Treatment of Acute Antibody-Mediated Renal Allograft Rejection With Cyclophosphamide

Transplant oncology and anti-cancer immunosuppressants

Organ transplantation is a life-saving intervention that enhances the quality of life for patients with end-stage organ failure. However, long-term immunosuppressive therapy is required to prevent allogeneic graft rejection, which inadvertently elevates the risk of post-transplant malignancies, especially for liver transplant recipients with a prior history of liver cancer. In response, the emerging field of transplant oncology integrates principles from oncology and immunology to improve outcomes for patients at high risk of tumor occurrence or recurrence following transplantation. Therefore, it is of substantial clinical significance to develop immunosuppressants that possess both immunosuppressive and anti-tumor properties. For instance, mTOR inhibitors demonstrate anti-tumor effects among antimetabolite immunosuppressive drugs, and recent studies indicate that capecitabine, an antimetabolite chemotherapeutic, may also exhibit immunosuppressive activity in the clinic for liver transplants suffering from hepatocellular carcinoma. This review systematically explores potential immunosuppressants with dual anti-tumor and immunosuppressive effects to support the management of transplant patients at elevated risk of tumor occurrence or recurrence.

Desensitization Strategies for Donor-Specific Antibodies in HLA-Mismatched Stem Cell Transplantation Recipients: What We Know and What We Do Not Know

In human leukocyte antigen (HLA)-mismatched allogeneic stem cell transplantation settings, donor-specific anti-HLA antibodies (DSAs) can independently lead to graft failure, including both primary graft rejection and primary poor graft function. Although several strategies, such as plasma exchange, intravenous immunoglobulin, rituximab, and bortezomib, have been used for DSA desensitization, the effectiveness of desensitization and transplantation outcomes in some patients remain unsatisfactory. In this review, we summarized recent research on the prevalence of anti-HLA antibodies and the underlying mechanism of DSAs in the pathogenesis of graft failure. We mainly focused on desensitization strategies for DSAs, especially novel methods that are being investigated in the preclinical stage and those with promising outcomes after preliminary clinical application.

Long-Term Outcome after Early Mammalian Target of Rapamycin Inhibitor-Based Immunosuppression in Kidney Transplant Recipients

Background: The use of mammalian target of rapamycin inhibitors (mTORis) in kidney transplantation increases the risk of donor-specific human leukocyte antigen (HLA) antibody formation and rejection. Here, we investigated the long-term consequences of early mTORi treatment compared to calcineurin inhibitor (CNI) treatment. Methods: In this retrospective single-center analysis, key outcome parameters were compared between patients participating in randomized controlled immunosuppression trials between 1998 and 2011, with complete follow-up until 2018. The outcomes of eligible patients on a CNI-based regimen (n = 384) were compared with those of patients randomized to a CNI-free mTORi-based regimen (n = 81) and 76 patients randomized to a combination of CNI and mTORi treatments. All data were analyzed according to the intention-to-treat (ITT) principle. Results: Deviation from randomized immunosuppression for clinical reasons occurred significantly more often and much earlier in both mTORi-containing regimens than in the CNI treatment. Overall patient survival, graft survival, and death-censored graft survival did not differ between the treatment groups. Donor-specific HLA antibody formation and BPARs were significantly more common in both mTORi regimens than in the CNI-based immunosuppression. Conclusions: The tolerability and efficacy of the mTORi treatment in kidney graft recipients are inferior to those of CNI-based immunosuppression, while the long-term patient and graft survival rates were similar.

