Successful treatment of acute thrombotic microangiopathy by eculizumab after combined lung and kidney transplantation

Eculizumab as Salvage Treatment for Thrombotic Microangiopathy After Lung Transplantation

BACKGROUND

Thrombotic microangiopathy (TMA) is a rare complication after lung transplantation (LT) that has seldom been characterized in detail. Recent evidence has linked TMA other than primary atypical hemolytic uremic syndrome (aHUS) with hyperactivation of the complement alternative pathway. The focus of this investigation was to analyze the treatment response with eculizumab in TMA after LT.

METHODS

Case series where we have studied 11 patients with TMA after LT from 2 Spanish tertiary healthcare centers. Clinical data and response rates to eculizumab are provided.

RESULTS

The main indication for lung transplant was chronic obstructive pulmonary disease (COPD) (36%) and most cases (82%) received bilateral LT. The median time to TMA diagnosis was 11.6 months (4.7-28.9) and the TMA trigger in the majority of cases (73%) was immunosuppressive drugs. Platelet and hemoglobin nadir were 58 × 103/µL (24-108) and 7.7 g/dL (7.1-7.9), respectively. All cases presented acute kidney injury (AKI) with a median creatinine of 4 mg/dL (3.2-4.8) and 54.5% required acute dialysis. Eculizumab was started after a median time of 8 days (6-14) with a median duration of 3 weeks (2-8). Complete TMA response was observed in 7 (63.6%) cases and hematologic response in 10 (90.9%). The time to hematologic and renal response was 23 days (13-29) and 28 days (14-46), respectively.

CONCLUSIONS

TMA after LT is infrequent but potentially devastating. Our findings suggest that short cycles of eculizumab may be effective for severe TMA after LT.

Immunosuppression considerations in simultaneous organ transplant

Solid organ transplantation is a life-saving procedure for patients in the end stage of heart, lung, kidney, and liver failure. For patients with more than one failing organ, simultaneous organ transplantation has emerged as a viable treatment option. Immunosuppression strategies and outcomes for simultaneous organ transplant recipients have been reported, but often involve limited populations. Transplanting dual organs poses challenges in terms of balancing immunosuppression with immunologic risk and allograft damage from surgical complications. Furthermore, transplanting certain organs can impose considerations on the management of immunosuppression. For example, liver allografts may confer immunologic privilege and lower rates of rejection of other allografts. This review article evaluates immunosuppression strategies for simultaneous kidney-pancreas, liver-kidney, heart-kidney, heart-liver, heart-lung, lung-liver, and lung-kidney transplants. To date, no comprehensive review exists to address immunosuppressive strategies in simultaneous organ transplant populations. Our review summarizes the available literature and provides evidence-based recommendations regarding immunosuppression strategies in simultaneous organ transplant recipients.

Drug-Induced Hematological Cytopenia in Kidney Transplantation and the Challenges It Poses for Kidney Transplant Physicians

Drug-induced hematological cytopenia is common in kidney transplantation. Various cytopenia including leucopenia (neutropenia), thrombocytopenia, and anemia can occur in kidney transplant recipients. Persistent severe leucopenia or neutropenia can lead to opportunistic infections of various etiologies. On the contrary, reducing or stopping immunosuppressive medications in these events can provoke a rejection. Transplant clinicians are often faced with the delicate dilemma of balancing cytopenia and rejection from adjustments of immunosuppressive regimen. Differentials of drug-induced cytopenia are wide. Identification of culprit medication and subsequent modification is also challenging. In this review, we will discuss individual drug implicated in causing cytopenia and correlate it with corresponding literature evidence.

Eculizumab in Transplant-Associated Thrombotic Microangiopathy

Introduction:

Transplant-associated thrombotic microangiopathy (TA-TMA) is a rare entity with no standard of care and high mortality, despite the use of plasma exchange.

Methods:

Using specific search terms, all cases having TA-TMA treated with eculizumab and indexed in MEDLINE (English language only) by November 2014 were reviewed.

