Clinical Trials

Key Inclusion Criteria:

• Diagnosed with 1 of the following diagnoses according to the 2022 WHO classification for systemic mastocytosis (SM):
  • ISM;
  • BMM;
  • SSM.
  • NOTE: An archival biopsy may be used for diagnosis, provided that the biopsy was collected within 6 months of Screening and at least 14 days after receiving any prior disease-modifying therapy for SM. The Screening or archival biopsy must support the diagnosis of NonAdvSM and will be sent to the central laboratory for prospective review of diagnosis in Part 2.
• Inadequate control of SM symptoms defined as MAS total score of ≥ 6 after a stable regimen of ≥ 2 antimediator therapies is established (ie, no modifications for 14 days).
  • NOTE: For Part 2, subjects who screen fail due to MAS total score < 26 cannot be rescreened. Acceptable antimediator therapies for BSC:
  • − Histamine receptor type 1 (H1) antagonist
  • − Histamine receptor type 2 (H2) antagonist
  • − Cromolyn sodium
  • − Leukotriene receptor antagonist
  • − Corticosteroids (≤10 mg/day prednisone or equivalent)
  • − Omalizumab
  • − Ketotifen
  • − Proton pump inhibitor.
• Able to provide written informed consent 4.
• Able and willing to commit to study assessments and visit schedule.
• ≥ 18 years of age.
• Eastern Cooperative Oncology Group (ECOG) Performance Status 0 to 2.
• For patients receiving corticosteroids, the dose must be ≤ 10 mg/day of prednisone or
• equivalent.

Key Exclusion Criteria:

• Diagnosed with any of the following WHO SM classifications: bone marrow mastocytosis, advanced systemic  mastocytosis including SM with associated hematologic neoplasm, aggressive SM, mast cell leukemia; or mast cell sarcoma.
• Diagnosed with mastocytosis of the skin without systemic involvement.
• Received prior treatment with any targeted KIT inhibitor.
• Received prior cytoreductive therapy or investigational agent for < 14 days or 5 half-lives of the drug and for cladribine, interferon alpha, pegylated interferon, or antibody therapy < 28 days or 5 half-lives of the drug (whichever is longer), before starting screening assessments.
• Received radiotherapy or psoralen and ultraviolet A therapy <14 days before starting screening assessments
• Received any hematopoietic growth factor support  < 14 days before starting screening assessments.
• Clinically significant cardiac disease, defined by any of the following:
  • Clinically significant cardiac arrhythmias, and/or the need for anti-arrhythmic therapy (excluding beta blockers or digoxin). (Subjects with controlled atrial fibrillation are not excluded);
  • Congenital long QT syndrome or concomitant medications known to prolong the QT interval as defined in Appendix F;
  • A marked baseline prolongation of QT/QTc interval (e.g., repeated demonstration of a QTc interval > 480 ms using Fridericia’s QT correction formula);
  • History of clinically significant cardiac disease or congestive heart failure > New York Heart Association Class II. Subjects must not have unstable angina (anginal symptoms at rest) or new-onset angina within the last 3 months or myocardial infarction within the past 6 months prior to enrollment;
  • Arterial or venous thrombotic or embolic events such as cerebrovascular accident (including transient ischemic attacks), deep vein thrombosis, or pulmonary embolism within the 6 months before study drug initiation (except for adequately treated catheter-related venous thrombosis occurring more than 1 month before the first dose of study drug).
• History of clinically significant bleeding event within 30 days before the first dose of study drug or need for therapeutic anticoagulation on study.
• Need for treatment of corticosteroids at > 10 mg/day of prednisone or equivalent.

Eligibility last updated 1/16/24. Questions regarding updates should be directed to the study team contact.