Facing up to toxic epidermal necrolysis

Effect of N-acetylcysteine combined with infliximab on toxic epidermal necrolysis. A proof-of-concept study

INTRODUCTION

The pathophysiology of toxic epidermal necrolysis (TEN) is thought to be related to a drug-induced oxidative stress combined with TNFα overexpression by keratinocytes. None of the current treatments for TEN including systemic corticosteroids, cyclosporine and intravenous administration of immunoglobulins has proven superior over supportive care only.

METHODS

A total of 10 TEN patients were enrolled to be treated at admission in burn units with the antioxidant N-acetylcysteine [NAC, 150mg/kg in a 20-h intravenous (IV) administration], or the combination of the same IV NAC perfusion with the anti-TNFα antibody infliximab (Remicade(®)), administered at a 5mg/kg dosage as a single 2-h IV administration. TEN was confirmed by a skin biopsy taken from a bullous lesion. At entry in the trial and 48h later, the illness auxiliary score (IAS) of clinical severity was determined and the extent in altered skin area (erythema and blisters) was assessed as a relative body area. Skin biopsies of both clinically uninvolved and erythematous areas were collected and immunohistochemistry was performed for assessing the density of inflammatory cells (CD8+ T cells, CD68+ macrophages) and keratinocytes enriched in intracellular calcium (Ca(++)) identified by the Mac387 anti-calprotectin antibody.

RESULTS

No unexpected drug-induced adverse event was noticed. After 48h of both treatment modalities, improvements were not observed in the extent of skin involvement and in IAS. Immunohistopathology showed the absence of reduction in the amount of intraepidermal inflammatory cells. An increased intracellular Ca(++) load in clinically uninvolved keratinocytes and in erythematous epidermis was noticed. This latter finding suggested the progression in the way of the apoptotic process. On burn unit discharge, the survival in each modality of treatment was not improved compared to the expected outcomes determined from the IAS at admission.

CONCLUSIONS

In this proof-to-concept attempt, NAC treatment or its combination with infliximab did not appear to reverse the evolving TEN process.

Toxic Epidermal Necrolysis and Graft-versus-Host Reaction: Revisiting a Puzzling Similarity

Drug-induced toxic epidermal necrolysis (TEN) and acute cutaneous graft-versus-host reaction (GVHR) under immunopreventive therapy share some histopathological resemblance. So far, there are no serum biomarkers and no immunohistochemical criteria distinguishing with confidence and specificity the skin lesions of TEN and GVHR. Both diseases present as an inflammatory cell-poor necrotic reaction of the epidermis. This report compares three sets of 15 immunostaining patterns found in TEN, GVHR, and partial thickness thermal burns (PTTB), respectively. Three series of 17 skin biopsies were scrutinized. Irrespective of the distinct causal pathobiology of TEN and GVHR, similar secondary effector cells were recruited in lesional skin. Burns were less enriched in cells of the monocyte-macrophage disease. These cells likely exert deleterious effects in TEN and GVHR and cannot be simply regarded as passive bystanders. These life-threatening conditions are probably nursed, at least in part, by macrophages.

Idiosyncratic adverse drug reactions: current concepts

Idiosyncratic drug reactions are a significant cause of morbidity and mortality for patients; they also markedly increase the uncertainty of drug development. The major targets are skin, liver, and bone marrow. Clinical characteristics suggest that IDRs are immune mediated, and there is substantive evidence that most, but not all, IDRs are caused by chemically reactive species. However, rigorous mechanistic studies are very difficult to perform, especially in the absence of valid animal models. Models to explain how drugs or reactive metabolites interact with the MHC/T-cell receptor complex include the hapten and P-I models, and most recently it was found that abacavir can interact reversibly with MHC to alter the endogenous peptides that are presented to T cells. The discovery of HLA molecules as important risk factors for some IDRs has also significantly contributed to our understanding of these adverse reactions, but it is not yet clear what fraction of IDRs have a strong HLA dependence. In addition, with the exception of abacavir, most patients who have the HLA that confers a higher IDR risk with a specific drug will not have an IDR when treated with that drug. Interindividual differences in T-cell receptors and other factors also presumably play a role in determining which patients will have an IDR. The immune response represents a delicate balance, and immune tolerance may be the dominant response to a drug that can cause IDRs.

