Discovery of KRB-456, a KRAS G12D Switch-I/II Allosteric Pocket Binder That Inhibits the Growth of Pancreatic Cancer Patient-derived Tumors.

Currently, there are no clinically approved drugs that directly thwart mutant KRAS G12D, a major driver of human cancer. Here, we report on the discovery of a small molecule, KRB-456, that binds KRAS G12D and inhibits the growth of pancreatic cancer patient-derived tumors. Protein nuclear magnetic resonance studies revealed that KRB-456 binds the GDP-bound and GCP-bound conformation of KRAS G12D by forming interactions with a dynamic allosteric binding pocket within the switch-I/II region. Isothermal titration calorimetry demonstrated that KRB-456 binds potently to KRAS G12D with 1.5-, 2-, and 6-fold higher affinity than to KRAS G12V, KRAS wild-type, and KRAS G12C, respectively. KRB-456 potently inhibits the binding of KRAS G12D to the RAS-binding domain (RBD) of RAF1 as demonstrated by GST-RBD pulldown and AlphaScreen assays. Treatment of KRAS G12D-harboring human pancreatic cancer cells with KRB-456 suppresses the cellular levels of KRAS bound to GTP and inhibits the binding of KRAS to RAF1. Importantly, KRB-456 inhibits P-MEK, P-AKT, and P-S6 levels in vivo and inhibits the growth of subcutaneous and orthotopic xenografts derived from patients with pancreatic cancer whose tumors harbor KRAS G12D and KRAS G12V and who relapsed after chemotherapy and radiotherapy. These results warrant further development of KRB-456 for pancreatic cancer. SIGNIFICANCE: There are no clinically approved drugs directly abrogating mutant KRAS G12D. Here, we discovered a small molecule, KRB-456, that binds a dynamic allosteric binding pocket within the switch-I/II region of KRAS G12D. KRB-456 inhibits P-MEK, P-AKT, and P-S6 levels in vivo and inhibits the growth of subcutaneous and orthotopic xenografts derived from patients with pancreatic cancer. This discovery warrants further advanced preclinical and clinical studies in pancreatic cancer.

Real time ex vivo chemosensitivity assay for pancreatic adenocarcinoma.

BACKGROUND: Patient-derived organoids (PDOs) and xenografts (PDXs) have been extensively studied for drug-screening. However, their usage is limited due to lengthy establishment time, high engraftment failure rates and different tumor microenvironment from original tumors. To overcome the limitations, we developed real time-live tissue sensitivity assay (RT-LTSA) using fresh tumor samples. METHODS: Tissue slices from resected pancreatic cancer samples were placed in 96-well plates, and the slices were treated with chemotherapeutic agents. The correlation between the chemo-sensitivity of tissue slices and each patient's clinical outcome was analyzed. RESULTS: The viability and tumor microenvironment of the tissue slices are well-preserved over 5 days. The drug sensitivity assay results are available within 5 days after tissue collection. While all 4 patients who received RT-LTSA sensitive adjuvant regimens did not develop recurrence, 7 of 8 patients who received resistant adjuvant regimens developed recurrence. We observed significantly improved disease-free survival in the patients who received RT-LTSA sensitive adjuvant regimens (median: not reached versus 10.6 months, P = 0.02) compared with the patient who received resistant regimens. A significant negative correlation between RT-LTSA value and relapse-free survival was observed (Somer's D: -0.58; P = 0.016). CONCLUSIONS: RT-LTSA which maintains the tumor microenvironment and architecture as found in patients may reflect clinical outcome and could be used as a personalized strategy for pancreatic adenocarcinoma. Further, studies are warranted to verify the findings.

Translational relevance of SOS1 targeting for KRAS-mutant colorectal cancer.

