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Elenestinib

Phase 2

Indolent Systemic Mastocytosis | Small molecule | Immunology |Blueprint Medicines Corporation|Last Updated: Aug 4, 2026

Success Probability

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Market & Valuation

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Trial Design

RandomizedDouble-BlindPLACEBO_CONTROLLEDDMC
Total Trials1
Total Enrollment534

FDA Designations

No designations recorded

Clinical trial landscape

Elenestinib · 2 trials · 3 indications

Phase 2 1Phase 1 1
NCT04910685(HARBOR) Study to Evaluate Efficacy and Safety of BLU-263 Versus Placebo in Patients With Indolent Systemic MastocytosisIndolent Systemic Mastocytosis
RECRUITING534 Analytics
PHASE2RECRUITING
(HARBOR) Study to Evaluate Efficacy and Safety of BLU-263 Versus Placebo in Patients With Indolent Systemic Mastocytosis
Indolent Systemic MastocytosisUnlock trial analytics

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
Area under the concentration-time curve, from time 0 to the last observed non-zero concentration (AUC0-t)
Up to 27 days
Area under the concentration-time curve from time 0 extrapolated to infinity (AUC0-inf)
Up to 27 days
Percent of AUC0-inf extrapolated (AUC%extrap)
Up to 27 days
Maximum observed concentration (Cmax)
Up to 27 days
Time to reach Cmax (Tmax)
Up to 27 days
Apparent first-order terminal elimination half-life (t1/2)
Up to 27 days
Apparent total plasma clearance after oral administration (CL/F)
Up to 27 days
Apparent volume of distribution during the terminal elimination phase after oral administration (Vz/F)
Up to 27 days

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.
Elenestinib, Midazolam, and Levonorgestrel/Ethinyl EstradiolEXPERIMENTAL -

Interventions

NameTypeDescription
ElenestinibDRUGElenestinib oral tablet
PlaceboDRUGPlacebo oral tablet
MidazolamDRUGSpecified dose on specified days
Levonorgestrel/Ethinyl EstradiolDRUGSpecified dose on specified days
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Eligibility Criteria

Age Range18 Years to N/A
SexALL
Healthy VolunteersNo
Study Sites75

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 StatesArgentinaAustraliaAustriaBelgiumBrazilColombiaCzechiaFranceGermanyGreeceIrelandItalyNetherlandsNorwayPolandPortugalSpainSwedenSwitzerlandTurkey (Türkiye)United Kingdom
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Recent Changes (Last 90 Days)

LOWAug 4, 2026NCT04910685lastUpdatePostDate: changed
LOWAug 4, 2026NCT04910685lastUpdatePostDate: changed
LOWJun 25, 2026NCT04910685lastUpdatePostDate: changed
LOWJun 25, 2026NCT04910685lastUpdatePostDate: changed
LOWJun 25, 2026NCT04910685lastUpdatePostDate: changed

Frequently asked questions about Elenestinib

What is Elenestinib used for?

Elenestinib is an investigational small molecule being studied for indolent systemic mastocytosis and smoldering systemic mastocytosis, as well as in healthy participants. It is being developed by Blueprint Medicines Corporation (BPMC) and is currently in Phase 1 clinical development.

What does Elenestinib target?

Elenestinib is a kinase inhibitor, as indicated by its '-tinib' suffix. It is designed to target kinases, which are enzymes involved in cellular signaling. The specific molecular target is not disclosed in the available information.

Who makes Elenestinib?

Elenestinib is being developed by Blueprint Medicines Corporation, a biopharmaceutical company traded on the stock exchange under the ticker symbol BPMC. The company is conducting clinical trials to evaluate the drug's safety and efficacy.

What phase is Elenestinib in?

Elenestinib is currently in Phase 1 clinical development. It is an investigational drug and has not been approved by regulatory authorities. Clinical trials are ongoing to assess its safety, tolerability, and potential efficacy in the studied conditions.

What clinical trials is Elenestinib in?

Elenestinib is being studied in two clinical trials. NCT04910685 is a Phase 2 study in patients with indolent or smoldering systemic mastocytosis, currently recruiting. NCT07388511 is a Phase 1 study in healthy adult female participants, which has been completed.

Is Elenestinib the same as BLU-263?

Elenestinib is also known as BLU-263. The Phase 2 trial NCT04910685, titled 'HARBOR Study to Evaluate Efficacy and Safety of BLU-263 Versus Placebo in Patients With Indolent Systemic Mastocytosis', confirms that BLU-263 is the same drug as Elenestinib.