Clazakizumab for desensitization in highly sensitized patients awaiting transplantation.

Alloantibodies are a significant barrier to successful transplantation. While desensitization has emerged, efficacy is limited. Interleukin-6 (IL-6) is an important mediator of inflammation and immune cell activation. Persistent IL-6 production increases the risk for alloantibody production. Here we report our experience with clazakizumab (anti-IL-6) for desensitization of highly HLA-sensitized patients (HS). From March 2018 to September 2020, 20 HS patients were enrolled in an open label pilot study to assess safety and limited efficacy of clazakizumab desensitization. Patients received PLEX, IVIg, and clazakizumab 25 mg monthly X6. If transplanted, graft function, pathology, HLA antibodies and regulatory immune cells were monitored. Transplanted patients received standard immunosuppression and clazakizumab 25 mg monthly posttransplant. Clazakizumab was well tolerated and associated with significant reductions in class I and class II antibodies allowing 18 of 20 patients to receive transplants with no DSA rebound in most. Significant increases in Treg and Breg cells were seen posttransplant. Antibody-mediated rejection occurred in three patients. The mean estimated glomerular filtration rate at 12 months was 58 ± 29 ml/min/1.73 m2 . Clazakizumab was generally safe and associated with significant reductions in HLA alloantibodies and high transplant rates for highly-sensitized patients. However, confirmation of efficacy for desensitization requires assessment in randomized controlled trials.

The role of novel therapeutic approaches for prevention of allosensitization and antibody-mediated rejection.

Modification of pathogenic antibodies and their effector functions in autoimmune diseases or use of B cell/plasma cell-directed anticancer therapies have illuminated the biologic relevance of B cells, plasma cells (PCs), and pathogenic antibodies and complement in alloimmunity. They have also rejuvenated interest in how B cells mediate multiple effector functions that include antibody production, antigen presentation to T cells, costimulation, and the production of immune stimulating and immune modulatory cytokines that drive dysfunctional immune responses. Current methods to reduce alloantibodies are only modestly successful. Rituximab is used for desensitization and antibody-mediated rejection (AMR) treatment by targeting CD20 found on B-lymphocytes. However, PCs do not express CD20, likely explaining the limited success of this approach. Intravenous immunoglobulin and plasmapheresis (PLEX) have limited success due to antibody rebound. Despite attempts to develop tolerable therapeutics for management of AMR, none, to date, have been universally accepted or obtained Food and Drug Administration approval. Lack of approved therapeutics often results in patients having a much shorter graft survival due to AMR. Repurposing drugs from autoimmunity and cancer immunotherapy has rapidly yielded important advancements in the care of AMR patients. Here we discuss emerging therapeutics aimed at prevention and treatment of AMR.

Evaluation of Clazakizumab (Anti-Interleukin-6) in Patients With Treatment-Resistant Chronic Active Antibody-Mediated Rejection of Kidney Allografts.

Introduction: Interleukin-6 (IL-6) is an important mediator of inflammation and activation of T cells, B cells, and plasma cells. Excessive IL-6 production is linked to human diseases characterized by unregulated antibody production, including alloimmunity, where persistence of donor-specific antibodies (DSAs), chronic active antibody-mediated rejection (cAMR), and graft loss are noted. Here, we report our experience investigating clazakizumab, a novel IL-6 inhibitor, in treating human leukocyte antigen (HLA)-sensitized patients with cAMR. Methods: Between February 2018 and January 2019, 10 adults with biopsy-proven cAMR were enrolled in a phase 2, single-center, open-label study. Patients received clazakizumab 25 mg subcutaneously (s.c.) monthly for 12 months, with a 6-month protocol biopsy. Primary end points included patient survival, graft survival, estimated glomerular filtration rate (eGFR), and safety. Secondary end points assessed immune markers (DSAs, IgG, T-regulatory [Treg] cells). At 12 months, stable patients entered a long-term extension (LTE). Results: LTE patients received clazakizumab for >2.5 years. Mean eGFRs showed significant declines from -24 months to study initiation (0 months) (52.8 ± 14.6 to 38.11 ± 12.23 ml/min per 1.73 m2, P = 0.03). However, after initiation of clazakizumab, eGFR stabilized at (41.6 ± 14.2 and 38.1 ± 20.3 ml/min per 1.73 m2, at 12 and 24 months, respectively). Banff 2017 analysis of pre- and post-treatment biopsies showed reductions in g+ptc and C4d scores. DSA reductions were seen in most patients. Adverse events (AEs) were minimal, and 2 graft losses occurred, both in patients who discontinued clazakizumab therapy at 6 months and 12 months after study initiation. Conclusion: In this small cohort of patients with cAMR, clazakizumab treatment showed a trend toward stabilization of eGFR and reductions in DSA and graft inflammation. No significant safety issues were observed. A randomized, placebo-controlled clinical trial (IMAGINE) of clazakizumab in cAMR treatment is underway (NCT03744910).

Outcomes of Conversion From Calcineurin Inhibitor to Belatacept-based Immunosuppression in HLA-sensitized Kidney Transplant Recipients.

