Thrombotic microangiopathies and antineoplastic agents

Chemotherapy-Associated Thrombotic Microangiopathy

Thrombotic microangiopathy (TMA) is a syndrome of microangiopathic hemolytic anemia and thrombocytopenia with end-organ dysfunction. Although the advent of plasma exchange, immunosuppression, and complement inhibition has improved morbidity and mortality for primary TMAs, the management of secondary TMAs, particularly drug-induced TMA, remains less clear. TMA related to cancer drugs disrupts the antineoplastic treatment course, increasing the risk of cancer progression. Chemotherapeutic agents such as mitomycin-C, gemcitabine, and platinum-based drugs as well as targeted therapies such as antiangiogenesis agents and proteasome inhibitors have been implicated in oncotherapy-associated TMA. Among TMA subtypes, drug-induced TMA is less well-understood. Treatment generally involves withdrawal of the offending agent and supportive care targeting blood pressure and proteinuria reduction. Immunosuppression and therapeutic plasma exchange have not shown clear benefit. The terminal complement inhibitor, eculizumab, has shown promising results in some cases of chemotherapy-associated TMA including in re-exposure. However, the data are limited, and unlike in primary atypical hemolytic uremic syndrome, the role of complement in the pathogenesis of drug-induced TMA is unclear. Larger multicenter studies and unified definitions are needed to elucidate the extent of the problem and potential treatment strategies.

Microangiopathy associated with gemcitabine: a drug interaction with nab-paclitaxel? A case series and literature review

PURPOSE

Gemcitabine and nab-paclitaxel association can be used in first- or second-line treatment for metastatic pancreatic adenocarcinoma. Here, we report five cases of supposed gemcitabine-induced thrombotic microangiopathy (G-TMA), four of them with nab-paclitaxel. We assumed that nab-paclitaxel could be responsible for a potential drug interaction with gemcitabine, increasing the risk of thrombotic microangiopathy occurrence.

METHODS

Clinicians reported cases of supposed G-TMA that were declared to the Pharmacovigilance center. We collected the patients' data (clinical and biological characteristics), calculated an incidence rate of G-TMA in our center, and a Naranjo score for each patient. We also reviewed literature on a potential drug interaction between nab-paclitaxel and gemcitabine.

RESULTS

Four patients were treated with nab-paclitaxel/gemcitabine and one with gemcitabine alone. The time onset of supposed G-TMA was 2 to 11 months. Patients developed anemia, thrombocytopenia, and renal failure. The incidence rate of supposed G-TMA was 2.7% in our center compared to 0.31% (Meyler's Side Effect of Drugs) and 0.01% in the gemcitabine's summary of product characteristics. Literature review outlined an increase of gemcitabine's plasmatic concentrations induced by nab-paclitaxel (Drugs® website) and a potentiation of gemcitabine's effect by nab-paclitaxel in murine models. This study showed that nab-paclitaxel inhibits cytidine deaminase's activity (responsible for gemcitabine's metabolism) and increases gemcitabine's active metabolite concentrations (gemcitabine triphosphate) in tumor tissues.

CONCLUSION

High incidence rate of G-TMA was observed in our cohort due to a potential drug interaction between nab-paclitaxel and gemcitabine with an increased risk of developing G-TMA. Additional pharmacological and pharmaco-epidemiological investigations are mandatory to explore this hypothesis.

The Impact of Renal Impairment on Survival Outcomes in Patients With Metastatic Renal Cell Carcinoma Treated With Tyrosine Kinase Inhibitors

Purpose:

It remained unclear whether tyrosine kinase inhibitors (TKIs) related renal impairment had impact on the survival of patients with metastatic renal cell carcinoma (mRCC).

Methods:

Clinicopathological parameters of patients with mRCC treated with TKIs were retrospectively reviewed. Blood urea nitrogen (BUN), proteinuria and estimated glomerular filtration rate (eGFR) at baseline and during TKIs treatment were recorded. BUN > 7.1mol/L, eGFR <60 ml/min/1.73m² and/or proteinuria level > 0.3 g/L were defined as renal impairment. eGFR and proteinuria were furtherly classified into different levels. Treatment outcomes were defined as progression-free survival (PFS) and overall survival (OS).

