Published Ahead of Print on September 14, 2015 as 10.1200IJCO.2015.61.5831
`The latest version is at http:lljco.ascopubs.orglcgildoil10.1200IJCO.2015.61.5831
`
`JOURNAL OF CLINICAL ONCOLOGY
`
`ORIGI NAL REPORT
`
`Matthew J Ellis Baylor College of
`Medicine, Houston, TX, Antonio
`LlombarteCussac, Hospital Arnau de
`\lilanova, Lerida, Spain, DaVId Feltl,
`FNsP Ostrava, OstravarPoruba, Czech
`Republic, John A. Dewar, Ninewells
`Hospital and Medical School, Dundee,
`Nicola Hewson and Yuri Rukazenkov,
`AstraZeneca Pharmaceuticals, Macclese
`field, John F R Robertson, UniverSIty of
`Nottingham, Derby, United Kingdom,
`and MarekJasiowka, Iristytut im Marii
`SkiodowskiejeCurie, Krakéw, Poland
`Published online ahead of print at
`Www JCO org on September 14, 2015
`Supported by AstraZeneca
`Terms in lulufl are defined in the glosr
`sary, found at the end of this article
`and online at WWW (Georg
`Presented at the 2014 San Antonio
`Breast Cancer Symposmm, San Antoe
`nio, TX, December 913, 2014
`
`Authors' disclosures of potential
`conflicts of interest are found in the
`article online at WWW Jco org Author
`contributions are found at the end of
`this article
`Clinical trial information NCT00274469
`
`Corresponding author Matthew J Ellis,
`MD, Lester and Sue Smith Breast
`Center, One Baylor Plaza, Baylor
`College of Medicrne, Houston, TX
`77030, email Matthew Ellis@bcm edu
`
`© 2015 by American SOCIety of Clinical
`Oncology Licensed under the Creative
`Commons Attribution 3 0 License
`
`0732183X/15/339971/$20 00
`DOI 101200/JCO 2015 61 5831
`
`Fulvestrant 500 mg Versus Anastrozole 1 mg for the
`First—Line Treatment of Advanced Breast Cancer: Overall
`
`Survival Analysis From the Phase 11 FIRST Study
`
`Matthew]. Ellis, Antonio Llombart—Cussac, David Feltl, John A. Dewar, Mareklasiowka, Nicola Hewson,
`YuriRukazenkov, andIOlm FR. Robertson
`
`ABSTRACT
`
`
`
`Purpose
`To compare overall survival (OS) for fulvestrant 500 mg versus anastrozole as first—line endocrine
`therapy for advanced breast cancer.
`
`Patients and Methods
`The Fulvestrant First—Line Study Comparing Endocrine Treatments (FIRST) was a phase II,
`randomized, open—label, multicenter trial. Postmenopausal women with estrogen receptor—
`positive,
`locally advanced/metastatic breast cancer who had no previous therapy for advanced
`disease received either fulvestrant 500 mg (days 0, 14, 28, and every 28 days thereafter) or
`anastrozole 1 mg (daily). The primary end point (clinical benefit rate [72.5% and 67.0%]) and a
`follow—up analysis (median time to progression [23.4 months and 13.1 months]) have been
`reported previously for fulvestrant 500 mg and anastrozole, respectively. Subsequently,
`the
`protocol was amended to assess OS by unadjusted log—rank test after approximately 65% of
`patients had died. Treatment effect on OS across several subgroups was examined. Tolerability
`was evaluated by adverse event monitoring.
`
`Results
`In total, 205 patients were randomly assigned (fulvestrant 500 mg, n = 102; anastrozole, n = 103).
`At data cutoff, 61.8% (fulvestrant 500 mg, n = 63) and 71.8% (anastrozole, n = 74) had died. The
`hazard ratio (95% CI) for OS with fulvestrant 500 mg versus anastrozole was 0.70 (0.50 to 0.98;
`
`P = .04; median OS, 54.1 months v48.4 months). Treatment effects seemed generally consistent
`across the subgroups analyz d. No n w saf ty issu s w re obs rv d.
