A Study to Assess the Safety and Tolerability of BMS-986158 Alone and in Combination With Either Ruxolitinib or Fedratinib in Participants With Blood Cancer (Myelofibrosis)

The purpose of this study is to assess the safety, tolerability, and efficacy of BMS-986158 alone and in combination with either Ruxolitinib or Fedratinib in participants with Dynamic International Prognostic Scoring System (DIPSS)-intermediate or high risk blood cancer. Part 1 consists of BMS-986158 in combination with either Ruxolitinib or Fedratinib and Part 2 consists of BMS-986158 in combination with either Ruxolitinib or Fedratinib and BMS-986158 alone.

Inclusion Criteria: * Diagnosis of primary myelofibrosis (PMF), post-essential thrombocythemia (ET) or post-polycythemia vera (PV) myelofibrosis * Treatment-related toxicities from prior therapy resolved to Grade 1 or pre-treatment baseline or determined to be irreversible prior to study treatment * Must agree to follow specific methods of contraception, if applicable Exclusion Criteria: * Women who are pregnant or breastfeeding at screening * Any significant acute or uncontrolled chronic medical illness Other protocol-defined inclusion/exclusion criteria apply