Cutaneous toxic effects associated with vemurafenib and inhibition of the BRAF pathway.

BACKGROUND: The development of a novel BRAF inhibitor, vemurafenib, has been associated with impressive tumor regression in patients with BRAF-positive stage IV melanoma. In the phase 3 clinical trials, dermatologic toxic effects associated with vemurafenib were described, namely, the development of eruptive squamous cell carcinomas. Herein, 3 cases are presented that highlight the development of squamous cell carcinomas and other cutaneous sequelae that have not been previously reported and are reminiscent of those observed with administration of the multikinase inhibitor sorafenib tosylate. In addition, the current understanding of the molecular mechanisms underlying these toxic effects is reviewed. OBSERVATIONS: The development of keratosis pilaris-like eruptions; seborrheic dermatitis-like rashes; and hyperkeratotic, tender plantar papules reminiscent of those seen in sorafenib-associated hand-foot skin reaction, as well as squamous cell carcinomas, is presented in association with vemurafenib-based treatment of metastatic melanoma. CONCLUSIONS: The development of sorafenib-like cutaneous sequelae (squamous cell carcinomas, keratosis pilaris-like eruptions, seborrheic dermatitis-like rashes, and hand-foot skin reaction) associated with vemurafenib administration suggests that BRAF inhibition alone may be sufficient to induce these changes.

NAT2, CYP2C9, CYP2C19, and CYP2E1 genetic polymorphisms in anti-TB drug-induced maculopapular eruption.

PURPOSE: It has been suggested that drug-metabolizing enzymes might play important roles in the development of anti-tuberculosis drug (ATD)-induced maculopapular eruption (MPE), as in ATD-induced hepatitis. We investigated the associations between the genetic polymorphisms of drug-metabolizing enzymes and ATD-induced MPE. METHODS: We enrolled 62 patients with ATD-induced MPE (mean age 47.2 ± 19.0, male 59.7%) and 159 patients without any adverse reactions to ATD (mean age 42.8 ± 17.6, male 65.4%), among patients with pulmonary tuberculosis (TB) and/or TB pleuritis and treated with first-line anti-TB medications, including isoniazid, rifampin, ethambutol, and pyrazinamide. We compared the genotype distributions of single nucleotide polymorphisms and haplotypes in four drug-metabolizing enzymes (N-acetyltransferase 2 (NAT2), cytochrome P450 (CYP) 2 C9, CYP2C19, and CYP2E1) among patients with ATD-induced MPE and patients tolerant to ATD using a multivariate logistic regression analysis. These analyses were made without identification of the responsible ATD. RESULTS: -1565 C > T of CYP2C9 showed a significant association with ATD-induced MPE (P = 0.022, OR = 0.23, 95% CI 0.07-0.78), with a lower frequency of genotypes carrying minor alleles (CT or TT) in the case group than in the controls. Additionally, W212X of CYP2C19 was significantly associated with the risk of ATD-induced MPE (P = 0.042, OR = 0.27, 95% CI 0.09-0.82). In an analysis of the CYP2C19-CYP2C9 haplotypes (-1418 C > T_W212X_-1565 C > T_-1188 C > T), ht3[T-A-T-C] showed a significant association with the development of ATD-induced MPE (P = 0.012, OR = 0.13, 95% CI 0.03-0.57). No significant associations between the other genetic polymorphisms and ATD-induced MPE were observed. CONCLUSIONS: CYP2C19 and CYP2C9 genetic polymorphisms are significantly associated with the risk of developing ATD-induced MPE, and the genetic variants in NAT2 and CYP2E1 are not closely related to the development of this adverse reaction.

The skin cancer chemotherapeutic agent ingenol-3-angelate (PEP005) is a substrate for the epidermal multidrug transporter (ABCB1) and targets tumor vasculature.