`
`There are several limitations of this OS analysis, including that it was not planned in the original
`protocol but instead was added after time—to—progression results were analyzed, and that not
`all patients participated in additional OS follow—up. However, the present results suggest
`fulvestrant 500 mg extends OS versus anastrozole. This finding now awaits prospective
`confirmation in the larger phase III FALCON (Fulvestrant and Anastrozole Compared in
`Hormonal Therapy Na'i've Advanced Breast Cancer)
`trial
`(ClinicalTrialsgov identifier:
`NCT01602380).
`
`J Clin Oncol © 2075 by American Society of Clinical Oncology. Licensed under the Creative
`Commons Attribution 3.0 License: http.'//creative-commons.org/licenses/by/S.0/
`
`
`
`Tamoxifen and third—generation aromatase in hi bi—
`tors (Als), such as anastrozole, exemestane, and
`letrozole are established first—line endocrine thera—
`
`pies for the treatment of postmenopausal women
`with estrogen receptor (ER) —positive, advanced
`breast cancerd"3 Given the high prevalence of resis—
`tance to AI therapy, multiple treatment optionswith
`distinct mechanisms of action are desirable.4
`
`Fulvestrant, a 17B—esfl’adiol analog, is a selec—
`tive ER antagonist that suppresses es‘nrogen signaling
`by binding to ER and inducing a conformational
`change?6 Dimerization is subsequently blocked,
`triggering accelerated degradation and downregula—
`tion of the ER protein.5 Fulves‘dant exhibits lack of
`cross—reactivity with tamoxifen. Consequently, pa—
`tients whose disease progresses on fulvestrant may
`retain sensitivity to treatment with further endo—
`crine therapies.7’8 The clinical efficacy of fulvestrant
`
`© 2015 by American SOCIety of Clinical Oncology
`on September 14, 2015 from 212.209.42.182
`Information downloaded from jco.ascopubs.org and provided by at AZ Library
`Copyright © 2015 American Society of Clinical Oncology. All rights reserved.
`Copyright 2015 by American Society of Clinical Oncology
`
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`
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`

`

`Ellis et al
`
`was initially demonstrated in two phase III trials that compared ful—
`vestrant 250 mg per month with anastrozole 1 mg daily as a second—
`line therapy for advanced breast cancer.9’lo A combined analysis of
`these trials demonstrated that time to progression (TTP) with fulves—
`trant 250 mg was noninferior to anastrozole.M
`Fulvestrant 250 mg was not proven to be superior to tamoxifen in
`a double—blind, randomized trial.12 This finding was unexpected given
`the superiority of anastrozole over tamoxifen13 and the comparable
`efficacy of anastrozole and fulvestrant 250 mg as second—line ther—
`apy.11 Pharmacokinetic modeling, as well as observations made dur—
`ing early clinical studies,11 suggested the efficacy of fulvestrant could
`be improved with use of a higher dose, which led to the development
`of a dosage regimen of fulvestrant 500 mg, including a loading dose
`component to reduce the time to reach steady—state plasma levels.
`Subsequently, the phase III Comparison of Faslodex in Recurrent
`or Metastatic Breast Cancer (CONFIRM) trial found that fulves—
`trant 500 mg was associated with improved progression—free sur—
`vival (PFS) and overall survival (OS) compared with the 250—mg
`dose in patients who experienced disease recurrence or progression
`after previous endocrine therapy.14’15
`The Fulvestrant First—Line Study Comparing Endocrine Treat—
`ments (FIRST) was a phase II, randomized, open—label, multicenter
`trial that also used the fulves‘uant 500—mg dose regimen, comparing
`efficacy and safety with anastrozole in the first—line setting. The pri—
`mary end point of clinical benefit rate was noninferior for fulvestrant
`500 mg compared with anastrozole,16 with both treatments demon—
`sfirating similar, well—tolerated safety profiles. A follow—up analysis,
`performed because only 35.6% of patients experienced disease pro—
`gression at the time of the primary analysis, reported a hazard ratio
`(HR) of TTP for fulvestrant 500 mg versus anastrozole of 0.66 with a
`95% CI of 0.47 to 0.92 (P = .01; median TTP, 23.4 months v
`13.1 months). No additional safety issues were reported.“ Given the
`improvement in TTP observed during fulvestrant 500 mg treatment
`comparedwith anastrozole in this phase II trial, a subsequent protocol
`amendment was made to address whether this apparent extension in
`disease control would translate into an improvement in OS.
