Early Prediction of Response Focused on Tumor Markers in Atezolizumab plus Bevacizumab Therapy for Hepatocellular Carcinoma.

Despite the promising efficacy of atezolizumab plus bevacizumab (atezo/bev), some patients with unresectable hepatocellular carcinoma (HCC) experience disease progression. This retrospective study, which included 154 patients, aimed to evaluate predictors of treatment efficacy of atezo/bev for unresectable HCC. Factors associated with treatment response were examined, focusing on tumor markers. In the high-alpha-fetoprotein (AFP) group (baseline AFP ≥ 20 ng/mL), a decrease in AFP level > 30% was an independent predictor of objective response (odds ratio, 5.517; p = 0.0032). In the low-AFP group (baseline AFP < 20 ng/mL), baseline des-gamma-carboxy prothrombin (DCP) level < 40 mAU/mL was an independent predictor of objective response (odds ratio, 3.978; p = 0.0206). The independent predictors of early progressive disease were an increase in AFP level ≥ 30% at 3 weeks (odds ratio, 4.077; p = 0.0264) and the presence of extrahepatic spread (odds ratio, 3.682; p = 0.0337) in the high-AFP group and up-to-seven criteria, OUT (odds ratio, 15.756; p = 0.0257) in the low-AFP group. In atezo/bev therapy, focusing on early AFP changes, baseline DCP, and tumor burden of up-to-seven criteria are useful in predicting response to treatment.

Methylated SEPT9 assay-based liquid biopsy as a biomarker in molecular targeted agent-treated hepatocellular carcinoma.

BACKGROUND: The development of molecular targeted agents (MTAs) has changed the treatment strategy for hepatocellular carcinoma (HCC). However, currently, there are no established predictive biomarkers for the treatment efficacy of MTAs. Previously, we developed a novel liquid biopsy test for HCC screening using sensitive methylated DNA testing of septin 9 gene (SEPT9). Here, we hypothesized that SEPT9 could be used as a biomarker for MTA treatment efficacy. METHODS: We enrolled 157 patients receiving sorafenib or lenvatinib as a first-line therapy and allocated 85 and 72 patients to the training and validation cohorts, respectively. For the methylation assay, DNA was treated with methylation-sensitive restriction enzymes, followed by multiplex droplet digital PCR. Various clinical parameters were compared with clinical outcomes. RESULTS: The multivariate analysis revealed Eastern Cooperative Oncology Group performance status (≥ 1; p = 0.048), alpha-fetoprotein (AFP) (≥ 400 ng/mL; p < 0.001), and methylated-septin-9 (m-SEPT9) (≥ 205 copies/mL; p = 0.018) as significant predictors of poor overall survival (OS) in the training cohort. m-SEPT9 was identified as a predictor of poor OS in the validation cohort. We developed a predictive score, called the MTA score, consisting of these three significant OS parameters (two points were added for AFP and one point for each of the other predictors). Patients with MTA scores ≥ 2 showed a significantly poor prognosis compared to those with MTA scores ≤ 1 in both the training and validation cohorts. CONCLUSIONS: m-SEPT9 could be a potential predictive biomarker for survival in patients with HCC treated with MTAs.

Double cancer of primary hepatic angiosarcoma and hepatocellular carcinoma treated with atezolizumab plus bevacizumab.

AIM: Primary hepatic angiosarcoma (PHA) is extremely rare, and its imaging findings are similar to those of other liver tumors including hepatocellular carcinoma (HCC). Here, we report a case of hepatitis C virus (HCV)-related HCC followed by PHA that showed remarkable clinical response to atezolizumab plus bevacizumab (Atezo/Bev) therapy. CASE PRESENTATION: A 78-year-old man with recurrent HCC had a liver tumor with lymphadenopathy. Although considered as HCC recurrence, microscopic examination of the resected liver and lymph node showed PHA. Three months later, a solitary lung nodule was newly detected and subsequently resected. The pathological diagnosis was poorly differentiated HCC. Therefore, the patient was finally diagnosed with double cancer of PHA and HCC. Thereafter, he developed a new liver tumor with lymphadenopathy and received Atezo/Bev therapy. Liver tumor biopsy was carried out before the treatment. The pathological diagnosis was angiosarcoma. The patient showed a partial response after two courses of Atezo/Bev therapy. CONCLUSION: To our best knowledge, this report is the first case to present HCV-related HCC followed by PHA and to show that Atezo/Bev therapy is beneficial for PHA.

