How I Treat Complement-Mediated TMA

Onconephrology and Thrombotic Microangiopathy: Looking Beyond the Horizon

Thrombotic microangiopathies (TMAs) represent a complex interaction of endothelial and podocyte biology, nephron physiology, complement genetics, and oncologic therapies with host immunology. The complexity of various factors, such as molecular causes, genetic expressions, and immune system mimicking, along with incomplete penetrance, make it difficult to find a straightforward solution. As a result, there may be variations in diagnosis, study, and treatment approaches, and achieving a consensus can be challenging. Here, we review the molecular biology, pharmacology, immunology, molecular genetics, and pathology of the various TMA syndromes in the setting of cancer. Controversies in etiology, nomenclature, and points requiring further clinical, translational, and bench research are discussed. Complement-mediated TMAs, chemotherapy drug-mediated TMAs, TMAs in monoclonal gammopathy, and other TMAs central to onconephrology practice are reviewed in detail. In addition, established and emerging therapies within the US Food and Drug Administration pipeline subsequently are discussed. Finally, a comprehensive review of critical areas of onconephrology clinical practice is presented as practical value to the clinical practitioner and seeds of investigation to be sown among the community of atypical hemolytic uremic syndrome researchers.

How I treat thrombotic microangiopathy in the era of rapid genomics

Thrombotic microangiopathy (TMA) encompasses various genetically-driven diseases. The emergence of ultrafast genomic sequencing has recently opened up new avenues of research for genetic investigations in the setting of intensive care units. TMA is likely to be a suitable focus for fast-track genomic sequencing. By establishing an expeditious molecular diagnosis of patients with the complement-dependent hemolytic uremic syndrome, fast-track genomic sequencing allows for the timely implementation or withdrawal of anti-C5 treatment while averting unnecessary, costly, and potentially harmful therapy in patients testing negative for the syndrome. Furthermore, genomics has the potential to reshape the taxonomic classification of TMA owing to comprehensive genomic analysis. The most significant results from such analysis can be categorized as (1) new descriptions of genetic diseases previously not recognized as associated with TMA and (2) an enrichment of the phenotypic spectrum of diseases traditionally related to TMA. The latter draws on the concept of retrophenotyping, wherein genomic investigation precedes full clinical description. By taking precedence over a phenotypic approach, an unbiased genomic-focused analysis maximizes the chances of discovering new descriptions of a given variant. Presented here are 4 cases of TMA which highlight these issues and substantiate the promise of fast-track genomic sequencing.

Case report: Thrombotic microangiopathy concomitant with macrophage activation syndrome in systemic lupus erythematosus refractory to conventional treatment successfully treated with eculizumab

Thrombotic microangiopathy (TMA) is a rare but life-threatening complication of systemic lupus erythematosus (SLE). Macrophage activation syndrome (MAS) is also a rare, life-threatening hyperinflammatory condition that is comorbid with SLE. However, the association between TMA and MAS in patients with SLE has rarely been assessed, and the difficulty of diagnosing these conditions remains prevalent. The efficacy of eculizumab has been reported for SLE patients whose conditions are complicated with TMA. However, no study has investigated the therapeutic efficacy of eculizumab for TMA concomitant with SLE-associated MAS. Herein, we report the first case of TMA concomitant with SLE-associated MAS that was initially refractory to conventional immunosuppressive therapy but showed remarkable recovery after eculizumab treatment. Furthermore, we evaluated serum syndecan-1 and hyaluronan levels, which are biomarkers of endothelial damage. We found that these levels decreased after the administration of eculizumab, suggesting that TMA was the main pathology of the patient. This case illustrates that it is important to appropriately assess the possibility of TMA during the course of SLE-associated MAS and consider the use of eculizumab as necessary.