It has been challenging to target mutant KRAS (mKRAS) in colorectal cancer (CRC) and other malignancies. Recent efforts have focused on developing inhibitors blocking molecules essential for KRAS activity. In this regard, SOS1 inhibition has arisen as an attractive approach for mKRAS CRC given its essential role as a guanine nucleotide exchange factor for this GTPase. Here, we demonstrated the translational value of SOS1 blockade in mKRAS CRC. We used CRC patient-derived organoids (PDOs) as preclinical models to evaluate their sensitivity to SOS1 inhibitor BI3406. A combination of in silico analyses and wet lab techniques was utilized to define potential predictive markers for SOS1 sensitivity and potential mechanisms of resistance in CRC. RNA-seq analysis of CRC PDOs revealed two groups of CRC PDOs with differential sensitivities to SOS1 inhibitor BI3406. The resistant group was enriched in gene sets involving cholesterol homeostasis, epithelial-mesenchymal transition, and TNF-α/NFκB signaling. Expression analysis identified a significant correlation between SOS1 and SOS2 mRNA levels (Spearman's ρ 0.56, p < 0.001). SOS1/2 protein expression was universally present with heterogeneous patterns in CRC cells but only minimal to none in surrounding nonmalignant cells. Only SOS1 protein expression was associated with worse survival in patients with RAS/RAF mutant CRC (p = 0.04). We also found that SOS1/SOS2 protein expression ratio >1 by immunohistochemistry (p = 0.03) instead of KRAS mutation (p = 1) was a better predictive marker to BI3406 sensitivity of CRC PDOs, concordant with the significant positive correlation between SOS1/SOS2 protein expression ratio and SOS1 dependency. Finally, we showed that GTP-bound RAS level underwent rebound even in BI3406-sensitive PDOs with no change of KRAS downstream effector genes, thus suggesting upregulation of guanine nucleotide exchange factor as potential cellular adaptation mechanisms to SOS1 inhibition. Taken together, our results show that high SOS1/SOS2 protein expression ratio predicts sensitivity to SOS1 inhibition and support further clinical development of SOS1-targeting agents in CRC.

Development of SOS1 Inhibitor-Based Degraders to Target KRAS-Mutant Colorectal Cancer.

Direct blockade of KRAS driver mutations in colorectal cancer (CRC) has been challenging. Targeting SOS1, a guanine nucleotide exchange factor, has arisen as an attractive approach for KRAS-mutant CRC. Here, we describe the development of novel SOS1 degraders and their activity in patient-derived CRC organoids (PDO). The design of these degraders as proteolysis-targeting chimera was based on the crystal structures of cereblon and SOS1. The synthesis used the 6- and 7-OH groups of a quinazoline core as anchor points to connect lenalidomide. Fifteen compounds were screened for SOS1 degradation. P7 was found to have up to 92% SOS1 degradation in both CRC cell lines and PDOs with excellent specificity. SOS1 degrader P7 demonstrated superior activity in inhibiting CRC PDO growth with an IC50 5 times lower than that of SOS1 inhibitor BI3406. In summary, we developed new SOS1 degraders and demonstrated SOS1 degradation as a feasible therapeutic strategy for KRAS-mutant CRC.

Global Phosphoproteomics Reveal CDK Suppression as a Vulnerability to KRas Addiction in Pancreatic Cancer.

