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The Hashimoto Research Group for Comprehensive Research of Gene Mutation-related Rare and Intractable Diseases of the Skin is a contributor to the Project for Research on Intractable Diseases of the Ministry of Health, Labor, and Welfare (MHLW) of Japan. Our research group performs clinical research on 23 rare intractable genetic skin diseases that are classified into eight disease groups. Among the 23 diseases, 17 are mainly studied by our research group, and 6 diseases are studied in collaboration with other research groups. Cockayne syndrome and familial chronic and benign pemphigus (also known as Hailey-Hailey disease) are the designated intractable diseases that are mainly studied by our research group. This review summarizes the activities of our research group for these 23 intractable hereditary skin diseases, including the MHLW tasks for designated intractable diseases, epidemiological studies using nationwide surveys, preparation of patient registries, creation of repositories, development and publication of clinical practice guidelines, clinical trials for novel treatments in collaboration with the Japanese Agency for Medical Research and Development, help with genetic diagnosis, applications for the listing of new designated intractable diseases, communication of information to academic societies, medical professionals and patients, spreading awareness of our activities to the public, supporting patient societies, and presentation and publication of achievements. These studies are performed in collaboration with the relevant academic societies, mainly the Japanese Dermatological Association.

Granular C3 dermatosis (GCD) is characterized by bullous, erythematous, and eczematous skin lesions similar to dermatitis herpetiformis, and granular deposition of complement C3 and C5b-9 along the epidermal basement membrane zone (BMZ) by direct immunofluorescence (IF). Here, we present two cases of GCD with different clinical features. Case 1, a 49-year-old man, showed pruritic blisters and erythema of the extremities. Case 2, a 53-year-old woman, showed severely pruritic papules, erythema, and erosions on the entire body with scattered blisters, mainly on the lower extremities. Both patients showed mild eosinophilia on blood tests, subepidermal blisters and prominent eosinophilic infiltration in the upper dermis on histopathological examination, and granular BMZ deposition of C3, but not of immunoglobulins or other complement components, on direct IF. No circulating autoantibodies were detected on enzyme-linked immunosorbent assays, chemiluminescent enzyme immunoassays, indirect IF using 1 mol/L NaCl-split normal human skin, or immunoblotting. Diagnosis of GCD was made in both cases. Case 1 was successfully treated with topical steroids, oral minocycline, and nicotinamide without any recurrence of symptoms. Case 2 was treated with oral steroids and showed remarkable improvement, although mild pruritic papules remained. We reviewed 30 reported GCD cases, including the two cases presented here, since Hashimoto et al. first described GCD in 2016. GCD should be more widely recognized, and further accumulation and validation of cases are required., (© 2024 Japanese Dermatological Association.)

Central hypothyroidism and dyslipidemia are well-known adverse events (AEs) of bexarotene therapy. Although hypothyroidism is known to cause dyslipidemia, no study has examined the association between hypothyroidism and dyslipidemia in patients undergoing bexarotene therapy. The aim of this study is to examine this association. A retrospective observational study was performed among 294 patients who initiated bexarotene therapy in Japan (nation-wide postmarketing complete surveillance). Jonckheere-Terpstra (one sided) test was performed to evaluate the effect of the bexarotene dose on lipid metabolisms, and regression analyses were performed to evaluate associations of bexarotene dose, free thyroxine (FT4), body mass index (BMI), and lipid metabolisms. Most patients developed hypothyroidism. Two-third of patients showed FT4 values below the lower limit at 1 week. Triglycerides (TG) increased in a bexarotene dose-dependent manner, and grade ≥3 AEs on hypertriglyceridemia was observed in 39% of the patients. Additionally, one-third of grade ≥3 AEs on hypertriglyceridemia occurred within 1 week. The delta_FT4 (difference in FT4 from baseline) negatively correlated with TG increase at 1 week (p = 0.012) but not with low density lipoprotein cholesterol (LDL-C) increase at any week. Bexarotene-induced hypothyroidism is almost inevitable and occurred quickly. Bexarotene-induced hypertriglyceridemia showed positive bexarotene dose dependency and negative delta_FT4 dependency. Prophylactic and appropriate thyroid hormone compensation therapy and starting bexarotene at low doses with subsequent titration while managing dyslipidemia may have a beneficial effect for the successful continuation of bexarotene therapy without severe endocrine and metabolic AEs.

