James J. Campbell

We have recently demonstrated that small molecule inhibitors of CCR2 rapidly reduced proteinuria and preserved renal structure in animal models of diabetic nephropathy (DN) and focal segmental glomerular sclerosis (FSGS). Similar beneficial effects of CCR2 inhibition were also observed in DN patients in a large diabetic nephropathy Phase 2 clinical trial. Despite its rapid and robust effects in these kidney diseases, the mechanism by which CCR2 inhibition affords such renal protection remains unclear. CCR2 is well-known to be expressed on cells of the immune system, where it mediates inflammation and immunological functions by controlling the trafficking of monocytes and T cells. However, immune cell expression of CCR2 may not adequately explain the rapid pharmacologic benefits of CCR2 inhibitors in DN and FSGS because these diseases do not exhibit appreciable kidney inflammation. To better understand the protective mechanism(s) of CCR2 inhibition in renal diseases, we have used a variety of in vivo nephropathy models to determine if CCR2 is expressed on kidney parenchymal cells. Our results suggest that a subset of CD45 negative, renal parietal epithelial cells express CCR2. To characterize CCR2 expression in the kidney we used CCR2 RFP heterozygous mice (CCR2^RFP/+) in which one copy of CCR2 was replaced by red fluorescent protein (RFP), whose expression is under the control of the endogenous CCR2 promoter. This approach provided a highly sensitive method for CCR2 detection by both flow cytometry and immunofluorescence, and compensated for the lack of validated, commercially available anti-CCR2 antibodies. Enriched glomerular cells were obtained by a non-enzymatic disruption of kidneys, followed by centrifugation at low speed (80gs), and sieving through 300µm and 150µm meshes. The Adriamycin (ADR)-nephropathy model with CCR2 RFP heterozygous mice was used to determine CCR2 expression on renal cells. 5/6 nephrectomy models of FSGS, as well as the db/db diabetic nephropathy model were used to access the change of activated parietal epithelial cells and proteinuria, both in the presence and absence of a CCR2 inhibitor in the setting of kidney injury. We observed dramatic increases in the number of activated parietal epithelial cells (PECs, identified as CD133⁺CD24⁺CD44^hi cells by flow cytometry) in all three renal disease models. In the ADR nephropathy model, we found that in 30-40% of activated PEC cells within an enriched population of glomerular cells expressed CCR2/RFP. CD44^hi RFP⁺ increased much more dramatically than CD44^hi RFP^- cells in response to ADR, and this was highly correlated with proteinuria, suggesting that CCR2 plays an important role in PEC cell activation and kidney pathology in ADR induced kidney injury. Furthermore, we found that blocking CCR2 with the CCR2-specific antagonist CCX872 significantly reduced both proteinuria and the number of activated PECs in the 5/6 nephropathy and db/db diabetic nephropathy models. This is the first report that CCR2 is present on a subset of activated renal PECs. This population is markedly upregulated during kidney injury in a variety of murine models of nephropathy. Changes in the abundance CCR2+ activated PECs in the glomerular enriched preparations in response to CCR2 inhibition suggests that CCR2 antagonism may represent a novel approach for the treatment of chronic kidney disease.

Background and Aims: Diabetic nephropathy (DN) is a syndrome characterized by pathological levels of proteinuria, glomerular lesions and reduction in the glomerular filtration rate (GFR) in diabetic patients. Several lines of evidence support a role of CCR2 in the pathogenesis of DN. Recent studies have demonstrated that existing small molecule CCR2 antagonists can be placed in two classes, distinguished by their interaction with one of two distinct binding sites on CCR2: an extracellular site for which antagonists compete directly with native ligands (the orthosteric site), or an intracellular allosteric binding site. To better understand the functional differences between these antagonists we compared an example of each class in a murine model of DN. Our results revealed that the allosteric, but not the orthosteric CCR2 inhibitors ameliorated the proteinuria and improved glomerular histopathology in this model of DN. Method: We used db/db mice to model DN. Several structurally distinct CCR2 inhibitors with that bind to either the allosteric (CCR2-RA-[R] and CCX872) or orthosteric (MK-0812 and CCX598) sites were compared. Pharmacokinetic (PK) properties and renal functional parameters were assessed, including trough drug levels and proteinuria (urinary albumin excretion rate UAER; urine albumin creatinine ratio UACR). Histopathology and electron microscopy (EM) were performed to assess any potential tissue-protective effects of the antagonists. Results: Both the allosteric inhibitors (CCR2-RA-[R] and CCX872) and the orthosteric inhibitors (MK-0812 and CCX598) were potent CCR2 antagonists with desirable PK in mouse in so far as both classes effectively blocked CCR2-mediated monocyte migration into the peritoneal cavity in the thioglycollate-induced peritonitis model. At comparable drug coverage levels, CCR2-RA-[R] and CCX872 rapidly and significantly reduced UAER/UACR (CCX872: 70 % at day 7 vs vehicle, p<0.0001; and 60 % at day 14 vs vehicle, p=0.001; CCR2-RA-[R]: 60 % at day 7 vs vehicle, p=0.0001; and 58 % at day 14 vs vehicle, p=0.005), but MK-0812 and CCX598 did not exhibit proteinuria lowering effect. Histological parameters including glomerular injury and glomerular basement membrane (GBM) thickness were also improved after CCX872 treatment in db/db mice. Conclusion: Allosteric antagonists of CCR2 provide significant and rapid renal protection in the db/db murine model of DN, as evidenced by improvements in renal function and histological parameters, while potent orthosteric CCR2 antagonists were not effective in the model. Our data suggest that targeting the effectiveness of CCR2 antagonists in DN are directly dependent on binding to the allosteric site of CCR2.