Ingenol-3-angelate (Ing3A), extracted from Euphorbia peplus, is currently in clinical trials for eradicating basal cell carcinoma, actinic keratosis, and squamous cell carcinoma (SCC) in situ by topical application. Although structurally related to phorbol esters and a protein kinase C activator, topical Ing3A, but not phorbol 12-myristate 13-acetate (PMA), inhibited the growth of subcutaneous tumors derived from PAM212 (mouse SCC) and B16 (mouse melanoma). Ing3A and PMA both induced acute neutrophilic inflammation on mouse skin, but only Ing3A caused subcutaneous hemorrhage and vascular damage. Both Ing3A and PMA activated extracellular signal-regulated kinase 1/2 (ERK1/2) in epidermis, but Ing3A also activated ERK1/2 in skin dermal fibroblasts and endothelial cells. Pretreatment with topical cyclosporin A (CsA), verapamil, or XR9576, modulators of P-glycoprotein (P-gp), prevented Ing3A-induced hemorrhage but not neutrophil infiltration. CsA also impaired the anticancer activity of Ing3A, whereas the anti-inflammatory dexamethasone did not. Ing3A, but not PMA, blocked photoaffinity labeling of human P-gp with [(125)I]iodoaryazidoprazosin and inhibited P-gp-mediated drug resistance to HCT-15 cells. The intracellular levels of Ing3A were significantly lower in P-gp-expressing cells, and treatment with XR9576 increased the levels to those of cells that do not express P-gp, showing that Ing3A binds to and is transported by P-gp. Taken together, our results suggest that P-gp-mediated absorptive transport, dermal penetration, and vascular damage contribute to the anticancer activity of Ing3A in vivo.

GSTT1 and GSTM1 null mutations and adverse reactions induced by antituberculosis drugs in Koreans.

Adverse reactions induced by antituberculosis drugs (ATD) often result in serious morbidities, impeding scheduled treatment and cure. In the development of ATD-induced adverse reactions, glutathione S-transferase has been suggested to play a protective role as an intracellular scavenger by conjugating toxic reactive metabolites of ATD. This study examined the association of null mutations in GST enzyme genes (GSTT1 and GSTM1) with the development of ATD-induced hepatitis and cutaneous reactions. We compared the frequencies of GSTT1 and GSTM1 null mutations in 57 patients with hepatitis, 94 patients with cutaneous adverse reactions, and 190 ATD-tolerant controls. The frequency of null mutations in GSTT1 and GSTM1 in patients with ATD-induced hepatitis was not significantly different from that of controls (59.6% vs. 54.2% and 45.6% vs. 54.7%, respectively). Additionally, no significant difference was observed in the frequency of either null mutation in patients with ATD-induced cutaneous reactions, including maculopapular eruption, compared with controls (58.5% vs. 54.1% for GSTT1 and 59.6% vs. 54.6% for GSTM1). These findings indicate that GSTT1 and GSTM1 null mutations are not associated with the development of ATD-induced hepatitis or cutaneous reactions in this Korean population, and suggest that glutathione S-transferase enzymes do not play important roles in the pathogenesis of these conditions.

Markers in the epidermal growth factor receptor pathway and skin toxicity during erlotinib treatment.

BACKGROUND: Skin toxicity is a common adverse effect of erlotinib and other anti-epidermal growth factor receptor (EGFR) agents. The aim of the study was to explore the relationship between markers in the EGFR pathway and skin rash. PATIENTS AND METHODS: Eighteen patients with metastatic breast cancer were treated with daily oral erlotinib at 150 mg. Skin biopsies were obtained at baseline and after 1 month of treatment in 15 patients. EGFR, phosphorylated EGFR (pEGFR), phosphorylated mitogen-activated protein kinase (pMAPK), and phosphorylated Akt (pAkt) or Ki67 were examined quantitatively by immunohistochemistry. RESULTS: 11 of 18 (61%, 95% confidence interval 35.7% to 82.7%) patients developed skin rash. pAkt at baseline was significantly higher in patients with no rash than those with a grade 1 or 2 rash (18.8 +/- 8.3 versus 2.4 +/- 1.2 versus 3.3 +/- 3.3; P = 0.0017 for trend). There was a trend towards a significant increase of pMAPK in skin posttreatment with increasing grade of rash (no rash versus grade 1 versus grade 2 rash: 4.5 +/- 2.3 versus 8.4 +/- 4.2 versus 19.4 +/- 4.6; P = 0.036). Other markers were not associated with rash. CONCLUSIONS: pAkt was significantly associated with not developing a rash and may have a predictive utility for skin toxicity in patients treated with erlotinib and possibly with other anti-EGFR agents.