Background: Atopic dermatitis (AD) is a common chronic eczematous skin disease with severe pruritus. Several new therapeutic agents for AD such as dupilumab, an anti-IL-4Rα antibody, have been developed in recent years. We need to predict which agent is the best choice for each patient, but this remains difficult., Objective: Our aim was to examine clinical background factors and baseline biomarkers that could predict the achievement of improved clinical outcomes in patients with AD treated with dupilumab., Methods: A multicenter, prospective observational study was conducted on 110 patients with AD. The Eczema Area and Severity Index was used as an objective assessment, and the Patient-Oriented Eczema Measure and Numerical Rating Scale for Pruritus were used as patient-reported outcomes. In addition, some clinical background factors were evaluated., Results: The achievement of an absolute Eczema Area and Severity Index of 7 or less was negatively associated with current comorbidity of food allergy and baseline serum lactate dehydrogenase (LDH) levels. There were negative associations between achievement of a Patient-Oriented Eczema Measure score of 7 or less and duration of severe AD and between achievement of an itching Numerical Rating Scale for Pruritus score of 1 or less and current comorbidity of allergic conjunctivitis or baseline serum periostin level. Furthermore, signal detection analysis showed that a baseline serum LDH level less than 328 U/L could potentially be used as a cutoff value for predicting the efficacy of dupilumab., Conclusion: Baseline biomarkers such as LDH and periostin and clinical background factors such as current comorbidity of food allergy and a long period of severe disease may be useful indicators when choosing dupilumab for systemic treatment for AD, as they can predict the efficacy of dupilumab., Competing Interests: Supported by 10.13039/100004339Sanofi and 10.13039/100009857Regeneron (grant SGZ-2018-11996). These companies had no influence on the design of the study, collection and analysis of the data, or decision to publish the article. Disclosure of potential conflict of interest: K. Izuhara has received grants and personal fees from Shino-test Co, Ltd. H. Saeki has received lecture fees, research costs, or scholarship donations from Mitsubishi Tanabe Pharma, Taiho Pharmaceutical, 10.13039/100016730Torii Pharmaceutical, Maruho, Kyowa Kirin, Sanofi, AbbVie, Novartis Pharma, Eli Lilly Japan, Kyorin Pharmaceutical, Eisai, Tokiwa Pharmaceutical, Japan Tobacco, and LEO Pharma. Y. Kataoka has received lecturer honoraria from Sanofi and AbbVie and research funding from Sanofi, Leo Pharma, Pfizer, Maruho, Lilly, AbbVie, and Otsuka. S. Kaneko has received grants as an investigator from Eli Lilly Japan and honoraria as a speaker from Eli Lilly Japan. A. Tanaka has received honoraria from Eli Lilly, Kaken Seiyaku, Sanofi, Taiho Pharma, AbbVie, Kyorin Pharmaceutical, Mitsubishi-Tanabe, Torii Pharmaceutical, and Maruho as a speaker and research grants from Eli Lilly, Sanofi, Teijin Pharma, Taiho Pharma, Mitsubishi-Tanabe, Torii Pharmaceutical, and Maruho. M. Hide has received lecture and/or consultation fees from AbbVie, Eli Lilly, Kaken Pharmaceutical, Kyowa Kirin, Kyorin Pharmaceutical, Maruho, Mitsubishi-Tanabe Pharma, MSD, Novartis, Sanofi, Taiho Pharma, Teikoku Seiyaku, Torii, and Uriach. R. Tamagawa-Mineoka has received research grants from Maruho and 10.13039/501100012351Mitsubishi Tanabe Pharma. K. Masuda has received honoraria as a speaker for Sanofi and grants as an investigator for Eli Lilly Japan. T. Takeichi has received grants paid to his institution (10.13039/501100004823Nagoya University) from Boehringer Ingelheim. M. Akiyama has received research support from Novartis and Boehringer Ingelheim; personal fees from Maruho and Sanofi; and grants paid to his institution (Nagoya University) from Mitsubishi-Tanabe, Taiho, AbbVie, Maruho, Ono, and Sun Pharma. Y. Ishiuji has received honoraria as a speaker for Eli Lilly Japan. Y. Hatano has received honoraria and consultancies to sponsoring organizations from 10.13039/100004339Sanofi, Taiho Pharma, Janssen Pharma, Maruho, Pfizer Japan, Sun Pharma Japan, Torii Pharmaceutical, AbbVie, KAKEN, and UCB Japan. N. Katoh has received honoraria as a speaker/consultant for Sanofi, Maruho, AbbVie, Eli Lilly Japan, and Leo Pharma and grants as an investigator from Maruho, Eli Lilly Japan, Sun Pharma, Taiho Pharmaceutical, Torii Pharmaceutical, Boehringer Ingelheim Japan, and Leo Pharma. Takeshi Nakahara has received lecture fees and research costs from Mitsubishi Tanabe Pharma, Taiho Pharmaceutical, Torii Pharmaceutical, Maruho, Sanofi, AbbVie, Eli Lilly Japan, and Sun Pharma. The rest of the authors declare that they have no relevant conflicts of interest., (© 2024 Published by Elsevier Inc. on behalf of the American Academy of Allergy, Asthma & Immunology.)