PURPOSE: Among human cancers that harbor mutant (mt) KRas, some, but not all, are dependent on mt KRas. However, little is known about what drives KRas dependency. EXPERIMENTAL DESIGN: Global phosphoproteomics, screening of a chemical library of FDA drugs, and genome-wide CRISPR/Cas9 viability database analysis were used to identify vulnerabilities of KRas dependency. RESULTS: Global phosphoproteomics revealed that KRas dependency is driven by a cyclin-dependent kinase (CDK) network. CRISPR/Cas9 viability database analysis revealed that, in mt KRas-driven pancreatic cancer cells, knocking out the cell-cycle regulators CDK1 or CDK2 or the transcriptional regulators CDK7 or CDK9 was as effective as knocking out KRas. Furthermore, screening of a library of FDA drugs identified AT7519, a CDK1, 2, 7, and 9 inhibitor, as a potent inducer of apoptosis in mt KRas-dependent, but not in mt KRas-independent, human cancer cells. In vivo AT7519 inhibited the phosphorylation of CDK1, 2, 7, and 9 substrates and suppressed growth of xenografts from 5 patients with pancreatic cancer. AT7519 also abrogated mt KRas and mt p53 primary and metastatic pancreatic cancer in three-dimensional (3D) organoids from 2 patients, 3D cocultures from 8 patients, and mouse 3D organoids from pancreatic intraepithelial neoplasia, primary, and metastatic tumors. CONCLUSIONS: A link between CDK hyperactivation and mt KRas dependency was uncovered and pharmacologically exploited to abrogate mt KRas-driven pancreatic cancer in highly relevant models, warranting clinical investigations of AT7519 in patients with pancreatic cancer.

The Florida Pancreas Collaborative Next-Generation Biobank: Infrastructure to Reduce Disparities and Improve Survival for a Diverse Cohort of Patients with Pancreatic Cancer.

Background: Well-annotated, high-quality biorepositories provide a valuable platform to support translational research. However, most biorepositories have poor representation of minority groups, limiting the ability to address health disparities. Methods: We describe the establishment of the Florida Pancreas Collaborative (FPC), the first state-wide prospective cohort study and biorepository designed to address the higher burden of pancreatic cancer (PaCa) in African Americans (AA) compared to Non-Hispanic Whites (NHW) and Hispanic/Latinx (H/L). We provide an overview of stakeholders; study eligibility and design; recruitment strategies; standard operating procedures to collect, process, store, and transfer biospecimens, medical images, and data; our cloud-based data management platform; and progress regarding recruitment and biobanking. Results: The FPC consists of multidisciplinary teams from fifteen Florida medical institutions. From March 2019 through August 2020, 350 patients were assessed for eligibility, 323 met inclusion/exclusion criteria, and 305 (94%) enrolled, including 228 NHW, 30 AA, and 47 H/L, with 94%, 100%, and 94% participation rates, respectively. A high percentage of participants have donated blood (87%), pancreatic tumor tissue (41%), computed tomography scans (76%), and questionnaires (62%). Conclusions: This biorepository addresses a critical gap in PaCa research and has potential to advance translational studies intended to minimize disparities and reduce PaCa-related morbidity and mortality.

Immune Regulatory 1 Cells: A Novel and Potent Subset of Human T Regulatory Cells.

A subset of T regulatory cells (Tregs), identified by TIRC7 (T cell immune response cDNA 7) expression is designated as Immune Regulatory 1 Cells (IR1 cells). TIRC7 is an immune checkpoint inhibitor, co-localized with the T- cell receptor, HLA-DR and CTLA-4 during T-cell activation, which delivers regulatory signals via binding to its ligand, HLA-DR α2 domain. IR1 cells express FOXP3, and multiple other markers associated with immune suppression. They constitute as much as 10% of Tregs. IR1 cells strongly inhibit proliferation in mixed lymphocyte reactions, where they express high levels of IL-10. Ex vivo expansion of Tregs over 2 weeks in the presence of an agonist TIRC7 antibody disproportionately expands the IR1 Treg subset, while maintaining high expression of suppressive markers including CD39, IL-10, LAP and GARP. Ex vivo expanded IR1 cells are a potent, homogeneous, stable set of suppressor Tregs with the potential to modulate immune dysregulation. The characteristics of IR1 cells suggest a therapeutic advantage over polyclonal Tregs for therapeutic interventions. Early restoration of immune homeostasis using IR1 cells has the potential to fundamentally alter the natural history of conditions characterized by abnormalities in the T regulatory cell compartment.

Establishing a living biobank of patient-derived organoids of intraductal papillary mucinous neoplasms of the pancreas.