Modulating T Cell Responses by Targeting CD3

Harnessing the immune system to fight cancer has become a reality with the clinical success of immune-checkpoint blockade (ICB) antibodies against PD(L)-1 and CTLA-4. However, not all cancer patients respond to ICB. Thus, there is a need to modulate the immune system through alternative strategies for improving clinical responses to ICB. The CD3-T cell receptor (TCR) is the canonical receptor complex on T cells. It provides the "first signal" that initiates T cell activation and determines the specificity of the immune response. The TCR confers the binding specificity whilst the CD3 subunits facilitate signal transduction necessary for T cell activation. While the mechanisms through which antigen sensing and signal transduction occur in the CD3-TCR complex are still under debate, recent revelations regarding the intricate 3D structure of the CD3-TCR complex might open the possibility of modulating its activity by designing targeted drugs and tools, including aptamers. In this review, we summarize the basis of CD3-TCR complex assembly and survey the clinical and preclinical therapeutic tools available to modulate CD3-TCR function for potentiating cancer immunotherapy.

Emerging drugs for antibody-mediated rejection after kidney transplantation: a focus on phase II & III trials

INTRODUCTION

Antibody-mediated rejection (ABMR) is a leading cause of kidney allograft failure. Its therapy continues to be challenge, and no treatment has been approved for the market thus far.

AREAS COVERED

In this article, we discuss the pathophysiology and phenotypic presentation of ABMR, the current level of evidence to support the use of available therapeutic strategies, and the emergence of tailored drugs now being evaluated in systematic clinical trials. We searched PubMed, Clinicaltrials.gov and Citeline's Pharmaprojects for pertinent information on emerging anti-rejection strategies, laying a focus on phase II and III trials.

EXPERT OPINION

Currently, we rely on the use of apheresis for alloantibody depletion and intravenous immunoglobulin (referred to as standard of care), preferentially in early active ABMR. Recent systematic trials have questioned the benefits of using the CD20 antibody rituximab or the proteasome inhibitor bortezomib. However, there are now several promising treatment approaches in the pipeline, which are being trialed in phase II and III studies. These include interleukin-6 antagonism, CD38-targeting antibodies, and selective inhibitors of complement. On the basis of the information that has emerged so far, it seems that innovative treatment strategies for clinical use in ABMR may be available within the next 5-10 years.

Prevalence and risk factors of antibodies to HLA according to different cut-off values of mean fluorescence intensity in haploidentical allograft candidates: A prospective study of 3805 subjects

The importance of anti-HLA antibodies in transplantation settings, such as HLA-mismatched or haploidentical hematopoietic stem cell transplantation and platelet refractoriness, is widely recognized. In previous reports, it was mentioned that several cut-off values of donor-specific anti-HLA antibodies mean fluorescence intensity (MFI) were related to graft rejection in the environment of HLA mismatched stem cell transplantation and the aim of this study was to investigate the prevalence and risk factors of anti-HLA antibodies according to those cut-off values of MFI. A total of 3805 patients with hematologic disease were prospectively enrolled and analyzed. When using MFI of anti-HLA antibodies ≥500, ≥1000, ≥1500, ≥2000, ≥5000, and ≥ 10,000 as cut-off values for positivity, the prevalence of class I or II anti-HLA antibodies ranged from 4.6% to 20.2% in all cases. When the MFI cut-off value was ≥500 for positivity, multivariate analysis indicated that platelet transfusion, underlying disease, and pregnancy were the most important risk factors for the presence of anti-HLA antibodies for the total patients. Subgroup analysis according to age, gender, and underlying disease showed that pregnancy was the most important risk factor for the presence of anti-HLA antibodies. For all patients (n = 3805), when anti-HLA antibody positivity was defined according to different MFI cut-off values, including ≥1000, ≥1500, ≥2000, ≥5000, and ≥ 10,000, an association of platelet transfusion and pregnancy with anti-HLA antibodies was also demonstrated. Our results suggest that pregnancy and platelet transfusion are the main risk factors for the prevalence of anti-HLA antibodies in haploid allograft candidates, providing evidence for guiding the evaluation of anti-HLA antibodies and helping donor selection for HLA-mismatched transplant candidates.

Poor Outcomes in Patients With Transplant Glomerulopathy Independent of Banff Categorization or Therapeutic Interventions

Background

Transplant glomerulopathy (TG) may indicate different disease entities including chronic AMR (antibody-mediated rejection). However, AMR criteria have been frequently changed, and long-term outcomes of allografts with AMR and TG according to Banff 2017 have rarely been investigated.