Background: Psoriatic arthritis (PsA) is characterized by enthesitis. As persistent inflammation around joints results in bone and cartilage destruction and physical impairment, a detailed assessment of inflammation is essential. We previously reported the difference between clinical assessment (tenderness) and ultrasound (US) assessment (inflammation) of entheses. Herein, we investigated whether clinical or US assessment of joints and entheses can predict the progression of joint destruction in Japanese patients with PsA., Methods: Thirty joints and 14 entheses in 47 patients were assessed using US and clinical examination. The US greyscale (GS) and power Doppler (PD) scores at the ultrasonographic synovitis, the US active enthesitis count, and the clinical tender joint/entheses count were assessed. Additionally, the yearly radiographic progression of the Sharp-van der Heijde scoring method for PsA was assessed. Their correlations were investigated., Results: About half of the patients with PsA experienced joint destruction during a follow-up period of 20.4 months. Progression of joint destruction in patients with PsA only correlated with joint GS and PD scores, reflecting the severity of ultrasonographic synovitis, not with the tender joint/entheses count., Conclusions: US examinations are essential for preventing joint destruction and physical impairment in patients with PsA.

Indocyanine green (ICG) with near-infrared (NIR) fluorescence imaging is used for lymphatic mapping. However, binding of ICG to blood proteins like serum albumin can shorten its retention time in sentinel lymph nodes (SLNs). Here, we investigated the efficacy and safety of a new fluorescence tracer comprising phytate and liposome (LP)-encapsulated ICG. Coadministration of phytate with LP containing phosphatidic acid promotes chelation mediated by Ca 2+ in bodily fluids to enhance SLN retention. Uniformly sized LPs (100 nm) encapsulating ICG under conditions that minimized fluorescence self-quenching during storage were produced. We analyzed the behavior of the new tracer (ICG-phytate-LP) and control tracers (ICG and ICG-LP) in the lymphatic flow of mice in terms of lymph node retention time. We also tested lymphatic flow and safety in pigs that have a more human-like lymphatic system. LPs encapsulating stabilized ICG were successfully prepared. Mixing LP with phytate in the presence of Ca 2+ increased both the particle size and negative surface charge. In mice, ICG-phytate-LP had the best lymph node retention, with a fluorescence intensity ratio that increased over 6 h and then decreased slowly over the next 24 h. In pigs, administration of ICG and ICG-phytate-LP resulted in no death or weight loss. There were no obvious differences between blood test results for the ICG and ICG-phytate-LP groups, and the overall safety was good. ICG-phytate-LP may be a useful new tracer for gynecological cancers that require time for lymph node identification due to a retroperitoneal approach., (© 2023 The Authors. Cancer Science published by John Wiley & Sons Australia, Ltd on behalf of Japanese Cancer Association.)