Pancreatic cancer (PaCa) is the third leading cause of cancer-related deaths in the United States. There is an unmet need to develop strategies to detect PaCa at an early, operable stage and prevent its progression. Intraductal papillary mucinous neoplasms (IPMNs) are cystic PaCa precursors that comprise nearly 50% of pancreatic cysts detected incidentally via cross-sectional imaging. Since IPMNs can progress from low- and moderate-grade dysplasia to high-grade dysplasia and invasion, the study of these lesions offers a prime opportunity to develop early detection and prevention strategies. Organoids are an ideal preclinical platform to study IPMNs, and the objective of the current investigation was to establish a living biobank of patient-derived organoids (PDO) from IPMNs. IPMN tumors and adjacent normal pancreatic tissues were successfully harvested from 15 patients with IPMNs undergoing pancreatic surgical resection at Moffitt Cancer Center & Research Institute (Tampa, FL) between May of 2017 and March of 2019. Organoid cultures were also generated from cryopreserved tissues. Organoid count and size were determined over time by both Image-Pro Premier 3D Version 9.1 digital platform and Matlab application of a Circular Hough Transform algorithm, and histologic and genomic characterization of a subset of the organoids was performed using immunohistochemistry and targeted sequencing, respectively. The success rates for organoid generation from IPMN tumor and adjacent normal pancreatic tissues were 81% and 87%, respectively. IPMN organoids derived from different epithelial subtypes showed different morphologies in vitro, and organoids recapitulated histologic and genomic characteristics of the parental IPMN tumor. In summary, this preclinical model has the potential to provide new opportunities to unveil mechanisms of IPMN progression to invasion and to shed insight into novel biomarkers for early detection and targets for chemoprevention.

Dual Farnesyl and Geranylgeranyl Transferase Inhibitor Thwarts Mutant KRAS-Driven Patient-Derived Pancreatic Tumors.

PURPOSE: Mutant KRAS is a major driver of pancreatic oncogenesis and therapy resistance, yet KRAS inhibitors are lacking in the clinic. KRAS requires farnesylation for membrane localization and cancer-causing activity prompting the development of farnesyltransferase inhibitors (FTIs) as anticancer agents. However, KRAS becomes geranylgeranylated and active when cancer cells are treated with FTIs. To overcome this geranylgeranylation-dependent resistance to FTIs, we designed FGTI-2734, a RAS C-terminal mimetic dual FT and geranylgeranyltransferase-1 inhibitor (GGTI). EXPERIMENTAL DESIGN: Immunofluorescence, cellular fractionation, and gel shift assays were used to assess RAS membrane association, Western blotting to evaluate FGTI-2734 effects on signaling, and mouse models to demonstrate its antitumor activity. RESULTS: FGTI-2734, but not the selective FTI-2148 and GGTI-2418, inhibited membrane localization of KRAS in pancreatic, lung, and colon human cancer cells. FGTI-2734 induced apoptosis and inhibited the growth in mice of mutant KRAS-dependent but not mutant KRAS-independent human tumors. Importantly, FGTI-2734 inhibited the growth of xenografts derived from four patients with pancreatic cancer with mutant KRAS (2 G12D and 2 G12V) tumors. FGTI-2734 was also highly effective at inhibiting, in three-dimensional cocultures with resistance promoting pancreatic stellate cells, the viability of primary and metastatic mutant KRAS tumor cells derived from eight patients with pancreatic cancer. Finally, FGTI-2734 suppressed oncogenic pathways mediated by AKT, mTOR, and cMYC while upregulating p53 and inducing apoptosis in patient-derived xenografts in vivo. CONCLUSIONS: The development of this novel dual FGTI overcomes a major hurdle in KRAS resistance, thwarting growth of patient-derived mutant KRAS-driven xenografts from patients with pancreatic cancer, and as such it warrants further preclinical and clinical studies.

Phase I trial of histone deacetylase inhibitor panobinostat in addition to glucocorticoids for primary therapy of acute graft-versus-host disease.

