Targeted Rho-associated kinase 2 inhibition suppresses murine and human chronic GVHD through a Stat3-dependent mechanism

Abstract

• The ROCK2 inhibitor, KD025, decreases chronic GVHD pathology in multiple murine models.• KD025 inhibits STAT3 phosphorylation to decrease RORgt and Bcl6 expression in both murine and human cells.Chronic graft-versus-host disease (cGVHD) remains a major complication following allogeneic bone marrow transplantation (BMT). The discovery of novel therapeutics is dependent on assessment in preclinical murine models of cGVHD. Rho-associated kinase 2 (ROCK2) recently was shown to be implicated in regulation of interleukin-21 (IL-21) and IL-17 secretion in mice and humans. Here, we report that the selective ROCK2 inhibitor KD025 effectively ameliorates cGVHD in multiple models: a full major histocompatibility complex (MHC) mismatch model of multiorgan system cGVHD with bronchiolitis obliterans syndrome and a minor MHC mismatch model of sclerodermatous GVHD. Treatment with KD025 resulted in normalization of pathogenic pulmonary function, which correlates with a marked reduction of antibody and collagen deposition in the lungs of treated mice to levels comparable to non-cGVHD controls. Spleens of mice treated with KD025 had decreased frequency of T follicular helper cells and increased frequency of T follicular regulatory cells, accompanied by a reduction in signal transducer and activator of transcription 3 (STAT3) and concurrent increase in STAT5 phosphorylation. The critical role of STAT3 in this cGVHD model was confirmed by data showing that mice transplanted with inducible STAT3-deficient T cells had pulmonary function comparable to the healthy negative controls. The therapeutic potential of targeted ROCK2 inhibition in the clinic was solidified further by human data demonstrating the KD025 inhibits the secretion of IL-21, IL-17, and interferon g along with decreasing phosphorylated STAT3 and reduced protein expression of interferon regulatory factor 4 and B-cell lymphoma 6 (BCL6) in human peripheral blood mononuclear cells purified from active cGVHD patients. Together these data highlight the potential of targeted ROCK2 inhibition for clinical cGVHD therapy. (Blood. 2016; 127(17):2144-2154

Cutting Edge: Selective Oral ROCK2 Inhibitor Reduces Clinical Scores in Patients with Psoriasis Vulgaris and Normalizes Skin Pathology via Concurrent Regulation of IL-17 and IL-10

“…In agreement with previous findings in animal models and Th17-skewing in vitro culture of human T cells (15)(16)(17), this study further confirmed the potential of selective ROCK2 inhibition to downregulate autoimmune-driven pathology via shifting the balance between proinflammatory and anti-inflammatory immune cell responses. Although the clinical improvement achieved in the same time span by treatment with KD025 was not as robust as the response seen with other oral treatments, such as methotrexate, JAK inhibitors, and apremilast, or newer biologics neutralizing cytokines in the Th17 pathway, future randomized trials of KD025 carried out for a longer time period (to account for a different molecular mechanism of action) in a larger population of psoriatic patients are required to further validate the therapeutic potential and risk-benefit profile of targeted ROCK2 inhibition in psoriasis.…”

“…ROCK2 is induced during Th17-skewing conditions and regulates IL-17 secretion via a STAT3/IRF4/RORgtdependent mechanism in mice and humans (13,(15)(16)(17). Histological assessment revealed that baseline pSTAT3, IRF4, RORgt, and ROCK2 staining were greater, whereas ROCK1 expression was diminished in lesional skin in comparison with nonlesional skin (Fig.…”

“…Pharmacokinetic analysis was performed at selected study sites, and peripheral blood samples were collected from a subgroup of subjects from each cohort at the following time points: predose (time 0) and 1, 2, 4,6,8,12,16,18, and 24 h after dosing on day 1 of month 1. For cytokine evaluation, peripheral blood samples were collected from all patients at baseline (predose), after 4, 8, and 12 wk of treatment with KD025, and at the follow-up visit, that is, 30 d after the last dosing with the drug.…”

“…Previous findings demonstrated that oral administration of a selective ROCK2 inhibitor (KD025) in healthy subjects decreases IL-17 and IL-21 secretion induced by ex vivo stimulation (15 immunosuppressive T cell subsets via concurrent regulation of STAT3/STAT5 phosphorylation (16)(17)(18). Thus, we have hypothesized that targeting of ROCK2 may restore disrupted immune homeostasis and could have a role in the treatment of Th17-mediated inflammatory disorders such as psoriasis.…”

An activated Th17-prone T cell subset involved in chronic graft-versus-host disease sensitive to pharmacological inhibition

“…Studies have demonstrated a role for Th17 cells in murine models with features of autoimmunity (26), scleroderma (28), and multiorgan system disease with bronchiolitis obliterans (BO) in a CSF-1/CSF-1R-(29) and STAT3-dependent manner (30,31). In humans, there is a paucity of data.…”