Background: To develop precision medicine for atopic dermatitis (AD), it is critical to establish relevant biomarkers. However, the characteristics of various biomarkers have not been fully understood. We previously carried out the Biomarkers to Predict Clinical Improvement of AD in Patients Treated with Dupilumab (B-PAD) study, a comprehensive nationwide study in Japan, to explore biomarkers for AD., Objective: The aim of this study is to find biomarkers associated with objective and subjective clinical findings in patients with moderate-to-severe AD based on the B-PAD study and to identify biomarkers sensitive enough to assess the severity of AD., Methods: We performed the B-PAD study as a consortium composed of 19 medical facilities in Japan, enrolling 110 patients with moderate-to-severe AD. We evaluated the Eczema Area and Severity Index (EASI) for objective assessment as well as the Patient-Oriented Eczema Measure (POEM) and a numeric rating scale for pruritus (pruritis-NRS) for subjective assessment, measuring 19 biomarkers at baseline., Results: We found that 12, 6, and 7 biomarkers showed significant and positive associations with the EASI, POEM, and pruritis-NRS, respectively. Most of the biomarkers associated with either the POEM or the pruritis-NRS were included among the biomarkers associated with EASI. Of the biomarkers examined, CCL26/eotaxin-3 and SCCA2 were the most capable of assessing severity for EASI, as shown by the 2 kinds of receiver operating characteristic analyses, respectively, whereas lactate dehydrogenase was the best for both the POEM and pruritis-NRS, again using the 2 analyses., Conclusion: We found biomarkers associated with the EASI, POEM, and pruritis-NRS, respectively, based on the B-PAD study. Moreover, we identified CCL26/eotaxin-3 and/or SCCA2 as the biomarkers having the greatest ability to assess severity in the EASI; lactate dehydrogenase did the same for the POEM and pruritis-NRS. These findings will be useful in treating patients with moderate-to-severe AD., (© 2023 The Author(s).)

Objective: This study aimed to reveal characteristic condylar movements in patients with jaw deformities., Study Design: Thirty patients with jaw deformities before surgery were enrolled and instructed to chew a cookie during 4-dimensional computed tomography (4DCT). The distance between the most anterior and posterior positions of the bilateral condyles on 4DCT images was measured and compared among patients with different skeletal classes. Correlations between the condylar protrusion and cephalometric values were also determined., Results: The distances of condylar protrusion during mastication were significantly greater in the skeletal class II group than in the skeletal class III group ( P =0.0002). Significant correlations were found between the distances of condylar protrusion during mastication and the sella-nasion-B point angle ( r =-0.442, P =0.015), A point-nasion-B point angle ( r =0.516, P =0.004), sella-nasion plane to ramus plane angle ( r =0.464, P =0.01), sella-nasion plane to occlusal plane angle ( r =0.367, P =0.047), and condylion-gonion length ( r =-0.366, P =0.048)., Conclusion: Motion analysis with 4DCT images revealed that condylar movement in patients with retrognathism was larger than in patients with mandibular prognathism. Skeletal structure was therefore correlated with condylar movement during mastication., Competing Interests: The authors report no conflicts of interest., (Copyright © 2023 by Mutaz B. Habal, MD.)

