Amphiregulin, ST2,and REG3α Biomarker Risk Algorithms as Predictors of Non-Relapse Mortality in Patients with Acute GVHD

Graft-vs-host disease (GVHD) is a major cause of non-relapse mortality (NRM) following allogeneic hematopoietic cell transplant (HCT). Algorithms containing either the GI GVHD biomarker amphiregulin (AREG) or a combination of two GI GVHD biomarkers, (ST2+REG3α) when measured at GVHD diagnosis are validated predictors of NRM risk, but have never been assessed in the same patients using identical statistical methods. We measured serum concentrations of ST2, REG3, and AREG by ELISA at the time of GVHD diagnosis in 715 patients divided by date of transplant into training (2004-2015) and validation (2015-2017) cohorts. The training cohort (n=341) was used to develop algorithms for predicting probability of 12 month NRM that contained all possible combinations of 1-3 biomarkers and a threshold corresponding to the concordance probability was used to stratify patients for risk of NRM. Algorithms were compared to each other based on several metrics including the area under the receiver operating characteristics curve (AUC), proportion of patients correctly classified, sensitivity, and specificity using only the validation cohort (n=374). All algorithms were strong discriminators of 12 month NRM, whether or not patients were systemically treated (n=321). An algorithm containing only ST2+REG3α had the highest AUC (0.757), correctly classified the most patients (75%), and more accurately risk stratified those who developed Minnesota standard risk GVHD and for patients who received post-transplant cyclophosphamide-based prophylaxis. An algorithm containing only AREG more accurately risk stratified patients with Minnesota high risk GVHD. Combining ST2, REG3α, and AREG into a single algorithm did not improve performance.

Bispecific CD33/CD123 targeted chimeric antigen receptor T cells for the treatment of acute myeloid leukemia

CD33 and CD123 are expressed on the surface of human acute myeloid leukemia blasts and other noncancerous tissues such as hematopoietic stem cells. On-target off-tumor toxicities may limit chimeric antigen receptor T cell therapies that target both CD33 and CD123. To overcome this limitation, we developed bispecific human CD33/CD123 chimeric antigen receptor (CAR) T cells with an "AND" logic gate. We produced novel CD33 and CD123 scFvs from monoclonal antibodies that bound CD33 and CD123 and activated T cells. Screening of CD33 and CD123 CAR T cells for cytotoxicity, cytokine production, and proliferation was performed, and we selected scFvs for CD33/CD123 bispecific CARs. The bispecific CARs split 4-1BB co-stimulation on one scFv and CD3ζ on the other. In vitro testing of cytokine secretion and cytotoxicity resulted in selecting bispecific CAR 1 construct for in vivo analysis. The CD33/CD123 bispecific CAR T cells were able to control acute myeloid leukemia (AML) in a xenograft AML mouse model similar to monospecific CD33 and CD123 CAR T cells while showing no on-target off-tumor effects. Based on our findings, human CD33/CD123 bispecific CAR T cells are a promising cell-based approach to prevent AML and support clinical investigation.

Pre-transplant and longitudinal changes in faecal microbiome characteristics are associated with subsequent development of chronic graft-versus-host disease

The role of the gastrointestinal microbiome in predisposing to chronic graft-versus-host disease (cGVHD), an immune-mediated haematopoietic cell transplant (HCT) complication, is not well defined. We examined the relationship of the host faecal microbiome with subsequent cGVHD development by analysing baseline stool samples as well as post-HCT changes in microbiome composition and metabolite pathway analyses. We analysed pre-transplant baseline samples from 11 patients who subsequently developed cGVHD compared to 13 controls who did not develop acute GVHD or cGVHD at any time. We found a significant differential abundance of multiple taxa at baseline between cGVHD versus controls, including the Actinobacteria phylum and Clostridium genus. A subgroup analysis of longitudinal samples within each patient revealed a greater loss of alpha diversity from baseline to post-engraftment in patients who subsequently developed cGVHD. Metabolic pathways analysis revealed that two pathways associated with short-chain fatty acid metabolism were enriched in cGVHD patient microbiomes: β-oxidation and acyl-CoA synthesis, and γ-aminobutyrate shunt. In contrast, a tryptophan catabolism pathway was enriched in controls. Our findings show a distinct pattern of baseline microbiome and metabolic capacity that may play a role in modulating alloreactivity in patients developing cGVHD. These findings support the therapeutic potential of microbiome manipulation for cGVHD prevention.

Amphiregulin as monitoring biomarker for life-threatening acute graft-versushost disease: secondary analysis of two prospective clinical trials

Not available.

Phase II Study of Myeloablative 7-8/8-Matched Allotransplantation with Post-Transplantation Cyclophosphamide, Tacrolimus, and Mycophenolate Mofetil

Graft-versus-host disease (GVHD) is the major toxicity of allogeneic hematopoietic cell transplantation (HCT). We hypothesized that a GVHD prophylaxis regimen of post-transplantation cyclophosphamide (PTCy), tacrolimus (Tac), and mycophenolate mofetil (MMF) would be associated with incidences of acute and chronic GVHD in patients receiving a matched or single antigen mismatched HCT. This Phase II study was conducted at the University of Minnesota using a myeloablative regimen of either total body irradiation (TBI) at a total dose of 1320 cGy, administered in 165-cGy fractions, twice daily from day -4 to day -1, or busulfan (Bu) 3.2 mg/kg daily (cumulative area under the curve, 19,000 to 21,000 μmol/min/L) plus fludarabine (Flu) 40 mg/m2 once daily on days -5 to -2, followed by a GVHD prophylaxis regimen of PTCy 50 mg/kg on days +3 and +4, Tac, and MMF beginning on day +5. The primary endpoint was the cumulative incidence of chronic GVHD necessitating systemic immunosuppression (IST) at 1 year post-transplantation. Between March 2018 and May 2022, we enrolled 125 pediatric and adult patients, with a median follow-up of 813 days. The incidence of chronic GVHD necessitating systemic IST at 1 year was 5.5%. The rate of grade II-IV acute GVHD was 17.1%, and that of grade III-IV acute GVHD was 5.5%. Two-year overall survival was 73.7%, and 2-year graft-versus-host disease-free, relapse-free survival was 52.2%. The 2-year cumulative incidence of nonrelapse mortality was 10.2%, and the rate of relapse was 39.1%. There was no statistically significant difference in survival outcomes between recipients of matched donor transplants versus recipients of 7/8 matched donor transplants. Our data show that myeloablative HCT with PTCy/Tac/MMF results in an extremely low incidence of severe acute and chronic GVHD in well-matched allogeneic HCT.

