Primary Outcomes

Measure: To evaluate the response rates and clinical benefits of letrozole + goserelin in premenopausal patients versus letrozole alone in postmenopausal patients with metastatic breast cancer as first line hormonal therapy

Time: 4 years

---

Primary Outcomes

Description: An adverse event (AE) was any untoward medical occurrence in a participant who received study drug without regard to possibility of causal relationship. Serious adverse event (SAE) was an AE resulting in any of the following outcomes or deemed significant for any other reason: death; initial or prolonged inpatient hospitalization; life-threatening experience (immediate risk of dying); persistent or significant disability/incapacity; congenital anomaly.

Measure: Number of Participants With Treatment-Emergent Adverse Events (TEAEs; All Causalities) at Phase 1

Time: Maximum treatment duration (approximately 55 months)

---

Description: An AE was any untoward medical occurrence attributed to study drug in a participant who received study drug. An SAE was an AE resulting in any of the following outcomes or deemed significant for any other reason: death; initial or prolonged inpatient hospitalization; life-threatening experience (immediate risk of dying); persistent or significant disability/incapacity; congenital anomaly.

Measure: Number of Participants With Treatment-Related Adverse Events at Phase 1

Time: Maximum treatment duration (approximately 55 months)

---

Description: Dose limiting toxicity was defined as any of the following TEAEs occurring during the second cycle of treatment and possibly attributable to the combination of letrozole plus Palbociclib: 1. Grade 4 hematologic toxicity (including platelets <25,000/μL, ANC <500/μL). 2. Grade 3 neutropenia associated with a documented infection or fever ≥38.5°C. 3. Grade ≥3 non-hematologic toxicities, except those that have not been maximally treated (eg, nausea, vomiting, diarrhea, hypertension). 4. Delay by ≥1 week in receiving the next scheduled dose of either study treatment due to persisting treatment-related toxicities (platelet count <50,000/μL; ANC <1,000/μL; nonhematologic toxicities of Grade ≥3 severity). 5. Inability to deliver at least 80% of the planned Palbociclib or letrozole doses during Cycle 2 due to toxicity possibly attributable to the study treatment.

Measure: Number of Participants With Dose Limiting Toxicities at Phase 1

Time: Cycle 2 (4 weeks)

---

Description: PFS was defined as the time from randomization (or the first dose of study treatment for non-randomized studies) to the first documentation of objective tumor progression or to death due to any cause, whichever occurred first. PFS calculated as (Weeks or Months) = (first event date minus randomization or the first dose date plus 1) divided by 7 (or 30.44 if in months). PFS is usually characterized by the median, 25% percentile,75% percentile and their 95% Confidence Intervals (CIs).

Measure: Progression-Free Survival (PFS) at Phase 2 - Investigator Assessment

Time: From randomization date to date of first documentation of progression or death (assessed up to 41 months)

---

Secondary Outcomes

Description: Percentage of participants with objective response based assessment of confirmed complete response (CR) or confirmed partial response (PR) according to Response Evaluation Criteria in Solid Tumors (RECIST). Confirmed responses are those that persist on repeat imaging study at least 4 weeks after initial documentation of response. Per RECIST v1.0: CR defined as disappearance of all target lesions and non-target lesions. PR defined as ≥30% decrease in sum of the longest diameters (LD) of the target lesions taking as a reference the baseline sum LD according to RECIST associated to non-progressive disease response for non target lesions.

Measure: Objective Response Rate - Percentage of Participants With Confirmed Objective Tumor Response at Phase 1

Time: From Baseline up to end of study (assessed up to 55 months)

---

Description: CBR is defined as a confirmed CR, confirmed PR, or stable disease (SD) for at least 24 weeks on study according to RECIST. Confirmed responses are those that persisted on repeat imaging >= 4 weeks after initial response.