Gorlin syndrome and Cowden syndrome are hereditary diseases that are characterized by multiple malignancies, cutaneous symptoms, and various other abnormalities. Both disorders are caused by a mutation of the gene that regulates cell proliferation and growth, resulting in tumorigenesis. Representative mutations are mutation in the patched 1 gene (PTCH1) in Gorlin syndrome and mutation in the phosphatase and tensin homolog deleted from chromosome 10 (PTEN) gene in Cowden syndrome. Making a diagnosis of these diseases in the early years of life is important because detection of malignancies at an early stage is linked to improved prognosis. Both Gorlin syndrome and Cowden syndrome have cutaneous findings in the early phase in childhood, and the role of dermatologists is therefore important. These diseases are generally diagnosed by clinical criteria, but some patients who do not meet the criteria need genetic examinations including a genetic diagnostic panel and next-generation sequencing. The most important treatment and management are detection and resection of malignancies in the early stage, and targeted therapies have recently been used for treatment of tumors and other symptoms in these diseases. Although evidence of the effectiveness of targeted therapies has been limited, they are promising therapeutic options and further clinical trials are needed in the future.

A prenatal second-hit genetic change that occurs on the wild-type allele in an embryo with a congenital pathogenic variant allele results in mosaicism of monoallelic and biallelic defect of the gene, which is called superimposed mosaicism. Superimposed mosaicism of Hailey-Hailey disease (HHD) has been demonstrated in one familial case. Here, we report two unrelated HHD cases with superimposed mosaicism: a congenital monoallelic pathogenic variant of ATP2C1, followed by a postzygotic copy-neutral loss of heterozygosity. Uniquely, neither patient had a family history of HHD at the time of presentation. In the first case, the congenital pathogenic variant had occurred de novo. In the second case, the father had the pathogenic variant but had not yet developed skin symptoms. Our cases showed that superimposed mosaicism in HHD can lack a family history and that genetic analysis is crucial to classify the type of mosaicism and evaluate the risk of familial occurrence., (© 2023. The Author(s).)

Enzymes are used to amplify signals for detection of antigen proteins in biological samples. However, the enzymes conventionally used for this purpose have limitations, such as the presence of the same ( i.e. , endogenous) activity in human cells and difficulty in simultaneous use of multiple enzymes because of differences in their required reaction conditions. In this report, we identify an enzyme that can overcome these problems: β-D-galacturonidase (GalUAase) from Eisenbergiella tayi . GalUAase activity was confirmed to be absent from human cells. The substrate of GalUAase, galacturonic acid, is highly hydrophilic because of its anionic carboxylate group; high substrate hydrophilicity is an ideal characteristic for the substrate of an enzyme used for detection because it decreases nonspecific adsorption to biological samples. We show that E. tayi GalUAase could be used in the detection of antigen proteins on live human cells with lower background signal than the conventionally used enzyme β-D-galactosidase. The combinatorial use of GalUAase with β-D-galactosidase enabled simultaneous detection of two antigens on live cells.

Autoimmune bullous diseases (AIBDs), which are a group of tissue-specific autoimmune diseases of the skin, present with various blistering lesions on the skin and mucous membranes, and show autoantibodies of IgG, IgA and IgM against epidermal cell surfaces and basement membrane zone. To date, AIBDs have been classified into a number of distinct subtypes by clinical and histopathological findings, and immunological characteristics. In addition, various biochemical and molecular biological studies have identified various novel autoantigens in AIBDs, which has resulted in proposals of new subtypes of AIBDs. In this article, we summarized various distinct AIBDs, and proposed the latest and most comprehensive classification of AIBDs with their autoantigen molecules.

Herein, we report engineered macrophages, termed "MacTrigger," acting as a trigger to induce an inflammatory environment only in tumor tissues. This led to intensive anti-tumor effects based on the removal potential of foreign substances. The strength of this study is the utilization of two unique functions of macrophages: (1) their ability to migrate to tumor tissues and (2) polarization into the anti-inflammatory M2 phenotype in the presence of tumor tissues. The MacTrigger accelerated the release of inflammatory cytokines, tumor necrosis factor-alpha (TNF-α), when it was polarized to the M2 phenotype. When the MacTrigger was administered to tumor-bearing mice, tumor growth was significantly inhibited compared with the non-treatment group, the un-transfected macrophages group, and the group with engineered macrophages capable of randomly releasing TNF-α. Additionally, the ratio of the M1 phenotype to the M2 phenotype in tumor tissues was >1 only in the MacTrigger group. Moreover, the ratios of natural killer cells and CD8 + T cells in tumor tissues were increased compared with other groups. These results indicate that MacTrigger can induce inflammation in tumor tissues, leading to effective anti-tumor effects. In normal tissues, especially the liver, notable side effects were not observed. This is because, in the liver, the MacTrigger was not polarized to the M2 phenotype and could not induce inflammation. These results suggest that the MacTrigger is a "trigger" that can induce inflammation only in tumor tissues, then allowing the body to attack tumor tissues through the innate immunity system., Competing Interests: Declaration of Competing Interest None., (Copyright © 2023. Published by Elsevier B.V.)

