Study of TL-895 in Subjects With Myelofibrosis or Indolent Systemic Mastocytosis

Cohorts 1-3

Key Inclusion Criteria:

Adults ≥18 years of age
Confirmed diagnosis of PMF, post-PV MF, or post-ET MF, as assessed by treating physician according to the World Health Organization (WHO) criteria
Eastern Cooperative Oncology Group (ECOG) performance status of ≤2
Adequate hematologic, hepatic, and renal functions
MF symptoms as defined by having at least 2 symptoms with an average baseline (Day -7 to Day -1) score of at least 1 for each of the 2 symptoms per MFSAF v4.0
Cohort 3 only: Ineligibility for JAKi treatment with a platelet count of ≥ 25 and < 50 x 10^9/L

Key Exclusion Criteria:

Prior treatment with any BTK or BMX inhibitors
Prior treatment with JAKi within 28 days prior to study treatment
Prior splenectomy or splenic irradiation within 24 weeks prior to first dose of study treatment

Cohort 5

Key Inclusion Criteria:

Adults ≥18 years of age
Confirmed diagnosis of ISM as defined by WHO diagnostic criteria based on review of bone marrow biopsy pathology report results
Subject must have moderate-to-severe symptoms

Key Exclusion Criteria:

Prior treatment with any BTK or BMX inhibitors
Prior treatment with Avapritinib, bezuclastinib, or BLU-263/elenestinib
Diagnosis with another myeloproliferative disorder