Mastocytosis, Aggressive Systemic

CP-MGD024-01 is a Phase 1, open-label, multi-center study of MGD024 as a single agent in participants with select blood cancers that have not responded to treatment with standard therapies or who have relapsed after treatment. The study is designed to determine the safety, tolerability, pharmacokinetics (affect of the body on the drug), pharmacodynamic (affect of the drug on the body), immunogenicity (development of antibodies against the drug), and preliminary anti-cancer effect of MGD024. Participants will receive treatment with MGD024 in consecutive 28-day cycles for a study treatment period of up to 12 cycles (approximately 1 year) or until treatment or study discontinuation criteria are met. Response assessments will be performed after Cycle 1 and then after every even numbered cycle starting with Cycle 2 until progression or study treatment discontinuation. Participants will be checked for side effects throughout the study.