Actively Recruiting
A Phase 3 Study of Palazestrant With Ribociclib Versus Letrozole With Ribociclib for First-Line Treatment of ER+, HER2- Advanced Breast Cancer
Led by Olema Pharmaceuticals, Inc. · Updated on 2026-05-15
1000
Participants Needed
124
Research Sites
160 weeks
Total Duration
On this page
Sponsors
O
Olema Pharmaceuticals, Inc.
Lead Sponsor
N
Novartis Pharmaceuticals
Collaborating Sponsor
AI-Summary
What this Trial Is About
Researchers are evaluating palazestrant combined with ribociclib compared to letrozole combined with ribociclib in adults with ER-positive, HER2-negative advanced breast cancer who have not received prior systemic anti-cancer treatment for their advanced disease. This international, phase 3 trial aims to assess the efficacy and safety of these drug combinations as first-line treatments for this type of breast cancer. The study includes both women and men and is sponsored by Olema Pharmaceuticals, Inc. Participants are randomly assigned in a double-blind manner to one of two groups: one receives palazestrant 90 mg once daily plus ribociclib 600 mg daily for 21 days in a 28-day cycle with a placebo matching letrozole, while the other receives letrozole 2.5 mg once daily plus ribociclib 600 mg daily for 21 days with a placebo matching palazestrant. Treatment cycles repeat every 28 days, continuing as per study protocol. During the trial, participants will be monitored with assessments including progression-free survival, overall survival, tumor response rates, duration of response, and clinical benefit rate, with evaluations lasting up to 3.5 years. Safety, drug levels, and patient-reported health outcomes will also be regularly collected every 28 days. The study involves approximately 1,000 participants and includes ongoing safety monitoring up to 42 days after treatment ends, with follow-up for survival and response outcomes extending up to 5.5 years.
CONDITIONS
Brief Title
Palazestrant in Combination With Ribociclib for the First-line Treatment of ER+/HER2- Advanced Breast Cancer
Who Can Participate
Eligibility Criteria
You may qualify if you...
- Adult female or male participants
- Diagnosed with ER-positive, HER2-negative locally advanced or metastatic breast cancer not suitable for curative therapy
- Have measurable disease or bone-only disease
- De novo advanced breast cancer or disease recurrence after 12 months of completing adjuvant endocrine therapy
- Eastern Cooperative Oncology Group (ECOG) performance status of 0 or 1
- Adequate blood, liver, and kidney function
- Female participants can be pre-, peri-, or postmenopausal
- Male and pre- or peri-menopausal female participants must be willing to take a GnRH or LHRH agonist
You will not qualify if you...
- Disease recurrence during adjuvant endocrine therapy
- Currently receiving or previously received systemic anti-cancer therapy for ER-positive, HER2-negative advanced breast cancer
- Prior treatment with fulvestrant, elacestrant, or investigational endocrine therapy
- History of allergic reactions to study treatments
- Contraindications to letrozole or ribociclib
- Symptomatic central nervous system metastases, carcinomatous meningitis, leptomeningeal disease, or spinal cord compression requiring immediate treatment
AI-Screening
AI-Powered Screening
Complete this quick 3-step screening to check your eligibility
Your Study Journey
Duration - 2 to 4 weeks
Participants are screened for eligibility to participate in the trial.
1 visit (in-person)
Duration - Repeated 28-day cycles until disease progression or discontinuation
Participants receive palazestrant or letrozole in combination with ribociclib as first-line treatment for ER+, HER2- advanced breast cancer.
Visits every 28 days corresponding with treatment cycles
Duration - Up to 42 days after end of treatment
Participants are monitored for safety, overall survival, and other long-term outcomes after treatment ends.
