The efficacy of fulvestrant 500 mg versus fulvestrant 250 mg was compared in CONFIRM. The efficacy of fulvestrant 250 mg was compared to 1 mg anastrozole in Studies 0020 and 0021. The efficacy of fulvestrant 500 mg was compared to 1 mg anastrozole in FALCON. The efficacy of fulvestrant 500 mg in combination with palbociclib 125 mg was compared to fulvestrant 500 mg plus placebo in PALOMA-3. The efficacy of fulvestrant 500 mg in combination with abemaciclib 150 mg was compared to fulvestrant 500 mg plus placebo in MONARCH 2. The efficacy of fulvestrant 500 mg in combination with ribociclib 600 mg was compared to fulvestrant 500 mg plus placebo in MONALEESA-3. 

Monotherapy

Comparison of Fulvestrant 500 mg and Fulvestrant 250 mg (CONFIRM)

A randomized, double-blind, controlled clinical trial (CONFIRM, NCT00099437) was completed in 736 postmenopausal women with advanced breast cancer who had disease recurrence on or after adjuvant endocrine therapy or progression following endocrine therapy for advanced disease. This trial compared the efficacy and safety of fulvestrant 500 mg (n=362) with fulvestrant 250 mg (n=374). 

Fulvestrant 500 mg was administered as two 5 mL injections each containing fulvestrant injection 250 mg/5 mL, one in each buttock, on Days 1, 15, 29, and every 28 (+/- 3) days thereafter. Fulvestrant 250 mg was administered as two 5 mL injections (one containing fulvestrant injection 250 mg/5 mL injection plus one placebo injection), one in each buttock, on Days 1, 15 (2 placebo injections only), 29, and every 28 (+/- 3) days thereafter. 

The median age of study participants was 61 years. All patients had ER+ advanced breast cancer. Approximately 30% of subjects had no measurable disease. Approximately 55% of patients had visceral disease. 

Results of CONFIRM are summarized in Table 12. The efficacy of fulvestrant 500 mg was compared to that of fulvestrant 250 mg. Figure 6 shows a Kaplan-Meier plot of the Progression Free Survival (PFS) data after a minimum follow-up duration of 18 months demonstrating statistically significant superiority of fulvestrant 500 mg vs. fulvestrant 250 mg. In the initial Overall Survival (OS) analysis after a minimum follow-up duration of 18 months, there was no statistically significant difference in OS between the two treatment groups. After a minimum follow-up duration of 50 months, an updated OS analysis was performed. Figure 7 shows a Kaplan-Meier plot of the updated OS data. 

Figure 6: Kaplan-Meier PFS: CONFIRM ITT Population

Figure 7: Kaplan-Meier OS (Minimum Follow-up Duration of 50 Months): CONFIRM ITT Population

Comparison of Fulvestrant 500 mg and Anastrozole 1 mg (FALCON)

A randomized, double-blind, double-dummy, multi-center study (FALCON, NCT01602380) of fulvestrant 500 mg versus anastrozole 1 mg was conducted in postmenopausal women with ER-positive and/or PgR-positive, HER2-negative locally advanced or metastatic breast cancer who had not previously been treated with any hormonal therapy. A total of 462 patients were randomized 1:1 to receive administration of fulvestrant 500 mg as an intramuscular injection on Days 1, 15, 29, and every 28 (+/-3) days thereafter or daily administration of 1 mg of anastrozole orally. This study compared the efficacy and safety of fulvestrant 500 mg and anastrozole 1 mg. 

Randomization was stratified by disease setting (locally advanced or metastatic), use of prior chemotherapy for advanced disease, and presence or absence of measurable disease. 

The major efficacy outcome measure of the study was investigator-assessed progression-free survival (PFS) evaluated according to RECIST v.1.1 (Response Evaluation Criteria in Solid Tumors). Key secondary efficacy outcome measures included overall survival (OS), objective response rate (ORR), and duration of response (DoR). 

Patients enrolled in this study had a median age of 63 years (range 36-90). The majority of patients (87%) had metastatic disease at baseline. Fifty-five percent (55%) of patients had visceral metastasis at baseline. A total of 17% of patients had received one prior chemotherapy regimen for advanced disease; 84% of patients had measurable disease. Sites of metastases were as follows: musculoskeletal 59%, lymph nodes 50%, respiratory 40%, liver (including gall bladder) 18%. 

The efficacy results of FALCON are presented in Table 13 and Figure 8. 

