PRIMARY OBJECTIVES:~I. To evaluate the safety and tolerability of BRD4 inhibitor PLX51107 (PLX51107) as a single agent for allogeneic transplant recipients with steroid-refractory acute graft versus host disease (GVHD).~II. To assess the pharmacokinetic (PK) and pharmacodynamic (PD) of orally administered PLX51107 in steroid-refractory acute GVHD patients.~SECONDARY OBJECTIVE:~I. To evaluate the preliminary efficacy of PLX51107 in steroid-refractory acute GVHD patients.~OUTLINE:~Patients receive BRD4 inhibitor PLX51107 orally (PO) once daily (QD) on days 1-28. Cycles repeat every 28 days in the absence of disease progression or unacceptable toxicity.~After completion of study treatment, patients are followed up at 30 days and then up to 6 months.
This phase Ib/II trial studies the side effects of PLX51107 in treating steroid-refractory acute graft versus host disease (GVHD). PLX51107 is a novel, potent non-benzodiazepine structured small molecule BET inhibitor with a unique binding mode selective for BRD4 inhibition and a more tolerable side effect profile. PLX51107 may work better in treating steroid-refractory acute GVHD.