Approximately 1 visit after treatment completion
Trial Site Locations
Total: 124 locations
1
Clinical Trial Site
Hot Springs, Arkansas, United States, 71913
Active, Not Recruiting
2
Clinical Trial Site
Beverly Hills, California, United States, 90211
Active, Not Recruiting
3
Clinical Trial Site
Santa Barbara, California, United States, 93105
Active, Not Recruiting
4
Clinical Trial Site
Aurora, Colorado, United States, 80045
Active, Not Recruiting
5
Clinical Trial Site
Denver, Colorado, United States, 80220
Actively Recruiting
6
Clinical Trial Site
Honolulu, Hawaii, United States, 96813
Active, Not Recruiting
7
Clinical Trial Site
Peoria, Illinois, United States, 61615
Actively Recruiting
8
Clinical Trial Site
Ames, Iowa, United States, 50010
Active, Not Recruiting
9
Clinical Trial Site
Scarborough, Maine, United States, 04074
Actively Recruiting
10
Clinical Trial Site
Annapolis, Maryland, United States, 21401
Active, Not Recruiting
11
Clinical Trial Site
Minneapolis, Minnesota, United States, 55404
Actively Recruiting
12
Clinical Trial Site
Kansas City, Missouri, United States, 64132
Actively Recruiting
13
Clinical Trial Site
Santa Fe, New Mexico, United States, 87505
Actively Recruiting
14
Clinical Trial Site
Cincinnati, Ohio, United States, 45245
Active, Not Recruiting
15
Clinical Trial Site
Columbus, Ohio, United States, 43219
Actively Recruiting
16
Clinical Trial Site
Horsham, Pennsylvania, United States, 19044
Active, Not Recruiting
17
Clinical Trial Site
Sayre, Pennsylvania, United States, 18840
Actively Recruiting
18
Clinical Trial Site
Knoxville, Tennessee, United States, 37909
Active, Not Recruiting
19
Clinical Trial Site
Tennessee City, Tennessee, United States, 37203
Actively Recruiting
20
Clinical Trial Site
Denton, Texas, United States, 76201
Actively Recruiting
21
Clinical Trial Site
El Paso, Texas, United States, 79902
Actively Recruiting
22
Clinical Trial Site
Houston, Texas, United States, 77024
Actively Recruiting
23
Clinical Trial Site
San Antonio, Texas, United States, 78229
Active, Not Recruiting
24
Clinical Trial Site
Salt Lake City, Utah, United States, 84106
Not Yet Recruiting
25
Clinical Trial Site
Fort Belvoir, Virginia, United States, 22060
Active, Not Recruiting
26
Clinical Trial Site
Norfolk, Virginia, United States, 23502
Active, Not Recruiting
27
Clinical Trial Site
Olympia, Washington, United States, 98502
Active, Not Recruiting
28
Clinical Trial Site
Vancouver, Washington, United States, 98684
Active, Not Recruiting
29
Clinical Trial Site
Sydney, New South Wales, Australia, 2109
Actively Recruiting
30
Clinical Trial Site
Waratah, New South Wales, Australia, 2298
Actively Recruiting
31
Clinical Trial Site
South Brisbane, Queensland, Australia, 4101
Actively Recruiting
32
Clinical Trial Site
Adelaide, South Australia, Australia, 5000
Actively Recruiting
33
Clinical Trial Site
Clayton, Victoria, Australia, 3168
Actively Recruiting
34
Clinical Trial Site
Geelong, Victoria, Australia, 3220
Actively Recruiting
35
Clinical Trial Site
Heidelberg, Victoria, Australia, 03084
Actively Recruiting
36
Clinical Trial Site
Nedlands, Western Australia, Australia, 6009
Actively Recruiting
37
Clinical Trial Site
Linz, Upper Austria, Austria, 4010
Active, Not Recruiting
38
Clinical Trial Site
Kortrijk, Flanders, Belgium, 8500
Active, Not Recruiting
39
Clinical Trial Site
Charleroi, Wallonia, Belgium, 6060
Active, Not Recruiting
40
Clinical Trial Site
Toronto, Ontario, Canada, M2J 1V1
Actively Recruiting
41
Clinical Trial Site
Prague, Prague, Czechia, 150 06