BACKGROUND: The efficacy and safety of belatacept when converted from calcineurin inhibitors (CNI) in HLA-sensitized (HS) kidney transplant recipients has not been established. METHODS: The study included 108 kidney transplant recipients converted from CNI to belatacept between July 1, 2012, and September 30, 2017. Rejection-free, patient, and graft survival over 5 years follow-up were compared between HS and non-HLA-sensitized (non-HS) recipients using the Kaplan-Meier product-limit method. The estimated glomerular filtration rate slope postconversion was compared using linear mixed effects models. RESULTS: There were 29 HS and 79 non-HS recipients included. Rejections after conversion were mostly cell-mediated. There was no difference in rejection-free survival (log-rank P = 0.30; at 5 y, HS: 82%; non-HS: 84.6%); however, rejection-free survival was lower among HS recipients converted within the first-year posttransplant compared to non-HS recipients (log-rank P = 0.03; at 5 y, HS: 55.6%; non-HS: 75.0%). There was no difference in patient survival (log-rank P = 0.75; at 5 y, HS: 85.7%, non-HS: 83.7%) or graft survival (log-rank P = 0.17; at 5 y, HS: 78.5%, non-HS: 89.8%) in the 2 groups. On average, estimated glomerular filtration rate slope improved postconversion in non-HS (0.28 mL/min/1.73 m/y [0.03 to 0.53]) but declined in HS recipients (-0.44 mL/min/1.73 m/y [-0.85 to -0.03]). CONCLUSIONS: There was no difference in rejection-free, patient, or graft survival after conversion to belatacept over 5 years among HS and non-HS recipients. However, rejection-free survival was lower in HS recipients converted to belatacept within the first-year posttransplant. Conversion from CNI to belatacept should be done cautiously in high immunologic risk patients.

Donor-derived Cell-free DNA Combined With Histology Improves Prediction of Estimated Glomerular Filtration Rate Over Time in Kidney Transplant Recipients Compared With Histology Alone.

Higher Banff inflammation and chronicity scores on kidney transplant biopsies are associated with poorer graft survival, although histology alone has limitations in predicting outcomes. We investigated if integrating donor-derived cell-free DNA (dd-cfDNA, Allosure; CareDx, Inc.) with Banff biopsy scores into a predictive model for estimated glomerular filtration rate over time can improve prognostic assessment versus histology alone. METHODS: We identified 180 kidney transplant patients with dd-cfDNA assessed within 1 mo of biopsy. Using linear mixed-effects models, a prediction model of Banff histology scores and dd-cfDNA on estimated glomerular filtration rate over time was derived. Nested models were compared using the likelihood-ratio test, Akaike Information Criterion, and Bayesian Information Criterion to assess if inclusion of dd-cfDNA into a model consisting of Banff biopsy scores would improve model fit. RESULTS: Univariate models identified significant covariate-by-time interactions for cg = 3 versus <3 (coefficient: -1.3 mL/min/1.73 m2/mo; 95% confidence interval [CI], -2.4 to -0.2; P = 0.02) and ci + ct ≥ 3 versus <3 (coefficient: -0.7 mL/min/1.73 m2/mo; 95% CI, -1.3 to -0.1; P = 0.03) and a trend toward significant covariate-by-time interaction for dd-cfDNA (coefficient: -0.5 mL/min/1.73 m2/mo; 95% CI, -1.0 to 0.1; P = 0.08). Addition of acute inflammation (i, t, and v), microvascular inflammation (g and ptc), and inflammation in area of interstitial fibrosis and tubular atrophy scores to chronicity scores (cg ≥ 3 and ci + ct ≥ 3) did not improve model fit. However, a model including dd-cfDNA with cg and ci + ct with covariate-by-time interactions had a better model fit compared with cg and ci + ct alone (likelihood-ratio test statistic = 21.1; df = 2; P < 0.001). CONCLUSIONS: Addition of dd-cfDNA to Banff biopsy scores provided better prognostic assessment over biopsy characteristics alone.

Three-Year Outcomes of a Randomized, Double-Blind, Placebo-Controlled Study Assessing Safety and Efficacy of C1 Esterase Inhibitor for Prevention of Delayed Graft Function in Deceased Donor Kidney Transplant Recipients.