Results:

At baseline, the presence of abnormal BUN, eGFR and proteinuria level were observed in 25 (22.7%), 27 (25.5%) and 30 (27.3%) patients, which increased to 46 (41.8%), 55 (50.0%) and 64 (58.2%) respectively after TKIs treatment. In the whole cohort (N = 110), survival analysis suggested that only post-treatment renal impairment was related to survival outcomes. Interestingly, sub-analysis showed that post-treatment eGFR level (p = 0.004), proteinuria (p = 0.014) and eGFR decrease >10% (p = 0.012) and elevated proteinuria compared with baseline (p = 0.006) were statistically correlated with OS among patients without RI at baseline (N = 51). On the contrary, deterioration of renal impairment after TKIs treatment in patients with renal impairment at baseline (N = 59) had no relationship with either PFS or OS. Furthermore, eGFR (p = 0.020) and eGFR decrease >10% (p = 0.016) within 1 year after TKIs therapy were potential biomarkers for OS.

Conclusion:

Dynamic changes of TKI-induced RI during TKIs treatment, especially eGFR and proteinuria level, could be considered as potential biomarkers predicting survival outcomes of mRCC patients.

An overview of thrombotic complications of old and new anticancer drugs

Thrombosis is a common complication of cancer with a mean prevalence of 15%. Most commonly, this presents as venous thromboembolism; however, other manifestations such as arterial thrombosis or thrombotic microangiopathy may occur. Cancer itself is not only associated with risk factors for thrombotic complications, including intrinsic biological effect of malignant cells, accompanying operations, or the presence of indwellingvascular catheters, but there is also an additional risk caused by anticancer agents including chemotherapy and immunotherapy. In most cases the underlying pathogenetic factor that contributes to the thrombotic risk associated with chemotherapy is endothelial cell injury (or loss of protection of endothelial integrity, for example by vascular endothelial growth factor inhibition). In addition, individual anticancer agents may have specific prothrombotic effects. As in recent years more intense anticancer drugs are administered, such as in myeloablative conditioning regimens preceding stem cell transplantation, thrombosis and in particular thrombotic microangiopathy are a more frequent complication in anticancer treatment.

Clinical significance of measuring ADAMTS-13, its inhibitor and von Willebrand factor in obstetric and gynecological practice

ADAMTS-13 is a crucial metalloproteinase involved in liberating fragments of von Willebrand factor (vWF) into the plasma as well as regulating its activity by cleaving "ultra-large" multimers into smaller and less active counterparts. Many pathological conditions, including those emerged during pregnancy are characterized by increased level of vWF and decreased ADAMTS-13 activity. In this regard, it is necessary to monitor the levels of vWF and ADAMTS-13 activity to prevent thrombotic thrombocytopenic purpura (Moschcowitz disease) as one of the most severe forms of thrombotic microangiopathy.

 

Complement in Secondary Thrombotic Microangiopathy

Thrombotic microangiopathy (TMA) is a condition characterized by thrombocytopenia and microangiopathic hemolytic anemia (MAHA) with varying degrees of organ damage in the setting of normal international normalized ratio and activated partial thromboplastin time. Complement has been implicated in the etiology of TMA, which are classified as primary TMA when genetic and acquired defects in complement proteins are the primary drivers of TMA (complement-mediated TMA or atypical hemolytic uremic syndrome, aHUS) or secondary TMA, when complement activation occurs in the context of other disease processes, such as infection, malignant hypertension, autoimmune disease, malignancy, transplantation, pregnancy, and drugs. It is important to recognize that this classification is not absolute because genetic variants in complement genes have been identified in patients with secondary TMA, and distinguishing complement/genetic-mediated TMA from secondary causes of TMA can be challenging and lead to potentially harmful delays in treatment. In this review, we focus on data supporting the involvement of complement in aHUS and in secondary forms of TMA associated with malignant hypertension, drugs, autoimmune diseases, pregnancy, and infections. In aHUS, genetic variants in complement genes are found in up to 60% of patients, whereas in the secondary forms, the finding of genetic defects is variable, ranging from almost 60% in TMA associated with malignant hypertension to less than 10% in drug-induced TMA. On the basis of these findings, a new approach to management of TMA is proposed.