Phase II, Open-Label Clinical Trial of Urinary-Derived Human Chorionic Gonadotropin/Epidermal Growth Factor for Life-Threatening Acute Graft-versus-Host Disease

Treatments that aid inflammation resolution, immune tolerance, and epithelial repair may improve outcomes beyond high-dose corticosteroids and other broad immunosuppressants for life-threatening acute graft-versus-host disease (aGVHD). We studied the addition of urinary-derived human chorionic gonadotropin/epidermal growth factor (uhCG/EGF; Pregnyl; Organon, Jersey City, NJ) to standard aGVHD therapy in a prospective Phase II clinical trial (ClinicalTrials.gov identifier NCT02525029). Twenty-two patients with Minnesota (MN) high-risk aGVHD received methylprednisolone 48 mg/m2/day plus 2000 units/m2 of uhCG/EGF s.c. every other day for 1 week. Patients requiring second-line aGVHD therapy received uhCG/EGF 2000 to 5000 units/m2 s.c. every other day for 2 weeks plus standard of care immunosuppression (physician's choice). Responding patients were eligible to receive maintenance doses twice weekly for 5 weeks. Immune cell subsets in peripheral blood were evaluated by mass cytometry and correlated with plasma amphiregulin (AREG) level and response to therapy. Most patients had stage 3-4 lower gastrointestinal tract GVHD (52%) and overall grade III-IV aGVHD (75%) at time of enrollment. The overall proportion of patients with a response at day 28 (primary endpoint) was 68% (57% with complete response, 11% with partial response). Nonresponders had higher baseline counts of KLRG1+ CD8 cells and T cell subsets expressing TIM-3. Plasma AREG levels remained persistently elevated in nonresponders and correlated with AREG expression on peripheral blood T cells and plasmablasts. The addition of uhCG/EGF to standard therapy is a feasible supportive care measure for patients with life-threatening aGVHD. As a commercially available, safe, and inexpensive drug, uhCG/EGF added to standard therapy may reduce morbidity and mortality from severe aGVHD and merits further study.

Phase II Study of Myeloablative 8/8- or 7/8-Matched Allotransplantation with Post-Transplant Cyclophosphamide, Tacrolimus, and Mycophenolate Mofetil: Marked Reduction in GVHD Risk Without Increased Relapse Risk Compared to Historical Cyclosporine/Methotrexate

Introduction

Graft-versus host disease (GVHD) is a major limitation to the success of allogeneic hematopoietic cell transplant (HCT). We hypothesized that the GVHD prophylaxis regimen of post-transplant cyclophosphamide (PTCy), tacrolimus (Tac) and mycophenolate mofetil (MMF) would reduce the incidence of GVHD in patients receiving a matched or single antigen mismatched HCT without an increase in risk of malignant relapse.

Methods

This is a phase II study conducted at the University of Minnesota using a myeloablative regimen of either: (A) total body irradiation (TBI, total dose 1320 cGy, administered in 165 cGy fractions, twice a day from days -4 to -1) or (B) Busulfan 3.2mg/kg daily (cumulative AUC 19,000 - 21,000 μmol/min/L) plus fludarabine 160mg/m2 days -5 to -2, followed by a GVHD prophylaxis regimen of PTCy (50mg/kg days +3 and +4), Tac and MMF (beginning day +5). The primary endpoint is cumulative incidence of chronic GVHD requiring systemic immunosuppression at 1-year post-transplant. We compared results to our previous myeloablative protocol for matched donors utilizing cyclosporine/methotrexate (CSA/MTX) GVHD prophylaxis.

Results

From March 2018 - June 2022, we enrolled and treated 125 pediatric and adult patients with a median follow up of 472 days. Grade II-IV acute GVHD occurred in 16% (95% confidence interval (CI): 9-23%); Grade III-IV acute GVHD was 4% (CI: 0-8%). No patients experienced grade IV GVHD, and there were no deaths due to GVHD before day 100. Only 3 developed chronic GVHD requiring immune suppression, (4%, CI: 0-8%). Two-year overall survival (OS) was 80% (CI: 69-87%), and (graft-versus-host disease-free, relapse-free survival) GRFS 57% (CI: 45-67%), both higher than historical CSA/MTX. The incidence of grade II-IV aGVHD, cGVHD, and NRM were all lower with PTCy/Tac/MMF compared to historical CSA/MTX. One-quarter (25%) experienced relapse (CI: 15-36%) similar to historical CSA/MTX. There was no statistically significant difference in survival outcomes between recipients of matched versus 7/8 donors.

Conclusion

Myeloablative HCT with PTCy/Tac/MMF results in extremely low incidence of severe acute or chronic GVHD, the primary endpoint of this clinical trial. Relapse risk is not increased compared to our historical CSA/MTX cohort.

Human Effectors of Acute and Chronic GVHD Overexpress CD83 and Predict Mortality

PURPOSE

Acute and chronic GVHD remain major causes of transplant-related morbidity and mortality (TRM) after allogeneic hematopoietic cell transplantation (alloHCT). We have shown CD83 chimeric antigen receptor (CAR) T cells prevent GVHD and kill myeloid leukemia cell lines. In this pilot study, we investigate CD83 expression on GVHD effector cells, correlate these discoveries with clinical outcomes, and evaluate critical therapeutic implications for transplant recipients.

EXPERIMENTAL DESIGN

CD83 expression was evaluated among circulating CD4+ T cells, B-cell subsets, T follicular helper (Tfh) cells, and monocytes from patients with/without acute or chronic GVHD (n = 48 for each group), respectively. CD83 expression was correlated with survival, TRM, and relapse after alloHCT. Differential effects of GVHD therapies on CD83 expression was determined.

RESULTS

CD83 overexpression on CD4+ T cells correlates with reduced survival and increased TRM. Increased CD83+ B cells and Tfh cells, but not monocytes, are associated with poor posttransplant survival. CD83 CAR T eliminate autoreactive CD83+ B cells isolated from patients with chronic GVHD, without B-cell aplasia as observed with CD19 CAR T. We demonstrate robust CD83 antigen density on human acute myeloid leukemia (AML), and confirm potent antileukemic activity of CD83 CAR T in vivo, without observed myeloablation.

CONCLUSIONS

CD83 is a promising diagnostic marker of GVHD and warrants further investigation as a therapeutic target of both GVHD and AML relapse after alloHCT.

