Ethnicity, Customized
Other-patient-NA patient
1 Participants1 Participants1 Participants0 Participants3 Participants
Race/Ethnicity, Customized
Other-UK-patients
1 Participants0 Participants0 Participants0 Participants1 Participants
Race/Ethnicity, Customized
White-British-UK patients
48 Participants32 Participants28 Participants30 Participants138 Participants
Race/Ethnicity, Customized
White-Hispanic/latino-NA patient
4 Participants1 Participants1 Participants1 Participants7 Participants
Race/Ethnicity, Customized
White-Not hispanic/latino-NA patient
38 Participants25 Participants26 Participants27 Participants116 Participants
Race/Ethnicity, Customized
White-Not known-NA patient
1 Participants0 Participants2 Participants1 Participants4 Participants
Race/Ethnicity, Customized
White-Other-UK patients
5 Participants1 Participants7 Participants2 Participants15 Participants
Region of Enrollment
North America
47 Participants31 Participants32 Participants31 Participants141 Participants
Region of Enrollment
United Kingdom
56 Participants37 Participants37 Participants36 Participants166 Participants
Sex: Female, Male
Female
103 Participants68 Participants69 Participants67 Participants307 Participants
Sex: Female, Male
Male
0 Participants0 Participants0 Participants0 Participants0 Participants

Adverse events

Event typeEG000
affected / at risk
EG001
affected / at risk
deaths
Total, all-cause mortality
1 / 1003 / 201
other
Total, other adverse events
91 / 100199 / 201
serious
Total, serious adverse events
3 / 10017 / 201

Outcome results

Primary

Clinical Response : Number of Patients Who Have Resolution of Measurable Lesions or no New Lesions or Other Signs of Disease Progression Compared to Baseline.

Clinical Response is assessed by ultrasound at the end of the treatment (week 14) according to ECOG response criteria defined in Appendix A1 of the protocol. Number of participants with clinical complete response.

Time frame: Baseline and at 14 weeks

Population: Clinical response data were available for 279 patients.

ArmMeasureValue (COUNT_OF_PARTICIPANTS)
A: LetrozoleClinical Response : Number of Patients Who Have Resolution of Measurable Lesions or no New Lesions or Other Signs of Disease Progression Compared to Baseline.46 Participants
B, C + D Palbociclib + Letrozole RegimenClinical Response : Number of Patients Who Have Resolution of Measurable Lesions or no New Lesions or Other Signs of Disease Progression Compared to Baseline.31 Participants
C: Palbociclib Then Letrozole + PalbociclibClinical Response : Number of Patients Who Have Resolution of Measurable Lesions or no New Lesions or Other Signs of Disease Progression Compared to Baseline.35 Participants
D: Letrozole + PalbociclibClinical Response : Number of Patients Who Have Resolution of Measurable Lesions or no New Lesions or Other Signs of Disease Progression Compared to Baseline.35 Participants
B, C + D Palbociclib + Letrozole RegimenClinical Response : Number of Patients Who Have Resolution of Measurable Lesions or no New Lesions or Other Signs of Disease Progression Compared to Baseline.101 Participants
Primary

Measurement of the Proliferation Marker Ki67 (% Positive Tumor Cells)

The change in Ki67 from baseline to 14 weeks.

Time frame: Baseline and at 14 weeks

Population: Paired Ki67 data from baseline and end of treatment were available for 190 patients. Patients treated with letrozole with palbociclib, i.e. groups B+C+D, were pooled and compared to those treated with letrozole alone (group A). The pooling of groups B-D was pre-planned and defined in the Statistical Analysis Plan.

ArmMeasureValue (MEDIAN)
A: LetrozoleMeasurement of the Proliferation Marker Ki67 (% Positive Tumor Cells)-2.2 log fold change in Ki67
B, C + D Palbociclib + Letrozole RegimenMeasurement of the Proliferation Marker Ki67 (% Positive Tumor Cells)-4.1 log fold change in Ki67
Secondary

Comparison of Surgical Intent (Mastectomy; Breast Conservation)

To compare changes between surgical intent at baseline; surgical intent after 14 weeks; and actual surgery received after treatment with letrozole with or without palbociclib. Percentage of patients change to receiving breast conservation and receiving breast conservation.

Time frame: Time frame between baseline and surgery date. (Note-surgical intent happened before randomization).

Population: Data included for 268 patients where surgical type and intent was available. Patients treated with letrozole with palbociclib, i.e. groups B+C+D, were pooled and compared to those treated with letrozole alone (group A). The pooling of groups B-D was pre-planned and defined in the Statistical Analysis Plan.