Bilateral sensorineural hearing loss induced by regorafenib

WHAT IS KNOWN AND OBJECTIVE

Regorafenib is a novel multi-targeted tyrosine kinase inhibitor approved for use in refractory metastatic colorectal cancer, advanced gastrointestinal stromal tumours and hepatocellular carcinoma. We report a case of bilateral sensorineural hearing loss caused by regorafenib.

CASE SUMMARY

A 48-year-old woman was diagnosed with colon cancer that had metastasized to the liver, ureter and left ovary. She was initially treated with oral regorafenib at the lowest recommended dosage of 80 mg/d for 2 weeks, at which point the dose was increased to 120 mg/d. On the second day after the regorafenib dosage increase (ie, 15 days after starting regorafenib), she suddenly developed a bilateral hearing loss. Regorafenib was discontinued immediately, and the patient was treated with a course of intravenous steroids. Five weeks later, her bilateral hearing had subjective partial improvement.

WHAT IS NEW AND CONCLUSION

This is the first report of bilateral sensorineural hearing loss induced by regorafenib.

Eculizumab therapy in gemcitabine-induced thrombotic microangiopathy in a renal transplant recipient

A renal transplant recipient 7 years post-transplantation, diagnosed with locally advanced pancreatic adenocarcinoma developed thrombotic microangiopathy (TMA) after treatment with gemcitabine and nab-paclitaxel. Gemcitabine was the most likely cause for TMA and was ceased. He received methylprednisolone and plasma exchange with fresh frozen plasma and albumin. Despite plasma exchange, his renal allograft function worsened, and he had persistent haematological evidence of haemolysis. Eculizumab was commenced with resolution-significant improvement in his renal and haematological markers. This case highlights an unusual occurrence of progressive gemcitabine-induced TMA in a renal allograft that had an excellent response to eculizumab. The clinical response also demonstrates involvement of complement dysregulation in gemcitabine-induced TNA.

Impact of a multidisciplinary team for the management of thrombotic microangiopathy

Background

Thrombotic microangiopathy (TMA) is an important complication associated with several diseases that are rare and life-threatening. TMA is common to thrombotic thrombocytopenic purpura (TTP) and hemolytic uremic syndrome (HUS). TTP is defined by a severe deficiency of ADAMTS13, and early treatment is associated with good prognosis. The diagnosis of HUS can be difficult due to the potential multiple etiologies, and the best treatment option in most cases is not well-established yet. The implementation of a multidisciplinary team (MDT) could decrease the time to diagnosis and treatment for HUS and may improve the outcomes of these patients.

Objective

To determine the impact of MDT on morbidity and mortality [death or chronic renal replacement therapy (CRRT) requirements], incidence and response time [(RT) defined as the period between hospital admission and the first day of direct therapy administration], length of stay at an intensive care unit (ICU-LOS) and total hospitalization (T-LOS) were also assessed.

Methods

We compared a pre-MDT implementation period (from January/2008 to May/2016) versus post-MDT period (from May/2016 to December/2016). The screening TMA diagnosis was made according the following criteria: hemolytic anemia, thrombocytopenia and acute renal damage and without ADAMTS13 deficiency. An online chat was implemented to provide instant medical information.

Results

Twenty-eight patients were included. The incidence changed from 2.3 cases/pre-MDT: (all cases: n = 18) to 10 cases/year post-MDT (all cases: n = 10). Two patients died in pre-MDT and post- MDT (11% versus 20%, P = 0.60). From pre-MDT, the number of patients who required CRRT by post-MDT decreased from 7 (39%) to 0, P = 0.03. Similarly, RT, ICU-LOS and T-LOS [median(p25-p75)] decreased from 10 (2–12) days to 0.5 (0–1.5) days, P = 0.04, from 16 (9–30) days to 10 (4–13) days, P = 0.01 and from 33 (22–53) days to 16 (12–32) days, P < 0.01, respectively.

Conclusion

MDT implementation was associated with a greater number of patients who meet TMA criteria. A decrease in the RT and T-LOS periods were observed and associated with better outcomes in these patients.