Active, Not Recruiting
42
Clinical Trial Site
Zlín, Zlín, Czechia, 762 75
Actively Recruiting
43
Clinical Trial Site
Pierre-Bénite, Auvergne-Rhône-Alpes, France, 69310
Active, Not Recruiting
44
Clinical Trial Site
Brest, Brittany Region, France, 29609
Active, Not Recruiting
45
Clinical Trial Site
Besançon, Doubs, France, 25000
Active, Not Recruiting
46
Clinical Trial Site
Montpellier, Hérault, France, 34070
Active, Not Recruiting
47
Clinical Trial Site
Toulouse, Occitanie, France, 31059
Active, Not Recruiting
48
Clinical Trial Site
Bobigny, France, 93000
Actively Recruiting
49
Clinical Trial Site
Torgau, Saxony, Germany, 04860
Active, Not Recruiting
50
Clinical Trial Site
Athens, Pireas, Greece, 18547
Active, Not Recruiting
51
Clinical Trial Site
Thessaloniki, Thessaloniki, Greece, 57001
Actively Recruiting
52
Clinical Trial Site
Hong Kong, Hong Kong, Hong Kong, 999077
Active, Not Recruiting
53
Clinical Trial Site
Hong Kong, Kowloon, Hong Kong, 999077
Actively Recruiting
54
Clinical Trial Site
Hong Kong, Pok Fu Lam, Hong Kong, 999077
Actively Recruiting
55
Clinical Trial Site
Kecskemét, Bács-Kiskun county, Hungary, 6000
Active, Not Recruiting
56
Clinical Trial Site
Debrecen, Hajdú-Bihar, Hungary, 4032
Actively Recruiting
57
Clinical Trial Site
Bologna, Emilia-Romagna, Italy, 40138
Active, Not Recruiting
58
Clinical Trial Site
Genoa, Liguria, Italy, 16132
Actively Recruiting
59
Clinical Trial Site
Milan, Milano, Italy, 20132
Active, Not Recruiting
60
Clinical Trial Site
Prato, Tuscany, Italy, 59100
Active, Not Recruiting
61
Clinical Trial Site
Milan, Varese, Italy, 21100
Actively Recruiting
62
Clinical Trial Site
Ipoh, Ipoh Perak, Malaysia, 30450
Actively Recruiting
63
Clinical Trial Site
Kuala Lumpur, Kuala Lumpur, Malaysia, 50586
Actively Recruiting
64
Clinical Trial Site
Kuala Lumpur, Kuala Lumpur, Malaysia, 59100
Actively Recruiting
65
Clinical Trial Site
George Town, Pulau Pinang, Malaysia, 10450
Actively Recruiting
66
Clinical Trial Site
Kota Kinabalu, Sabah, Malaysia, 88996
Actively Recruiting
67
Clinical Trial Site
Kuching, Sarawak, Malaysia, 93586
Actively Recruiting
68
Clinical Trial Site
Petaling Jaya, Selangor, Malaysia, 46050
Actively Recruiting
69
Clinical Trial Site
Putrajaya, Wilayah PE, Malaysia, 62250
Actively Recruiting
70
Clinical Trial Site
Apeldoorn, Gelderland, Netherlands, 7334 DZ
Actively Recruiting
71
Clinical Trial Site
Amsterdam, North Holland, Netherlands, 1081 HV
Active, Not Recruiting
72
Clinical Trial Site
Rzeszów, Podkarpackie Voivodeship, Poland, 35-055
Active, Not Recruiting
73
Clinical Trial Site
Rzeszów, Podkarpackie Voivodeship, Poland, 35-922
Active, Not Recruiting
74
Clinical Trial Site
Brzozów, Woj Podkarpackie, Poland, 36-200
Active, Not Recruiting
75
Clinical Trial Site
Lodz, Łódź Voivodeship, Poland, 90-302
Actively Recruiting
76
Clinical Trial Site
Porto, Porto District, Portugal, 4464-513
Active, Not Recruiting
77
Clinical Trial Site
Bucharest, Bucharest, Romania, 11171
Active, Not Recruiting
78
Clinical Trial Site
Cluj-Napoca, Cluj, Romania, 400641
Actively Recruiting
79
Clinical Trial Site
Ovidiu, Constanța County, Romania, 905900
Active, Not Recruiting
80
Clinical Trial Site
Craiova, Dolj, Romania, 200542
Actively Recruiting
81
Clinical Trial Site
Iași, Iaşi, Romania, 700106
Actively Recruiting
82
Clinical Trial Site
Timișoara, Timiș County, Romania, 300239
Active, Not Recruiting
83
Clinical Trial Site
Busan, Busan Metropolitan City, South Korea, 49201
Active, Not Recruiting
84
Clinical Trial Site
Daegu, Daegu Metropolitan City, South Korea, 41404