Dual JAK2/Aurora kinase A inhibition prevents human skin graft rejection by allo-inactivation and ILC2-mediated tissue repair

Prevention of allograft rejection often requires lifelong immune suppression, risking broad impairment of host immunity. Nonselective inhibition of host T cell function increases recipient risk of opportunistic infections and secondary malignancies. Here we demonstrate that AJI-100, a dual inhibitor of JAK2 and Aurora kinase A, ameliorates skin graft rejection by human T cells and provides durable allo-inactivation. AJI-100 significantly reduces the frequency of skin-homing CLA⁺ donor T cells, limiting allograft invasion and tissue destruction by T effectors. AJI-100 also suppresses pathogenic Th1 and Th17 cells in the spleen yet spares beneficial regulatory T cells. We show dual JAK2/Aurora kinase A blockade enhances human type 2 innate lymphoid cell (ILC2) responses, which are capable of tissue repair. ILC2 differentiation mediated by GATA3 requires STAT5 phosphorylation (pSTAT5) but is opposed by STAT3. Further, we demonstrate that Aurora kinase A activation correlates with low pSTAT5 in ILC2s. Importantly, AJI-100 maintains pSTAT5 levels in ILC2s by blocking Aurora kinase A and reduces interference by STAT3. Therefore, combined JAK2/Aurora kinase A inhibition is an innovative strategy to merge immune suppression with tissue repair after transplantation.

High Cutaneous Amphiregulin Expression Predicts Fatal Acute Graft‐versus‐Host Disease

Background

Amphiregulin (AREG) is increased in circulation in acute graft‐versus‐host disease (aGVHD) and is associated with poor steroid response and lower survival. The expression of AREG in aGVHD target organs and its association with clinical outcomes are unknown.

Methods

We performed AREG immunohistochemical staining on skin specimens from 67 patients with aGVHD between the years 2010 and 2015. Two blinded reviewers assessed AREG expression and scored specimens with a semiquantitative scale ranging from 0 (absent) to 4 (most intense).

Results

Median AREG score of aGVHD cases was 3. Sixteen of 67 (23.9%) aGVHD cases had an AREG >3. High skin AREG expression (>3 vs. ≤3) was associated with increased overall clinical grade of aGVHD (52.9% vs. 33.4% clinical grade III‐IV, p = 0.02), reduced 3‐year overall survival (OS; 13% vs. 61%, p < 0.01), and increased 3‐year non‐relapse mortality (NRM; 56% vs. 20%, p = 0.05).

Conclusion

High skin AREG immunohistochemical expression is associated with high clinical grade aGVHD, poor OS, and increased NRM.

Association of CD34 Cell Dose with 5-Year Overall Survival after Peripheral Blood Allogeneic Hematopoietic Cell Transplantation in Adults with Hematologic Malignancies

Higher CD34 cell dose is associated with improved engraftment after peripheral blood allogeneic hematopoietic stem cell transplantation (alloHCT) but also may increase the risk of long-term complications, such as graft-versus-host disease (GVHD). Prior studies examining the relationship between CD34 cell dose and long-term survival outcomes have yielded conflicting results. In this study, we sought to clarify the prognostic impact of CD34 cell dose by examining a large contemporary cohort of patients undergoing alloHCT with a matched sibling peripheral blood stem cell (PBSC) donor. We retrospectively examined the impact of CD34 cell dose on overall survival (OS), neutrophil engraftment, platelet engraftment, treatment-related mortality, relapse, acute GVHD grade II-IV and III-IV, and chronic GVHD in 377 consecutive patients undergoing alloHCT with a PBSC graft source from a matched sibling donor at the University of Minnesota between 2002 and 2015. The patients were classified into 3 groups based on the tertile (T) of CD34 cell dose received: T1, <5 × 10⁶ cells/kg; T2, 5 to 7.5 × 10⁶ cells/kg; and T3, ≥7.5 × 10⁶ cells/kg. Multivariable analysis demonstrated that high CD34 cell dose was associated with superior 5-year OS (hazard ratio [HR], 0.57; P = .01) and more rapid platelet engraftment (HR, 1.70; P < .01). Higher CD34 cell dose also was associated with improved absolute neutrophil count engraftment (T2: HR, 1.54; T3: HR, 1.52; P < .01). There was no association between CD34 cell dose and TRM or relapse at 5 years. Although higher CD34 cell dose was not associated with acute GVHD grade II-IV, it was associated with chronic GVHD (T2: HR, 1.68; T3: HR, 1.50; P = .04). Our data indicate that higher CD34 cell dose (>7.5 × 10⁶/kg) is associated with superior OS at 5 years and improved engraftment but carries an increased risk of chronic GVHD. These data support a target CD34 cell dose goal of 7.5 × 10⁶/kg for sibling PBSC graft donors.

High incidence of thromboembolism in patients with chronic GVHD: association with severity of GVHD and donor-recipient ABO blood group

Chronic graft-versus-host disease (cGVHD) after allogeneic hematopoietic cell transplantation (HCT) is associated with systemic inflammation and endothelial dysfunction, increasing risk for thromboembolic events (TEE). In 145 adult recipients who developed cGVHD after a matched sibling or umbilical cord blood donor HCT from 2010 to 2018, 32(22%) developed at least 1 TEE event, and 14(10%) developed 2 TEE events. The 5-year cumulative incidence of TEE was 22% (95% CI, 15–29%) with a median time from cGVHD to TEE of 234 days (range, 12–2050). Median time to the development of LE DVT or PE was 107 (range, 12–1925) compared to 450 days (range, 158–1300) for UE DVT. Cumulative incidence of TEE was 9% (95% CI, 0–20%), 17% (95% CI, 9–25%), and 38% (95% CI, 22–55%) in those with mild, moderate, and severe GVHD, respectively. Higher risk for TEE was associated with cGVHD severity (hazard ratio [HR] 4.9, [95% CI, 1.1–22.0]; p = 0.03), non-O-donor to recipient ABO match compared to O-donor to O-recipient match (HR 2.7, [95% CI, 1.0–7.5]; p = 0.053), and personal history of coronary artery disease (HR 2.4, [95% CI, 1.1–5.3]; p = 0.03). TEE was not associated with 2-year non-relapse mortality or 5-year overall survival.

Patients with chronic GVHD after allogeneic hematopoietic cell transplantation are at high risk for thromboembolic events occurring years after diagnosis.

More severe chronic GVHD, non-O donor-recipient ABO compared to O-O match and personal history of coronary artery disease are associated with higher risk of thromboembolic events.

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

PURPOSE

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.

PATIENTS AND METHODS

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.

RESULTS

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.

CONCLUSIONS

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.

Current Concepts and Advances in Graft-Versus-Host Disease Immunology

Worldwide, each year over 30,000 patients undergo an allogeneic hema-topoietic stem cell transplantation with the intent to cure high-risk hematologic malignancy, immunodeficiency, metabolic disease, or a life-threatening bone marrow failure syndrome. Despite substantial advances in donor selection and conditioning regimens and greater availability of allograft sources, transplant recipients still endure the morbidity and mortality of graft-versus-host disease (GVHD). Herein, we identify key aspects of acute and chronic GVHD pathophysiology, including host/donor cell effectors, gut dysbiosis, immune system and cytokine imbalance, and the interface between inflammation and tissue fibrosis. In particular, we also summarize the translational application of this heightened understanding of immune dysregulation in the design of novel therapies to prevent and treat GVHD.