`
`PATIENTS AND' METHODS
`
`Study Design and Participants
`FIRST was a phase II, randomized, openelabel, multicenter, parallelr
`group trial comparing fulvestrant 500 mg with anastrozole 1 mg. Postmenor
`pausal women with ERrpositive locally advanced or metastatic breast cancer
`who had not received any previous systemic therapy for locally advanced or
`metastatic disease were included. Patients were permitted to have received
`previous endocrine therapy for early disease, providing this had been come
`pleted more man 12 months before random assignment. This trial was con
`ducted in accordance with the Declaration ofHelsinki, was consistent with the
`International Conference on Harmonisationfiood Clinical Practice guide
`lines, and is registered with ClinicaltriangOV. All patients provided written,
`informed consent Full details ofthis trial have been reported previously.‘l5’17
`
`Random Assignment and Procedures
`Eligible patients were randomly assigned sequentially 1 : 1 to either fillVeS*
`trant 500 mg (administered intramuscularly on days 0, 14, 28, and every
`2 8 days thereafter) or anastrozole 1 mg (administered orally once per day) . The
`data cutoff for the primary analysis was 6 months after the last patient was
`randomly assigned. On disease progression or after data cutofffor the primary
`analysis, all patients entered a followup phase after a protocol amendment for
`
`an analysis of TTP. The TTP followrup required a questionnaire to be come
`pleted for each patient 12 months after the patient entered the followrup phase
`and every 12 months thereafter for patients continuing to receive randomized
`treatment. After the TTP analysis was performed, a further protocol amend
`ment was developed to enter patients into an optional followrup phase to
`establish OS. To ensure sufficient maturity, the OS analysis was planned for
`when approximately 65% ofpatients had died. Patients who did not contribr
`ute additional data to the followrup extension were rightrcensored at the last
`known date they were alive, and their data until this point were included in the
`analysis. Sites were invited to request written consent from patients for the
`collection of additional data. Patients were contacted every 3 months until the
`first ofthe following events: death, patientwithdrawal, data cutoffwas reached,
`or the patient was lostto followup. Patients with a last known survival status of
`alive were contacted within 2 weeks ofdata cutoffto ensure they were still alive.
`
`Outcomes
`
`The primary study end point was clinical benefit rate; secondary end
`points included objective response rate, TTP, duration of clinical benefit, and
`duration of response. These primary and secondary end points have been
`reported previously. 16’”
`The followrup analysis assessed OS, defined as the time from being
`randomlyassigned to death from any cause. A logeranktest (unadjusted model
`with treatment factor only) was performed for the primary analysis ofOS. HRs
`with 95% CIs were used to compare fiilvestrant 500 mg with anastrozole; no
`adjustments were made for multiplicity. A statistical significance level of .05
`was used to indicate a difference in OS between the treatment groups. For
`patients for whom followrup responses could not be obtained, data were
`censored at the date the patient was last known to be alive.
`Exploratory subgroup analyses were conducted using the logrank test to
`compare OS for the following prespecified patient subgroups:
`less than
`65 years of age versus 65 years of age or greater; not positive for both ER and
`progesterone receptor versus positive for both ER and progesterone receptor;
`no visceral involvement versus visceral involvement; no previous chemotherr
`apy versus previous adjuvant chemotherapy; no measurable disease versus
`measurable disease; and no previous endocrine therapyversus previous endor
`crine therapy.
`Two sensitivity analyses were performed to examine any potential
`impact ofnonparticipation on OS results: a KaplanrMeier OS analysis was
`performed in which the censoring indicator was reversed; and baseline
`covariates were assessed for patients censored greater than 3 months before
`data cutoff and for those censored 3 months or less before data cutoff,
`which corresponds to patients who did not participate in the OS followrup
`and to those who did, respectively.