Methods

282 kidney allograft recipients with biopsy-proven TG were retrospectively investigated and diagnosed according to Banff'17 criteria: chronic AMR (cAMR, n = 72), chronic active AMR (cAAMR, n = 76) and isolated TG (iTG, n = 134). Of which 25/72 (34.7%) patients of cAMR group and 46/76 (60.5%) of cAAMR group were treated with antihumoral therapy (AHT).

Results

Up to 5 years after indication biopsy, no statistically significant differences were detected among iTG, cAMR and cAAMR groups in annual eGFR decline (−3.0 vs. −2.0 vs. −2.8 ml/min/1.73 m2 per year), 5-year median eGFR (21.5 vs. 16.0 vs. 20.0 ml/min/1.73 m2), 5-year graft survival rates (34.1 vs. 40.6 vs. 31.8%) as well as urinary protein excretion during follow-up. In addition, cAMR and cAAMR patients treated with AHT had similar graft and patient survival rates in comparison with those free of AHT, and similar comparing with iTG group. The TG scores were not associated with 5-year postbiopsy graft failure; whereas the patients with higher scores of chronic allograft scarring (by mm-, ci- and ct-lesions) had significantly lower graft survival rates than those with mild scores. The logistic-regression analysis demonstrated that Banff mm-, ah-, t-, ci-, ct-lesions and the eGFR level at biopsy were associated with 5-year graft failure.

Conclusions

The occurrence of TG is closely associated with graft failure independent of disease categories and TG score, and the long-term clinical outcomes were not influenced by AHT. The Banff lesions indicating progressive scarring might be better suited to predict an unfavorable outcome.

Evaluation of severity of delayed graft function in kidney transplant recipients

BACKGROUND

The most common definition of delayed graft function (DGF) relies on dialysis during the first week post-transplant and does not consider DGF severity. The impact of DGF severity on long-term graft outcome remains controversial.

METHODS

We analyzed 627 deceased-donor kidney transplant recipients (KTR) transplanted 2005-2015 at our center for DGF-severity, associated risk factors and long-term consequences of DGF.

RESULTS

We found 349 (55.7%) KTR with DGF, which were classified into 4 groups according to DGF duration (0-1, 2-7, 8-14, >14 days) and were compared to KTR with no DGF. Increasing duration of DGF was associated with progressive worsening of 10-year death-censored graft survival (no DGF: 88.3% (95%CI: 82.4-94.2), 0-1 day: 81.3% (95%CI: 68.2-94.4), 2-7 days: 61.5% (95%CI: 43.1.1-79.9), 8-14 days: 66.6% (95%CI: 47.4-85.8), >14 days: 51.2% (95%CI: 33-69.4); p < 0.001). In kidneys with a Kidney Donor Profile Index (KDPI) ≥85% all DGF severity groups demonstrated reduced graft survival. However, in < 85%KDPI kidneys, only > 14 days DGF duration showed worse outcomes.

CONCLUSIONS

DGF had a duration-dependent effect on graft survival, which varied depending on KDPI. Of note, 0-1-day DGF showed comparable results to no DGF in the whole cohort.

Recommended Treatment for Antibody-mediated Rejection After Kidney Transplantation: The 2019 Expert Consensus From the Transplantion Society Working Group

With the development of modern solid-phase assays to detect anti-HLA antibodies and a more precise histological classification, the diagnosis of antibody-mediated rejection (AMR) has become more common and is a major cause of kidney graft loss. Currently, there are no approved therapies and treatment guidelines are based on low-level evidence. The number of prospective randomized trials for the treatment of AMR is small, and the lack of an accepted common standard for care has been an impediment to the development of new therapies. To help alleviate this, The Transplantation Society convened a meeting of international experts to develop a consensus as to what is appropriate treatment for active and chronic active AMR. The aim was to reach a consensus for standard of care treatment against which new therapies could be evaluated. At the meeting, the underlying biology of AMR, the criteria for diagnosis, the clinical phenotypes, and outcomes were discussed. The evidence for different treatments was reviewed, and a consensus for what is acceptable standard of care for the treatment of active and chronic active AMR was presented. While it was agreed that the aims of treatment are to preserve renal function, reduce histological injury, and reduce the titer of donor-specific antibody, there was no conclusive evidence to support any specific therapy. As a result, the treatment recommendations are largely based on expert opinion. It is acknowledged that properly conducted and powered clinical trials of biologically plausible agents are urgently needed to improve patient outcomes.