Figure 8: Kaplan-Meier Plot of Progression-Free Survival (Investigator Assessment, ITT Population) - FALCON

Comparison of Fulvestrant 250 mg and Anastrozole 1 mg in Combined Data (Studies 0020 and 0021)

Efficacy of fulvestrant injection was established by comparison to the selective aromatase inhibitor anastrozole in two randomized, controlled clinical trials (one conducted in North America, Study 0021, NCT00635713; the other predominantly in Europe, Study 0020) in postmenopausal women with locally advanced or metastatic breast cancer. All patients had progressed after previous therapy with an antiestrogen or progestin for breast cancer in the adjuvant or advanced disease setting. 

The median age of study participants was 64 years. 81.6% of patients had ER+ and/or PgR+ tumors. Patients with ER-/PgR- or unknown tumors were required to have demonstrated a prior response to endocrine therapy. Sites of metastases occurred as follows: visceral only 18.2%; viscera – liver involvement 23.0%; lung involvement 28.1%; bone only 19.7%; soft tissue only 5.2%; skin and soft tissue 18.7%. 

In both trials, eligible patients with measurable and/or evaluable disease were randomized to receive either fulvestrant 250 mg intramuscularly once a month (28 days ± 3 days) or anastrozole 1 mg orally once a day. All patients were assessed monthly for the first three months and every three months thereafter. Study 0021 was a double-blind, randomized trial in 400 postmenopausal women. Study 0020 was an open-label, randomized trial conducted in 451 postmenopausal women. Patients on the fulvestrant injection arm of Study 0021 received two separate injections (2 x 2.5 mL), whereas fulvestrant injection patients received a single injection (1 x 5 mL) in Study 0020. In both trials, patients were initially randomized to a 125 mg per month dose as well, but interim analysis showed a very low response rate, and low dose groups were dropped. 

Results of the trials, after a minimum follow-up duration of 14.6 months, are summarized in Table 14. The effectiveness of fulvestrant 250 mg was determined by comparing Objective Response Rate (ORR) and Time to Progression (TTP) results to anastrozole 1 mg, the active control. The two studies ruled out (by one-sided 97.7% confidence limit) inferiority of fulvestrant injection to anastrozole of 6.3% and 1.4% in terms of ORR. There was no statistically significant difference in overall survival (OS) between the two treatment groups after a follow-up duration of 28.2 months in Study 0021 and 24.4 months in Study 0020. 

Combination Therapy

Patients with HR-positive, HER2-negative advanced or metastatic breast cancer who have had disease progression on or after prior adjuvant or metastatic endocrine therapy

Fulvestrant 500 mg in Combination with Palbociclib 125 mg (PALOMA-3)

PALOMA-3 (NCT-1942135) was an international, randomized, double-blind, parallel group, multi-center study of fulvestrant plus palbociclib versus fulvestrant plus placebo conducted in women with HR-positive, HER2-negative advanced breast cancer, regardless of their menopausal status, whose disease progressed on or after prior endocrine therapy. 

A total of 521 pre/postmenopausal women were randomized 2:1 to fulvestrant plus palbociclib or fulvestrant plus placebo and stratified by documented sensitivity to prior hormonal therapy, menopausal status at study entry (pre/peri versus postmenopausal), and presence of visceral metastases. Palbociclib was given orally at a dose of 125 mg daily for 21 consecutive days followed by 7 days off treatment. Fulvestrant 500 mg was administered as two 5 mL injections each containing fulvestrant 250 mg/5 mL, one in each buttock, on Days 1, 15, 29, and every 28 (+/- 3) days thereafter. Pre/perimenopausal women were enrolled in the study and received the LHRH agonist goserelin for at least 4 weeks prior to and for the duration of PALOMA-3. 

Patients continued to receive assigned treatment until objective disease progression, symptomatic deterioration, unacceptable toxicity, death, or withdrawal of consent, whichever occurred first. The major efficacy outcome of the study was investigator-assessed PFS evaluated according to RECIST v.1.1. 

Patients enrolled in this study had a median age of 57 years (range 29 to 88). The majority of patients on study were White (74%), all patients had an ECOG PS of 0 or 1, and 80% were postmenopausal. All patients had received prior systemic therapy and 75% of patients had received a previous chemotherapy regimen. Twenty-five percent of patients had received no prior therapy in the metastatic disease setting, 60% had visceral metastases, and 23% had bone only disease. 

The results from the investigator-assessed PFS and final OS data from PALOMA-3 are summarized in Table 15. The relevant Kaplan-Meier plots are shown in Figures 9 and 10, respectively. Consistent PFS results were observed across patient subgroups of disease site, sensitivity to prior hormonal therapy, and menopausal status. After a median follow-up time of 45 months, the final OS results were not statistically significant.