`Tolerability was assessed by serious adverse event (SAE) monitoring. All
`SAEs were coded in compliance with the Medical Dictionary for Regulatory
`Activities and recorded in an internal AstIaZeneca database for evaluation.
`
`SAEs were monitored for up to 8 weeks after the last dose offulvestrant500 mg
`or for 30 days after the last dose of anastrozole.
`
`RESULTS
`
`In total, 205 patients were randomly assigned to receive fulvestrant
`500 mg (n = 102) or anastrozole 1 mg (n = 103) at 62 centers in nine
`countries (Brazil, Bulgaria, the Czech Republic, France, Italy, Poland,
`Spain, the United Kingdom, and the United States).
`Baseline characteristics and patient demographics were similar
`between the trea’unent groups as reported previously.16 The propor—
`tion of patients who had not received previous endocrine treatment
`for early disease was similar for the fiflvesfiaiit 500 mg and anastrozole
`treatment groups (71.6% and 77.7% of patients at baseline, respec—
`tively). Of those that did, almost all had received tamoxifen exclu—
`sively. Of the 205 randomly assigned patients, 35 (16 in the fulvestrant
`500 mg group and 19 in the anastrozole group) did not participate in
`
`Z
`
`© 2015 by American SOCIety of Clinical Oncology
`on September 14, 2015 from 212.209.42.182
`Information downloaded from jco.ascopubs.org and provided by at AZ Library
`Copyright © 2015 American Society of Clinical Oncology. All rights reserved.
`
`JOURNAL or CLINICAL ONCOLOGY
`
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`

`

`Fulvestrant 500 mg: Overall Survival Versus Anastrozole
`
`Enrolled
`(N = 233)
`
`Not randomly allocated
`Incorrect enrollment
`Death
`Adverse event
`Volu nta ry patient disconti nuatio n
`Other
`
`(n=28)
`(n=20)
`(n=1l
`(n=1l
`(n=4l
`(n=2l
`
`(h :10)
`
`Randomly allocated
`(n = 205)
`
`i—l—l
`
`Fulvestr-ant 500 mg
`(n = 102)
`
`Anastrozole 1 mg
`(n =103)
`
`Fig 1. Study overview. (*) These patients
`were right censored at the time of their last
`known date alive, and data until this point
`were used in the overall survival (08) analysis.
`
`Data cutoff for analysis of overall survival
`Alive
`(n = 23.)
`Dead
`(n = 63)
`Did not contribute additional data
`(n = 16.)
`during 08 follow-up extensions“
`Patient declined to participate
`Site declined to participate
`
`(n =6)
`
`Data cutoff for analysis of mere” survival
`AI iv’e
`in =10)
`Dead
`(n=74)
`Did not contribute additional data
`(n =19)
`during OS follow-up extension*
`Patient declined to participate
`Site declined to participate
`
`(‘n =
`(n = ‘10)
`
`Safety
`The occurrence of SAEs during the main study period and the
`follow—up period combined is detailed in Table 2. The majority of
`SAEs were considered by the investigator to be unrelated to the Heat—
`ment. Two SAEs considered to be treatment related were documented
`
`(one case of hypertension and one case of pulmonary embolism,both
`in the fulvestrant 500 mg trea’unent group).
`
`DISCUSSION,
`
`This study reports improved OS with fulvestrant 500 mg treatment
`compared with anaonzole in the first—line setting for ER—positive
`
`— Fulvestrant 500 mg
`----Anastrozo|e 1 mg
`
`
`
`L .
`
`Median overall survival:
`Fulvestrant 500 mg: 54.1 months
`Anastrozole 1 mg: 48.4 months
`Hazard ratio, 0.70; 95% CI, 0.50 to 0.98; P: .04
`
`lll'fiu
`""'"
`
`6 12 18 2430 36 4248 54 60 66 72 78 84 90 96102
`
`
`
`OverallSurvival
`
`.0 07
`
`(proportion) 52
`
`.0 N
`
`No. at risk
`Fulvestrant 500 mg 102
`Anastrozole 1 mg
`103
`
`90 84 77
`90 80 72
`
`Time (months)
`47
`39
`31
`39
`29
`21
`
`57
`49
`
`24
`14
`
`Fig 2. Kaplan-Meier plot of overall survival.
