Potential and Uncertainties of RejectClass in Acute Kidney Graft Dysfunction: An Independent Validation Study

BACKGROUND

Kidney graft rejections are classified based on the Banff classification. The RejectClass algorithm, initially derived from a cohort comprising mostly protocol biopsies, identifies data-driven phenotypes of acute rejection and chronic pathology using Banff lesion scores. It also provides composite scores for inflammation activity and chronicity. This study independently evaluates the performance of RejectClass in a cohort consisting entirely of indication biopsies.

METHODS

We retrospectively applied RejectClass to 441 patients from the German TRABIO (TRAnsplant BIOpsies) cohort who had received indication biopsies. The primary endpoint was death-censored graft failure during 2 y of follow-up.

RESULTS

The application of RejectClass to our cohort demonstrated moderately comparable phenotypic features with the derivation cohort, and most clusters indicated an elevated risk of graft loss. However, the reproduction of all phenotypes and the associated risks of graft failure, as depicted in the original studies, was not fully accomplished. In contrast, adjusted Cox proportional hazards analyses substantiated that both the inflammation score and the chronicity score are independently associated with graft loss, exhibiting hazard ratios of 1.7 (95% confidence interval, 1.2-2.3; P = 0.002) and 2.2 (95% confidence interval, 1.8-2.6; P < 0.001), respectively, per 0.25-point increment (scale: 0.0-1.0).

CONCLUSIONS

The composite inflammation and chronicity scores may already have direct utility in quantitatively assessing the disease stage. Further refinement and validation of RejectClass clusters are necessary to achieve more reliable and accurate phenotyping of rejection.

Study protocol: the TRAnsplant BIOpsies (TRABIO) study - a prospective, observational, multicentre cohort study to assess the treatment of kidney graft rejections

INTRODUCTION

Despite continued efforts, long-term outcomes of kidney transplantation remain unsatisfactory. Kidney graft rejections are independent risk factors for graft failure. At the participating centres of the TRAnsplant BIOpsies study group, a common therapeutic standard has previously been defined for the treatment of graft rejections. The outcomes of this strategy will be assessed in a prospective, observational cohort study.

METHODS AND ANALYSIS

A total of 800 kidney transplantation patients will be enrolled who undergo a graft biopsy because of deteriorating kidney function. Patients will be stratified according to the Banff classification, and the influence of the treatment strategy on end points will be assessed using regression analysis. Primary end points will be all-cause mortality and graft survival. Secondary end points will be worsening of kidney function (≥30% decline of estimated Glomerular Filtration Rate [eGFR] or new-onset large proteinuria), recurrence of graft rejection and treatment response. Baseline data and detailed histopathology data will be entered into an electronic database on enrolment. During a first follow-up period (within 14 days) and subsequent yearly follow-ups (for 5 years), treatment strategies and clinical course will be recorded. Recruitment at the four participating centres started in September 2016. As of August 2020, 495 patients have been included.

ETHICS AND DISSEMINATION

Ethical approval for the study has been obtained from the ethics committee of Kiel (AZ B 278/16) and was confirmed by the committees of Munich, Mainz and Stuttgart. The results will be reported in a peer-reviewed journal, according to the Strengthening the Reporting of Observational Studies in Epidemiology criteria.

TRIAL REGISTRATION NUMBER

ISRCTN78772632; Pre-results.

Adult macrophage activation syndrome-haemophagocytic lymphohistiocytosis: 'of plasma exchange and immunosuppressive escalation strategies' - a single centre reflection

OBJECTIVE

In the context of systemic autoimmunity, that is systemic lupus erythematosus (SLE) or adult-onset Still's disease (AOSD), secondary haemophagocytic lymphohistiocytosis (HLH; also referred to as macrophage activation syndrome (MAS) or more recently MAS-HLH) is a rare and potentially life-threatening complication. Pathophysiological hallmarks are aberrant macrophage and T cell hyperactivation and a systemic cytokine flare, which generate a sepsis-like, tissue-damaging, cytopenic phenotype. Unfortunately, for adult MAS-HLH we lack standardized treatment protocols that go beyond high-dose corticosteroids. Consequently, outcome data are scarce on steroid refractory cases. Aside from protocols based on treatment with calcineurin inhibitors, etoposide, cyclophosphamide and anti-IL-1, favourable outcomes have been reported with the use of intravenous immunoglobulin (IvIG) and plasma exchange (PE).

METHODS

Here we report a retrospective series of steroid refractory MAS-HLH, the associated therapeutic regimes and outcomes.

RESULTS

In this single-centre experience, 6/8 steroid refractory patients survived (median follow-up: 54.4 (interquartile range: 23.3-113.3) weeks). All were initially treated with PE, which induced partial response in 5/8 patients. Yet, all patients required escalation of immunosuppressive therapies. One case of MAS-HLH in new-onset AOSD had to be escalated to etoposide, whereas most SLE-associated MAS-HLH patients responded well to cyclophosphamide. Relapses occurred in 2/8 cases.

CONCLUSION

Together, early use of PE is at most a supportive measure, not a promising monotherapy of adult MAS-HLH. In refractory cases, conventional cytoreductive therapies (i.e. cyclophosphamide and etoposide) constitute potent and reliable rescue approaches, whereas IvIG, anti-thymoglobulin, and biologic agents appear to be less effective.