Measure: Percentage of Participants With Clinical Benefit Response (CBR) at Phase 1

Time: From Baseline up to end of study (assessed up to 55 months)

---

Description: On Cycle 1 Day 14, plasma pharmacokinetic samples were collected prior to and 1, 2, 4, 8, 12, 24, 48, 96 and 120 hours after Palbociclib dosing. On Cycle 2 Day 14, plasma pharmacokinetic samples for Palbociclib and letrozole were collected prior to and 1, 2, 4, 8, 12 and 24 hours after Palbociclib and letrozole dosing.

Measure: Summary of Plasma Palbociclib Steady-state Pharmacokinetic Parameter Following Palbociclib Alone and in Combination With Letrozole: Area Under the Plasma Concentration-time Curve From Time 0 to 24 Hours (AUC24) at Phase 1

Time: Cycle 1 Day 14, and Cycle 2 Day 14

---

Description: On Cycle 1 Day 14, plasma pharmacokinetic samples were collected prior to and 1, 2, 4, 8, 12, 24, 48, 96 and 120 hours after Palbociclib dosing. On Cycle 2 Day 14, plasma pharmacokinetic samples for Palbociclib and letrozole were collected prior to and 1, 2, 4, 8, 12 and 24 hours after Palbociclib and letrozole dosing.

Measure: Summary of Plasma Palbociclib Steady-state Pharmacokinetic Parameter Following Palbociclib Alone and in Combination With Letrozole: Maximum Observed Plasma Concentration (Cmax) at Phase 1

Time: Cycle 1 Day 14, and Cycle 2 Day 14

---

Description: On Cycle 1 Day 14, plasma pharmacokinetic samples were collected prior to and 1, 2, 4, 8, 12, 24, 48, 96 and 120 hours after Palbociclib dosing. On Cycle 2 Day 14, plasma pharmacokinetic samples for Palbociclib and letrozole were collected prior to and 1, 2, 4, 8, 12 and 24 hours after Palbociclib and letrozole dosing.

Measure: Summary of Plasma Palbociclib Steady-state Pharmacokinetic Parameter Following Palbociclib Alone and in Combination With Letrozole: Time to Maximum Plasma Concentration (Tmax) at Phase 1

Time: Cycle 1 Day 14, and Cycle 2 Day 14

---

Description: On Cycle 1 Day 14, plasma pharmacokinetic samples were collected prior to and 1, 2, 4, 8, 12, 24, 48, 96 and 120 hours after Palbociclib dosing. On Cycle 2 Day 14, plasma pharmacokinetic samples for Palbociclib and letrozole were collected prior to and 1, 2, 4, 8, 12 and 24 hours after Palbociclib and letrozole dosing.

Measure: Summary of Plasma Palbociclib Steady-state Pharmacokinetic Parameter Following Palbociclib Alone and in Combination With Letrozole: Terminal Plasma Half-life (t1/2) at Phase 1

Time: Cycle 1 Day 14, and Cycle 2 Day 14

---

Description: On Cycle 1 Day 14, plasma pharmacokinetic samples were collected prior to and 1, 2, 4, 8, 12, 24, 48, 96 and 120 hours after Palbociclib dosing. On Cycle 2 Day 14, plasma pharmacokinetic samples for Palbociclib and letrozole were collected prior to and 1, 2, 4, 8, 12 and 24 hours after Palbociclib and letrozole dosing.

Measure: Summary of Plasma Palbociclib Steady-state Pharmacokinetic Parameter Following Palbociclib Alone and in Combination With Letrozole: Apparent Clearance (CL/F) at Phase 1

Time: Cycle 1 Day 14, and Cycle 2 Day 14

---

Description: On Cycle 1 Day 14, plasma pharmacokinetic samples were collected prior to and 1, 2, 4, 8, 12, 24, 48, 96 and 120 hours after Palbociclib dosing. On Cycle 2 Day 14, plasma pharmacokinetic samples for Palbociclib and letrozole were collected prior to and 1, 2, 4, 8, 12 and 24 hours after Palbociclib and letrozole dosing.

