Study of TL-895 Combined With Ruxolitinib in JAKi Treatment-Naïve MF Subjects and Subjects With MF Who Have a Suboptimal Response to Ruxolitinib

Inclusion Criteria: Subjects with suboptimal response to ruxolitinib: * Treatment with at a stable dose of ruxolitinib prior to study entry * Subjects ≥ 18 years of age and able to provide informed consent. * Confirmed diagnosis of PMF, post-PV MF, or post-ET MF, as assessed by treating physician according to the World Health Organization (WHO) criteria * High-risk, intermediate-2 risk, or intermediate-1 risk, defined by Dynamic International Prognostic System (DIPSS) * Palpable spleen measuring ≥ 5 cm below the left lower coastal margin (LLCM) or spleen volume of ≥ 450 cm3 by MRI or CT scan assessment * Eastern Cooperative Oncology Group (ECOG) performance status of 0 to 2 * Adequate hematological, hepatic, \& renal function. Exclusion Criteria: Treatment-naive subjects: * Prior treatment with any JAKi Subjects with suboptimal response to ruxolitinib: * Documented disease progression while on ruxolitinib treatment All subjects: * Prior splenectomy or splenic irradiation within 24 weeks prior to first dose of study treatment * Prior treatment with a BTK or BMX inhibitor