`
`the OS follow—up phase and were censored at the date theywere last
`known to be alive; for these patients, data until this time are
`included in the OS analysis, and thus all patients contributed data
`to the analysis. The majority of the nonparticipating patients (n =
`20) did not contribute additional data because they attended cen—
`ters that declined to contribute to the OS follow—up phase. An
`additional 15 individual patients from nine participating centers
`did not consent to follow—up. No patients participating in the OS
`phase were lost to follow—up, and the survival status at data cutoff
`was known for all patients consenting to the OS follow—up.
`
`Efficacy
`At the time of the follow—up analysis for OS, 63 of 102 patients in
`the fulvestrant 500 mg group (61.8%) and 74 of 103 patients in the
`anastrozole group (71.8%) were known to have died (Fig '1). The
`primary analysis of OS was improved in the fulvestrant 500 mg group
`compared with anastrozole 1 mg; the HR was 0.70 (95% CI, 0.50 to
`0.98; log—rank test P = .04; median OS, 54.1 months v 48.4 months;
`Fig 2). The HR for fulvestrant 500 mg versus anastrozole was found to
`be generally consistent across all subgroup analyses (Fig 3). At 3 years,
`64% (fulvestrant 500 mg) and 58% (anastrozole) of patients were
`event free; at 5 years, the equivalent values were 47% and 38%.
`
`Sensitivity Analyses
`There were no important differences between the treatment
`groups in time to censoring (data not shown). Furthermore, when key
`baseline covariates for patients censored within the last 3 months
`before data cutoff and for those censored more than 3 months before
`
`data cutoff were summarized, there were no important differences
`between treaUnent groups, indicating that the results were not caused
`by differences between patients who did and did not consent to OS
`follow—up (Table 1).
`
`WWW.jctmrg
`
`© 2015 by American Socrety of Clinical Oncology
`on September 14, 2015 from 212.209.42.182
`Information downloaded from jco.ascopubs.org and provided by at AZ Library
`Copyright © 2015 American Society of Clinical Oncology. All rights reserved.
`
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`Ellis et al
`
`Fulvestrant Anastrozole
`Hazard ratio
`500 mg
`1 mg
`
`events (n)events (n) (95% CI)
`
`Hazard ratio and 95% Cl
`0.70 (0.50 to 0.98)
`—o—i
`All patients
`63 (102)
`74 (103)
`Age, yea rs
`< 65
`2 65
`
`0.73 (0.44 to 1.24)
`0.68 (0.44 to 1.06)
`
`29 (45)
`34 (57)
`
`Favors fulvestrant 500 mg
`
`Both ER+ and PgR+
`No
`Yes
`Visceral involvement
`No
`Yes
`
`Prior chemotherapy
`No
`Yes
`Measurable disease
`No
`Yes
`
`Prior endocrine therapy
`No
`Yes
`
`14 (24)
`49 (78)
`
`43 (73)
`20 (29)
`
`11 (13)
`52 (89)
`
`44 (73)
`19 (29)
`
`0.66 (0.33 to 1.32)
`0.72 (0.49 to 1.06)
`
`0_68 (040 to 118)
`0_86 (056 to 134)
`
`0.63 (0.43 to 0.94)
`0.93 (0.48 to 1.78)
`
`NC
`0.67 (0.46 to 0.96)
`
`Fig 3. Overall survival subgroup analy-
`sis. ER+, estrogen receptor positive;
`NC, not calculable; PgR+, progesterone
`receptor positive.
`
`7 (10)
`67 (93)
`
`NC
`—o— i
`
`0.63 (0.42 to 0.93)
`59 (80)
`15 (23)
`1.01 (0.51 to 1.99)
`fi—l—l—l—
`2.00
`0.25
`0.50
`1.00
`
`.