BACKGROUND AND OBJECTIVES: Delayed graft function is related to ischemia-reperfusion injury and may be complement dependent. We previously reported from a randomized, placebo-controlled trial that treatment with C1 esterase inhibitor was associated with a shorter duration of delayed graft function and higher eGFR at 1 year. Here, we report longer-term outcomes from this trial. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS: This is a post hoc analysis of a phase 1/2, randomized, controlled trial enrolling 70 recipients of deceased donor kidney transplants at risk for delayed graft function (NCT02134314). Subjects were randomized to receive C1 esterase inhibitor 50 U/kg (n=35) or placebo (n=35) intraoperatively and at 24 hours. The cumulative incidence functions method was used to compare graft failure and death over 3.5 years. eGFR slopes were compared using a linear mixed effects model. RESULTS: Three deaths occurred among C1 esterase inhibitor-treated patients compared with none receiving placebo. Seven graft failures developed in the placebo group compared with one among C1 esterase inhibitor-treated recipients; the cumulative incidence of graft failure was lower over 3.5 years among C1 esterase inhibitor-treated recipients compared with placebo (P=0.03). Although no difference in eGFR slopes was observed between groups (P for group-time interaction =0.12), eGFR declined in placebo-treated recipients (-4 ml/min per 1.73 m2 per year; 95% confidence interval, -8 to -0.1) but was stable in C1 esterase inhibitor-treated patients (eGFR slope: 0.5 ml/min per 1.73 m2 per year; 95% confidence interval, -4 to 5). At 3.5 years, eGFR was 56 ml/min per 1.73 m2 (95% confidence interval, 42 to 70) in the C1 esterase inhibitor group versus 35 ml/min per 1.73 m2 (95% confidence interval, 21 to 48) in the placebo group, with an estimated mean eGFR difference of 21 ml/min per 1.73 m2 (95% confidence interval, 2 to 41 ml/min per 1.73 m2). CONCLUSIONS: Treatment of patients at risk for ischemia-reperfusion injury and delayed graft function with C1 esterase inhibitor was associated with a lower incidence of graft failure.

Cefotetan-Induced Hemolytic Anemia: Case Series and Review.

PURPOSE: To raise awareness of cefotetan-induced hemolytic anemia, a known rare but serious side effect that occurred in 5 patients at our medical center. SUMMARY: Five cases of cefotetan-induced hemolytic anemia, which presented over the period of a single year at our center, are described. In each case, hemolytic anemia was confirmed by testing for the presence of anti-cefotetan antibodies. Each case occurred approximately 1 to 2 weeks following exposure to the drug. All five patients survived. A brief review of drug-induced immune hemolytic anemia (DIIHA) is also discussed. CONCLUSION: DIIHA may be difficult to distinguish from other causes of hemolytic anemia, but should be included in the differential in patients exposed to medications associated with DIIHA. Once suspected, antibody testing should be performed, and once diagnosed, further exposure should be avoided.

Clinical Relevance of Posttransplant DSAs in Patients Receiving Desensitization for HLA-incompatible Kidney Transplantation.

BACKGROUND: Highly HLA-sensitized (HS) patients have an increased risk for the development of donor-specific antibodies (DSA) and antibody-mediated rejection (AMR) posttransplant. Here, we examined the risk for AMR in HS patients transplanted after desensitization (DES) who were DSA+ versus DSA- at transplant. We also examined the incidence and clinical impact of de novo DSAs (dnDSAs) and compared with dnDSA- patients. METHODS: From January 2013 to October 2016, 90 HS patients (PRA > 80%, DSA+ = 50 versus DSA- = 40) received kidney transplantation after DES with IVIG + rituximab ± PLEX (plasma exchange) ± tocilizumab. DSAs were monitored at transplant and at 1, 3, 6, 12, 24, 36, and 48 months posttransplant. RESULTS: Patients were divided into 4 groups: DSA+/+ (n = 31), DSA+/- (n=19), DSA-/+ (n=10), and DSA-/- (n = 30). Median follow-up time was 2.9 years. DSA-negative patients who developed dnDSA had the highest incidence of AMR (70%) compared with the DSA+/+ (45%), DSA+/- (11%), and DSA-/- (10%) patients (P < 0.0001). Among patients who developed AMR, Banff 2013 AMR scores did not differ among the 4 groups. Graft survival and estimated glomerular filtration rate determinations at 4 years were similar. CONCLUSIONS: Persistence of preexisting DSAs or development of dnDSA after transplant is associated with an increased risk for AMR. Despite this, we did not observe a difference in Banff biopsy scores, graft survival, or patient survival compared with those without DSAs after transplant. Thus, for HS patients undergoing HLA-incompatible kidney transplant, DES therapy and frequent monitoring for dnDSAs appears critical for good long-term survival in at-risk groups.

Novel Therapeutic Approaches to Allosensitization and Antibody-mediated Rejection.

Modification of pathogenic antibodies for autoimmune diseases illuminated the biologic relevance of B cells, plasma cells, and pathogenic antibodies in autoimmunity. They have also rejuvenated interest in how B cells mediate multiple effector functions that include antibody production, antigen presentation to T cells, costimulation, and the production of immune stimulating and immune modulatory cytokines. Repurposing these drugs from autoimmunity and cancer immunotherapy has yielded important advancements in the care of antibody-mediated rejection patients and novel drug development aimed at HLA desensitization have recently emerged. We now stand on an important threshold that promises many advances in the care of our allosensitized patients. We hope that these initial advances will encourage basic scientist, clinical investigators, industry, National Institutes of Health, our academic societies, and the Food and Drug Administration to continue support of these important objectives. These advances clearly have implications for sensitized patients receiving solid organ transplants and antibody-mediated rejection treatment. Modification of alloimmunity and alloantibodies will also have relevance to xenotransplantation where the xenoantibodies present a formidable obstacle to advancement of this important therapy. Working together, we can advance transplant therapeutics where biologic agents are likely to play novel and important roles. Here, we discuss novel drugs emerging in this area.