The development of anti-TNFα immunotherapies has led to great advances in quality of life for Crohn’s and colitis patients, and has allowed a reduction in steroid use for these diseases. However, a significant proportion of IBD patients is resistant to anti-TNFα agents, or becomes resistant over time. Preclinical research and clinical trials suggest that CCR9 antagonism can effectively reduce colon inflammation. CCR9 is expressed on a subset of T cells dedicated to intestinal trafficking. Antagonism of this receptor inhibits the accumulation of T cells within inflamed intestinal epithelium and lamina propria. Since anti-TNFα and CCR9 antagonists act through entirely different mechanisms, we asked whether these two approaches might synergize and expand the effectiveness and scope of each therapy. We used a piroxicam-accelerated version of the MDR1a−/− spontaneous colitis model in mice. We have found that combined dosing of piroxicam-fed MDR1a−/− mice with a CCR9 antagonist and an anti-TNFα MAb significantly reverses loss of body weight, diarrhea score and colon inflammation. The combined dosing was more effective than anti-TNFα or CCR9 antagonist alone, as measured by colon length/weight ratio, neutrophil accumulation in the colonic epithelium and reversal of the loss in body weight characteristic of this model. These data suggest that combining a CCR9 antagonist with existing anti-TNFα treatment regimens may extend the benefits of anti-TNFα immunotherapy to a larger class of patients suffering from IBD, and may prolong the effectiveness of anti-TNFα immunotherapy for those patients already undergoing such treatments.

Introduction: Chemokines and their receptors influence many of the hallmark processes in cancer: they act not only on infiltrating leukocytes, but also on fibroblasts, endothelial cells, and directly on some types of tumor cells. C-C chemokine receptor 4 (CCR4) and its ligands have been found to be highly expressed in multiple types of human tumors and are associated with poor prognosis. CCR4 antagonism has been demonstrated to reduce tumor growth in various mouse tumor models. Here we assess small-molecule inhibition of CCR4 as a therapeutic agent to potentiate the effects of checkpoint inhibitors in the CT26 and KCM tumor models. Methods: The subcutaneous CT26 colon cancer model and the orthotopic KCM pancreatic cancer model were used to assess the effects of a CCR4 inhibitor, CCX6239, in combination with anti-CTLA-4 antibody. CT26 cells were implanted into the flanks of 9wk female Balb/c mice. Mice were randomized into study groups based on the tumor sizes on day 6, and dosing of both CCX6239 and anti-CTLA-4 started on day 7. For the orthotopic pancreatic cancer model, KCM cells were implanted directly into the pancreas, and dosing of CCX6239 and anti-CTLA-4 also began on day 7. CCX6239 was dosed orally twice daily at 30mg/kg, and anti-CTLA-4 was dosed IP on days 7, 11 and 15 at 100μg/mouse. Results: Blockade of CCR4 appreciably enhanced the therapeutic effects of anti-CTLA-4 in both models. Combined anti-CTLA-4/CCR4 inhibitor significantly decreased tumor size and increased the proportion of long-term survivors in the CT26 model. The antitumor response was CT26-specific; long-term survivors were resistant to reinoculation with CT26 cells (without further dosing of either drug), but 4T1 breast tumors grew well upon challenge of CT26 survivors. Mice with tumor regression exhibited a high proportion of CD8 T cells that recognized a CT26-specific neoantigen, as illustrated by AH1 peptide-MHC tetramer staining. Although long-term survival has not yet been examined in the KCM model, CCX6239 alone significantly reduced tumor burden in 3 independent studies. Anti-CTLA-4 alone provided substantial inhibition of tumor growth in this model, which was further enhanced by CCX6239. Summary: A specific CCR4 small-molecule inhibitor enhanced the effectiveness of anti-CTLA-4 in 2 preclinical models, suggesting that targeting CCR4 may be a viable clinical approach for combinatorial treatment with checkpoint blockers. Citation Format: Shijie “Chris” Li, James J. Campbell, Linda S. Ertl, Zhenhua Miao, Vicky Chhina, Alice Kumamoto, Simon Yau, Ton Dang, Penglie Zhang, Thomas J. Schall, Rajinder Singh. C-C chemokine receptor 4 (CCR4) antagonism enhances the effectiveness of checkpoint Inhibition in mouse tumor models [abstract]. In: Proceedings of the AACR Special Conference on Tumor Immunology and Immunotherapy; 2018 Nov 27-30; Miami Beach, FL. Philadelphia (PA): AACR; Cancer Immunol Res 2020;8(4 Suppl):Abstract nr B08.