Glucocorticoids for primary therapy of acute GVHD have limited responses. A phase I/II trial tested 4 weeks of deacetylase inhibitor panobinostat started within 48 h of glucocorticoids (1 mg/kg/day prednisone or equivalent) as primary treatment for patients with either classic acute GVHD (n = 16) or acute GVHD overlapping with chronic (n = 6). Four patients received 2.5 mg/m2 IV three times a week (TIW). Subsequent to discontinuation of IV panobinostat, patients received oral doses (PO). Two patients treated with 10 mg TIW (PO level 1) had progressive GVHD, after which patients were treated with 5 mg TIW (PO level -1; n = 16); 31/41 adverse events were possibly related, including thrombocytopenia (n = 13), leukopenia (n = 7), hypercholesterolemia (n = 3), hypertriglyceridemia (n = 5), anemia (n = 1), fatigue (n = 1), and hepatobiliary disorder (n = 1). GVHD responses were complete (n = 12) or partial (n = 3), with 1 progression at PO level -1. T-regulatory cells increased at day 8, CD4/CD8 and monocytes exhibited enhanced H3 acetylation, and CD4 or CD8 numbers remained unchanged with a decreased interleukin 12p40 plasma level. Panobinostat in combination with prednisone is safe and warrants further testing in GVHD.

In vivo IL-12/IL-23p40 neutralization blocks Th1/Th17 response after allogeneic hematopoietic cell transplantation.

T-helper 1 and T-helper 17 lymphocytes mediate acute graft-versus-host disease (GvHD). Interleukin 12 is critical for T-helper 1 differentiation and interleukin 23 for T-helper 17 maintenance. Interleukin 12 and 23 are heterodimeric cytokines that share the p40 subunit (IL-12/IL-23p40). In a randomized, blinded, placebo-controlled trial, we examined the biological impact and clinical outcomes following IL-12/IL-23p40 neutralization using ustekinumab. Thirty patients received peripheral blood mobilized hematopoietic cell transplantation (HCT) from HLA-matched sibling or unrelated donors, received sirolimus plus tacrolimus as GvHD prophylaxis, and were randomized to ustekinumab versus placebo with 1:1 allocation after stratification by donor type. The primary end point of the trial was the mean percentage (%) T-regulatory (Treg) cells on day 30 post HCT. Ustekinumab was delivered by subcutaneous injection on day -1 and day +20 after transplantation. On day 30 post transplant, no significant difference in % Treg was observed. Ustekinumab suppressed serum IL-12/IL-23p40 levels. Host-reactive donor alloresponse at days 30 and 90 after transplantation was polarized with significant reduction in IL-17 and IFN-α production and increase in IL-4. No toxicity attributed to ustekinumab was observed. Overall survival and National Institute of Health moderate/severe chronic GvHD-free, relapse-free survival were significantly improved among ustekinumab-treated patients. No significant improvements were observed in acute or chronic GvHD, relapse, or non-relapse mortality. These data provide first evidence that IL-12/IL-23p40 neutralization can polarize donor anti-host alloresponse in vivo and provide initial clinical efficacy evidence to be tested in subsequent trials. (Trial registered at clinicaltrials.gov identifier: 01713400).

CD25 Blockade Delays Regulatory T Cell Reconstitution and Does Not Prevent Graft-versus-Host Disease After Allogeneic Hematopoietic Cell Transplantation.