Eruptive papules during efalizumab (anti-CD11a) therapy of psoriasis vulgaris: a case series.

BACKGROUND: Newer biological therapies for moderate-to-severe psoriasis are being used more frequently, but unexpected effects may occur. CASE PRESENTATIONS: We present a group of 15 patients who developed inflammatory papules while on efalizumab therapy (Raptiva, Genentech Inc, anti-CD11a). Immunohistochemistry showed that there were increased CD11b+, CD11c+ and iNOS+ cells (myeloid leukocytes) in the papules, with relatively few CD3+ T cells. While efalizumab caused a decreased expression of CD11a on T cells, other circulating leukocytes from patients receiving this therapy often showed increased CD11b and CD11c. In the setting of an additional stimulus such as skin trauma, this may predispose to increased trafficking into the skin using these alternative beta2 integrins. In addition, there may be impaired immune synapse formation, limiting the development of these lesions to small papules. There is little evidence for these papular lesions being "allergic" in nature as there are few eosinophils on biopsy, and they respond to minimal or no therapy even if efalizumab is continued. CONCLUSION: We hypothesize that these papules may represent a unique type of "mechanistic" inflammatory reaction, seen only in the context of drug-induced CD11a blockade, and not during the natural disease process.

Inhibition of chronic skin inflammation by topical anti-inflammatory flavonoid preparation, Ato Formula.

Flavonoids are known as natural anti-inflammatory agents. In this investigation, an anti-inflammatory potential of new topical preparation (SK Ato Formula) containing flavonoid mixtures from Scutellaria baicalensis Georgi roots and Ginkgo biloba L. leaves with an extract of Gentiana scabra Bunge roots was evaluated in an animal model of chronic skin inflammation. Multiple 12-O-tetradecanoylphorbol-13-acetate treatments for 7 consecutive days on ICR mouse ear provoked a chronic type of skin inflammation: dermal edema, epidermal hyperplasia and infiltration of inflammatory cells. When topically applied in this model, this new formulation (5-20 microL/ear/treatment) reduced these responses. Furthermore, it inhibited prostaglandin E2 generation (17.1-33.3%) and suppressed the expression of proinflammatory genes, cyclooxygenase-2 and interleulin-1beta in the skin lesion. Although the potency of inhibition was lower than that of prednisolone, all these results suggest that Ato Formula may be beneficial for treating chronic skin inflammatory disorders such as atopic dermatitis.

Pathology and management of dermatologic toxicities associated with anti-EGFR therapy.

As inhibitors of the epidermal growth factor receptor (EGFR) become an increasingly common therapeutic option in cancer, appropriate management of their associated toxicities emerges as a critical part of treatment. Cutaneous manifestations, probably linked to the function of the EGFR in epithelial development, are the most common adverse reactions to EGFR inhibition. The key manifestations are follicular eruptions, nail disorders, xerosis, and desquamation. Growing attention continues to be devoted to the analysis of these events, particularly given their potential role as markers of responsiveness to treatment. However, to date, there are few evidence-based guidelines for the appropriate management of these dermatologic events. Multidisciplinary collaboration between oncologists and dermatologists will be required to improve our understanding and optimize the characterization of these skin toxicities, and to design effective management approaches.