Outcomes of Prolonged Treatment With Intravenous Immunoglobulin Infusions for Acute Antibody-mediated Rejection in Kidney Transplant Recipients

BACKGROUND

Treatment of antibody-mediated rejection (AMR) is one of the main problems after kidney transplantation (KTx). The results of intensive AMR treatment with plasmapheresis (PF) and repeated infusions of intravenous immunoglobulin (IVIg) are presented.

METHODS

Diagnosis of AMR was based on graft biopsy and the presence of donor-specific antibodies (DSAs). AMR therapy consisted of 5 PF and IVIg infusions given after the last PF. Subsequent IVIg doses were given every 4 weeks for 6 months. Graft biopsy and DSA assessment were repeated at the end of the treatment (ET).

RESULTS

Four women and 10 men were included in our study; mean time from KTx to AMR was 79 (range, 3-193) months. During the treatment, 4 patients had graft failure. Graft function at baseline was significantly worse (P = .02) in this group compared with patients who completed the therapy. At baseline, mean flourescence intensity (MFI) was 6574 (range, 852-15,917) in the whole group, 7088 (range, 1054-15,917) in patients who completed treatment, and 4828 (range, 852-11,797) in patients who restarted hemodialysis. At ET, DSA MFI decreased in 8 of 10 patients (80%) who completed the therapy. The MFI decrease was 3946 (range, 959-11,203). Control graft biopsies revealed decreased intensity of C4d deposits in peritubular capillaries in 7 patients (78%) and decreased peritubular capillaritis in 2 patients (22%).

CONCLUSION

Intensive, prolonged AMR therapy with PF and IVIg resulted in a decrease in DSA titer and intensity of C4d deposits, but was not associated with reduction of microcirculation inflammation. Treatment was ineffective in patients with baseline advanced graft insufficiency.

Late Steroid Withdrawal Following AB0-Incompatible Renal Transplantation

BACKGROUND

Current evidence on steroid withdrawal following AB0-incompatible (AB0i) renal transplantation is low. We compared clinical outcomes of patients who agreed to late steroid withdrawal and patients who remained on steroid treatment.

METHODS

Steroid withdrawal was carried out in 11 patients at ≥12 months after transplantation (group W). For comparison, we analyzed 19 patients who remained on triple immunosuppression including steroids (group M). Minimum follow-up was 24 months following transplantation and 12 months after steroid withdrawal.

RESULTS

Baseline characteristics, including observation times, were not different between groups W and M. Graft survival was 100% in group W compared with 84% (16/19) in group M (P = .15). In group M, 1 patient experienced graft failure because of suspected antibody-mediated rejection (ABMR) following temporary cessation of mycophenolate treatment after a diagnosis of cryptococcal pneumonia. Two patients died with functioning graft because of sepsis. In group W, we observed 1 episode of ABMR following steroid withdrawal. At the end of follow-up, estimated glomerular filtration rates (eGFR) were 54 (19-91) versus 60 (15-85) mL/min/1.73 m² in group W versus M, respectively (P = .67).

CONCLUSIONS

Late steroid withdrawal following AB0i transplantation is feasible at a moderate risk of rejection. We recommend close monitoring of renal function and HLA antibodies during and after steroid withdrawal. On the other hand, the occurrence of severe infections causing death and graft loss in patients on triple maintenance immunosuppression including steroids should remind us to consider the overall immunosuppressive burden.