Daclizumab, a humanized monoclonal antibody, binds CD25 and blocks formation of the IL-2 receptor on T cells. A study of daclizumab as acute graft-versus-host disease (GVHD) prophylaxis after unrelated bone marrow transplantation was conducted before the importance of CD25+FOXP3+ regulatory T cells (Tregs) was recognized. Tregs can abrogate the onset of GVHD. The relation between Tregs and a graft-versus-malignancy effect is not fully understood. An international, multicenter, double-blind clinical trial randomized 210 adult or pediatric patients to receive 5 weekly doses of daclizumab at 0.3 mg/kg (n = 69) or 1.2 mg/kg (n = 76) or placebo (n = 65) after unrelated marrow transplantation for treatment of hematologic malignancies or severe aplastic anemia. The risk of acute GVHD did not differ among the groups (P = .68). Long-term follow-up of clinical outcomes and correlative analysis of peripheral blood T cell phenotype suggested that the patients treated with daclizumab had an increased risk of chronic GVHD (hazard ratio [HR], 1.49; 95% confidence interval [CI], 1.0 to 2.3; P = .08) and a decreased risk of relapse (HR, 0.57; 95% CI, 0.3 to 1.0; P = .05), but similar survival (HR, 0.89; 95% CI, 0.6 to 1.3; P = .53). T cells from a subset of patients (n = 107) were analyzed by flow cytometry. Compared with placebo, treatment with daclizumab decreased the proportion of Tregs among CD4 T cells at days 11-35 and increased the proportion of central memory cells among CD4 T cells at 1 year. Prophylactic administration of daclizumab does not prevent acute GVHD, but may increase the risk of chronic GVHD and decrease the risk of relapse. By delaying Treg reconstitution and promoting immunologic memory, anti-CD25 therapy may augment alloreactivity and antitumor immunity.

Tolerance associated gene expression following allogeneic hematopoietic cell transplantation.

Biologic markers of immune tolerance may facilitate tailoring of immune suppression duration after allogeneic hematopoietic cell transplantation (HCT). In a cross-sectional study, peripheral blood samples were obtained from tolerant (n = 15, median 38.5 months post-HCT) and non-tolerant (n = 17, median 39.5 post-HCT) HCT recipients and healthy control subjects (n = 10) for analysis of immune cell subsets and differential gene expression. There were no significant differences in immune subsets across groups. We identified 281 probe sets unique to the tolerant (TOL) group and 122 for non-tolerant (non-TOL). These were enriched for process networks including NK cell cytotoxicity, antigen presentation, lymphocyte proliferation, and cell cycle and apoptosis. Differential gene expression was enriched for CD56, CD66, and CD14 human lineage-specific gene expression. Differential expression of 20 probe sets between groups was sufficient to develop a classifier with > 90% accuracy, correctly classifying 14/15 TOL cases and 15/17 non-TOL cases. These data suggest that differential gene expression can be utilized to accurately classify tolerant patients following HCT. Prospective investigation of immune tolerance biologic markers is warranted.

CD4+ T cell STAT3 phosphorylation precedes acute GVHD, and subsequent Th17 tissue invasion correlates with GVHD severity and therapeutic response.

Th17 cells contribute to severe GVHD in murine bone marrow transplantation. Targeted deletion of the RORγt transcription factor or blockade of the JAK2-STAT3 axis suppresses IL-17 production and alloreactivity by Th17 cells. Here, we show that pSTAT3 Y705 is increased significantly in CD4(+) T cells among human recipients of allogeneic HCT before the onset of Grade II-IV acute GVHD. Examination of target-organ tissues at the time of GVHD diagnosis indicates that the amount of RORγt + Th17 cells is significantly higher in severe GVHD. Greater accumulation of tissue-resident Th17 cells also correlates with the use of MTX- compared with Rapa-based GVHD prophylaxis, as well as a poor therapeutic response to glucocorticoids. RORγt is optimally suppressed by concurrent neutralization of TORC1 with Rapa and inhibition of STAT3 activation with S3I-201, supporting that mTOR- and STAT3-dependent pathways converge upon RORγt gene expression. Rapa-resistant T cell proliferation can be totally inhibited by STAT3 blockade during initial allosensitization. We conclude that STAT3 signaling and resultant Th17 tissue accumulation are closely associated with acute GVHD onset, severity, and treatment outcome. Future studies are needed to validate the association of STAT3 activity in acute GVHD. Novel GVHD prevention strategies that incorporate dual STAT3 and mTOR inhibition merit investigation.