Measure: Summary of Plasma Palbociclib Steady-state Pharmacokinetic Parameter Following Palbociclib Alone and in Combination With Letrozole: Apparent Volume of Distribution (Vz/F) at Phase 1

Time: Cycle 1 Day 14, and Cycle 2 Day 14

---

Description: On Cycle 2 Day 14, plasma pharmacokinetic samples for Palbociclib and letrozole were collected prior to and 1, 2, 4, 8, 12 and 24 hours after Palbociclib and letrozole dosing. On Cycle 2 Day 28, plasma pharmacokinetic samples were collected prior to and 1, 2, 4, 8, 12, and 24 hours after letrozole dosing.

Measure: Summary of Plasma Letrozole Pharmacokinetic Parameter Following Letrozole Alone and in Combination With Palbociclib: AUC24 at Phase 1

Time: Cycle 2 Day 14, Cycle 2 Day 28

---

Description: On Cycle 2 Day 14, plasma pharmacokinetic samples for Palbociclib and letrozole were collected prior to and 1, 2, 4, 8, 12 and 24 hours after Palbociclib and letrozole dosing. On Cycle 2 Day 28, plasma pharmacokinetic samples were collected prior to and 1, 2, 4, 8, 12, and 24 hours after letrozole dosing.

Measure: Summary of Plasma Letrozole Pharmacokinetic Parameter Following Letrozole Alone and in Combination With Palbociclib: Cmax at Phase 1

Time: Cycle 2 Day 14, and Cycle 2 Day 28

---

Description: On Cycle 2 Day 14, plasma pharmacokinetic samples for Palbociclib and letrozole were collected prior to and 1, 2, 4, 8, 12 and 24 hours after Palbociclib and letrozole dosing. On Cycle 2 Day 28, plasma pharmacokinetic samples were collected prior to and 1, 2, 4, 8, 12, and 24 hours after letrozole dosing.

Measure: Summary of Plasma Letrozole Pharmacokinetic Parameter Following Letrozole Alone and in Combination With Palbociclib: Tmax at Phase 1

Time: Cycle 2 Day 14, and Cycle 2 Day 28

---

Description: Triplicate 12-lead ECG measurements (each recording separated by approximately 2 minutes) were performed and average was calculated. The time corresponding to beginning of depolarization to repolarization of the ventricles (QT interval) was adjusted for RR interval using QT and RR from each ECG by Fridericia's formula (QTcF = QT divided by cube root of RR), by Bazette's formula (QTcB = QT divided by square root of RR) and corrected QT interval according to study-specific criteria (QTcS). Participants with maximum increase from baseline of 30 to less than (<) 60 msec(borderline) and greater than or equal to (>=) 60 msec (prolonged) were summarized.

Measure: Number of Participants With Increase From Baseline in Corrected QT (QTc) Interval at Phase 1

Time: Cycle 1 Day 1 prior to dosing, Cycle 1 Day 14 (2, 4 [prior to meal], 8, 24, 48, and 96 hours after dosing of Palbociclib), Cycle 2 Day 1 and Day 14 (prior to and 4 hours after dosing of letrozole)

---

Description: Time in weeks or months from randomization to date of death due to any cause. OS was calculated as (the death date or last known alive date (if death date unavailable) minus the date of randomization plus 1) divided by 7 or 30.44 if in months.

Measure: Overall Survival (OS) at Phase 2

Time: From randomization until death (assessed up to 86 months)

---

Description: Percentage of participants with objective response based assessment of confirmed CR or confirmed PR according to RECIST. Confirmed responses are those that persist on repeat imaging study at least 4 weeks after initial documentation of response. Per RECIST v1.0: CR defined as disappearance of all target lesions and non-target lesions. PR defined as ≥30% decrease in sum of the longest diameters (LD) of the target lesions taking as a reference the baseline sum LD according to RECIST associated to non-progressive disease response for non target lesions.