ArmMeasureGroupValue (COUNT_OF_PARTICIPANTS)
A: LetrozoleComparison of Surgical Intent (Mastectomy; Breast Conservation)Change to breast conservation (actual surgery received) from mastectomy (intended at baseline)16 Participants
A: LetrozoleComparison of Surgical Intent (Mastectomy; Breast Conservation)Breast conservation received (actual surgery) unchanged from what was intended at baseline63 Participants
A: LetrozoleComparison of Surgical Intent (Mastectomy; Breast Conservation)Change to planned breast conservation (intended at the end of tx) from planned mastectomy14 Participants
A: LetrozoleComparison of Surgical Intent (Mastectomy; Breast Conservation)Breast conservation planned (at the end of tx) unchanged from what was intended at baseline62 Participants
B, C + D Palbociclib + Letrozole RegimenComparison of Surgical Intent (Mastectomy; Breast Conservation)Breast conservation planned (at the end of tx) unchanged from what was intended at baseline118 Participants
B, C + D Palbociclib + Letrozole RegimenComparison of Surgical Intent (Mastectomy; Breast Conservation)Change to breast conservation (actual surgery received) from mastectomy (intended at baseline)25 Participants
B, C + D Palbociclib + Letrozole RegimenComparison of Surgical Intent (Mastectomy; Breast Conservation)Change to planned breast conservation (intended at the end of tx) from planned mastectomy25 Participants
B, C + D Palbociclib + Letrozole RegimenComparison of Surgical Intent (Mastectomy; Breast Conservation)Breast conservation received (actual surgery) unchanged from what was intended at baseline123 Participants
Secondary

Measurement of Ki67 Marker

To compare Ki67 results after 2 weeks and 14 weeks of study therapy. Log fold change in Ki67 from week 2-week 14.

Time frame: Week 2 and week 14

Population: Data included for 176 patients that had a 2 week sample.

ArmMeasureValue (MEDIAN)
A: LetrozoleMeasurement of Ki67 Marker-0.1 log fold change in Ki67
B, C + D Palbociclib + Letrozole RegimenMeasurement of Ki67 Marker-2.1 log fold change in Ki67
C: Palbociclib Then Letrozole + PalbociclibMeasurement of Ki67 Marker-0.4 log fold change in Ki67
D: Letrozole + PalbociclibMeasurement of Ki67 Marker0.0 log fold change in Ki67
B, C + D Palbociclib + Letrozole RegimenMeasurement of Ki67 Marker-1.0 log fold change in Ki67
Secondary

Number and Severity of Adverse Events

To evaluate the overall safety and tolerability for the combination of letrozole and palbociclib. The number of patients experiencing at least one adverse event. Refer to Adverse Events section for more details.

Time frame: Baseline and weekly through 12 months after randomization

Population: Patients treated with letrozole with palbociclib, i.e. groups B+C+D, were pooled and compared to those treated with letrozole alone (group A). The pooling of groups B-D was pre-planned and defined in the Statistical Analysis Plan.

ArmMeasureValue (COUNT_OF_PARTICIPANTS)
A: LetrozoleNumber and Severity of Adverse Events91 Participants
B, C + D Palbociclib + Letrozole RegimenNumber and Severity of Adverse Events199 Participants
Secondary

Pathological Complete Response (pCR): Number of Patients With no Lesions in Breast and Nodes at Time of Surgery

Pathologic complete response in the breast (pCR breast) is defined as no histologic evidence of invasive tumour cells in the surgical breast specimen. Pathologic complete response in breast and axillary lymph nodes as well as non-axillary SN (pCR breast & nodes) is defined as no histologic evidence of invasive tumour cells in the surgical breast specimen, axillary nodes, or SNs identified after neoadjuvant treatment. Data shows the pCR rates by randomised group.

Time frame: 14 weeks

Population: There is response data for 279 patients. Patients treated with letrozole with palbociclib, i.e. groups B+C+D, were pooled and compared to those treated with letrozole alone (group A). The pooling of groups B-D was pre-planned and defined in the Statistical Analysis Plan.

ArmMeasureValue (NUMBER)
A: LetrozolePathological Complete Response (pCR): Number of Patients With no Lesions in Breast and Nodes at Time of Surgery0.0 percentage of participants
B, C + D Palbociclib + Letrozole RegimenPathological Complete Response (pCR): Number of Patients With no Lesions in Breast and Nodes at Time of Surgery1.1 percentage of participants
Secondary

Preoperative Endocrine Prognostic Index (PEPI) Score:

The PEPI score estimates the risk of cancer recurrence after treatment. Analysis of the PEPI score were pre-specified in the protocol and statistical analysis plan. However, pathological/biomarker characteristics which comprise this score such as the Allred score for ER status were not collected during the trial so cannot be calculated at this stage. PEPI Scale range is 0-16 for RFS. Higher score represents worse outcome. No combination of subscales.

Time frame: 14 weeks

Population: 194 patients have ER, Ki67, tumour size and nodal status available. Patients treated with letrozole with palbociclib, i.e. groups B+C+D, were pooled and compared to those treated with letrozole alone (group A). The pooling of groups B-D was pre-planned and defined in the Statistical Analysis Plan.

ArmMeasureValue (MEAN)Dispersion
A: LetrozolePreoperative Endocrine Prognostic Index (PEPI) Score:3.7 score on a scaleStandard Deviation 2.3
B, C + D Palbociclib + Letrozole RegimenPreoperative Endocrine Prognostic Index (PEPI) Score:3.6 score on a scaleStandard Deviation 2.3

Source: ClinicalTrials.gov · Data processed: Feb 21, 2026