Actively Recruiting
A Randomized, Double-Blind, Placebo-Controlled Phase 2/3 Study of BLU-263 in Indolent Systemic Mastocytosis
Led by Blueprint Medicines Corporation · Updated on 2026-05-22
534
Participants Needed
68
Research Sites
N/A
Total Duration
On this page
AI-Summary
What this Trial Is About
Researchers are studying the effects of elenestinib (BLU-263) combined with symptom directed therapy (SDT) compared to placebo plus SDT in adults with indolent systemic mastocytosis (ISM) who have symptoms not well controlled by current treatments. This randomized, double-blind, placebo-controlled Phase 2/3 trial includes participants with ISM and smoldering systemic mastocytosis (SSM), aiming to evaluate both safety and efficacy of the treatments. The study is sponsored by Blueprint Medicines Corporation and includes participants who have previously used selective KIT inhibitors as well as pharmacokinetic groups. Participants will be assigned to receive either elenestinib or placebo along with symptom directed therapies tailored individually. Elenestinib is taken orally once daily. The study is organized into multiple parts: Parts 1 and 2 involve treatment periods lasting up to approximately 48 weeks, after which participants in Part 2 may continue into Part 3 and receive open-label elenestinib for up to five years. Part K enrolls those previously treated with KIT inhibitors. Symptom directed therapy doses are stabilized before treatment and maintained throughout. During the trial, participants will be monitored regularly for side effects and symptom changes using the ISM-Symptom Assessment Form (ISM-SAF) and other measures such as serum tryptase levels, KIT D816V allele fraction, bone marrow mast cell counts, and quality of life assessments. Safety will be tracked through adverse event reporting. The study duration can extend up to five years, allowing long-term evaluation of treatment effects and symptom control. Participants will have ongoing evaluations at set intervals including baseline, weeks 13, 24, 48, and beyond as applicable.
CONDITIONS
Brief Title
(HARBOR) Study to Evaluate Efficacy and Safety of BLU-263 Versus Placebo in Patients With Indolent Systemic Mastocytosis
Who Can Participate
Eligibility Criteria
You may qualify if you...
- Participant must have an Eastern Cooperative Oncology Group Performance Status (ECOG PS) of 0 to 2.
- Participant has confirmed diagnosis of indolent systemic mastocytosis (ISM) verified by central pathology review.
- Participant has symptoms not adequately controlled by at least two symptom directed therapies.
- Participant's symptom directed therapy for ISM must be stable for at least 14 days before screening.
- For those on corticosteroids, dose must be 20 mg/day prednisone or equivalent or less, stable for at least 14 days.
- Participants in Part S must have confirmed smoldering systemic mastocytosis (SSM) diagnosis.
- Participants in Part K must have confirmed ISM diagnosis and prior selective KIT inhibitor treatment.
You will not qualify if you...
- Diagnosis of cutaneous mastocytosis only, aggressive systemic mastocytosis, mast cell leukemia, mast cell sarcoma, or systemic mastocytosis with associated hematologic neoplasm.
- Diagnosis of another myeloproliferative disorder.
- Organ damage caused by systemic mastocytosis.
- Clinically significant uncontrolled cardiovascular disease.
- QTcF greater than 470 msec for females or greater than 450 msec for males.
- History of primary malignancy diagnosed or treated within the last 3 years, except certain skin and prostate cancers.
- Recent cytoreductive therapy or antibody therapy within specified washout periods.
- Recent radiotherapy or PUVA therapy within 14 days before screening.
- Other protocol-defined exclusion criteria apply.
AI-Screening
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Your Study Journey
Duration - 2 to 4 weeks
Participants are screened for eligibility to participate in the trial.
Duration - Up to 5 years depending on study part
Participants receive Elenestinib or placebo orally once daily along with symptom directed therapy (SDT) determined individually. Treatment duration varies by study part, lasting from up to 12 weeks in Part 1, approximately 48 weeks in Part 2, and up to approximately 5 years in Part 3 and other parts.