Measure: Objective Response Rate - Percentage of Participants With Confirmed Objective Response at Phase 2- Investigator Assessment

Time: From randomization up to the end of treatment (approximately 41 months)

---

Description: Percentage of participants with objective response based assessment of confirmed CR or PR according to RECIST. Confirmed responses are those that persist on repeat imaging study at least 4 weeks after initial documentation of response. Per RECIST v1.0: CR defined as disappearance of all target lesions and non-target lesions. PR defined as ≥30% decrease in sum of the LD of the target lesions taking as a reference the baseline sum LD according to RECIST associated to non-progressive disease response for non target lesions. Measurable disease referred to the lesions that was accurately measured in at least 1 dimension (longest diameter to be recorded) as ≥20 mm with conventional techniques or as ≥10-16 mm with spiral computer tomography scan (depending on reconstruction interval). Clinical lesions were only be considered measurable when they were superficial (eg, skin nodules, palpable lymph nodes).

Measure: Objective Response Rate - Percentage of Participants With Confirmed Objective Response in Participants With Measurable Disease at Phase 2- Investigator Assessment

Time: From randomization up to the end of treatment (approximately 41 months)

---

Description: Time in weeks, (months or years) from randomization or (start of study treatment for non-randomized studies) to first documentation of objective tumor progression. TTP was calculated as (first event date or last known progression-free date minus the date of randomization [or first dose of study medication for non-randomized studies] plus 1) divided by 7 or 30.44 if in months. Tumor progression was determined from oncologic assessment data (where data meet the criteria for progressive disease [PD] per RECIST).

Measure: Duration of Response at Phase 2 - Investigator Assessment

Time: From randomization up to the end of treatment (approximately 41 months)

---

Description: CBR is defined as a confirmed complete response (CR), confirmed partial response (PR), or stable disease (SD) for at least 24 weeks on study according to RECIST.

Measure: Number of Participants With CBR at Phase 2 - Investigator Assessment

Time: From randomization up to the end of treatment (approximately 41 months)

---

Description: Time in weeks, (months or years) from randomization or (start of study treatment for non-randomized studies) to first documentation of objective tumor progression. TTP was calculated as (first event date or last known progression-free date minus the date of randomization [or first dose of study medication for non-randomized studies] plus 1) divided by 7 or 30.44 if in months. Tumor progression was determined from oncologic assessment data (where data meet the criteria for progressive disease [PD] per RECIST).

Measure: Time to Tumor Progression (TTP) at Phase 2-Investigator Assessment

Time: From randomization up to the end of treatment (approximately 41 months)

---

Description: The mBPI-sf is a validated and reliable self-report questionnaire which consists of 13 questions that assess the severity and impact of pain on daily function. The 13 items of the questionnaire make up two scales and two single items. The scales include the 4-item Pain Severity Scale (worst pain, least pain, average pain, and pain right now) and the 7-item Pain Interference Scale (general activity, mood, walking ability, normal work, relations with other people, sleep, and enjoyment of life). Each item of the pain severity and pain interference scales are based on a 11-point numeric rating scale from 0 ("no pain" or "does not interfere") to 10 ("pain as bad as you can imagine" or "completely interferes").

Measure: Change From Baseline in Modified Brief Pain Inventory in Pain Severity Scale (mBPI-sf) Questionnaire at Phase 2

Time: Baseline, End of treatment (approximately 41 months)

---

Description: The mBPI-sf is a validated and reliable self-report questionnaire which consists of 13 questions that assess the severity and impact of pain on daily function. The 13 items of the questionnaire make up two scales and two single items. The scales include the 4-item Pain Severity Scale (worst pain, least pain, average pain, and pain right now) and the 7-item Pain Interference Scale (general activity, mood, walking ability, normal work, relations with other people, sleep, and enjoyment of life). Each item of the pain severity and pain interference scales are based on a 11-point numeric rating scale from 0 ("no pain" or "does not interfere") to 10 ("pain as bad as you can imagine" or "completely interferes").

Measure: Change From Baseline in Modified Brief Pain Inventory in Pain Interference Scale (mBPI-sf) Questionnaire at Phase 2

Time: Baseline, End of treatment (approximately 41 months)

---

Description: Tissue samples were used for retrospective biomarker analyses. For Phase 2 Part 2, the tissue samples were sent to a central laboratory for the assessment of participant selection biomarkers. For Phase 2 Part 1, the assessment of the biomarkers (CCND1 amplification and/or loss of p16) were performed retrospectively from the available samples.