Human regulatory T cells against minor histocompatibility antigens: ex vivo expansion for prevention of graft-versus-host disease.

Alloreactive donor T cells against host minor histocompatibility antigens (mHAs) cause graft-versus-host disease (GVHD) after marrow transplantation from HLA-identical siblings. We sought to identify and expand regulatory CD4 T cells (Tregs) specific for human mHAs in numbers and potency adequate for clinical testing. Purified Tregs from normal donors were stimulated by dendritic cells (DCs) from their HLA-matched siblings in the presence of interleukin 2, interleukin 15, and rapamycin. Male-specific Treg clones against H-Y antigens DBY, UTY, or DFFRY-2 suppressed conventional CD4 T cell (Tconv) response to the specific antigen. In the blood of 16 donors, we found a 24-fold (range, 8-fold to 39-fold) excess Tconvs over Tregs reactive against sibling mHAs. We expanded mHA-specific Tregs from 4 blood samples and 4 leukaphereses by 155- to 405-fold. Cultured Tregs produced allospecific suppression, maintained demethylation of the Treg-specific Foxp3 gene promoter, Foxp3 expression, and transforming growth factor ß production. The rare CD4 T conv and CD8 T cells in the end product were anergic. This is the first report of detection and expansion of potent mHA-specific Tregs from HLA-matched siblings in sufficient numbers for application in human transplant trials.

Ex vivo expansion of human Tregs specific for alloantigens presented directly or indirectly.

Adoptive transfer of regulatory T cells (Tregs) prevents GVHD in experimental animals. Because antigen activation drives Treg function, we measured the frequency, growth requirements, and function of alloantigen-specific (allospecific) Tregs from human blood. When alloantigen was presented directly, the precursor frequency of allo-specific Tregs in normal individuals was 1.02% (95% confidence interval [95% CI]: 0.65-1.59) and non-Tregs 1.56% (95% CI: 0.94-2.55). When alloantigen was presented indirectly, the frequency of specific Tregs was approximately 100-fold less. Purified Tregs were expanded with APCs, rapamycin, IL-2, and IL-15. In 12 days, allo-specific Tregs expanded 793-fold (95% CI: 480-1107), with duplication approximately every 24 hours. Purified allo-specific Tregs suppressed responses to specific alloantigen selectively and were approximately 100-fold more potent than polyspecific Tregs and nonexpanded Tregs. Allo-specific Tregs maintained high expression of Foxp3, Bcl-2, lymphoid homing receptor CD62L, and chemokine receptor CCR7, predicting sustained function and migration to lymphoid tissues in vivo. Allo-specific Tregs produced TGF-ß and IL-10 and expressed more cytoplasmic CTLA-4 compared with non-Tregs. These data provide a platform for the selective expansion of Tregs against major and possibly minor histocompatibility antigens and predict the feasibility of adoptive immunotherapy trials using Tregs with indirect allo-recognition for preventing GVHD while sparing GVL effects.

Monitoring changes in gene expression in renal ischemia-reperfusion in the rat.

BACKGROUND: Although acute renal failure (ARF) is a relatively common disorder with major morbidity and mortality, its molecular basis remains incompletely defined. The present study examined global gene expression in the well-characterized ischemia-reperfusion model of ARF using DNA microarray technology. METHODS: Male Wistar rats underwent bilateral renal ischemia (30 min) or sham operation, followed by reperfusion for 1, 2, 3 or 4 days. Plasma creatinine increased approximately fivefold over baseline, peaking on day 1. Renal total RNA was used to probe cDNA microarrays. RESULTS: Alterations in expression of 18 genes were identified by microarray analysis. Nine genes were up-regulated (ADAM2, HO-1, UCP-2, and thymosin beta4 in the early phase and clusterin, vanin1, fibronectin, heat-responsive protein 12 and FK506 binding protein in the established phase), whereas another nine were down-regulated (glutamine synthetase, cytochrome p450 IId6, and cyp 2d9 in the early phase and cyp 4a14, Xist gene, PPARgamma, alpha-albumin, uromodulin, and ADH B2 in the established phase). The identities of these 18 genes were sequence-verified. Changes in gene expression of ADAM2, cyp2d6, fibronectin, HO-1 and PPARgamma were confirmed by quantitative real-time polymerase chain reaction (PCR). ADAM2, cyp2d6, and PPARgamma have not previously been known to be involved in ARF. CONCLUSION: Using DNA microarray technology, we identified changes in expression of 18 genes during renal ischemia-reperfusion injury in the rat. We confirmed changes in five genes (fibronectin, ADAM2, cyp 2d6, HO-1 and PPARgamma) by quantitative real-time PCR. Several genes, not previously been identified as playing a role in ischemic ARF, may have importance in this disease.