Results:

A total of 26 cases, 53% men, had a median age of 33 years (range 2-61). Transplant-associated thrombotic microangiopathy occurred after stem-cell transplant (35%) or solid-organ transplant (65%), frequently associated with the use of cyclosporine or tacrolimus (96%). A disintegrin and metalloproteinase with a thrombospondin type 1 motif, member 13 (ADAMTS 13) level was always >10%. After TA-TMA diagnosis, the following drug adjustments were made: discontinuation of cyclosporine or tacrolimus in 45%, dose reduction in another 27%, continuation of the drugs in 23%, and switch from cyclosporine to tacrolimus in remaining 5%. Plasma exchange was performed in ∼43%. The median interval between transplant and initiation of eculizumab was 63 days (range 11-512). A median of 5.5 doses (range 2-21) of eculizumab was utilized with 92% response occurring after a median of 2 doses (range 1-18). At a median follow-up of 52 weeks (range 3-113), the survivors (92%) were doing well.

Conclusion:

Within the limits of this retrospective analysis, our study demonstrates that eculizumab use may result in high response rate and 1-year survival in patients with TA-TMA refractory to discontinuation of calcineurin inhibitor and plasma exchange.

The alternative pathway of complement and the thrombotic microangiopathies

Thrombotic microangiopathies (TMA) are disorders defined by microangiopathic hemolytic anemia, non-immune thrombocytopenia and have multi-organ involvement including the kidneys, brain, gastrointestinal, respiratory tract and skin. Emerging evidence points to the central role of complement dysregulation in leading to microvascular endothelial injury which is crucial for the development of TMAs. This key insight has led to the development of complement-targeted therapy. Eculizumab is an anti-C5 monoclonal antibody, which has revolutionized the treatment of atypical hemolytic uremic syndrome. Several other anti-complement therapeutic agents are currently in development, offering a potential armamentarium of therapies available to treat complement-mediated TMAs. The development of sensitive, reliable and easy to perform assays to monitor complement activity and therapeutic efficacy will be key to devising an individualized treatment regime with the potential of safely weaning or discontinuing treatment in the appropriate clinical setting.

Antibody-mediated rejection

PURPOSE OF REVIEW

Pulmonary antibody-mediated rejection (AMR) while contributing to acute and chronic allograft dysfunction remains a diagnostic and therapeutic challenge. The diagnostic tenets upon which AMR is defined will be reviewed in the light of recent studies.

RECENT FINDINGS

The introduction of solid phase assays such as the Luminex platform has provided a wealth of quantitative data on the presence of anti-human leukocyte antigen (HLA) donor-specific antibodies (DSA). Further studies are required to better define the relationship of circulating DSA and activation of proinflammatory immune pathways that result in allograft dysfunction. The limitations of C4d staining in defining AMR are highlighted from recent studies in lung transplantation and from the 2013 Banff meeting on renal transplantation.

SUMMARY

The current challenge to the lung transplant community is to agree on a working definition of pulmonary AMR. Only then can we better appreciate the epidemiology, clinical phenotypes, and treatment of AMR.