Outcomes of chronic graft-versus-host disease following matched sibling donor versus umbilical cord blood transplant

We compared chronic graft-versus-host disease (cGvHD) following umbilical cord blood (UCBT) and matched sibling donor peripheral blood transplant (MSD). 145 patients (2010-2017) with cGvHD after MSD (n = 104) and UCBT (n = 41) were included. Prior acute GvHD was less frequent in MSD (55% vs. 85%; p = 0.01). Severe cGvHD (32% vs. 15%, p = 0.01) and de-novo onset (45% vs. 15%, p < 0.01) were more frequent following MSD. Liver was more frequently involved in MSD recipients (38% vs. 6%); and GI in UCBT (33% vs. 63%), both p < 0.01. Overall response (CR + PR) was similar between both cohorts. 2-year CR was higher in UCBT (14% vs 33%, p = 0.02). Karnofsky score (KPS) ≥ 90 at cGvHD diagnosis was associated with higher odds of response (95%CI: 1.42-10, p < 0.01). The cumulative incidence of durable discontinuation of immune-suppressive therapy, failure-free survival (FFS) and NRM at 2-years were similar between cohorts. KPS < 90 (95%CI: 3.1-24.9, p < 0.01) and platelets <100 × 10e9/L (95%CI: 1.25-10, p = 0.01) were associated with higher risk of NRM. UCBT patients were more likely to have a prior acute GvHD, less severe cGvHD and more likely to attain CR. Despite differences, both cohorts had similar NRM and FFS. High-risk groups, including those with platelets <100 × 10e9/L and KPS < 90, need careful monitoring and intensified therapy.

Human CD83-targeted chimeric antigen receptor T cells prevent and treat graft-versus-host disease

Graft-versus-host disease (GVHD) remains an important cause of morbidity and mortality after allogeneic hematopoietic cell transplantation (allo-HCT). For decades, GVHD prophylaxis has included calcineurin inhibitors, despite their incomplete efficacy and impairment of graft-versus-leukemia (GVL). Distinct from pharmacologic immune suppression, we have developed what we believe is a novel, human CD83-targeted chimeric antigen receptor (CAR) T cell for GVHD prevention. CD83 is expressed on allo-activated conventional CD4+ T cells (Tconvs) and proinflammatory dendritic cells (DCs), which are both implicated in GVHD pathogenesis. Human CD83 CAR T cells eradicate pathogenic CD83+ target cells, substantially increase the ratio of regulatory T cells (Tregs) to allo-activated Tconvs, and provide durable prevention of xenogeneic GVHD. CD83 CAR T cells are also capable of treating xenogeneic GVHD. We show that human acute myeloid leukemia (AML) expresses CD83 and that myeloid leukemia cell lines are readily killed by CD83 CAR T cells. Human CD83 CAR T cells are a promising cell-based approach to preventing 2 critical complications of allo-HCT - GVHD and relapse. Thus, the use of human CD83 CAR T cells for GVHD prevention and treatment, as well as for targeting CD83+ AML, warrants clinical investigation.

Less Can Be More When Targeting Interleukin-6-Mediated Cytokine Release Syndrome in Coronavirus Disease 2019

Coronavirus disease 2019 pandemic caused by severe acute respiratory syndrome-coronavirus-2 is a worldwide public health emergency that will have a lasting generational impact in terms of mortality and economic devastation. Social distancing to prevent viral transmission and supportive care of infected patients are the main interventions now available. This global health crisis therefore merits innovative therapies. Cytokine release syndrome mediated by interleukin-6 is a critical driver of coronavirus disease 2019 mortality. Herein, we review and discuss key immunologic effects of direct interleukin-6 blockade, downstream nonselective Janus kinase inhibition, and selective Janus kinase 2 suppression to treat coronavirus disease 2019-related cytokine release syndrome. We provide evidence that selective targeting of interleukin-6 or Janus kinase 2 is well informed by existing data. This contrasts with broad, nonselective blockade of Janus kinase-mediated signaling, which would inhibit both deleterious and beneficial cytokines, as well as critical host antiviral immunity.

Metabolic reprogramming augments potency of human pSTAT3-inhibited iTregs to suppress alloreactivity

Immunosuppressive donor Tregs can prevent graft-versus-host disease (GVHD) or solid-organ allograft rejection. We previously demonstrated that inhibiting STAT3 phosphorylation (pSTAT3) augments FOXP3 expression, stabilizing induced Tregs (iTregs). Here we report that human pSTAT3-inhibited iTregs prevent human skin graft rejection and xenogeneic GVHD yet spare donor antileukemia immunity. pSTAT3-inhibited iTregs express increased levels of skin-homing cutaneous lymphocyte-associated antigen, immunosuppressive GARP and PD-1, and IL-9 that supports tolerizing mast cells. Further, pSTAT3-inhibited iTregs significantly reduced alloreactive conventional T cells, Th1, and Th17 cells implicated in GVHD and tissue rejection and impaired infiltration by pathogenic Th2 cells. Mechanistically, pSTAT3 inhibition of iTregs provoked a shift in metabolism from oxidative phosphorylation (OxPhos) to glycolysis and reduced electron transport chain activity. Strikingly, cotreatment with coenzyme Q10 restored OxPhos in pSTAT3-inhibited iTregs and augmented their suppressive potency. These findings support the rationale for clinically testing the safety and efficacy of metabolically tuned, human pSTAT3-inhibited iTregs to control alloreactive T cells.

Sole Upfront Therapy with Beclomethasone and Budesonide for Upper Gastrointestinal Acute Graft-versus-Host Disease

Systemic glucocorticoids remain the standard treatment for gastrointestinal (GI) acute graft-versus-host disease (aGVHD) despite their toxicity and incomplete efficacy. Controlled trials have tested poorly absorbable steroids as adjuncts with systemic glucocorticoids, but only small case series have reported treatment with poorly absorbed beclomethasone dipropionate (BDP) and budesonide (BUD) alone. Our team has adopted the practice of administering BDP or BDP+BUD without systemic glucocorticoids as first-line therapy for isolated upper GI (UGI) aGVHD. We report results in 76 patients treated with BDP alone and in 81 patients treated with BDP+BUD, with allocation by physician choice. Almost all patients received peripheral blood stem cells (92%) from a fully HLA-matched related or unrelated donor (80%) after myeloablative conditioning (76%) for acute leukemia (49%), myelodysplastic syndrome (17%), non-Hodgkin lymphoma (14%), or another hematopoietic disorders (20%). After 28 days of treatment with BDP, 46% of the patients had a complete response (CR) and 10% had a partial response (PR); after 200 days, 61 (80%) patients were alive, 34% maintained a CR, and 3% maintained a PR, whereas 53% required additional immunosuppression (IS). After 28 days of treatment with BDP+BUD, 67% had a CR and 10% a PR; after 200 days, 74 (91%) patients were alive, 46% maintained a CR, and 2% maintained a PR, whereas 43% required additional IS. Among the entire cohort of 157 patients, 66 (42%) were treated successfully without systemic glucocorticoids. This study reports the efficacy of poorly absorbable steroids alone for patients with isolated UGI aGVHD. Prospective trials should test for the potential advantages of BDP and BUD use over systemic glucocorticoids.