Herein, we report engineered macrophages, termed "MacTrigger," acting as a trigger to induce an inflammatory environment only in tumor tissues. This led to intensive anti-tumor effects based on the removal potential of foreign substances. The strength of this study is the utilization of two unique functions of macrophages: (1) their ability to migrate to tumor tissues and (2) polarization into the anti-inflammatory M2 phenotype in the presence of tumor tissues. The MacTrigger accelerated the release of inflammatory cytokines, tumor necrosis factor-alpha (TNF-α), when it was polarized to the M2 phenotype. When the MacTrigger was administered to tumor-bearing mice, tumor growth was significantly inhibited compared with the non-treatment group, the un-transfected macrophages group, and the group with engineered macrophages capable of randomly releasing TNF-α. Additionally, the ratio of the M1 phenotype to the M2 phenotype in tumor tissues was >1 only in the MacTrigger group. Moreover, the ratios of natural killer cells and CD8 + T cells in tumor tissues were increased compared with other groups. These results indicate that MacTrigger can induce inflammation in tumor tissues, leading to effective anti-tumor effects. In normal tissues, especially the liver, notable side effects were not observed. This is because, in the liver, the MacTrigger was not polarized to the M2 phenotype and could not induce inflammation. These results suggest that the MacTrigger is a "trigger" that can induce inflammation only in tumor tissues, then allowing the body to attack tumor tissues through the innate immunity system., Competing Interests: Declaration of Competing Interest None., (Copyright © 2023. Published by Elsevier B.V.)

Phototherapy and apremilast (oral phosphodiesterase-4 inhibitor) are well-known in the treatment of moderate to severe psoriasis vulgaris. However, current evidence on the efficacy and safety of their combination is not sufficient. This multicenter, randomized controlled study compared the efficacy and safety between phototherapy as monotherapy and phototherapy and apremilast as combination therapy in patients with psoriasis vulgaris. Patients with moderate to severe psoriasis vulgaris were assigned to combination (n = 29) and monotherapy (n = 13) groups. All patients underwent an 8-week phototherapy regimen comprising irradiation with narrowband UV-B. The patients in the combination group were also administered 10 mg to 60 mg of oral apremilast. We evaluated the improvement percentage based on the Psoriasis Area and Severity Index (PASI) score from baseline to week 8. Additionally, we evaluated the percentage of patients who achieved ≥75% improvement; changes in body surface area (BSA) and scores of EuroQol 5-dimensions 5-level, Dermatology Life Quality Index, and visual analog scale for pruritis from baseline to 4 and 8 weeks; and adverse events. Compared with the monotherapy group, the combination group had significantly lower PASI scores at 4 and 8 weeks and more patients who achieved a PASI score improvement of ≥75% at 8 weeks. Both groups exhibited a significant decrease in BSA; at 8 weeks, no significant difference was observed between the two groups, although the combination group tended toward a greater reduction in BSA. The intergroup differences in the changes at the three time points were not significant. Adverse events were more frequent in the combination group than in the monotherapy group. Our findings suggest that an 8-week combined apremilast and phototherapy regimen may not be adequate in patients for improvements in their subjective assessment of psoriasis, and longer treatment periods may be necessary., (© 2022 The Authors. The Journal of Dermatology published by John Wiley & Sons Australia, Ltd on behalf of Japanese Dermatological Association.)