Immunological mechanisms of epidermal damage in toxic epidermal necrolysis

PURPOSE OF REVIEW

The purpose of the present review is to introduce recent findings on the pathomechanisms of toxic epidermal necrolysis (TEN), which is characterized by widespread epidermal detachment due to keratinocyte apoptosis.

RECENT FINDINGS

In the mechanism of epidermal damage, the roles of drug metabolites, cytotoxic lymphocytes, and apoptosis-inducing factors have been noted. In addition, recent studies have focused on monocytes/macrophages, which may participate in epidermal damage through the production of apoptosis-inducing factors and the expression of costimulatory factors with the ability to activate CD8 T cells.

SUMMARY

Epidermal keratinocyte death is a hallmark of TEN. In a very high proportion of cases, drugs are responsible for TEN. It has been suggested that toxic drug metabolites produced by keratinocytes act like electrophilic agents to induce apoptosis and inflammation. Next, cytotoxic lymphocytes and monocytes function in the development of widespread epidermal damage through direct or indirect cytotoxic pathways. In addition, T-cell activation may be strengthened by the impairment of regulatory T-cell function and activated monocytes. The development of epidermal damage in TEN may require the coordinated action of these factors.

Toxic epidermal necrolysis related to Cisplatin and pemetrexed for metastatic non-small cell lung cancer

BACKGROUND

Toxic epidermal necrolysis (TEN) is an uncommon but life-threatening adverse drug reaction. Pemetrexed is a multitargeted antifolate. It was first used in combination with cisplatin as a front-line treatment for malignant pleural mesothelioma. The same combination is nowadays approved in the first-line setting for locally advanced or metastatic nonsquamous non-small cell lung cancer (NSCLC).

PATIENT AND METHODS

We report the case of a 50-year-old man treated for metastatic NSCLC. Within 5 days after administration of the second cycle of cisplatin and pemetrexed, he developed large blisters, which secondarily became hemorrhagic, and mucosal lesions. The characteristic clinical appearance, the histopathological findings, and the clinical course were decisive for the diagnosis of TEN. Treatment with systemic steroids and intravenous antibiotics as well as topical wound treatment led to resolution and improvement of his general condition.

CONCLUSIONS

To the best of our knowledge, this is the third case of TEN due to pemetrexed in a patient with NSCLC. Clinicians should be aware of TEN as a rare but potentially fatal disorder requiring hospitalization and multidisciplinary management.

Revisiting cutaneous adverse reactions to pemetrexed

Pemetrexed (Alimta®) is a multitargeted antifolate drug approved as a single agent or in combination with cisplatin for the treatment of a small number of malignancies including advanced and metastatic non-squamous non-small cell lung cancer (NSCLC), and malignant pleural mesothelioma. This review reports the recent peer-reviewed publications and original findings regarding cutaneous adverse reactions (CARs) to pemetrexed. Pemetrexed-related CARs are frequently reported under the unspecific term 'skin rash'. However, more specific diseases were tentatively identified as alopecias, urticarial vasculitis, acute generalized exanthematous pustulosis, toxic epidermal necrolysis, radiation recall dermatitis and pityriasis lichenoides. Most of the skin reactions occur shortly after pemetrexed administration. As with methotrexate-related CARs, the cell cycle arrest in the S phase may be regarded as a direct and major cause of the cytotoxic pathobiology. An adverse immune reaction is unlikely. In conclusion, pemetrexed is responsible for CARs exhibiting a variety of clinical presentations. Their origin is likely attributed to direct cytotoxicity following the cell cycle arrest in the S phase and cell necrosis.