Stress responses, M2 macrophages, and a distinct microbial signature in fatal intestinal acute graft-versus-host disease

Steroid-refractory intestinal acute graft-versus-host disease (aGVHD) is a frequently fatal condition with little known about mechanisms driving failed steroid responses in gut mucosa. To uncover novel molecular insights in steroid-refractory aGVHD, we compared gene expression profiles of rectosigmoid biopsies from patients at diagnosis of clinical stage 3-4 lower intestinal aGVHD (N=22), to repeat biopsies when the patients became steroid refractory (N=22), and normal controls (N=10). We also performed single gene analyses of factors associated with tolerance (programmed death ligand-1 [PDL1], indoleamine 2,3 dioxygenase [IDO1], and T cell immunoreceptor with Ig and ITIM domains [TIGIT]) and found that significantly higher expression levels of these aGVHD inhibitory genes (PDL1, IDO1, TIGIT) at aGVHD onset became decreased in the steroid-refractory state. We examined genes triggered by microbial ligands to stimulate gut repair, amphiregulin (AREG) and the aryl hydrocarbon receptor (AhR), and found that both AREG and AhR gene expression levels were increased at aGVHD onset and remained elevated in steroid-refractory aGVHD. We also identified higher expression levels of metallothioneines, metal-binding enzymes induced in stress responses, and M2 macrophage genes in steroid-refractory aGVHD. We observed no differences in T-cell subsets between onset and steroid-refractory aGVHD. Patients with a rapidly fatal course showed greater DNA damage and a distinct microbial signature at aGVHD onset, whereas patients with more prolonged survival exhibited a gene expression profile consistent with activation of Smoothened. Our results extend the paradigm beyond T cell-centric therapies for steroid-refractory GI aGVHD and highlight new mechanisms for therapeutic exploration.

The IL-12 Cytokine and Receptor Family in Graft-vs.-Host Disease

Allogeneic hematopoietic cell transplantation (allo-HCT) is performed with curative intent for high- risk blood cancers and bone marrow failure syndromes; yet the development of acute and chronic graft-vs.-host disease (GVHD) remain preeminent causes of death and morbidity. The IL-12 family of cytokines is comprised of IL-12, IL-23, IL-27, IL-35, and IL-39. This family of cytokines is biologically distinct in that they are composed of functional heterodimers, which bind to cognate heterodimeric receptor chains expressed on T cells. Of these, IL-12 and IL-23 share a common β cytokine subunit, p40, as well as a receptor chain: IL-12Rβ1. IL-12 and IL-23 have been documented as proinflammatory mediators of GVHD, responsible for T helper 1 (Th1) differentiation and T helper 17 (Th17) stabilization, respectively. The role of IL-27 is less defined, seemingly immune suppressive via IL-10 secretion by Type 1 regulatory (Tr1) cells yet promoting inflammation through impairing CD4⁺ T regulatory (Treg) development and/or enhancing Th1 differentiation. More recently, IL-35 was described as a potent anti-inflammatory agent produced by regulatory B and T cells. The role of the newest member, IL-39, has been implicated in proinflammatory B cell responses but has not been explored in the context of allo-HCT. This review is directed at discussing the current literature relevant to each IL-12-family cytokine and cognate receptor engagement, as well as the consequential downstream signaling implications, during GVHD pathogenesis. Additionally, we will provide an overview of translational strategies targeting the IL-12 family cytokines, their receptors, and subsequent signal transduction to control GVHD.

HDAC6 selective inhibition of melanoma patient T-cells augments anti-tumor characteristics

Background

Therapies targeting anti-tumor T-cell responses have proven successful in the treatment of a variety of malignancies. However, as most patients still fail to respond, approaches to augment immunotherapeutic efficacy are needed. Here, we investigated the ability of histone deacetylase 6 (HDAC6)-selective inhibitors to decrease immunosuppression and enhance immune function of melanoma patient T-cells in ex vivo cultures.

Methods

T-cells were harvested from peripheral blood or tumor biopsies of metastatic melanoma patients and cultured in the presence of pan-, class-specific or class-selective histone deacetylase (HDAC) inhibitors. Changes in cytokine production were evaluated by Luminex and intracellular flow cytometry staining. Expression of surface markers, transcription factors, protein phosphorylation, and cell viability were assessed by flow cytometry. Changes in chromatin structure were determined by ATAC-seq.

Results

T-cell viability was impaired with low doses of pan-HDAC inhibitors but not with specific or selective HDAC inhibitors. The HDAC6-selective inhibitors ACY-1215 (ricolinostat) and ACY-241 (citarinostat) decreased Th2 cytokine production (i.e. IL-4, IL-5, IL-6, IL-10 and IL-13). Expansion of peripheral blood T-cells from melanoma patients in the presence of these inhibitors resulted in downregulation of the Th2 transcription factor GATA3, upregulation of the Th1 transcription factor T-BET, accumulation of central memory phenotype T-cells (CD45RA-CD45RO + CD62L + CCR7+), reduced exhaustion-associated phenotypes (i.e. TIM3 + LAG3 + PD1+ and EOMES+PD1+), and enhanced killing in mixed lymphocyte reactions. The frequency, FOXP3 expression, and suppressive function of T regulatory cells (Tregs) were decreased after exposure to ACY-1215 or ACY-241. Higher frequencies of T-cells expressing CD107a + IFNγ+ and central memory markers were observed in melanoma tumor-infiltrating lymphocytes (TIL), which persisted after drug removal and further expansion. After ACY-1215 treatment, increased chromatin accessibility was observed in regions associated with T-cell effector function and memory phenotypes, while condensed chromatin was found in regions encoding the mTOR downstream molecules AKT, SGK1 and S6K. Decreased phosphorylation of these proteins was observed in ACY-1215 and ACY-241-treated T-cells. AKT- and SGK1-specific inhibition recapitulated the increase in central memory frequency and decrease in IL-4 production, respectively, similar to the observed effects of HDAC6-selective inhibition.

Conclusions

HDAC6-selective inhibitors augmented melanoma patient T-cell immune properties, providing a rationale for translational investigation assessing their potential clinical efficacy.

Electronic supplementary material

The online version of this article (10.1186/s40425-019-0517-0) contains supplementary material, which is available to authorized users.