A combination of liver stiffness and international normalized ratio is an ideal prognostic predictor of portosystemic shunt occlusion in patients with portal hypertension.

BACKGROUND: We previously reported liver stiffness (LS) as a prognostic predictor of portosystemic shunt (PSS) occlusion. This study aims to reinvestigate the predictive factors of the model for end-stage liver disease-sodium (MELD-Na) score amelioration following balloon-occluded retrograde transvenous obliteration (BRTO) and to evaluate the postoperative prognoses of patients with portal hypertension by using newly identified factors. METHODS: Seventy-five patients who underwent BRTO between 2008 and 2021 were retrospectively enrolled. The MELD-Na scores were calculated preoperatively and one month postoperatively. We monitored long-term outcomes and analyzed postoperative survival. RESULTS: At one month postoperatively, the MELD-Na score decreased in 46 (61.3%) patients. Univariate analyses revealed a significant association of the score amelioration with nine factors, including lower LS levels and a higher international normalized ratio (INR). A multivariate logistic regression analysis with receiver operating characteristic curve analyses identified preoperative LS levels and INR as significant independent predictors of the postoperative MELD-Na score amelioration, with optimal cutoffs of 28.1 kPa and 1.06, respectively. The combination of LS < 28.1 kPa and INR ≥ 1.06 showed a sensitivity and specificity of 84.8% and 75.9% for the prediction of the score amelioration, respectively. For the propensity score model, we matched 24 patients with similar age, sex, MELD-Na score, and concomitant hepatocellular carcinoma. Kaplan-Meier analysis determined significantly higher cumulative survival rates in patients with LS < 28.1 kPa and INR ≥ 1.06 than in other populations. CONCLUSIONS: A combination of LS and INR can predict the MELD-Na score amelioration and prognosis improvement following PSS occlusion.

Albumin-bilirubin score as a useful predictor of energy malnutrition in patients with hepatocellular carcinoma.

BACKGROUND & AIMS: Chronic liver diseases, including hepatocellular carcinoma (HCC), lead to an imbalance in energy metabolism. The non-protein respiratory quotient (npRQ), which estimates energy malnutrition, can be evaluated using an indirect calorimeter; however, npRQ measurement is limited in routine work. This study aimed to investigate the relationship between the albumin-bilirubin (ALBI) score and npRQ in patients with HCC. METHODS: We conducted a retrospective cohort study in 109 patients with HCC who underwent indirect calorimetry and then compared the npRQ with various clinical parameters, including liver function and tumor factors. RESULTS: The median npRQ was 0.82. A significant negative correlation was found between the npRQ and the ALBI score (r = -0.35, p < 0.001). The median npRQ in modified ALBI (mALBI) grades 1, 2a, 2b, and 3 were 0.84, 0.86, 0.81, and 0.79, respectively (grade 2a vs. 2b, p = 0.002). Factors associated with npRQ <0.85, which is reported to be the best cutoff value for energy malnutrition, were analyzed. On multivariate analysis, the ALBI score (cutoff value, -2.18) was the only significant independent factor (odds ratio, 7.65; p < 0.001). The proportion of HCC patients with npRQ <0.85 significantly increased among patients with an ALBI score ≥-2.18 (45/51, 88.2%) compared with those with an ALBI score <-2.18 (29/58, 50%) (p < 0.001). CONCLUSIONS: The ALBI score might be a useful predictor for energy malnutrition in patients with HCC. In addition, most HCC patients with mALBI grade 2b or 3 can be considered to have energy malnutrition.

Early Predictors of Objective Response in Patients with Hepatocellular Carcinoma Undergoing Lenvatinib Treatment.

There are limited reports regarding early predictors of objective response (OR) in patients with hepatocellular carcinoma (HCC) treated with lenvatinib. This retrospective study including 70 patients aimed to investigate the efficacy of hepatic biochemical markers. Changes in tumor marker (alpha-fetoprotein (AFP)/des-gamma-carboxy prothrombin (DCP)) levels and albumin-bilirubin (ALBI) score between the baseline value and that estimated one month after treatment were evaluated. We identified several predictors of OR, including changes in tumor marker levels. The OR rate calculated using modified Response Evaluation Criteria in Solid Tumor (mRECIST) was 41.4%. Response was defined as a reduction in AFP and DCP levels of ≥40% from baseline. OR was significantly associated with AFP response, but not with DCP. Predictors of OR were evaluated in two groups (high-AFP group: baseline AFP ≥ 10 ng/mL; low-AFP group: remaining patients). A multivariate analysis identified AFP response (odds ratio, 51.389; p = 0.001) and ALBI score (odds ratio, 6.866; p = 0.039) as independent predictors of OR in the high-AFP and low-AFP groups, respectively. Changes in the ALBI score indicated deterioration in both responders and non-responders, with a significant difference in non-responders (p = 0.003). AFP response, baseline ALBI score, and change in the ALBI score were early predictors of OR in patients with HCC undergoing lenvatinib treatment.

