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Elenestinib

Phase 2

Indolent Systemic Mastocytosis | Small molecule | Other |Blueprint Medicines Corporation|Last Updated: May 22, 2026

Success Probability
Approval Probability 71%
TA Base Rate26%
Adjusted LOA41%
ML RiskLOW_RISK
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Market & Valuation
rNPV $3.2B
Market Size $9.4B
Revenue Basis $1.6B
Competitors 6
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Trial Design
RandomizedDouble-BlindPLACEBO_CONTROLLEDDMCBiomarker
Total Trials1
Total Enrollment534
FDA Designations
No designations recorded
Clinical Trials (1)
NCT IDTitlePhaseStatusEnrollmentVelocityDesignStartCompletionLast UpdatedSitesCountries
NCT04910685(HARBOR) Study to Evaluate Efficacy and Safety of BLU-263 Versus Placebo in Patients With Indolent Systemic MastocytosisPHASE2 RECRUITING 534Nov 30, 2021Sep 30, 2032May 22, 202668 United States, Argentina +17
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Study Endpoints
Primary Endpoints
Part 1: Number of participants with Treatment-emergent Adverse Events (TEAEs)
Up to 12 weeks
Part 1: Mean change from baseline in ISM-Symptom in Assessment Form (ISM-SAF) Total Symptom Score (TSS)
Baseline, Week 13
Part 2: Mean change from baseline in ISM-SAF TSS
Baseline, Week 49
Part 3: Number of participants with Adverse Events (AEs)
Up to 5 years
Part 3: Change from baseline in ISM-SAF TSS
Baseline up to 5 years
Secondary Endpoints
Part 1: Change from baseline in serum tryptase
Baseline, Week 13
Part 1: Change from baseline in KIT D816V allele fraction in blood
Baseline, Week 13
Part 1: Change from baseline in Bone Marrow (BM) mast cells
Baseline, Week 13
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Study Design & Arms
AllocationRANDOMIZED
MaskingQUADRUPLE
ModelPARALLEL
PurposeTREATMENT
Treatment Arms
ArmTypeDescription
(Part 1) Elenestinib Dose 1 + SDTEXPERIMENTALParticipants will receive SDT and elenestinib. SDT will be determined on a per participant basis. Elenestinib will be administered orally, once daily until completion of Part 1.
(Part 1) Elenestinib Dose 2 + SDTEXPERIMENTALParticipants will receive SDT and elenestinib. SDT will be determined on a per participant basis. Elenestinib will be administered orally, once daily until completion of Part 1.
(Part 1) Elenestinib Dose 3 + SDTEXPERIMENTALParticipants will receive SDT and elenestinib. SDT will be determined on a per participant basis. Elenestinib will be administered orally, once daily until completion of Part 1.
(Part 1) Placebo + SDTPLACEBO_COMPARATORParticipants will receive SDT and matching placebo. SDT will be determined on a per participant basis. Placebo will be administered orally, once daily until completion of Part 1.
(Part 2) Elenestinib Dose 1 + SDTEXPERIMENTALParticipants will receive SDT and elenestinib. SDT will be determined on a per participant basis. Elenestinib will be administered orally, once daily for approximately 48 weeks.
(Part 2) Placebo + SDTPLACEBO_COMPARATORParticipants will receive SDT and matching placebo. SDT will be determined on a per participant basis. Placebo will be administered orally, once daily for approximately 48 weeks.
(Part 3) Elenestinib + SDTEXPERIMENTALParticipants will receive SDT and elenestinib. SDT will be determined on a per participant basis. Elenestinib will be administered orally, once daily for up to approximately 5 years.
(Part S) Elenestinib Dose 1 + SDTEXPERIMENTALParticipants will receive SDT and elenestinib. SDT will be determined on a per participant basis. Elenestinib will be administered orally, once daily for up to approximately 5 years.
(Part K) Elenestinib Dose 1 + SDTEXPERIMENTALParticipants will receive SDT and elenestinib. SDT will be determined on a per participant basis. Elenestinib will be administered orally, once daily for up to approximately 5 years.
(PK groups) Elenestinib + SDTEXPERIMENTALParticipants will receive SDT and elenestinib. SDT will be determined on a per participant basis. Elenestinib will be administered orally, once daily for up to approximately 5 years.
Interventions
NameTypeDescription
ElenestinibDRUGElenestinib oral tablet
PlaceboDRUGPlacebo oral tablet
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Eligibility Criteria
Age Range18 Years — N/A
SexALL
Healthy VolunteersNo
Study Sites68

Key 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 adequ...

Countries:United StatesArgentinaAustraliaAustriaBelgiumCzechiaFranceGermanyGreeceItalyNetherlandsNorwayPolandPortugalSpainSwedenSwitzerlandTurkey (Türkiye)United Kingdom
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Recent Changes (Last 90 Days)
LOWMay 26, 2026NCT04910685primaryCompletionDate: changed
LOWMay 24, 2026NCT04910685studyFirstPostDate: changed