`
`Favors anastrozole
`
`advanced breast cancer, with an approximately 30% reduction in
`mortality risk The previously reported improvements in TTP have
`translated into an improvement in OS of approximately 6 months
`with fulves‘urant 500 mg (54.1 months) compared with anastrozole
`(48.4 months). This OS advantage is consistent with the OS benefit for
`fulves‘urant 500 mg versus 250 mg in the second—line setting in the
`CONFIRM trial.” The effect of fulvestrant 500 mg on OS was gener—
`ally consistent across all prespecified subgroups (Fig 3). Furthermore,
`
`no new safety or tolerability issues were reported from the OS
`follow—up phase of this study, consistent with previously reported
`safety data. 16517
`The improved OS with fulvestrant 500 mg (54.1 months) relative
`to anastrozole (48.4 months) was observed although the median OS
`for the anaonzole group in this study was higher than has previously
`been reported. For example, OS of 39.2 months was reported for
`anastrozole as first—line endocrine therapy for advanced breast cancer
`
`
`
`Table 1. Baseline Covariates and Subgroups by Patients Censored 2 3 Months and S 3 Months Before DCO
`No. of Patients We)
`
`Censored > 3 Months Before DCO Censored S 3 Months Before DCO
`
`Subgroup
`
`Fulvestrant 500 mg (n : 16)
`
`Anastrozole 1 mg (n : 19)
`
`Fulvestrant 500 mg (n : 23)
`
`Anastrozole 1 mg (n : 10)
`
`5 (31 .3)
`11 (68.8)
`
`6 (37.5)
`10 (62.5)
`
`9 (56.3)
`7 (43.8)
`
`11 (68.8)
`5 (31 .3)
`
`1 (6.3)
`15 (93.8)
`
`
`
`
`
`Age, years
`< 65
`2 65
`Receptor status at diagnosis
`ot both ER+ and PgR+
`Both ER+ and PgR+
`Visceral involvement
`0
`Yes
`Previous chemotherapy
`o
`Yes
`Measurable disease at diagnosis
`0
`Yes
`Previous endocrine therapy
`8 (80.0)
`18 (78.3)
`3 (68.4)
`11 (68.8)
`0
`
`Yes 2 (20.0) 5 (31 .3) 6 (31.6) 5 (21.7)
`
`
`
`
`
`
`7 (36.8)
`2 (63.2)
`
`5 (26.3)
`4 (73.7)
`
`1 (57.9)
`8 (42.1)
`
`3 (68.4)
`6 (31.6)
`
`3 (15.8)
`6 (84.2)
`
`11 (47.8)
`12 (52.2)
`
`4 (17.4)
`19 (82.6)
`
`16 (69.6)
`7 (30.4)
`
`19 (82.6)
`4 (17.4)
`
`1 (4.3)
`22 (95.7)
`
`4 (40.0)
`6 (60.0)
`
`2 (20.0)
`8 (80.0)
`
`8 (80.0)
`2 (20.0)
`
`8 (80.0)
`2 (20.0)
`
`0
`10 (100.0)
`
`Abbreviations: DCO, data cutoff; ER+, estrogen receptor—positive; PgR+, progesterone receptor—positive.
`
`4
`
`JOURNAL OF CLINICAL ONCOLOGY
`© 2015 by American Seeiety of Clinical Oncology
`Information downloaded from jco.ascopubs.org and provided by at AZ Library on September 14, 2015 from 212.209.42.182
`Copyright © 2015 American Society of Clinical Oncology. All rights reserved.