Clinical manifestations of skin, lung and muscle diseases in dermatomyositis positive for anti-aminoacyl tRNA synthetase antibodies.

Patients with dermatomyositis positive for anti-aminoacyl tRNA synthetase (ARS) antibodies, also known as antisynthetase syndrome (ASS), frequently present with mechanic's hand and interstitial lung disease (ILD). We first screened the antibody profiles of 59 patients with dermatomyositis, and then examined the cutaneous, muscular and pulmonary manifestations characteristic for patients with ASS. The anti-ARS antibodies Jo-1, PL-7, PL-12, EJ and KS, along with antibodies to TIF1-γ, MDA5 and Mi-2, were examined. Among the 59 patients, 20, 21, 15 and three patients were classified into the ASS, non-ASS, myositis-specific antibody-negative and unknown groups, respectively. Five of 16 patients (31%) with ASS had six relatives with a history of collagen diseases, within the second degree of relationship, including two cases of dermatomyositis (vs the non-ASS group, P = 0.018). Patients with ASS more frequently presented with fever and arthralgia, and had elevated levels of C-reactive protein. Nine of the 11 finger lesions (82%) clinically diagnosed as mechanic's hands showed a psoriasiform tissue reaction. ILD was observed in 19 of 20 patients (95%) with ASS, and eight of 21 patients (38%) in the non-ASS group, in which six patients possessed anti-MDA5 antibody. Patients with ASS showed higher serum levels of muscle enzymes, and four of 12 patients (33%) had fasciitis-dominant myopathy, while only one of 11 patients (9%) in the non-ASS group had fasciitis-dominant myopathy. Patients with ASS often present with a psoriasiform tissue reaction in the hand lesions and fasciitis-dominant myopathy, and the relatives of those with ASS are at high risk for collagen diseases.

[A Case of Carcinomatous Pericarditis of Breast Cancer Successfully Treated with Intrapericardial Mitomycin C Instillations and Systemic Chemotherapy].

A 67-year-old woman who underwent left breast mastectomy and right breast partial mastectomy under the diagnosis of left breast cancer and suspected right breast cancer 10 years earlier was admitted because of dyspnea. Chest computed tomography revealed pericardial fluid accumulation. The patient was treated with pericardial drainage; thereby, 800 mL of bloody fluid was removed. The cytological diagnosis was malignancy. After receiving mitomycin C instillation, she underwent systemic chemotherapy and endocrine therapy. At the last follow-up more than 5 years after the recurrence, no reaccumulation of the pericardial fluid was observed, and she remained alive in good condition.

Status and prospects of liver cirrhosis treatment by using bone marrow-derived cells and mesenchymal cells.

In 2003, we started autologous bone marrow cell infusion (ABMi) therapy for treating liver cirrhosis. ABMi therapy uses 400 mL of autologous bone marrow obtained under general anesthesia and infused mononuclear cells from the peripheral vein. The clinical study expanded and we treated liver cirrhosis induced by HCV and HBV infection and alcohol consumption. We found that the ABMi therapy was effective for cirrhosis patients and now we are treating patients with combined HIV and HCV infection and with metabolic syndrome-induced liver cirrhosis. Currently, to substantiate our findings that liver cirrhosis can be successfully treated by the ABMi therapy, we are conducting randomized multicenter clinical studies designated "Advanced medical technology B" for HCV-related liver cirrhosis in Japan. On the basis of our clinical study, we developed a proof-of-concept showing that infusion of bone marrow cells (BMCs) improved liver fibrosis and sequentially activated proliferation of hepatic progenitor cells and hepatocytes, further promoting restoration of liver functions. To treat patients with severe forms of liver cirrhosis, we continued translational research to develop less invasive therapies by using mesenchymal stem cells derived from bone marrow. We obtained a small quantity of BMCs under local anesthesia and expanded them into mesenchymal stem cells that will then be used for treating cirrhosis. In this review, we present our strategy to apply the results of our laboratory research to clinical studies.

Association of tyrosine with insulin resistance in hepatitis C virus-related chronic liver disease.