Anti-CD28 monoclonal antibody therapy prevents chronic rejection of renal allografts in rats.

The effects of a signaling anti-CD28 mAb (JJ319), which interferes with the CD28-B7 T cell costimulation pathway thought to be involved in the development of chronic rejection of organ transplants, was investigated. Functional, morphologic, and molecular changes in rat renal allografts were examined up to 24 wk after placement. Control Lewis rats, recipients of F344 kidneys, received a single dose of a nonspecific mouse mAb intravenously on the day of transplantation (group 1). Group 2 animals were given anti-CD28 mAb in similar fashion. Group 3 animals were treated with a short course of cyclosporin A (CsA), and group 4 received both anti-CD 28 mAb and CsA. The majority (>95%) of animals in groups 2, 3, and 4 survived throughout the follow-up, compared with 28% in group 1 (P < 0.001). Group 2 and 4 recipients produced negligible proteinuria, whereas group 1 controls developed progressively increasing proteinuria after 4 wk and group 3 animals developed proteinuria by 24 wk. Allografts in groups 2 and 4 were morphologically unremarkable at 24 wk. Kidneys of group 1 animals rapidly developed changes of acute rejection, and those that survived long-term showed extensive glomerulosclerosis and interstitial fibrosis. Changes of early chronic rejection were noted in group 3 grafts. By reverse transcriptase-PCR, expression of representative inflammatory factors interferon-gamma and interleukin-10 were significantly elevated at 24 wk only in the surviving group 1 animals. A single dose of a signaling anti-CD28 mAb administered at transplantation or in combination with a short course of CsA significantly prolonged recipient survival, normalized function, and preserved the morphology of renal allografts in an established model of chronic rejection. These data support an important role for T cell costimulation in the evolution of the chronic process.

Influence of donor brain death on chronic rejection of renal transplants in rats.

The clinical observation that the results of kidney grafts from living donors (LD), regardless of relationship with the host, are consistently superior to those of cadavers suggests an effect of brain death (BD) on organ quality and function. This condition triggers a series of nonspecific inflammatory events that increase the intensity of the acute immunologic host responses after transplantation (Tx). Herein are examined the influences of this central injury on late changes in renal transplants in rats. A standardized model of BD was used. Groups included both allografts and isografts from normotensive brain dead donors and anesthetized LD. Renal function was determined every 4 wk after Tx, at which time representative grafts were examined by morphology and by reverse transcriptase-PCR. Long-term survival of brain-dead donor transplants was significantly less than LD grafts. Proteinuria was significantly elevated in recipients of grafts from BD donors versus LD controls as early as 6 wk postoperatively and increased progressively through the 52-wk follow up. These kidneys also showed consistently more intense and progressive deterioration in renal morphology. Changes in isografts from brain-dead donors were less marked and developed at a slower tempo than in allografts but were always greater than those in controls. The transcription of cytokines was significantly increased in all brain-dead donor grafts. Donor BD accelerates the progression of long-term changes associated with kidney Tx and is an important risk factor for chronic rejection. These results explain in part the clinically noted difference in long-term function between organs from cadaver and living sources.