Brief Summary:
The goal of this clinical trial is to assess the efficacy, safety and tolerability of the
combination of lasofoxifene and abemaciclib compared to fulvestrant and abemaciclib for the
treatment of pre- and postmenopausal women and men who have previously received ribociclib or
palbociclib-based treatment and have locally advanced or metastatic estrogen receptor
positive (ER+)/human epidermal growth factor 2 negative (HER2-) breast cancer with an
estrogen receptor 1 (ESR1) mutation.
The main question the study aims to answer is:
• To compare the efficacy of the combination of lasofoxifene and abemaciclib with that of
fulvestrant and abemaciclib Participants will receive either receive 5 mg/d of oral
lasofoxifene plus oral abemaciclib 150 mg twice a day or the combination of fulvestrant 500
mg intramuscular (IM) on Days 1, 15, and 29 and then once monthly thereafter plus oral
abemaciclib 150 mg twice a day.
Inclusion Criteria:
1. Pre- or postmenopausal women or men.
2. Locally advanced and/or metastatic ER+ breast cancer with radiological or clinical
evidence of progression on an AI in combination with either palbociclib or ribociclib
as their first hormonal treatment for metastatic disease.
3. Histological or cytological confirmation of ER+/HER2 - disease
4. No evidence of progression for at least 6 months on an AI/CDKi combination for
advanced breast cancer.
5. At least 1 or more ESR1 point mutations in the ESR1 ligand binding domain as assessed
in cell- free ctDNA obtained from a blood or breast cancer tissue.
6. Locally advanced or metastatic breast cancer with either measurable (according to
RECIST 1.1) or non-measurable lesions.
7. Subjects may have received 1 cytotoxic chemotherapy regimen in the metastatic disease
setting prior to study entry, but must have recovered from chemotherapy acute toxicity
excluding alopecia and Grade 2 peripheral neuropathy.
8. Eastern Cooperative Oncology Group (ECOG) performance score of 0 or 1
9. Adequate organ function
10. Able to swallow tablets
11. Brain metastases are allowed only if the following 4 parameters hold:
1. Asymptomatic,
2. Definitively treated (e.g., radiotherapy, surgery),
3. Not requiring steroids up to 4 weeks before study treatment initiation, AND
4. Central nervous system disease stable for >3 months prior to registration as
documented by magnetic resonance imagining (MRI).
12. Able to understand and voluntarily sign a written informed consent before any
screening procedures.
Exclusion Criteria:
1. Lymphangitic carcinomatosis involving the lung.
2. History of Grade 3 or Grade 4 interstitial lung disease (ILD) on previous therapy.
3. Visceral crisis in need of cytotoxic chemotherapy as assessed by the investigator.
4. Prior progression of disease on abemaciclib, fulvestrant, or other selective estrogen
receptor degrader (SERD) therapy.
5. Subjects with a known hypersensitivity to fulvestrant or to any of the excipients
6. Radiotherapy within 30 days prior to Visit 0 (Day 1) except in case of localized
radiotherapy for analgesic purposes or for lytic lesions at risk of fracture, which
can then be completed within 7 days prior to Visit 0 (Day 1). Subjects must have
recovered from radiotherapy toxicities prior to Visit 0 (Day 1).
7. Known RB1 mutations or deletions that in the opinion of the investigator confer
resistance to CDK4/6i. (Screening for RB1 mutation is not required for entry.)
8. History of long QTc (Q-T interval corrected for heart rate) syndrome or a QTc of >480
msec.
9. History of a pulmonary embolus (PE), deep vein thrombosis (DVT), or any known
thrombophilia.
10. Lasofoxifene is not recommended for use in subjects with conditions that place them at
increased risk for VTEs (such as severe congestive heart failure [CHF] or prolonged
immobilization).
11. On concomitant strong CYP3A4 inhibitors.
12. On strong and moderate CYP3A4 inducers.
13. Any significant co-morbidity that would impact the study or the subject's safety,
including subjects with significant malabsorption.