AIM: Insulin resistance (IR) increases during the early stages of hepatitis C virus (HCV)-related chronic liver disease and is a sign of poor prognosis as well as a risk factor for hepatic fibrosis and hepatocellular carcinoma. We aimed to determine the factors affecting IR in HCV-related chronic liver disease. METHODS: We retrospectively examined 71 patients with HCV-related chronic liver disease and analyzed various parameters, including amino acids, as possible predictors of IR. IR was assessed using the Homeostasis Model of Assessment - Insulin Resistance (HOMA-IR). Amino acids were assayed by examining branched-chain amino acids (BCAA), tyrosine level, and the ratio of BCAA to tyrosine level (BTR). RESULTS: HOMA-IR was significantly correlated with body mass index, platelet count, prothrombin time, hemoglobin, total bilirubin, total protein, albumin, total cholesterol, fasting glucose, BTR (r = -0.46, P = 0.0001) and tyrosine (r = 0.55, P < 0.0001). However, BCAA were not significantly correlated with HOMA-IR (r = -0.21, P = 0.082). In multivariate analysis, only two factors were identified as independent parameters contributing to a HOMA-IR of 2.5 or more: total cholesterol (odds ratio [OR], 6.511; 95% confidence interval [95% CI], 1.554-27.284; P = 0.010) and tyrosine (OR, 4.839; 95% CI, 1.087-21.549; P = 0.039). CONCLUSION: Serum tyrosine levels may be associated with IR in patients with HCV-related chronic liver disease.

Novel and recurrent PORCN gene mutations in almost unilateral and typical focal dermal hypoplasia patients.

Goltz syndrome or Focal dermal hypoplasia (FDH) is an X-linked dominant disorder characterized by malformations affecting the skin, eyes, central nervous system, and skeletonC:\GetARef\Refs\focal dermal hypoplasia (2007-).re. Mutations in the PORCN gene were identified as the molecular basis of FDH. We report two cases, one caused by a current mutation c.129G>A, which leads to a nonsense mutation W43X, and the other one caused by a novel mutation, c.386delT. The female patient with the recurrent mutation presented with typical cutaneous symptoms and skeletal abnormality, but the female patient with the novel mutation manifested only cutaneous symptoms, with hypo-pigmentation along Blaschko's lines, mainly on her right hemibody. In the latter case, DNA was isolated from peripheral blood cells, lesional skin, and non-lesional skin. The percentage of cells carrying the mutation estimated by subcloning and sequencing of the PCR products was 3.1% in peripheral blood cells, 21% in lesional skin, and 16% in non-lesional skin. X-chromosome inactivation assay showed a slightly skewed pattern in lesional skin, but a random pattern in non-lesional skin and blood. RT-PCR analysis from skin samples showed that PORCN mRNA of the mutated allele had a 13bp nucleotide insertion created by an alternative splicing site. This resulted in abnormal PORCN protein with in-frame insertion of eight amino acids, TTHRGTDD, instead of the original four amino acids, AQMI (126-129). We report a typical FDH patient with a recurrent PORCN mutation, which was previously identified in a male Japanese FDH patient, and a second female, an almost unilateral FDH patient with a postzygotic PORCN mutation.

Retinal vasoproliferative granulomatous lesion associated with hand pyoderma caused by Streptococcus pyogenes.

PURPOSE: To report a retinal vasoproliferative granulomatous lesion in association with pyoderma. DESIGN: Single case report. METHODS: A 32-year-old woman had blurred central vision in the right eye, concurrent with pyoderma of the fingers of both hands, 2 days later followed by fever. RESULTS: The patient had a granulomatous lesion in the upper retina, which caused leakage, leading to subretinal and intraretinal accumulation of hard exudates in the posterior pole, together with periphlebitis extending over the wider area of the retina. The culture of the pyodermic lesion detected Streptococcus pyogenes. With the 2-month course of amoxicillin-clavulanate, combined with prednisolone tapered from 30 mg daily, the visual acuity (decimal fraction) in the right eye returned from 0.01 (logMAR = 2) to 0.9 (logMAR = 0.1). However, after the discontinuation of the antibiotics and prednisolone, the retinal lesion became more vasoproliferative and caused leakage to reduce the vision again. The leakage was remedied by laser photocoagulation to the retinal lesion. CONCLUSIONS: The retinal granulomatous lesion was caused by streptococcal infection in pyoderma and later became more vasoproliferative with macroaneurysms and microaneurysms even after the initial subsidence of the lesion with antibiotics treatment.