The Differential Diagnosis and Treatment of Thrombotic Microangiopathies

BACKGROUND

Thrombotic microangiopathies are rare, life-threatening diseaseswhose care involves physicians from multiple specialties. The past five years haveseen major advances in our understanding of the pathophysiology, classification,and treatment of these conditions. Their timely diagnosis and prompt treatment cansave lives.

METHODS

This review is based on pertinent articles published up to 17 December2017 that were retrieved by a selective search of the National Library of Medicine'sPubMed database employing the terms "thrombotic microangiopathy," "thromboticthrombocytopenic purpura," "hemolytic-uremic syndrome," "drug-induced TMA," and"EHEC-HUS."

RESULTS

The classic types of thrombotic microangiopathy are thrombotic thrombo -cytopenic purpura (TTP) and typical hemolytic-uremic syndrome (HUS), also knownas enterohemorrhagic Escherichia coli-associated HUS (EHEC-HUS). There are anumber of further types from which these must be differentiated. The key test,beyond a basic hematological evaluation including a peripheral blood smear, ismeasurement of the blood level of the protease that splits von Willebrand factor,which is designated ADAMTS13 (a disintegrin and metalloprotease with thrombo -spondin type 1 motif, member 13). The quantitative determination of ADAMTS13, ofADAMTS13 activity, and of the ADAMTS13 inhibitor serves to differentiate TTP fromother types of thrombotic microangiopathy. As TTP requires urgent treatment,plasmapheresis should be begun as soon as TTP is suspected on the basis of afinding of hemolysis with schistocytes and thrombocytopenia. The treatment shouldbe altered as indicated once the laboratory findings become available.

CONCLUSION

Rapid differential diagnosis is needed in order to determine the specifictype of thrombotic microangiopathy that is present, because only patients with TTPand only a very small percentage of those with atypical hemolytic-uremic syndrome(aHUS) can benefit from plasmapheresis. The establishment of a nationwideregistry in Germany with an attached biobank might help reveal yet unknowngenetic predispositions.

Thrombotic microangiopathy in cancer

Thrombotic microangiopathy (TMA) is clinical syndrome based on the presence of thrombocytopenia (platelet count <150 K or a reduction of the platelet count by >30% from baseline) accompanied by fragmentation hemolysis (MAHA) and evidence of organ damage. It can be seen in a variety of disorders including thrombotic thrombocytopenic purpura (TTP), atypical hemolytic uremic syndrome (aHUS), shigatoxin related hemolytic uremic syndrome (STEC-HUS). Cancer itself has long been associated with both macro and microvascular thrombosis. In addition, treatment with chemotherapy as well as hematopoetic stem cell transplantation (HCST) has been associated with atypical hemolytic uremic (aHUS) like syndrome. In this review, I will discuss the pathophysiology of TMA in cancer, chemotherapy associated HUS, and HSCT, well as new therapeutic interventions.

Thrombocytopenia in hospitalized patients: approach to the patient with thrombotic microangiopathy

Thrombotic microangiopathies (TMAs), specifically, thrombotic thrombocytopenic purpura (TTP) and complement-mediated hemolytic uremic syndrome (CM-HUS) are acute life-threatening disorders that require prompt consideration, diagnosis, and treatment to improve the high inherent mortality and morbidity. Presentation is with microangiopathic hemolytic anemia and thrombocytopenia (MAHAT) and variable organ symptoms resulting from microvascular thrombi. Neurological and cardiac involvement is most common in TTP and associated with poorer prognosis and primarily renal involvement in CM-HUS. TTP is confirmed by severe ADAMTS13 deficiency (which can be undertaken in real time) and CM-HUS by an abnormality in complement regulators, confirmed by mutational analysis (in 60% to 70% of cases) or the presence of Factor H antibodies (which may not be available for weeks or months). Plasma exchange (PEX) should be started as soon as possible following consideration of these TMAs. Differentiation of the diagnosis requires specific treatment pathways thereafter (immunosuppression primarily for TTP and complement inhibitor therapy for CM-HUS). As the diagnosis is based on MAHAT, there are a number of other medical situations that need to be excluded and these are discussed within the article. Other differentials presenting as TMAs may also be associated with micro- or macrovascular thrombosis, yet are more likely to be due to direct endothelial damage, many of which do not have a clear therapeutic benefit with PEX.