`
`AstraZeneca Exhibit 2058 p. 4
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`

`Fulvestrant 500 mg: Overall Survival Versus Anastrozole
`
`
`
`Table 2. Incidence of SAEs and Deaths
`
`Fulvestra nt
`Anastrozole
`500 mg
`1 mg
`
`SAE
`(n : 101)
`(n : 103)
`
`No. of Patients (%)
`
`22 (21.4)
`5 (4.9)
`18 (17.5)
`0
`
`24 (23.8)
`3 (3.0)
`21 (20.8)
`2 (2.0)
`
`Any SAE
`Any SAE related to death
`Any SAE With outcome other than death
`Any causally related SAE
`Most commonly reported (2 two patients)
`SAEs
`1 (1.0)
`1 (1.0)
`Atrial fibrillation
`0
`2 (2.0)
`Cardiac failure
`2 (1 .9)
`0
`Death
`0
`2 (2.0)
`Decreased appetite
`0
`2 (2.0)
`Dehydration
`0
`2 (2.0)
`Dyspnea
`2 (1.9)
`1 (1.0)
`Femur fracture
`1 (1.0)
`1 (1.0)
`Neuralgia
`
`Transient ischemic attack 2 (1.9) 0
`
`
`Abbreviation: SAE, serious adverse event.
`
`in a combined analysis of two phase III studies,18 and OS of 41.3
`months was reported for the anastrozole monotherapy arm of a phase
`III combination study.19 In addition, corresponding median OS val—
`ues of 34.0 months (letrozole)20 and 37.2 months (exemestane)21L have
`been reported for other AIs. It is therefore unlikely that the present
`analysis overestimates the margin of improvement with fulvestrant
`500 mg over anastrozole, which might have been possible had the
`control arm underperformed.
`The role of fulvestrant 500 mg as first—line therapy will be further
`defined by the ongoing phase III, double—blind FALCON (Fulvestrant
`and Anastrozole Compared in Hormonal Therapy Naive Advanced
`Breast Cancer) trial (ClinicalTrialsgov identifier: NCT01602380). The
`FALCON trialwill assess the efficacy offulvesfirant 500 mg versus anasfi'o—
`zole in women with locally advanced or metastatic breast cancer with strict
`definitions of endocrine therapy—naive disease, including resfiictions on
`exposure to hormone replacement therapy.
`Endocrine therapy—naive advanced breast cancer is relatively un—
`common in countries with advanced health care, but represents a
`numerically substantial patient population, given the high disease
`prevalence. Furthermore, in unscreened populations and in develop—
`ing countries, metastatic disease at presentation is a significant prob—
`lem. Recent clinical trials reporting on first—line endocrine therapy in
`patients with ER—positive breast cancer have contained a substantial
`proportion, and often a majority, of endocrine therapy—naive
`patientsd‘E’LD'Z4 In FIRST, previous endocrine therapy had been re—
`ceived by 29 (28.4%) of the patients treated with fulvestrant 500 mg
`and 23 (22.3%) of the anastrozole—Heated patients. Of these 52 pa—
`tients, only 3 had received AI previoust (2 in the anaonzole group and
`1 in the fulvestrant 500 mg group); the remainder had received adjuvant
`tamoxifen. Therefore, AI resistance resulting from previous AI exposure
`cannot account for the observed OS difference. Indeed, hypothetically,
`previous exposure to tamoxifen may bias against fulvestrant as both
`agents are in the same therapeutic class. Upon disease progression, pa—
`tients were treated according to the standard of care, and therefore, there
`could potentially be imbalances between the two fireatment groups that
`
`could have affected the OS analysis. However, response to subsequent
`therapies (systemic chemotherapy or endocrine therapy) has previously
`been shown to be similar between the treatment groups, demonstrating
`that patients with disease progression on fulvestrant retain sensitivity to
`subsequent fireatments.” Differential second—line response, therefore, is
`also an unlikely explanation for the observed OS effect.
`There are significant limitations to this report. The sample size was
`relatively small, and the OS analysis was not specified in the original
`protocol but was added as a hypothesis in a protocol amendment after
`TTP results were known. Furthermore, 35 patients did not contribute
`additional data to the OS follow—up; the decision not to participate in the
`extended follow—up for OS was made solely by the patient or participating
`center and was known at the start of the OS follow— up and before the data
`were collected and analyzed. Data from these patients until the time of
`censoring were included in the OS analysis, and similar censoring patterns
`were seen in the two fireatment groups. The sensitivity analyses support
`the main findings, that is, the differences in OS between Ueatment arms
`were unrelated to differences in censoring patterns. All—cause mortality
`was used to determine OS in this analysis because it is regarded as the most
`unbiased and objective end point used in oncology.” This point is partic—
`ularly relevant to an open —label study like FIRST. A final limitation was
`that the number ofpatients within subgroups was relatively small There—
`fore, care should be taken when interpreting results.
