PhaseII TL-895 Myelofibrosis JAKi IntolerantMyelofibrosis JAKi TxIneligibleMyelofibrosis orISM

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