Hematopoietic Stem Cell Transplant-Associated Thrombotic Microangiopathy

Hematopoietic stem cell transplant-associated thrombotic microangiopathy (TA-TMA) is a fatal, multifactorial disorder, which may present with thrombocytopenia, hemolysis, acute renal failure, mental status changes and involvement of other organs. The pathogenesis of TA-TMA is complex and includes multiple risk factors such as certain conditioning regimens, calcineurin inhibitors (CNIs), graft-versus-host disease (GVHD), human leukocyte antigen mismatch, and opportunistic infections. The end result of these insults is endothelial injury in the kidney and other organs. Recent studies also indicate a role of complement activation in tissue damage. The lack of sensitive and specific diagnostic tests for TA-TMA often results in delayed diagnosis. Biopsy is not always possible for diagnosis because of the risk of complications such as bleeding. Recently, an emerging role of renal-centered screening approach has been demonstrated, which utilize the monitoring of blood pressure, urine protein, serum lactate dehydrogenase and hemogram for early detection. Therapeutic options are limited, and plasma exchange plays a minor role. Withdrawal of offending agent such as CNIs and the use of rituximab can be effective in some patients. However, the current treatment strategy is suboptimal and associated with high mortality rate. Recently, eculizumab has been utilized in a few patients with good outcomes. Patients, who develop TA-TMA, are also at an increased risk of GVHD, infection, renal, cardiovascular, and other complications, which can contribute to high mortality. Better understanding of molecular pathogenesis, improvement in posttransplant management, leading to early diagnosis, and management of TA-TMA are required to improve outcomes of this fatal entity.

The local complement activation on vascular bed of patients with systemic sclerosis: a hypothesis-generating study

Objective

The role of complement system in the pathogenesis of systemic sclerosis (SSc) has been debated during the last decade but an evident implication in this disease has never been found. We carried out an explorative study on SSc patients to evaluate the expression of soluble and local C5b-9 complement complex and its relation with a complement regulator, the Membrane Cofactor Protein (MCP, CD46) on skin vascular bed as target distinctive of SSc disease. We also analyzed two polymorphic variants in the complement activation gene cluster involving the MCP region.

Methods

C5b-9 plasma levels of SSc patients and healthy subjects were analyzed by ELISA assay. Archival skin biopsies of SSc patients and controls were subjected to immunofluorescence analysis to detect C5b-9 and MCP on vascular endothelial cells. The expression of MCP was validated by immunoblot analysis with specific antibody. Polymorphic variants in the MCP gene promoter were tested by a quantitative PCR technique-based allelic discrimination method.

Results

Even though circulating levels of C5b-9 did not differ between SSc and controls, C5b-9 deposition was detected in skin biopsies of SSc patients but not in healthy subjects. MCP was significantly lower in skin vessels of SSc patients than in healthy controls and was associated with the over-expression of two polymorphic variants in the MCP gene promoter, which has been related to more aggressive phenotypes in other immune-mediated diseases.

Conclusions

Our results firsty document the local complement activation with an abnormal expression of MCP in skin vessels of SSc patients, suggesting that a subset of SSc patients might be exposed to more severe organ complications and clinical evolution due to abnormal local complement activation.

Thrombotic microangiopathy in renal allografts: the diagnostic challenge

PURPOSE OF REVIEW

The diagnosis of thrombotic microangiopathy (TMA) is complex and often difficult. This review provides an approach to the diagnosis with emphasis on recent relevant developments.

RECENT FINDINGS

There is increasing evidence that most cases of recurrent TMA in renal allografts are secondary to mutations in genes encoding complement regulatory factors and complement components, such as factor H, factor I, membrane cofactor protein, C3, and others. Genetic work-up for these potential complement abnormalities is now available and recommended. Another important cause for recurrent TMA is the presence of autoantibodies, such as antibodies to factor H and antiphospholipid antibodies. De-novo TMA is much more common than recurrent TMA in renal allografts. De-novo TMA can be secondary to calcineurin inhibitor treatment, mammalian target of rapamycin inhibitor treatment, but frequently also to antibody-mediated rejection and less commonly to infections. Systemic signs of TMA are often absent, and the gold standard for diagnosis is the renal allograft biopsy. Unfortunately, diagnostic criteria for TMA are somewhat subjective, and the biopsy provides limited information regarding the exact underlying cause.

SUMMARY

TMA is a serious complication of renal transplantation, usually with poor outcome. However, with improving understanding of underlying pathogeneses, more effective disease-specific therapeutic interventions can be designed. Appropriate treatment depends on the correct diagnosis, which relies primarily on renal allograft biopsy. Standardization of pathologic criteria and introduction of new molecular testing methods in renal biopsy specimens hopefully will improve diagnostic accuracy.