`Recent results from several trials with the cyclin—dependent ki—
`nase 4/6 (CDK4/6) inhibitor palbociclib are also pertinent to the
`discussion. PALOMA—l (Palbociclib Ongoing Trials in the Manage—
`ment of Breast Cancer), a phase II trial of letrozole plus palbociclib
`versus letrozole alone, provided provisional US Food and Drug Ad—
`ministration approval for palbocich in the first—line setting on the
`basis of PFS.23 No positive OS data have been reported to date; the
`results of aphase III trial ofthis comparison are pending (PALOMA—Z,
`NCT01740427). Data from the phase III PALOMA—3 trial, comparing
`fulves‘urant 500 mg plus palbociclib versus fulvestrant 500 mg alone in
`the second—line or subsequent setting in postmenopausal women (or
`pre— or perimenopausal women receiving goserelin), reported a
`marked PFS advantage for the combination, but OS data were also
`pending at the time of erblication.Z6‘ The median PFS for fulvestrant
`500 mg alone was shorter in PALOMA—3 than in previous studies,
`indicative of the younger, higher—risk, and more heavily pretreated
`population recruited into the PALOMA—3 trial.
`The treatment algorithm for ER—positive advanced breast cancer,
`therefore, is in a state of flux. Currently, it is rational to consider
`fulves‘urant 500 mg as a first—line treatment option given the potential
`for survival benefits, particularly in settings where palbociclib is not
`available or palbociclib cost or adverse effects are a significant concern,
`and especially if these results are confirmed in FALCON. These data
`also suggest that a first—line study offulvestrant 500 mg with a CDK4/6
`inhibitor versus fulvesUant 500 mg alone is a logical proposition that
`could lead to further prolonged TTP. Recent preclinical data on the
`efficacy of an ER degrading agent with a CDK4/6 inhibitor in ESR1—
`mutant breast cancer provides further rationale for this population,
`because improvements in TTP or OS could be caused by suppression
`of ESRl—mutant AI—resistant clones;27
`
`In conclusion, we report that fulvestrant 500 mg may be associ—
`ated with improved OS versus anastrozole in the first—line setting for
`ER—positive advanced breast cancer. To our knowledge, this repre—
`sents the first time an endocrine monotherapy has demonstrated
`
`www.jc0.org
`
`© 2015 by American Socrety of Clinical Oncology
`on September 14, 2015 from 212.209.42.182
`Information downloaded from jco.ascopubs.org and provided by at AZ Library
`Copyright © 2015 American Society of Clinical Oncology. All rights reserved.
`
`5
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`AstraZeneca Exhibit 2058 p. 5
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`Ellis et al
`
`improved efficacy compared with a third—generation A1. The phase III
`FALCON n‘ial may provide confirmation for these OS results; until
`then, the findings reported here should be regarded as preliminary,
`but clinically relevant
`
`AUTHORS' DISCLOSURES OF POTENTIAL OONHIOTS
`
`OF INTEREST
`
`Disclosures provided by the authors are available with this article at
`www.jco.org.
`
`AUTHOR CONTRIBUTIONS
`
`Conception and design: Matthew J. Ellis, John RR. Robertson
`Provision of study materials or patients: Matthew J. Ellis, John ER.
`Robertson
`
`Collection and assembly of data: Matthew J. Ellis, David Feltl, John ER.
`Robertson
`
`Data analysis and interpretation: Matthew J. Ellis, Antonio
`LlombarteCussac, John A. Dewar, Marel: Jasi’éwka, Nicola Hewson, Yuri
`Rukazenkov, John ER. Robertson
`Manuscript writing: All authors
`Final approval of manuscript: All authors
`
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