Trial Site Locations
Total: 68 locations
1
University of Alabama at Birmingham
Birmingham, Alabama, United States, 35294
Actively Recruiting
2
David Geffen School of Medicine at UCLA
Los Angeles, California, United States, 90095
Actively Recruiting
3
Stanford Cancer Institute
Palo Alto, California, United States, 94305
Actively Recruiting
4
UCHealth Blood Disorders and Cell Therapies Center - Anschutz Medical Campus
Aurora, Colorado, United States, 80045
Actively Recruiting
5
Winship Cancer Institute, Emory University
Atlanta, Georgia, United States, 30322
Actively Recruiting
6
Brigham and Women's Hospital
Boston, Massachusetts, United States, 02115
Actively Recruiting
7
Michigan Medicine University of Michigan
Ann Arbor, Michigan, United States, 48109
Actively Recruiting
8
Mayo Clinic
Rochester, Minnesota, United States, 55902
Actively Recruiting
9
Roswell Park Cancer Institute
Buffalo, New York, United States, 14263
Actively Recruiting
10
Columbia University Medical Center
New York, New York, United States, 10032
Actively Recruiting
11
Duke Asthma, Allergy and Airway Center
Durham, North Carolina, United States, 27705
Actively Recruiting
12
University of Cincinnati Medical Center
Cincinnati, Ohio, United States, 45219
Actively Recruiting
13
The University of Texas, MD Anderson Cancer Center
Houston, Texas, United States, 77030
Actively Recruiting
14
Huntsman Cancer Institute, University of Utah
Salt Lake City, Utah, United States, 84112
Actively Recruiting
15
CHP Centro Hematologico Pavlovsky
Buenos Aires, Argentina, 1113
Actively Recruiting
16
Consultorios Medicos Dr. Doreski - Fundacion Respirar
Buenos Aires, Argentina, 1426
Actively Recruiting
17
Princess Alexandra Hospital
Woolloongabba, Queensland, Australia
Actively Recruiting
18
The Alfred Hospital
Melbourne, Victoria, Australia, 3004
Actively Recruiting
19
Kepler Universitatsklinikum, Med Campus III. Clinic of Internal Medicine 3 - Hematology and Oncology
Linz, Austria, 4021
Actively Recruiting
20
Unitversitair Ziekenhuis Antwerpen
Edegem, Antwerpen, Belgium
Actively Recruiting
21
Universitair Ziekenhuis Gent
Ghent, Belgium, 9000
Actively Recruiting
22
CHU Tivoli
La Louvière, Belgium, 7100
Actively Recruiting
23
Fakultní nemocnice Brno, Interní hematologická a onkologická klinika
Brno, Czechia, 625 00
Actively Recruiting
24
Fakultní nemocnice Královské Vinohrady, Hematologická klinika 3. LF UK v Praze a FNKV
Prague, Czechia, 100 34
Actively Recruiting
25
CHU Amiens-Picardie
Amiens, France, 80000
Actively Recruiting
26
CHU de Caen
Caen, France
Actively Recruiting
27
CHU Grenoble
Grenoble, France, 38043
Actively Recruiting
28
CHU de Limoges
Limoges, France, 87042
Actively Recruiting
29
CHU de Nantes
Nantes, France, 44093
Actively Recruiting
30
Hôpital de la Pitié Salpétrière
Paris, France, 75013
Actively Recruiting
31
Hôpital Necker - Départementd 'HématologieA dultes
Paris, France, 75015
Actively Recruiting
32
CHU de Poitiers
Poitiers, France, 86000
Actively Recruiting
33
CHU Toulouse - Hopital Larrey
Toulouse, France
Actively Recruiting
34
Universitätsklinikum RWTH Aachen Klinik für Hämatologie, Onkologie, Hämostaseologie und Stammzelltransplantation
Aachen, Germany
Actively Recruiting
35
Charité - Universitätsmedizin Berlin Institute of Allergology
Berlin, Germany, 12203
Actively Recruiting
36
University Clinic Erlangen
Erlangen, Germany, 91054
Actively Recruiting
37