Cyclooxygenases: new forms, new inhibitors, and lessons from the clinic.

The beneficial actions of nonsteroidal anti-inflammatory drugs (NSAIDs) have been linked to their ability to inhibit inducible COX-2 at sites of inflammation, and their side effects (e.g., gastric damage) to inhibition of constitutive COX-1. Selective inhibitors of COX-2, such as celecoxib, etoricoxib, lumiracoxib, rofecoxib, and valdecoxib have been developed and the greatest recent growth in our knowledge in this area has been come from the clinical use of these compounds. Although clinical data indicate that COX-2 selectivity is associated with a reduction in severe gastrointestinal events, they also reveal there are roles for constitutive COX-2 within tissues such as the brain, kidney, pancreas, intestine, and blood vessels. We now better understand the roles of COX-1 and COX-2 in functions as disparate as the perception of pain and the progression of cancers. Clinical use of COX-2-selective compounds has ignited strong debates regarding potential side effects, most notably those within the cardiovascular system such as myocardial infarctions, strokes, and elevation in blood pressure. This review will discuss how the latest studies help us understand the roles of COX-1 and COX-2 and what clinically proven benefits the newer generation of COX-2-selective inhibitors offer

Crossreacting drugs and chemicals.

Aspirin and nonsteroidal antiinflammatory drugs (NSAIDs) exert their clinical effect through inhibition of prostaglandin H synthases 1 and 2, also known as cyclooxygenase. This shared effect of COX-inhibition is also the mechanism for shared adverse effects. Much of our understanding of cross-reacting drugs and chemicals with aspirin comes from studying asthmatics with aspirin-exacerbated respiratory disease (AERD). Aspirin exacerbated respiratory disease is characterized by recalcitrant sinusitis/polyposis, asthma and precipitation of asthma after ingestion of aspirin and most NSAIDs. Cross-reactions between ASA and NSAIDs occur with first exposure unlike IgE-mediated allergic drug reactions. Cross-reactions between aspirin and other drugs are dependent upon inhibition of the cyclooxygenase-1 isoenzyme. Desensitization to aspirin will result in cross-desensitization to all NSATDs that inhibit COX-1. Despite reports in the literature, there does not appear to he cross-reactions between food coloring, hydrocortisone succinate and monosodium glutamate in individuals with aspirin exacerbated respiratory disease. The new highly selective cyclooxygenase 2 inhibitors are well tolerated in AERD asthmatics who have not been desensitized to aspirin. Because low-dose ASA exerts a cardioprotective effect by irreversible inhibition of COX-1, AERD patients who are at risk for coronary artery disease should be considered for aspirin desensitization.

Hyperosmotic stress induces phosphorylation of cytosolic phospholipase A(2) in HaCaT cells by an epidermal growth factor receptor-mediated process.

Cytosolic phospholipase A(2) (cPLA(2)) is an enzyme involved in the formation of proinflammatory mediators by catalyzing the release of arachidonic acid, thereby mediating eicosanoid biosynthesis. Using HaCaT keratinocytes as a model system, we present experimental evidence that in these cells, cPLA(2) is constitutively phosphorylated and that the degree of phosphorylation dramatically increases in cells under hyperosmotic stress induced by sorbitol. In parallel, a rapid release of arachidonic acid followed by prostaglandin E(2) formation was detected. Elucidating the mechanism of cPLA(2) upregulation, we observed that it is mediated via epidermal growth factor receptor (EGFR) activation, since tyrphostin AG1478, a selective inhibitor of EGFR tyrosine kinase, completely inhibited cPLA(2) phosphorylation. Furthermore, addition of PD98059, which is an inhibitor of MEK1 activation, but not of SB203580, which is an inhibitor of p38 stress kinase, inhibited cPLA(2) phosphorylation, indicating that the ras-raf-MEK cascade is the major signalling pathway involved in cPLA(2) phosphorylation. In addition, depletion of the cells from intracellular calcium does not prevent sorbitol-elicited cPLA(2) phosphorylation, suggesting that this process is independent of the presence of calcium. Together, our results demonstrate that hyperosmotic stress phosphorylates cPLA(2) in human keratinocytes by an EGFR-mediated process.

