A Phase I, First-in-Human Study to Evaluate the Safety and Tolerability, Pharmacokinetics and Pharmacodynamics of MRG-001 in Healthy Subjects
BACKGROUND: Preclinical studies have demonstrated that pharmacological mobilization and recruitment of endogenous bone marrow stem cells and immunoregulatory cells by a combination of plerixafor and low-dose tacrolimus (MRG-001) improves wound healing, promotes tissue regeneration and prevents allograft rejection. This first-in-human phase I dose-escalation study evaluates the safety, tolerability, pharmacokinetics and pharmacodynamics of MRG-001, a novel fixed-dose combination drug.  METHODS: In this Phase 1, double-blind, randomized, placebo-controlled study, multiple ascending dose (MAD) cohorts are randomized to receive MRG-001 containing up to 0.02 mL/kg (plerixafor 24 mg/mL and tacrolimus 0.5 mg/mL) or saline placebo, subcutaneously every other day (SC, QAD) for 5 days (ClinicalTrials.gov: NCT04646603)The primary outcome is safety and tolerability. Safety and functional assessments are performed throughout the study. Blood samples are collected to evaluate systemic exposure. Fluorescence-activated cell sorting analysis and RNA expression of peripheral blood mononuclear cells (PBMCs) are used to evaluate the pharmacodynamics.  RESULTS: Fourteen subjects received MRG-001 and 7 received a placebo. MRG-001 is safe and well-tolerated over the selected dose range. No deaths or severe adverse events are reported. There are no clinically significant laboratory changes after MRG-001 administration, apart from the predicted generalized leukocytosis. The intermediate dose group (0.01 mL/kg) showed the most significant white blood cell mobilization over time and increased by 2-4 fold from baseline and returned to baseline levels prior to the next injection. Circulating immune cells including FOXP3+ regulatory T cells and hematopoietic stem cells (CD45IntCD34+) increased significantly after MRG-001 injection. PBMC RNA sequencing and gene set enrichment analysis revealeds 31 down-regulated pathways in the intermediate dose MRG-001 group compared to no changes in the placebo group.  CONCLUSION: MRG-001 is safe and well-tolerated across the full dose ranges tested. MRG-001 may be a clinically useful therapy for immunoregulation and tissue regeneration. A Phase II trial to treat severely and critically ill COVID-19 patients with MRG-001 has been initiated (NCT04646603) and a second phase II trial will explore the potential of MRG-001 to accelerate wound healing (NCT05844527),   Overall design: To investigate the dynamic differences of gene expression of the peripheral mononuclear blood cells after injection of placebo compared to different dosages of the investigational drug MRG-001.