University Clinic Hamburg Eppendorf
Hamburg, Germany, 20246
Actively Recruiting
38
Universitätsmedizin Mannheim III. Medizinische Klinik Universität Heidelberg Medizinische Fakultät Mannheim
Mannheim, Germany, 68167
Actively Recruiting
39
LMU Klinikum
Munich, Germany, 80377
Actively Recruiting
40
University General Hospital - General Hospital of West Attica
Chaïdári, Greece, 12462
Actively Recruiting
41
General Hospital of Thessaloniki "G. Papanikolaou"
Thessaloniki, Greece, 57010
Actively Recruiting
42
UOC Ematologia
Milan, Lombardy, Italy, 20122
Actively Recruiting
43
SOD Ematologia (Ambulatori)- AOUC Azienda Ospedaliero Universitaria Careggi
Florence, Tuscany, Italy, 50134
Actively Recruiting
44
Unita Operativa di Ematologia AOU Policlinico S. Orsola-Malpighi
Bologna, Italy, 40138
Actively Recruiting
45
AOU Policlinico G.Rodolico - San Marco
Catania, Italy, 95123
Actively Recruiting
46
S.C. Ematologia Fondazione I.R.C.C.S. Policlinico San Matteo
Pavia, Italy, 27100
Actively Recruiting
47
S.S.D. Immunologia Clinica e Allergologia Azienda Ospedaliera Universitaria San Giovanni di Dio e Ruggi d'Aragona
Salerno, Italy, 84131
Actively Recruiting
48
Unità Operativa di Allergologia Azienda Ospedaliera Universitaria Integrata di Verona
Verona, Italy, 37126
Actively Recruiting
49
ErasmusMC
Rotterdam, South Holland, Netherlands, 3015 GD
Actively Recruiting
50
University Medical Center Groningen
Groningen, Netherlands, 9713 GZ
Actively Recruiting
51
Oslo University Hospital
Oslo, Norway, N-0424
Actively Recruiting
52
Uniwersyteckie Centrum Kliniczne Klinika Alergologii
Gdansk, Poland, 80-214
Actively Recruiting
53
Centro Hospitalar de Lisboa Central, E.P.E. - Hospital de Santo Antonio dos Capuchos
Lisbon, Portugal, 1169-050
Actively Recruiting
54
CHUPorto, EPE - Hospital de Santo António
Porto, Portugal, 4099-001
Actively Recruiting
55
Centro Hospitalar Universitario Sao Joao, E.P.E.
Porto, Portugal, 4200-139
Actively Recruiting
56
Hospital Universitario Vall d'Hebron
Barcelona, Spain
Actively Recruiting
57
Hospital Universitario Ramon y Cajal
Madrid, Spain, 28034
Actively Recruiting
58
Hospital Virgen del Valle - Instituto de Estudios de Mastocitosis de Castilla-La Mancha
Toledo, Spain, 45071
Actively Recruiting
59
Uppsala University Hospital
Uppsala, Sweden, 751 85
Actively Recruiting
60
University Hospital Basel
Basel, Switzerland, C-4031
Actively Recruiting
61
Luzerner Kantonsspital
Lucerne, Switzerland, 6000
Actively Recruiting
62
lstanbul Universitesi lstanbul Tip Fakultesi Hastanesi
Istanbul, Turkey (Türkiye), 34093
Actively Recruiting
63
University Hospital of Wales
Cardiff, Wales, United Kingdom, CF14 4XW
Actively Recruiting
64
University Hospital of Wales
Cardiff, United Kingdom, CF14 4XW
Actively Recruiting
65
University College London Hospitals (UCLH), Haematology Cancer Clinical Trials Unit
London, United Kingdom, NW1 2PG
Actively Recruiting
66
Guy's and St Thomas's NHS Foundation Trust
London, United Kingdom, SE1 7EH
Actively Recruiting
67
Cancer and Haematology Centre
Oxford, United Kingdom, OX3 7LE
Actively Recruiting
68
University Hospital Plymouth NHS Trust
Plymouth, United Kingdom, PL6 8DH
Actively Recruiting
Research Team
B
Blueprint Medicines
How is the study designed?
Study Type
INTERVENTIONAL
Masking
QUADRUPLE
Allocation
RANDOMIZED
Model
PARALLEL
Primary Purpose
TREATMENT
Number of Arms
10
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