Inhibition of Human Dendritic Cell ER Stress Response Reduces T Cell Alloreactivity Yet Spares Donor Anti-tumor Immunity

Acute graft- vs. -host disease (GVHD) is an important cause of morbidity and death after allogeneic hematopoietic cell transplantation (HCT). We identify a new approach to prevent GVHD that impairs monocyte-derived dendritic cell (moDC) alloactivation of T cells, yet preserves graft- vs.-leukemia (GVL). Exceeding endoplasmic reticulum (ER) capacity results in a spliced form of X-box binding protein-1 (XBP-1s). XBP-1s mediates ER stress and inflammatory responses. We demonstrate that siRNA targeting XBP-1 in moDCs abrogates their stimulation of allogeneic T cells. B-I09, an inositol-requiring enzyme-1α (IRE1α) inhibitor that prevents XBP-1 splicing, reduces human moDC migration, allo-stimulatory potency, and curtails moDC IL-1β, TGFβ, and p40 cytokines, suppressing Th1 and Th17 cell priming. B-I09-treated moDCs reduce responder T cell activation via calcium flux without interfering with regulatory T cell (Treg) function or GVL effects by cytotoxic T lymphocytes (CTL) and NK cells. In a human T cell mediated xenogeneic GVHD model, B-I09 inhibition of XBP-1s reduced target-organ damage and pathogenic Th1 and Th17 cells without impacting donor Tregs or anti-tumor CTL. DC XBP-1s inhibition provides an innovative strategy to prevent GVHD and retain GVL.

Decreased Suppression and Increased Phosphorylated STAT3 in Regulatory T Cells are Associated with Benefit from Adjuvant PD-1 Blockade in Resected Metastatic Melanoma

PURPOSE

PD-1 blockade induces durable responses in patients with metastatic melanoma and prolongs relapse-free survival in patients with resected melanoma; however, current biomarkers do not consistently associate with patient responses. In this study, we investigated the impact of nivolumab therapy on peripheral blood regulatory T cells (Treg) and its relation to patient outcomes.

EXPERIMENTAL DESIGN

Peripheral blood Tregs and conventional CD4⁺ T cells from patients with resected high-risk melanoma treated with adjuvant nivolumab were assessed for gene expression changes by RNA-seq. Percentages of circulating Tregs and phosphorylated-STAT3 (pSTAT3) expression levels were assessed by flow cytometry and validated in an independent cohort of active disease patients. Suppressive function of Tregs was assessed in allogeneic mixed lymphocyte reactions.

RESULTS

Tregs from non-relapse patients had increased expression of proliferation associated genes. An increase in the proportion of circulating Tregs and pSTAT3 expression and a reduction in Treg-suppressive capacity were observed in non-relapsing, but not relapsing patient samples 13 weeks after starting treatment. In vitro blockade of PD-1 increased Treg percentages and pSTAT3 expression, and reduced Treg-suppressive function. PD-1 blockade also led to IL10 production by T cells, resulting in higher Treg proliferation. The addition of a STAT3 inhibitor ameliorated the increase in Tregs, enhanced suppressive function, and decreased T-cell IL10 production in vitro.

CONCLUSIONS

These results demonstrate that induction of pSTAT3, reduced suppressive function, and a paradoxical increase in Treg proliferation are novel correlates of patient benefit from PD-1 blockade.

Targeting Aurora kinase A and JAK2 prevents GVHD while maintaining Treg and antitumor CTL function

Graft-versus-host disease (GVHD) is a leading cause of nonrelapse mortality after allogeneic hematopoietic cell transplantation. T cell costimulation by CD28 contributes to GVHD, but prevention is incomplete when targeting CD28, downstream mammalian target of rapamycin (mTOR), or Aurora A. Likewise, interleukin-6 (IL-6)-mediated Janus kinase 2 (JAK2) signaling promotes alloreactivity, yet JAK2 inhibition does not eliminate GVHD. We provide evidence that blocking Aurora A and JAK2 in human T cells is synergistic in vitro, prevents xenogeneic GVHD, and maintains antitumor responses by cytotoxic T lymphocytes (CTLs). Aurora A/JAK2 inhibition is immunosuppressive but permits the differentiation of inducible regulatory T cells (iT_regs) that are hyperfunctional and CD39 bright and efficiently scavenge adenosine triphosphate (ATP). Increased iT_reg potency is primarily a function of Aurora A blockade, whereas JAK2 inhibition suppresses T helper 17 (T_H17) differentiation. Inhibiting either Aurora A or JAK2 significantly suppresses T_H1 T cells. However, CTL generated in vivo retains tumor-specific killing despite Aurora A/JAK2 blockade. Thus, inhibiting CD28 and IL-6 signal transduction pathways in donor T cells can increase the T_reg/T_conv ratio, prevent GVHD, and preserve antitumor CTL.

IL-2 promotes early Treg reconstitution after allogeneic hematopoietic cell transplantation

Graft-versus-host disease (GvHD) remains a major cause of transplant-related mortality. Interleukin-2 (IL-2) plus sirolimus (SIR) synergistically reduces acute GvHD in rodents and promotes regulatory T cells. This phase II trial tested the hypothesis that IL-2 would facilitate STAT5 phosphorylation in donor T cells, expand regulatory T cells, and ameliorate GvHD. Between 16th April 2014 and 19th December 2015, 20 patients received IL-2 (200,000 IU/m2 thrice weekly, days 0 to +90) with SIR (5-14 ng/mL) and tacrolimus (TAC) (3-7 ng/mL) after HLA-matched related or unrelated allogeneic hematopoietic cell transplantation (HCT). The study was designed to capture an increase in regulatory T cells from 16.0% to more than 23.2% at day +30. IL-2/SIR/TAC significantly increased regulatory T cells at day +30 compared to our published data with SIR/TAC (23.8% vs. 16.0%, P=0.0016; 0.052 k/uL vs. 0.037 k/uL, P=0.0163), achieving the primary study end point. However, adding IL-2 to SIR/TAC led to a fall in regulatory T cells by day +90 and did not reduce acute or chronic GvHD. Patients who discontinued IL-2 before day +100 showed a suggested trend toward less grade II-IV acute GvHD (16.7% vs. 50%, P=0.1475). We surmise that the reported accumulation of IL-2 receptors in circulation over time may neutralize IL-2, lead to progressive loss of regulatory T cells, and offset its clinical efficacy. The amount of phospho-STAT3+ CD4+ T cells correlated with donor T-cell activation and acute GvHD incidence despite early T-cell STAT5 phosphorylation by IL-2. Optimizing IL-2 dosing and overcoming cytokine sequestration by soluble IL-2 receptor may sustain lasting regulatory T cells after transplantation. However, an approach to target STAT3 is needed to enhance GvHD prevention. (clinicaltrials.gov identifier: 01927120).