Emerging evidence suggests that cancer cell metabolism can be regulated by cancer-associated fibroblasts (CAFs), but the mechanisms are poorly defined. Here we show that CAFs regulate malignant cell metabolism through pathways under the control of FAK. In breast and pancreatic cancer patients we find that low FAK expression, specifically in the stromal compartment, predicts reduced overall survival. In mice, depletion of FAK in a subpopulation of CAFs regulates paracrine signals that increase malignant cell glycolysis and tumour growth. Proteomic and phosphoproteomic analysis in our mouse model identifies metabolic alterations which are reflected at the transcriptomic level in patients with low stromal FAK. Mechanistically we demonstrate that FAK-depletion in CAFs increases chemokine production, which via CCR1/CCR2 on cancer cells, activate protein kinase A, leading to enhanced malignant cell glycolysis. Our data uncover mechanisms whereby stromal fibroblasts regulate cancer cell metabolism independent of genetic mutations in cancer cells.

The development of anti-TNFα immunotherapies has led to great advances in quality of life for Crohn’s and colitis patients and has allowed a reduction in steroid use for these diseases. However, a significant proportion of IBD patients is resistant to anti-TNFα agents, or becomes resistant to such treatments over time. Preclinical research and clinical trials have suggested that CCR9 antagonism can effectively reduce colon inflammation. CCR9 is expressed on a subset of T cells dedicated to monitoring the immune status of the intestine. When activated by its only known chemokine ligand, CCL25/TECK, CCR9 triggers the adhesion of gut-specific T cells to vascular endothelium and the subsequent ingress of these cells to intestinal tissues. Antagonism of this receptor inhibits the accumulation of T cells within inflamed intestinal epithelium and lamina propria. Since anti-TNFα and CCR9 antagonists act through entirely different mechanisms, we asked whether these two approaches might synergise and expand the effectiveness and scope of each therapy. We used a piroxicam-accelerated version of the MDR1a^−/− spontaneous colitis model in mice. In this model, 7week MDR1a^−/− mice (or WT FVB controls) receive piroxicam in powdered chow for 10 days. Mice are monitored both during and after the piroxicam feeding period, for a total of 21 days. Treatment groups (eight mice each) include an antibody (a saturating dose of either anti-TNFα or its isotype-matched control) and a CCR9 antagonist (or its vehicle alone as a control). Body weight and diarrhoea score were recorded throughout the entire 21 days period, after which colons were obtained from sacrificed animals for weighing, length measurement and imaging. We have found that combined dosing of piroxicam-fed MDR1a^−/− mice with a CCR9 antagonist and an anti-TNFα MAb significantly reverses loss of body weight, diarrhoea score and colon inflammation. The combined dosing was more effective than anti-TNFα or CCR9 antagonist alone, as measured by colon length/weight ratio, neutrophil accumulation in the colonic epithelium and reversal of the loss in body weight characteristic of this model. These data suggest that combining a CCR9 antagonist with existing anti-TNFα treatment regimens may extend the benefits of anti-TNFα immunotherapy to a larger class of patients suffering from IBD and may prolong the effectiveness of anti-TNFα immunotherapy for those patients already undergoing such treatments.