Measure: Presence or Absence of Tumor Tissue Biomarkers at Phase 2 - p16/INK4A, CCND1

Time: Screening visit (≤ 28 Days prior to dosing)

---

Description: Frequency of tumor tissue biomarker Ki67 was evaluated in across treatment groups.

Measure: Presence or Absence of Tumor Tissue Biomarkers at Phase 2 - Ki67

Time: Screening visit (≤ 28 Days prior to dosing)

---

Description: Presence or absence of tumor RB and CyclinD1 were evaluated. The following definitions of expression applied in the below table: Positive: any expression >0 and Negative: any expression=0.

Measure: Presence or Absence of Tumor Tissue Biomarkers at Phase 2 - Tumor Retinoblastoma (RB) and CyclinD1

Time: Screening visit (≤ 28 Days prior to dosing)

---

Description: Gene copy number for CCND1 (CCND1/CEP11) and p16/INK4A (p16/CEP9) were evaluated. This analysis was done for Phase 2 combined group.

Measure: Summary of Copy Number for CCND1 (CCND1/CEP11) and p16/INK4A (p16/CEP9) at Phase 2

Time: Screening visit (≤ 28 Days prior to dosing)

---

Description: One 2-mL blood specimen was collected for the analysis of germline polymorphism in CYP19A1 and CCND1 genes. A single nucleotide polymorphism (SNP) rs4646 as defined in the National Center for Biotechnology Information (NCBI) database in the aromatase gene (CYP19A1) was analyzed. A germline polymorphism G/A870 (rs9344) in the CCND1 gene was analyzed.

Measure: Percentage of Participants With Tumor Expression of CYP19A1 and CCND1 Genotypes at Phase 2

Time: Screening visit (≤ 28 Days prior to dosing)

---

Description: AE:any untoward medical occurrence in participant who received study drug without regard to possibility of causal relationship.AEs included both serious and non-serious AEs.SAE:AE resulting in any of following outcomes/deemed significant and jeopardized participants or required treatment to prevent other AE outcomes for any other reason:death;initial or prolonged inpatient hospitalization;life-threatening experience (immediate risk of dying);persistent or significant disability/incapacity;congenital anomaly.Treatment emergent AEs:events occurred between first dose of study drug and up to 28 days after last dose that were absent before treatment or worsened relative to pre-treatment state.AEs were graded as per the Common Terminology Criteria for Adverse Events (CTCAE) version 3.0 and coded using Medical Dictionary for Regulatory Activities (MedDRA). Participants with AE of grade 3 or 4 and grade 5 were reported as Grade 3:Severe, Grade 4:Life threatening, Grade 5:Death related to AE.

Measure: Number of Participants With TEAEs (All Causalities) at Phase 2

Time: Baseline up to 28 days after last dose of study drug (for a maximum of 86 months)

---

Description: AE: any untoward medical occurrence in a participant who received study drug. AEs included both serious and non-serious adverse events. SAE: AE resulting in any of the following outcomes or deemed significant for any other reason: death; initial or prolonged inpatient hospitalization; life-threatening experience (immediate risk of dying); persistent or significant disability/incapacity; congenital anomaly. Treatment emergent AEs: events occurred between first dose of study drug and up to 28 days after last dose that were absent before treatment or that worsened relative to pre-treatment state. Treatment related AEs: all AEs with causality related to treatment. Relatedness to drug was assessed by the investigator. AEs were graded according to the CTCAE version 3.0 and coded using the MedDRA. Number of participants with AE of grade 3 or 4 and with AE of grade 5 were reported as Grade 3: Severe, Grade 4: Life threatening, Grade 5: Death related to AE.

Measure: Number of Participants With Treatment-Related Adverse Events at Phase 2

Time: Baseline up to 28 days after last dose of study drug (for a maximum of 86 months)

---