Human Dendritic Cells Mitigate NK-Cell Dysfunction Mediated by Nonselective JAK1/2 Blockade

Janus kinase (JAK) inhibitors have achieved positive responses in myeloproliferative neoplasms, but at the expense of decreased natural killer (NK) cell numbers and compromised function. Selective JAK2 inhibition may also have a role in preventing and treating graft-versus-host disease after allogeneic hematopoietic stem cell transplantation. Although JAK inhibitors can impair monocyte-derived dendritic cell (moDC) activation and function and suppress effector T-cell responses, the effects on NK cells and the relevant mechanisms remain undefined. Using common γ_c cytokines and distinct human dendritic cell (DC) subtypes, we compared the effects of a JAK2-specific (TG101348) with a less selective JAK1/2 (ruxolitinib) inhibitor on NK-cell activation and function. Ruxolitinib treatment completely blocked IL2, IL15, and DC-mediated STAT5 phosphorylation, along with the capacity of NK cells to secrete IFNγ or lyse NK cell-sensitive targets. Only NK-cell proliferation stimulated by moDCs resisted ruxolitinib treatment. In contrast, TG101348 treatment of stimulated NK cells resulted in far less functional compromise. TG101348 completely inhibited only soluble IL15-mediated STAT5 phosphorylation, which Langerhans-type DCs (LCs), presenting membrane-bound IL15 in trans, could salvage. These results demonstrate that ruxolitinib's nonselective inhibition of JAK1/2 results in profound NK-cell dysfunction by blocking downstream pSTAT5, hence providing a persuasive rationale for the development of selective JAK2 inhibitors for immunotherapeutic applications. Cancer Immunol Res; 5(1); 52-60. ©2016 AACR.

Abstract B109: Epigenetic reprogramming of T-cells from metastatic melanoma patients enhances central memory and decreases Th2/Treg phenotypes

Immunotherapy strategies for the treatment of melanoma have achieved impressive clinical outcomes over the past decade. Response rates to checkpoint blockade by PD-1 and CTLA-4 antibodies range from 15-40%, while in adoptive cell therapy using tumor infiltrating lymphocytes (TILs), anti-tumor response is observed in approximately 50%. However, the need to improve immunotherapies is evident as the majority of patients are unresponsive to treatment. Dysfunctional T-cells are thought to contribute to failed responses to checkpoint inhibition. As such we sought to investigate the ability of drugs targeting the epigenetic regulatory machinery as a means to alter T-cell function(s) and improve the anti-melanoma response. Here we demonstrate that the HDAC6 selective inhibitor ACY1215 disrupts mTORC signaling pathways in T-cells obtained from melanoma patients. Phosphorylation of mTOR, RAPTOR and the downstream molecules AKT, SGK1, PKCa and S6K were reduced on CD4 and CD8 T-cells after ACY1215 in vitro treatment (p&lt;0.05). The levels of the Th2 cytokines IL-4, IL-6, IL-10 generated by ACY1215-treated T-cells (p&lt;0.05) were also decreased. Similar results were achieved with an SGK1 inhibitor, in agreement with published data demonstrating SGK1 as a regulator of Th2 polarization. Since the mTOR/RAPTOR complex is known to be involved in determining T regulatory (Treg) function, the effects of ACY1215 on Tregs were evaluated. Treatment in vitro with ACY1215 decreased phosphorylated mTOR and RAPTOR in Tregs, and reduced the levels of FOXP3. In a functional suppression assay, ACY1215-treated Tregs displayed a reduced ability to impair proliferation of effector T-cells (Teff) compared to control (DMSO: 10% vs ACY1215: 25% Teff proliferation, p&lt;0.05). To explore whether HDAC inhibition during expansion of tumor infiltrating lymphocytes (TIL) for adoptive transfer would improve their quality and anti-tumor reactivity, TIL isolated from melanoma surgical biopsies were cultured in vitro with IL-2 and ACY1215. Treatment with ACY1215 led to an accumulation of central memory CD4 and CD8 TILs (p&lt;0.01 and p&lt;0.05, respectively), which was maintained even after rapid expansion with anti-CD3 and anti-CD28 stimulation in vitro. Similarly, ACY1215 treatment of T-cells derived from peripheral blood of melanoma patients and healthy donors also displayed an increased central memory phenotype, characterized by expression of CD45RO, CD62L and CCR7 (p&lt;0.05). Inhibition of AKT has been shown to increase T-cells with memory characteristics, and the use of an AKT inhibitor also resulted in accumulation of central memory T-cells. Confirming the observed phenotypic changes, microarray analysis of ACY1215-treated TILs revealed up-regulation of genes associated with a T-cell central memory and inflammatory response (e.g. SELL, LEF1, TNFRSF9) and downregulation of genes associated with Treg function (e.g. LGMN, CXCL8). Collectively these data suggest that reprogramming T-cells with epigenetic modulators may improve melanoma immunotherapy by reducing Treg suppression and production of immunosuppressive cytokines, while favoring generation of central memory T-cells.

Citation Format: Andressa L. Sodre, David M. Woods, Amod Sarnaik, Brian C. Betts, Jeffrey S. Weber. Epigenetic reprogramming of T-cells from metastatic melanoma patients enhances central memory and decreases Th2/Treg phenotypes [abstract]. In: Proceedings of the Second CRI-CIMT-EATI-AACR International Cancer Immunotherapy Conference: Translating Science into Survival; 2016 Sept 25-28; New York, NY. Philadelphia (PA): AACR; Cancer Immunol Res 2016;4(11 Suppl):Abstract nr B109.

Prolonged sirolimus administration after allogeneic hematopoietic cell transplantation is associated with decreased risk for moderate-severe chronic graft-versus-host disease

Effective pharmacological strategies employed in allogeneic hematopoietic cell transplantation should prevent serious chronic graft-versus-host disease and facilitate donor-recipient immune tolerance. Based on demonstrated pro-tolerogenic activity, sirolimus (rapamycin) is an agent with promise to achieve these goals. In a long-term follow-up analysis of a randomized phase II trial comparing sirolimus/tacrolimus versus methotrexate/tacrolimus for graft-versus-host disease prevention in matched sibling or unrelated donor transplant, we examined the impact of prolonged sirolimus administration (≥ 1 year post-transplant). Median follow-up time for surviving patients at time of this analysis was 41 months (range 27-60) for sirolimus/tacrolimus and 49 months (range 29-63) for methotrexate/tacrolimus. Sirolimus/tacrolimus patients had significantly lower National Institutes of Health Consensus moderate-severe chronic graft-versus-host disease (34% vs. 65%; P=0.004) and late acute graft-versus-host disease (20% vs. 43%; P=0.04). While sirolimus/tacrolimus patients had lower prednisone exposure and earlier discontinuation of tacrolimus (median time to tacrolimus discontinuation 368 days vs. 821 days; P=0.002), there was no significant difference in complete immune suppression discontinuation (60-month estimate: 43% vs. 31%; P=0.78). Prolonged sirolimus administration represents a viable approach to mitigate risk for moderate-severe chronic and late acute graft-versus-host disease. Further study of determinants of successful immune suppression discontinuation is needed.