A case of epidermolysis bullosa acquisita with clinical features of Brunsting-Perry pemphigoid showing an excellent response to colchicine.

BACKGROUND: Brunsting-Perry pemphigoid is a rare subepidermal blistering disease characterized by scarring blisters on the head and neck. However, the identity of the responsible autoantigens is still unresolved. METHODS: We reported a patient with epidermolysis bullosa acquisita who had clinical features typical of Brunsting-Perry pemphigoid and investigated the involved type VII collagen epitopes. The patient was a 65-year-old Japanese woman with a 20-month history of recurrent subepidermal bullae on her head, face, and neck. RESULTS: Immunoblot studies revealed that the serum of this patient reacted with type VII collagen, specifically with the noncollagenous domain 1 and the triple-helical domain. The patient responded completely to colchicine monotherapy. LIMITATIONS: This study was performed on only one case. CONCLUSION: This study suggests that Brunsting-Perry pemphigoid may be a clinical variant of epidermolysis bullosa acquisita.

Karyotypic analysis of bone marrow cells in pyodermic lesions associated with myelodysplastic syndrome.

BACKGROUND: Recalcitrant pyodermic lesions and neutrophilic dermatoses are often associated with subclinical myelodysplastic syndrome (MDS). In this case series, we assessed the diagnostic importance of karyotypic analysis of bone marrow cells in 4 patients with MDS-associated pyodermic eruptions treated at our university hospital. Karyotypic analysis was performed in bone marrow cells and peripheral blood lymphocytes obtained. Serum levels of granulocyte colony-stimulating factor were measured. OBSERVATIONS: Four patients with pyodermic eruptions or neutrophilic dermatosis had chromosomal abnormalities in bone marrow cells, including del(20)(q11;q13.3) in 2 patients, trisomy 8 in 1 patient, and t(11;22)(q23;q11) in 1 patient. Three patients without morphologic findings suggestive of MDS were diagnosed as having refractory anemia. One female patient had refractory anemia with ringed sideroblasts associated with del(20). Two patients with refractory anemia had a normal karyotype in peripheral blood lymphocytes. Two patients with elevated serum levels of granulocyte colony-stimulating factor had more active or widespread cutaneous diseases. CONCLUSIONS: Karyotypic analysis of bone marrow cells, but not of peripheral blood lymphocytes, is essential in proving a diagnosis of MDS-associated pyodermic lesions. The overexpression of granulocyte colony-stimulating factor, which may compensate for impaired hematopoiesis in patients with MDS, seems to be a key cytokine leading to neutrophilic infiltration.

Leukocyte common antigen-negative, aggressive cutaneous anaplastic large cell lymphoma with prominent pseudocarcinomatous hyperplasia.

Patients with anaplastic large cell lymphoma (ALCL) often present with tumor-mediated skin changes, including pseudocarcinomatous hyperplasia (PCH), acquired ichthyosis, and tissue neutrophilia. We report a 58-year-old male patient with leukocyte common antigen (LCA)-negative, null cell-type ALCL associated with marked PCH mimicking undifferentiated squamous cell carcinoma. Although lymphocyte markers were lacking, the CD30 expression and the clonal rearrangement of the T-cell receptor gamma gene confirmed the diagnosis of ALCL. The patient had an aggressive clinical course, in which the tumor cells metastasized to the regional lymph nodes a few months after surgical removal of the primary lesion, and skin nodules recurred on the face despite intensive polychemotherapy, followed by autologous peripheral blood stem cell transplantation. The diagnosis of ALCL was delayed in our case because of the prominent PCH, the lack of LCA, and the unusually rapid progression of the tumor.

Oculocutaneous albinism type 4: six novel mutations in the membrane-associated transporter protein gene and their phenotypes.

Oculocutaneous albinism type 4 (OCA4) is an autosomal recessive hypopigmentary disorder caused by mutations in the Membrane-Associated Transporter Protein gene (SLC45A2). The SLC45A2 protein is a 530-amino-acid polypeptide that contains 12 putative transmembrane domains, and appears to be a transporter that mediates melanin synthesis. Eighteen pathological mutations have been reported so far. In this study, six novel mutations, p.Y49C (c.146A > G), p.G89R (c.265G > A), p.C229Y (c.686G > A), p.T437A (c.1309A > G), p.T440A (c.1318A > G) and p.G473D (c.1418G > A) were found in eight Japanese patients with various clinical phenotypes. The phenotypes of OCA4 were as various as the other types of OCA and probably depended on the mutation sites in the SLC45A2 gene.

