American Association for Cancer Research
10780432ccr204725-sup-256631_2_supp_6948571_qp38gr.pdf (152.69 kB)

Supplementary Figure 3 from Pacritinib Combined with Sirolimus and Low-Dose Tacrolimus for GVHD Prevention after Allogeneic Hematopoietic Cell Transplantation: Preclinical and Phase I Trial Results

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journal contribution
posted on 2023-03-31, 22:27 authored by Joseph Pidala, Kelly Walton, Hany Elmariah, Jongphil Kim, Asmita Mishra, Nelli Bejanyan, Taiga Nishihori, Farhad Khimani, Lia Perez, Rawan G. Faramand, Marco L. Davila, Michael L. Nieder, Elizabeth M. Sagatys, Shernan G. Holtan, Nicholas J. Lawrence, Harshani R. Lawrence, Bruce R. Blazar, Claudio Anasetti, Said M. Sebti, Brian C. Betts

Serial measures of absolute neutrophil count (ANC), hemoglobin (Hgb) and platelet counts (PLT) through complete pacritinib treatment period


The University of Minnesota Research Animal Resource and Flow Cytometry Resource



In this first-in-human, phase I, GVHD prevention trial (NCT02891603), we combine pacritinib (PAC), a JAK2 inhibitor, with sirolimus to concurrently reduce T-cell costimulation via mTOR and IL6 activity. We evaluate the safety of pacritinib when administered with sirolimus plus low-dose tacrolimus (PAC/SIR/TAC) after allogeneic hematopoietic cell transplantation. The preclinical efficacy and immune modulation of PAC/SIR were investigated in xenogeneic GVHD. Our phase I trial followed a 3+3 dose-escalation design, including dose level 1 (pacritinib 100 mg daily), level 2 (pacritinib 100 mg twice daily), and level 3 (pacritinib 200 mg twice daily). The primary endpoint was to identify the lowest biologically active and safe dose of pacritinib with SIR/TAC (n = 12). Acute GVHD was scored through day +100. Allografts included 8/8 HLA-matched related or unrelated donor peripheral blood stem cells. In mice, we show that dual JAK2/mTOR inhibition significantly reduces xenogeneic GVHD and increases peripheral regulatory T cell (Treg) potency as well as Treg induction from conventional CD4+ T cells. Pacritinib 100 mg twice a day was identified as the minimum biologically active and safe dose for further study. JAK2/mTOR inhibition suppresses pathogenic Th1 and Th17 cells, spares Tregs and antileukemia effector cells, and exhibits preliminary activity in preventing GVHD. PAC/SIR/TAC preserves donor cytomegalovirus (CMV) immunity and permits timely engraftment without cytopenias. We demonstrate that PAC/SIR/TAC is safe and preliminarily limits acute GVHD, preserves donor CMV immunity, and permits timely engraftment. The efficacy of PAC/SIR/TAC will be tested in our ongoing phase II GVHD prevention trial.

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