Introduction: Cutaneous T-cell lymphoma (CTCL) is a chronic condition with low malignancy. The combined use of therapeutic agents and photo(chemo)therapy is widely applied for the treatment of CTCL. The efficacy and safety of bexarotene and photo(chemo)therapy combination therapy were previously confirmed in Japanese patients with CTCL. The efficacy and safety of the bexarotene and photo(chemo)therapy combination therapy was compared with bexarotene monotherapy in Japanese patients with CTCL., Methods: This was a randomized, open-label, two-parallel-group, active-control specified clinical study in Japanese patients diagnosed with CTCL carried out over 8 weeks with a study extension conducted at two institutions. This study was registered in Japan Registry of Clinical Trials (jRCTs041180094)., Results: In the combination therapy group, 22 subjects received oral bexarotene (300 mg/m 2 body surface area) once daily, followed by bath-psoralen and ultraviolet (UV) A or narrowband UVB. In the monotherapy group, 24 subjects received oral bexarotene (300 mg/m 2 ) once daily. The efficacy analysis using the modified Severity-Weighted Assessment Tool, which included 39 patients, showed a response rate of 81.0% (17/21) in the combination therapy group and 83.3% (15/18) in the monotherapy group. No statistically significant difference was detected between groups. In the combination therapy group, four subjects showed a complete clinical response or complete response, and subjects with a partial response exhibited a high rate of skin lesion resolution, significantly better than in the monotherapy group. In the safety analysis, which included 46 treated subjects (22 in the combination therapy group and 24 in the monotherapy group), no adverse events or adverse drug reactions were reported in either group., Conclusion: Both bexarotene and photo(chemo)therapy combination therapy and bexarotene monotherapy were therapeutically effective in Japanese patients with CTCL and well tolerated. Combination therapy led to a higher skin lesion resolution rate and greater therapeutic effects compared with monotherapy., Trial Registration: jRCTs041180094., (© 2022. The Author(s).)

To establish real-world evidence about the safety and efficacy of bexarotene for Japanese patients with cutaneous T-cell lymphoma, we conducted a nationwide cohort study using data from post-marketing surveillance for bexarotene treatment. In total, 294 patients with cutaneous T-cell lymphoma were identified between June 2016 and June 2018. Of these, 267 patients were included as the safety analysis set. Of the 267 patients, 175 were included in the efficacy analysis set. Of these, 139 patients had mycosis fungoides, including 46 with early stage disease and 93 with advanced stage disease. Among the 139 patients with mycosis fungoides, the objective response rate was 46.8%. A significant difference in objective response rate was detected between patients who started with bexarotene at 300 mg/m 2 (61.6%) and patients who started with bexarotene at less than 300 mg/m 2 (22.6%, p < 0.001). Of the 139 patients with mycosis fungoides, 92 were treated with a combination of bexarotene plus photo(chemo)therapy. A significant difference in objective response rate was seen between bexarotene with a combination of photo(chemo)therapy (57.6%) and bexarotene without a combination of photo(chemo)therapy (25.5%, p < 0.001). Starting bexarotene at 300 mg/m 2 and combination with photo(chemo)therapy were detected as independent factors influencing response. Common treatment-related adverse events included hypothyroidism (85.8%), hypertriglyceridemia (68.5%), hypercholesterolemia (43.8%), and neutropenia (21.3%). Hypertriglyceridemia, hypercholesterolemia, and neutropenia occurred more frequently in patients who started with bexarotene at 300 mg/m 2 than patients who started with bexarotene at less than 300 mg/m 2 (hypertriglyceridemia, 76.4% vs. 57.0%, p = 0.001; hypercholesterolemia, 49.0% vs. 36.4%, p = 0.045; neutropenia, 28.0% vs. 12.1%, p = 0.002; respectively). The present study indicates that starting bexarotene at 300 mg/m 2 and combination of photo(chemo)therapy offer a promising efficacy for the treatment of patients with mycosis fungoides. Efficacy of low-dose bexarotene plus photo(chemo)therapy should be evaluated in future., (© 2021 Japanese Dermatological Association.)