Figure 9: Kaplan-Meier Plot of Progression-Free Survival (Investigator Assessment, ITT Population) - PALOMA-3

Figure 10: Kaplan-Meier Plot of Overall Survival (ITT Population) - PALOMA-3

Fulvestrant 500 mg in Combination with Abemaciclib 150 mg (MONARCH 2)

MONARCH 2 (NCT02107703) was a randomized, placebo-controlled, multi-center study conducted in women with HR-positive, HER2-negative metastatic breast cancer with disease progression following endocrine therapy treated with fulvestrant plus abemaciclib versus fulvestrant plus placebo. Randomization was stratified by disease site (visceral, bone only, or other) and by sensitivity to prior endocrine therapy (primary or secondary resistance). A total of 669 patients received intramuscular injection of fulvestrant 500 mg on Days 1 and 15 of cycle 1 and then on Day 1 of cycle 2 and beyond (28-day cycles), plus abemaciclib or placebo orally twice daily. Pre/perimenopausal women were enrolled in the study and received the gonadotropin-releasing hormone agonist goserelin for at least 4 weeks prior to and for the duration of MONARCH 2. Patients remained on continuous treatment until development of progressive disease or unmanageable toxicity. 

Patient median age was 60 years (range, 32-91 years), and 37% of patients were older than 65. The majority were White (56%), and 99% of patients had an Eastern Cooperative Oncology Group (ECOG) performance status of 0 or 1. Twenty percent (20%) of patients had de novo metastatic disease, 27% had bone only disease, and 56% had visceral disease. Twenty-five percent (25%) of patients had primary endocrine therapy resistance. Seventeen percent (17%) of patients were pre- or perimenopausal. 

The efficacy results from the MONARCH 2 study are summarized in Table 16, Figure 11, and Figure 12. PFS assessment based on a blinded independent radiologic review was consistent with the investigator assessment. Consistent results were observed across patient stratification subgroups of disease site and endocrine therapy resistance for PFS and OS. 

Figure 11: Kaplan-Meier Curves of Progression-Free Survival: Fulvestrant Plus Abemaciclib versus Fulvestrant Plus Placebo (MONARCH 2)

Figure 12: Kaplan-Meier Curves of Overall Survival: Fulvestrant Plus Abemaciclib versus Fulvestrant Plus Placebo (MONARCH 2) 

Postmenopausal women with HR-positive, HER2-negative advanced or metastatic breast cancer for initial endocrine based therapy or after disease progression on endocrine therapy

Fulvestrant 500 mg in Combination with Ribociclib 600 mg (MONALEESA-3)

MONALEESA-3 (NCT 02422615) was a randomized double-blind, placebo-controlled study of fulvestrant plus ribociclib versus fulvestrant plus placebo conducted in postmenopausal women with hormone receptor positive, HER2-negative, advanced breast cancer who have received no or only one line of prior endocrine treatment. 

A total of 726 patients were randomized in a 2:1 ratio to receive fulvestrant plus ribociclib or fulvestrant plus placebo and stratified according to the presence of liver and/or lung metastases and prior endocrine therapy for advanced or metastatic disease. Fulvestrant 500 mg was administered intramuscularly on Days 1, 15, 29, and once monthly thereafter, with either ribociclib 600 mg or placebo given orally once daily for 21 consecutive days followed by 7 days off until disease progression or unacceptable toxicity. The major efficacy outcome measure for the study was investigator-assessed progression-free survival (PFS) using Response Evaluation Criteria in Solid Tumors (RECIST) v1.1. 

Patients enrolled in this study had a median age of 63 years (range 31 to 89). Of the patients enrolled, 47% were 65 years and older, including 14% age 75 years and older. The patients enrolled were primarily Caucasian (85%), Asian (9%), and Black (0.7%). Nearly all patients (99.7%) had an ECOG performance status of 0 or 1. First and second line patients were enrolled in this study (of which 19% had de novo metastatic disease). Forty-three percent (43%) of patients had received chemotherapy in the adjuvant vs. 13% in the neoadjuvant setting and 59% had received endocrine therapy in the adjuvant vs. 1% in the neoadjuvant setting prior to study entry. Twenty-one percent (21%) of patients had bone-only disease and 61% had visceral disease. Demographics and baseline disease characteristics were balanced and comparable between study arms. 

The efficacy results from MONALEESA-3 are summarized in Table 17, and Figure 13, and Figure 14. Consistent results were observed in stratification factor subgroups of disease site and prior endocrine treatment for advanced disease. 

Figure 13: Kaplan-Meier Progression Free Survival Curves - MONALEESA-3 (Intent-To-Treat Population, Investigator Assessment)

Figure 14: Kaplan-Meier Plot of Overall Survival - MONALEESA-3 (Intent-To-Treat Population)