14. Active systemic bacterial or fungal infection (requiring intravenous [IV] antibiotics
or antifungals at the time of initiating study treatment).
15. Known infection with human immunodeficiency virus (HIV), hepatitis B virus (HBV), or
hepatitis C virus (HCV).
16. History of malignancy within the past 5 years (excluding breast cancer), except basal
cell or squamous cell carcinoma of the skin curatively treated by surgery.
17. Positive serum pregnancy test (only if premenopausal).
18. Sexually active premenopausal women and men unwilling to use double-barrier
contraception.
19. Women who are breast feeding
20. History of non-compliance to medical regimens.
21. Unwilling or unable to comply with the protocol.
22. Current participation in any clinical research trial involving an investigational drug
or device within the last 30 days.
Primary outcome:
1. Progression free survival (PFS) (Time Frame - Within approximately 3 years):
PFS is defined as the time from the date of randomization [Visit 0 (Day 1)] to the earliest date of first documented progression per RECIST 1.1 or death due to any cause.
Secondary outcome:
1. Objective response rate (ORR) (Time Frame - Within approximately 3 years):
ORR is defined as the percentage of subjects with measurable disease at baseline whose best overall response is either a confirmed CR or a confirmed PR according to RECIST 1.1.
2. Overall survival (OS) (Time Frame - Within approximately 3 years):
Overall survival is defined as time from the date of Visit 0 (Day 1) to death due to any cause.
3. Clinical benefit rate (CBR) (Time Frame - Within approximately 3 years):
CBR is defined as the percentage of subjects with best overall response of confirmed CR, confirmed PR, or stable disease (SD) with a duration of 24 weeks or longer according to RECIST 1.1. As used in this calculation, stable disease is defined as stable disease in those subjects with measurable disease plus nonPR/non progressive disease (PD) in subjects with non-measurable disease.
4. Duration of response (DoR) in subjects with an objective response (Time Frame - Within approximately 3 years):
DoR is from the date of first documented confirmed response (CR or PR) to the date of first documented progression of disease or death due to any cause, whichever is earlier.
5. Time to response (TTR) in subjects with an objective response (Time Frame - Within approximately 3 years):
TTR is from the date of randomization to the date of first documented confirmed response (CR or PR).
6. Time to cytotoxic chemotherapy (Time Frame - Within approximately 3 years):
From the date of randomization to the date of first documented use of cytotoxic chemotherapy.
7. Quality of Life (QoL) evaluated using the Functional Assessment of Cancer Therapy-Breast Cancer-Endocrine Subscale (FACT B-ES) (Time Frame - Within approximately 3 years):
Scale ranges from 'Not at all' to 'Very much'
8. Incidence of Adverse Events (AEs) and Serious AEs (Time Frame - Within approximately 3 years):
The type, severity (graded by Common Terminology Criteria for Adverse Events [CTCAE version 5.0]), course, duration, seriousness, and relationship to study treatment will be assessed at each visit
- Experimental: Treatment
Pre- and Postmenopausal Women and Men with locally advanced or metastatic ER+/HER2- breast cancer who have disease progression on an AI in combination with either palbociclib or ribociclib as their first hormonal treatment for metastatic disease and who have an ESR1 mutation. - Active Comparator: Reference Therapy
Pre- and Postmenopausal Women and Men with locally advanced or metastatic ER+/HER2- breast cancer who have disease progression on an AI in combination with either palbociclib or ribociclib as their first hormonal treatment for metastatic disease and who have an ESR1 mutation.
- Lasofoxifene in combination with abemaciclib:
5 mg/d of oral lasofoxifene plus oral abemaciclib 150 mg twice a day - Fulvestrant in combination with abemaciclib:
Fulvestrant 500 mg intramuscular (IM) on Days 1, 15, and 29 and then once monthly thereafter plus oral abemaciclib 150 mg twice a day
Quelle: ClinicalTrials.gov