Ofatumumab in combination with glucocorticoids for primary therapy of chronic graft-versus-host disease: phase I trial results

Standard primary therapy for chronic graft-versus-host disease (GVHD) is incompletely effective. Based on biologic insights implicating pathogenic B cells, we conducted a phase I trial examining the combination of standard (1 mg/kg/day prednisone) glucocorticoid therapy with ofatumumab, a humanized anti-CD20 monoclonal antibody, for primary chronic GVHD therapy. Patients ages ≥ 18 with National Institutes of Health Consensus moderate-to-severe chronic GVHD newly requiring 1 mg/kg/day prednisone were treated at 3 escalating dose levels (300 mg, 700 mg, and 1000 mg) of i.v. ofatumumab on days 1 and 14 of initial glucocorticoid therapy. Dose-limiting toxicity (DLT) was defined by grade 4 infusion reactions, related grade 4 constitutional symptoms, related grade ≥ 3 organ toxicities, or grade 4 neutropenia lasting > 14 days. A total of 12 patients (median age 54; range, 25 to 72) were treated (dose level 1: n = 3; level 2: n = 3; level 3: n = 6). At enrollment, overall chronic GVHD was moderate (n = 7) or severe (n = 5), with diverse organ involvement (skin: n = 8; mouth: n = 8; eye: n = 8; lung: n = 4; gastrointestinal: n = 3; liver: n = 5; genital: n = 2; joint/fascia: n = 5). Infusion of ofatumumab was well tolerated, and no DLT was observed. From the total number of adverse events (n = 29), possibly related adverse events (n = 4) included grade 1 fatigue, grade 1 transaminitis, and 2 infusion reactions (grades 2 and 3). Infectious complications were expected, and there were no cases of hepatitis B reactivation or progressive multifocal leukoencephalopathy. Ofatumumab in combination with prednisone is safe and a phase II examination of efficacy is ongoing.

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.

STAT5 polarization promotes iTregs and suppresses human T-cell alloresponses while preserving CTL capacity

Alloreactivity negatively influences outcomes of organ transplantation or HCT from allogeneic donors. Standard pharmacologic immune suppression impairs T-cell function and jeopardizes the beneficial reconstitution of Tregs. Murine transplantation models have shown that STAT3 is highly expressed in alloreactive T cells and may be therapeutically targeted. The influence and effects of STAT3 neutralization in human alloreactivity, however, remain to be elucidated. In this study, S3I-201, a selective small-molecule inhibitor of STAT3, suppressed human DC-allosensitized T-cell proliferation and abrogated Th17 responses. STAT3 blockade significantly enhanced the expansion of potent iTregs and permitted CD8(+) cytolytic effector function. Mechanistically, S3I-201 polarized the ratio of STAT phosphorylation in favor of STAT5 over STAT3 and also achieved a significant degree of Foxp3 demethylation among the iTregs. Conversely, selective impairment of STAT5 phosphorylation with CAS 285986-31-4 markedly reduced iTregs. STAT3 represents a relevant target for achieving control over human alloresponses, where its suppression facilitates STAT5-mediated iTreg growth and function.

A randomized phase II study to evaluate tacrolimus in combination with sirolimus or methotrexate after allogeneic hematopoietic cell transplantation

BACKGROUND

There is evidence suggesting that sirolimus, in combination with tacrolimus, is active in the prevention of graft-versus-host disease. Sirolimus-based immune suppression may suppress alloreactive T cells, while sparing the survival and function of regulatory T cells.

DESIGN AND METHODS

We conducted a randomized trial to compare the impact of sirolimus/tacrolimus against that of methotrexate/tacrolimus on the prevention of graft-versus-host disease and regulatory T-cell reconstitution.

RESULTS

Seventy-four patients were randomized 1:1 to sirolimus/tacrolimus or methotrexate/tacrolimus, stratified for type of donor (sibling or unrelated) and the patients' age. The rate of grade II-IV acute graft-versus-host disease at 100 days was 43% (95% CI: 27-59%) in the sirolimus/tacrolimus group and 89% (95% CI: 72-96%) in the methotrexate/tacrolimus group (P<0.001). The rate of moderate/severe chronic graft-versus-host disease was 24% (95% CI: 7-47%) in the sirolimus/tacrolimus group and 64% (95% CI: 41-79%) in the methotrexate/tacrolimus group (P=0.008). Overall survival and patient-reported quality of life did not differ between the two groups. On days 30 and 90 post-transplant, sirolimus-treated patients had a significantly greater proportion of regulatory T cells among the CD4(+) cells in the peripheral blood, and isolated regulatory T cells were functional.

CONCLUSIONS

These data demonstrate that sirolimus/tacrolimus prevents grade II-IV acute graft-versus-host disease and moderate-severe chronic graft-versus-host disease more effectively than does methotrexate/tacrolimus, and supports regulatory T-cell reconstitution following allogeneic hematopoietic cell transplantation.

Human herpesvirus 6 infection after hematopoietic cell transplantation: is routine surveillance necessary?

Human herpesvirus 6 (HHV6) may be an important pathogen following allogeneic hematopoietic cell transplantation (HCT). We prospectively evaluated weekly HHV6 viremia testing after allogeneic HCT using a quantitative polymerase chain reaction (PCR)-based assay. HHV-6 viremia was detected in 46 of 82 (56%) patients at a median of 23 days post-HCT (range: day +10 to +168). More males (65% vs females 39%, P = .03) and recipients of umbilical cord blood (UCB 69% vs unrelated donor [URD], 46% vs sibling donor [20%] grafts, P = 0.01) reactivated HHV-6. Patients with HHV6 viremia had more cytomegalovirus (CMV) reactivation (26% vs 5.5%, P = .01) and unexplained fever and rash (23.9% vs 2.7%, P = .01) compared with patients without HHV6 viremia. High-level HHV6 (≥ 25,000 copies/mL) versus lower levels were associated with more culture-negative pneumonitis (72.7% vs 22.8%, P = .01). Twenty HHV6-positive patients were treated with foscarnet, ganciclovir, or cidofovir for HHV6 or other coexistent viruses. Within 2 weeks, HHV6 viremia resolved more commonly in treated (65%) than untreated patients (31%), P = .02. Survival at 3 months was similar in treated and untreated patients (90% vs 81%, P = .4). Survival at 3 and 6 months post-HCT were not affected by HHV6 positivity (3 months HHV6+ 85% vs 78%, P = .46; 6 months HHV6+ 70% vs 72%, P = .89) or by HHV6 level (3-month high level 73% vs 89%, P = .23; 6-month high level 64% vs 71%, P = .54). Neither the occurrence of HHV6, degree of viremia, nor use of antiviral drugs influenced short-term survival after HCT.