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NCT04910685Recruiting

(HARBOR) Study to Evaluate Efficacy and Safety of BLU-263 Versus Placebo in Patients With Indolent Systemic Mastocytosis

Official recordSimplified version

Summary

This is a randomized, double-blind, placebo-controlled, Phase 2/3 study comparing the efficacy and safety of elenestinib (BLU-263) + symptom directed therapy (SDT) with placebo + SDT in participants with indolent systemic mastocytosis (ISM) whose symptoms are not adequately controlled by SDT. Parts 1 and 2 will enroll participants with ISM. Participants enrolled in Part 2 will roll over onto Part 3 to receive treatment with elenestinib in an open-label fashion following completion of the earlier Part. Part K will enroll participants with ISM who have previously received an approved selective KIT inhibitor. The study also includes pharmacokinetic (PK) groups that will enroll participants with ISM.

Inclusion criteria

All Participants: -Participant must have an Eastern Cooperative Oncology Group Performance Status (ECOG PS) of 0 to 2. Part 1 and PK groups: • Participant has confirmed diagnosis of ISM, confirmed by Central Pathology Review • Participant must have failed to achieve adequate symptom control for 1 or more Baseline symptoms, as determined by the Investigator, with at least 2 of the following symptom-directed therapies administered: H1 blockers, H2 blockers, proton-pump inhibitors, leukotriene inhibitors, cromolyn sodium, corticosteroids, or omalizumab. • Participants must have SDT for ISM symptom management stabilized for at least 14 days prior to starting screening procedures. • For participants receiving corticosteroids, the dose must be ≤ 20 mg/day prednisone or equivalent, and the dose must be stable for ≥ 14 days. Part K: -Participant has confirmed diagnosis of ISM, confirmed by Central Pathology Review Part S: -Participant has confirmed diagnosis of SSM, confirmed by Central Pathology Review of BM biopsy and central review of B- and C-findings by WHO diagnostic criteria. Part 2: -Participant has confirmed diagnosis of ISM, confirmed by Central Pathology Review

Exclusion criteria

• Participant has been diagnosed with any of the following WHO systemic mastocytosis (SM) sub-classifications: cutaneous mastocytosis only, SM with an associated hematologic neoplasm of non-MC lineage (SM-AHN), aggressive SM, mast cell leukemia, or mast cell sarcoma. • Participant has been diagnosed with another myeloproliferative disorder. • Participant has organ damage attributable to SM. • Participant has clinically significant, uncontrolled, cardiovascular disease • Participant has a QT interval corrected using Fridericia's formula (QTcF) \> \> 470 milliseconds (msec) (for females) or \> 450 msec (for males). • Participant has a history of a primary malignancy that has been diagnosed or required therapy within 3 years. The following prior malignancies are not exclusionary: completely resected basal cell and squamous cell skin cancer, curatively treated localized prostate cancer, and completely resected carcinoma in situ of any site. • Time since any cytoreductive therapy including masitinib and midostaurin should be at least 5 half-lives or 14 days (whichever is longer), and for cladribine, interferon alpha, pegylated interferon, or antibody therapy \< 28 days or 5 half-lives of the drug (whichever is longer), before beginning the screening period. • Participant has received radiotherapy or psoralen and ultraviolet A (PUVA) therapy \< 14 days before beginning the screening period. Other protocol-defined criteria apply.

Contacts

The trial team's contact details are shown on request.

See the official trial record
Status
Recruiting
Phase
Phase 2 · Phase 3
Study type
Interventional
Countries
Switzerland, France, Germany, Italy, Austria, United States, Argentina, Australia, Belgium, Brazil, Chile, Colombia, Czechia, Denmark, Greece, Ireland, Netherlands, Norway, Poland, Portugal, Romania, Spain, Sweden, Turkey (Türkiye), United Kingdom
Sponsor
Blueprint Medicines Corporation(Industry)
Protocol no.
BLU-263-1201
Conditions
Indolent Systemic Mastocytosis, Smoldering Systemic Mastocytosis
Interventions
Drug

Treatments studied

  • Elenestinib
  • Placebo

Locations · 88

  • Basel, SwitzerlandUniversity Hospital BaselRecruiting at this site
  • Lucerne, SwitzerlandLuzerner KantonsspitalRecruiting at this site
  • Amiens, FranceCHU Amiens-PicardieRecruiting at this site
  • Caen, FranceCHU de CaenRecruiting at this site
  • Grenoble, FranceCHU GrenobleRecruiting at this site
  • Limoges, FranceCHU de LimogesRecruiting at this site
  • Nantes, FranceCHU de NantesRecruiting at this site
  • Paris, FranceHôpital de la Pitié SalpétrièreRecruiting at this site
  • Paris, FranceHôpital Necker - Départementd 'HématologieA dultesRecruiting at this site
  • Poitiers, FranceCHU de PoitiersRecruiting at this site
  • Toulouse, FranceCHU Toulouse - Hopital LarreyRecruiting at this site
  • Aachen, GermanyUniversitätsklinikum RWTH Aachen Klinik für Hämatologie, Onkologie, Hämostaseologie und StammzelltransplantationRecruiting at this site
  • Berlin, GermanyCharité - Universitätsmedizin Berlin Institute of AllergologyRecruiting at this site
  • Erlangen, GermanyUniversity Clinic ErlangenRecruiting at this site
  • Hamburg, GermanyUniversity Clinic Hamburg EppendorfRecruiting at this site
  • Lübeck, GermanyUniversitatsklinikum Schleswig-Holstein, Campus LubeckRecruiting at this site
  • Mannheim, GermanyUniversitätsmedizin Mannheim III. Medizinische Klinik Universität Heidelberg Medizinische Fakultät MannheimRecruiting at this site
  • Munich, GermanyLMU KlinikumRecruiting at this site
  • München, GermanyKlinikum rechts der Isar der Technischen Universitaet MuenchenRecruiting at this site
  • Milan, ItalyUOC EmatologiaRecruiting at this site
  • Florence, ItalySOD Ematologia (Ambulatori)- AOUC Azienda Ospedaliero Universitaria CareggiRecruiting at this site
  • Bologna, ItalyUnita Operativa di Ematologia AOU Policlinico S. Orsola-MalpighiRecruiting at this site
  • Catania, ItalyAOU Policlinico G.Rodolico - San MarcoRecruiting at this site
  • Milan, ItalyFondazione IRCCS Cà Granda Ospedale Maggiore PoliclinicoRecruiting at this site
  • Pavia, ItalyS.C. Ematologia Fondazione I.R.C.C.S. Policlinico San MatteoRecruiting at this site
  • Salerno, ItalyS.S.D. Immunologia Clinica e Allergologia Azienda Ospedaliera Universitaria San Giovanni di Dio e Ruggi d'AragonaRecruiting at this site
  • Verona, ItalyUnità Operativa di Allergologia Azienda Ospedaliera Universitaria Integrata di VeronaRecruiting at this site
  • Vicenza, ItalyAzienda Unita Locale Socia Sanitaria N8 BericaRecruiting at this site
  • Linz, AustriaKepler Universitatsklinikum, Med Campus III. Clinic of Internal Medicine 3 - Hematology and OncologyRecruiting at this site
  • Birmingham, United StatesUniversity of Alabama at BirminghamRecruiting at this site

In total, worldwide, all 88 sites listed in the registry are recruiting.

Site status per the ClinicalTrials.gov registry (last update posted: October 7, 2026).

This status may have changed and says nothing about your eligibility: before taking any step, check with your oncologist or the site.

+ 58 more locations

See also

Other versions

These results are indicative and do not replace medical advice — discuss them with your doctor.