Pathogenic link between hydroa vacciniforme and Epstein-Barr virus-associated hematologic disorders.

OBJECTIVES: To determine the pathogenic association of latent Epstein-Barr virus (EBV) infections with both typical hydroa vacciniforme (HV) and severe HV-like eruptions, and to survey the complications and outcomes of patients. DESIGN: Case series. PATIENTS: Twenty-nine patients with HV or severe HV-like eruptions. INTERVENTIONS: In situ hybridization and immunostaining of biopsy specimens; extraction of DNA samples from cutaneous lesions and/or peripheral blood mononuclear cells for EBV DNA assay. MAIN OUTCOME MEASURES: Clinicopathologic manifestations, hematologic findings, complications, and outcomes; presence of latent EBV infection. RESULTS: T cells positive for EBV-encoded small nuclear RNA (EBER) were detected, to various degrees, in cutaneous infiltrates in 28 (97%) of 29 patients, including all 6 patients with definite HV with a positive phototest reaction, 11 of 12 patients with probable HV without evidence of photosensitivity, and all 11 patients with severe HV associated with systemic symptoms. In addition to EBER-positive T cells, many cytotoxic T lymphocytes expressing T-cell intracellular antigen 1 and granzyme B were present in the cutaneous lesions. Natural killer (NK) cells were absent or at a background level. The UV-induced cutaneous lesions showed histopathologic findings consistent with those of HV, containing many EBER-positive cells. Although no hematologic abnormalities were found in the definite and probable HV groups, the amounts of EBV DNA were increased in the peripheral blood mononuclear cells. By contrast, the severe HV group had markedly increased levels of EBV DNA associated with NK-cell lymphocytosis, and complications including chronic active EBV infection, hypersensitivity to mosquito bites, and hemophagocytic syndrome. Five patients with severe disease died of EBV-associated NK/T-cell lymphomas or hemophagocytic syndrome 2 to 14 years after onset. CONCLUSION: Both typical and severe HV are included within the spectrum of cutaneous disorders mediated by EBV-infected T cells, and the severe HV group may have overt EBV-associated NK/T-cell lymphoproliferative disorders with a frequently fatal outcome.

Generalized morphea-like lesions arising in mechanically-compressed areas by underclothes.

We report two patients with generalized morphea-like eruptions, the distribution of which was confined to areas mechanically compressed by underclothes. One patient had Raynaud's phenomenon and anti-centromere antibodies, and the other patient had a long history of occupational exposure to organic solvents. We believe that the Koebner phenomenon, resulting from local compression by underclothes, might be responsible for the development of morphea-like lesions in patients with subclinical systemic sclerosis.

Staphylococcal cutaneous infections: invasion, evasion and aggression.

Staphylococcal infections cause a variety of cutaneous and systemic infections, including impetigo, furuncle, subcutaneous abscess, staphylococcal scalded skin syndrome (SSSS), toxic shock syndrome (TSS) and neonatal toxic shock syndrome-like exanthematous disease (NTED), in association with microbial virulence factors. The virulence factors produced by Staphylococcus aureus have a wide array of biological properties, including disruption of the epithelial barrier, inhibition of opsonization by antibody and complement, interference with neutrophil chemotaxis, cytolysis of neutrophils, and inactivation of antimicrobial peptides. Exfoliative toxins (ETs) induce the 'acantholytic' infection of S. aureus due to the disruption of cell-to-cell cohesion, which allows the pathogenic organisms to spread within the epithelium. Furthermore, S. aureus expresses exotoxins with biological properties of superantigens that induce T-cell activation with subsequent anergy and immunosuppression. Of the S. aureus leukotoxins, Panton-Valentine leukocidin (PVL) is involved in the development of multiple furuncles with more intense erythema, particularly in healthy young adults. TSS is an acute life-threatening illness caused by TSS toxin-1 (TSST-1) and is usually classified into two categories; menstrual TSS, originally described in association with tampon use, and nonmenstrual TSS with a variety of clinical settings. NTED is a neonatal disease induced by TSST-1 although clinical symptoms are much milder than those of TSS. In TSS and NTED, the expansion of TSST-1-reactive Vbeta2-positive T cells is observed. The production of pathogenic S. aureus exotoxins and biofilm formation is regulated by the accessory gene regulator (agr) locus in the quorum-sensing signaling pathway. There is no doubt that targeting the quorum-sensing signaling pathway or anti-toxin therapy is a promising therapeutic approach supportive of primary antibiotic therapy.