Serum tryptase levels in adverse drug reactions.

We evaluated the usefulness of individual tryptase levels and variations after adverse drug reactions in 64 patients. Our aim was to find a tool for the diagnosis of drug allergy. Thirty-seven subjects were confirmed to have drug allergy, 12 had nonsteroidal anti-inflammatory drug (NSAID) reactions, five had negative controlled drug challenges (NAAR), and 10 had symptoms after placebo intake (PLA). Serum tryptase levels greatly increased after anaphylactic shocks (2242%) and anaphylaxis (710.5%). Patients with allergic urticaria and those with idiosyncratic responses to acetylsalicylic acid (ASA) exhibited a small increase in serum tryptase (49.5% and 38.2%, respectively). In the other two groups (NAAR and PLA), no variation in this serum protease was observed. The time of appearance of the serum tryptase peak differed considerably among patients with similar clinical reactions (from 30 min to 6 h) and was independent of the latent period, severity of symptoms, or the amount of tryptase released. We conclude that serum tryptase determinations are helpful in the diagnosis of anaphylactic shock and anaphylaxis, but serial measurements may be needed to confirm mast-cell participation in milder reactions.

Myeloperoxidase as a biomarker of skin irritation and inflammation.

Topical exposure to many occupational and environmental chemicals is often accompanied by the induction of a cutaneous inflammatory response characterized by the influx of polymorphonuclear leucocytes (PMNs). In this study, the accumulation of myeloperoxidase (MPO), an enzyme found at high content in PMNs, was used as a biomarker to assess the inflammatory response to a number of well characterized skin irritants and tumour promoters. Of the chemicals examined, there was a good agreement between MPO accumulation and morphometric indicators of PMNs. Therefore, it was suggested that MPO accumulation could be an additional and useful toxicological tool for determining the dermal irritancy of chemicals.

Macro lactate dehydrogenase: an LDH-immunoglobulin M complex that inhibits lactate dehydrogenase activity in a patient's serum.

A macro lactate dehydrogenase (LDH, EC 1.1.1.27) isoenzyme with a low total LDH activity was present in the serum of a 57-year-old woman with a drug eruption (cutaneous lesions from an allergic reaction to drug administration). The patient's LDH was shown by immunoelectrophoresis to be bound to immunoglobulin G (IgG) and M (IgM). It was found that the patient's IgM acted as an inhibitor of LDH that was specific for the M subunit. When IgM was treated with 0.1 mol/l of 2-mercaptoethanol (2-ME), the inhibiting effect of the IgM to LDH activity disappeared, while treated IgM continued to bind to the LDH molecule. The LDH activity increased approximately two-fold when the patient's serum was treated with 2-ME. LDH activity in normal human serum was inhibited and an abnormal pattern of LDH isoenzyme appeared when the patient's IgM was added to normal serum. The present case seems to be the first report of LDH-IgM complex with a marked decrease of LDH activity.

The release of beta glucuronidase from the white cells of patients with drug rashes when incubated in autologous plasma, with and without the addition of the causal drug.

In seven out of 16 patients with drug rashes, the leucocytes selectively released beta glucuronidase when incubated in autologous plasma, indicating the possible presence of immune complexes. When the white cells were incubated with the suspected drug in vitro, they tended to react in three different ways. In four out of 16 cases additional beta glucuronidase was released, perhaps due to the formation of immune complexes, in two out of the 16, beta glucuronidase release was suppressed, perhaps due to antigen excess, and in two cases LDH release was decreased while beta glucuronidase remained unaltered.