Actively Recruiting
85
Clinical Trial Site
Goyang-si, Gyeonggi-do, South Korea, 10408
Actively Recruiting
86
Clinical Trial Site
Seongnam-si, Gyeonggi-do, South Korea, 13620
Actively Recruiting
87
Clinical Trial Site
Suwon, Gyeonggi-do, South Korea, 16247
Actively Recruiting
88
Clinical Trial Site
Yongin-si, Gyeonggi-do, South Korea, 16499
Active, Not Recruiting
89
Clinical Trial Site
Seoul, Seoul, South Korea, 02841
Active, Not Recruiting
90
Clinical Trial Site 1
Seoul, Seoul, South Korea, 03080
Actively Recruiting
91
Clinical Trial Site 2
Seoul, Seoul, South Korea, 03080
Actively Recruiting
92
Clinical Trial Site
Seoul, Seoul, South Korea, 03722
Actively Recruiting
93
Clinical Trial Site
Seoul, Seoul Special City, South Korea, 05505
Actively Recruiting
94
Clinical Trial Site
Seoul, Seoul Special City, South Korea, 08308
Active, Not Recruiting
95
Clinical Trial Site
Alicante, Alicante, Spain, 3010
Active, Not Recruiting
96
Clinical Trial Site
Barcelona, Barcelona, Spain, 08028
Actively Recruiting
97
Clinical Trial Site
Barcelona, Barcelona, Spain, 08035
Active, Not Recruiting
98
Clinical Trial Site
Barcelona, Barcelona, Spain, 08036
Actively Recruiting
99
Clinical Trial Site
Granada, Granada, Spain, 18012
Actively Recruiting
100
Clinical Trial Site
Lleida, Lleida, Spain, 25198
Active, Not Recruiting
101
Clinical Trial Site
Madrid, Madrid, Spain, 28007
Active, Not Recruiting
102
Clinical Trial Site
Madrid, Madrid, Spain, 28040
Actively Recruiting
103
Clinical Trial Site
Madrid, Madrid, Spain, 28046
Active, Not Recruiting
104
Clinical Trial Site
Madrid, Madrid, Spain, 28050
Actively Recruiting
105
Clinical Trial Site
Murcia, Murcia, Spain, 30120
Actively Recruiting
106
Clinical Trial Site
Seville, Sevilla, Spain, 41009
Active, Not Recruiting
107
Clinical Trial Site
Valencia, Valencia, Spain, 46010
Active, Not Recruiting
108
Clinical Trial Site
Zaragoza, Zaragoza, Spain, 50009
Active, Not Recruiting
109
Clinical Trial Site
Chang-hua, Chang Hua, Taiwan, 50006
Active, Not Recruiting
110
Clinical Trial Site
Kaohsiung City, Sanmin, Taiwan, 80756
Actively Recruiting
111
Clinical Trial Site
Taipei, Special Municipality, Taiwan, 11217
Actively Recruiting
112
Clinical Trial Site
Taipei, Special Municipality, Taiwan, 11490
Actively Recruiting
113
Clinical Trial Site
Taipei, Taipei City, Taiwan, 100
Actively Recruiting
114
Clinical Trial Site
Taipei, Taipei City, Taiwan, 10449
Actively Recruiting
115
Clinical Trial Site
Bangkok, Bangkok, Thailand, 10700
Actively Recruiting
116
Clinical Trial Site
Dusit, Bangkok, Thailand, 10300
Actively Recruiting
117
Clinical Trial Site
Ban Phaeo, Changwat Samut Sakhon, Thailand, 74120
Actively Recruiting
118
Clinical Trial Site
Hat Yai, Changwat Songkhla, Thailand, 90110
Actively Recruiting
119
Clinical Trial Site
Chiang Mai, Chiang Mai, Thailand, 50200
Actively Recruiting
120
Clinical Trial Site
Brighton, England, United Kingdom, BN2 5BE
Actively Recruiting
121
Clinical Trial Site
London, England, United Kingdom, WC1E 6AG
Active, Not Recruiting
122
Clinical Trial Site
London, Greater London, United Kingdom, EC1M 6BQ
Active, Not Recruiting
123
Clinical Trial Site
Taunton, Somerset, United Kingdom, TA1 5DA
Actively Recruiting
124
Clinical Trial Site
Guildford, Surrey, United Kingdom, GU2 7XX
Actively Recruiting
Research Team
O
Olema Pharmaceuticals, Inc.
How is the study designed?
Study Type
INTERVENTIONAL
Masking
TRIPLE
Allocation
RANDOMIZED
Model
PARALLEL
Primary Purpose
TREATMENT
Number of Arms
2
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