Phase I/II study of the oral retinoid X receptor agonist bexarotene in Japanese patients with cutaneous T-cell lymphomas

CD4/CD8 double-negative mycosis fungoides: a review

Mycosis fungoides (MF) stands as the predominant form of primary cutaneous T-cell lymphoma (CTCL). It manifests a diverse array of clinical, histological, and immunophenotypic variations, each bearing distinct prognostic implications. The typical immunophenotypic profile of mycosis fungoides involves CD3+/CD4+/CD45RO+ memory T cells. Notably, the CD4-/CD8- double-negative variant of MF is a rare occurrence, observed in approximately 12% of early-stage cases and more prevalent in tumor-stage instances, often correlated with atypical clinical presentations. Despite its rarity, scant information is available about double-negative mycosis fungoides, with only a limited number of cases documented in the existing literature. This review aims to provide enhanced clarity, comprehension, and a detailed exploration of the spectrum encompassing double-negative mycosis fungoides.

Structure-Guided Design of a Highly Potent Partial RXR Agonist with Superior Physicochemical Properties

Retinoid X receptors (RXRs, NR2B1-3) hold therapeutic potential in oncology, neurodegeneration, and metabolic diseases, but traditional RXR agonists mimicking the natural ligand 9-cis retinoic acid exhibit poor physicochemical properties, pharmacokinetics, and safety profiles. Improved RXR ligands are needed to exploit RXR modulation as a promising therapeutic concept in various indications beyond its current role in second-line cancer treatment. Here, we report the co-crystal structure of RXR in complex with a novel pyrimidine-based ligand and the structure-informed optimization of this scaffold to highly potent and highly soluble RXR agonists. Focused structure-activity relationship elucidation and rigidization resulted in a substantially optimized partial RXR agonist with low nanomolar potency, no cytotoxic activity, and very favorable physicochemical properties highlighting this promising scaffold for the development of next-generation RXR targeting drugs.

Structural Fusion of Natural and Synthetic Ligand Features Boosts RXR Agonist Potency

The retinoid X receptors (RXRs) are ligand-activated transcription factors involved in, for example, differentiation and apoptosis regulation. Currently used reference RXR agonists suffer from insufficient specificity and poor physicochemical properties, and improved tools are needed to capture the unexplored therapeutic potential of RXR. Endogenous vitamin A-derived RXR ligands and the natural product RXR agonist valerenic acid comprise acrylic acid residues with varying substitution patterns to engage the critical ionic contact with the binding site arginine. To mimic and exploit this natural ligand motif, we probed its structural fusion with synthetic RXR modulator scaffolds, which had profound effects on agonist activity and remarkably boosted potency of an oxaprozin-derived RXR agonist chemotype. Bioisosteric replacement of the acrylic acid to overcome its pan-assay interference compounds (PAINS) character enabled the development of a highly optimized RXR agonist chemical probe.

EORTC consensus recommendations for the treatment of mycosis fungoides/Sézary syndrome - Update 2023

On behalf of the EORTC Cutaneous Lymphoma Tumours Group (EORTC-CLTG) and following up on earlier versions published in 2006 and 2017 this document provides an updated standard for the treatment of mycosis fungoides and Sézary syndrome (MF/SS). It considers recent relevant publications and treatment options introduced into clinical practice after 2017. Consensus was established among the authors through a series of consecutive consultations in writing and a round of discussion. Treatment options are assigned to each disease stage and, whenever possible and clinically useful, separated into first- and second line options annotated with levels of evidence. Major changes to the previous version include the incorporation of chlormethine, brentuximab vedotin, and mogamulizumab, recommendations on the use of pegylated interferon α (after withdrawal of recombinant unpegylated interferons), and the addition of paragraphs on supportive therapy and on the care of older patients. Still, skin-directed therapies are the most appropriate option for early-stage MF and most patients have a normal life expectancy but may suffer morbidity and impaired quality of life. In advanced disease treatment options have expanded recently. Most patients receive multiple consecutive therapies with treatments often having a relatively short duration of response. For those patients prognosis is still poor and only for a highly selected subset long term remission can be achieved with allogeneic stem cell transplantation. Understanding of the disease, its epidemiology and clinical course, and its most appropriate management are gradually advancing, and there is well-founded hope that this will lead to further improvements in the care of patients with MF/SS.

The Use of Retinoids for the Prevention and Treatment of Skin Cancers: An Updated Review

Retinoids are natural and synthetic vitamin A derivatives that are effective for the prevention and the treatment of non-melanoma skin cancers (NMSC). NMSCs constitute a heterogenous group of non-melanocyte-derived skin cancers that impose substantial burdens on patients and healthcare systems. They include entities such as basal cell carcinoma and cutaneous squamous cell carcinoma (collectively called keratinocyte carcinomas), cutaneous lymphomas and Kaposi’s sarcoma among others. The retinoid signaling pathway plays influential roles in skin physiology and pathology. These compounds regulate diverse biological processes within the skin, including proliferation, differentiation, angiogenesis and immune regulation. Collectively, retinoids can suppress skin carcinogenesis. Both topical and systemic retinoids have been investigated in clinical trials as NMSC prophylactics and treatments. Desirable efficacy and tolerability in clinical trials have prompted health regulatory bodies to approve the use of retinoids for NMSC management. Acceptable off-label uses of these compounds as drugs for skin cancers are also described. This review is a comprehensive outline on the biochemistry of retinoids, their activities in the skin, their effects on cancer cells and their adoption in clinical practice.

Single-cell RNA sequencing of mycosis fungoides reveals a cluster of actively proliferating lymphocytes

A 70-year-old man's chronic erythematous skin lesion in the extremity had developed into a tumour one year before his first visit at our hospital. A biopsy showed atypical lymphocyte-like cells, and immunostaining identified atypical cells as CD3+, CD4+, CD5+ and FOXP3+. Single-cell RNA sequencing (scRNA-seq) analysis using BD Rhapsody revealed the higher expression of CD3, CD4, CD5 and FOXP3 genes in a group of cells that highly expressed genes, such as PCNA, in the S/M phase, which is in agreement with immunofluorescence staining results. The use of scRNA-seq analysis data is expected to promote personalised medicine for cutaneous lymphoma.

Comparison of the Efficacy and Safety of Bexarotene and Photo(Chemo)Therapy Combination Therapy and Bexarotene Monotherapy for Cutaneous T-Cell Lymphoma

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/m² 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/m²) 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.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13555-021-00655-0.

This study evaluated the efficacy and safety of bexarotene monotherapy compared with bexarotene and photo(chemo)therapy combination therapy in Japanese patients with cutaneous T-cell lymphoma (CTCL). The study was a randomized, open-label, two-parallel-group, active-control specified clinical study in patients diagnosed with CTCL performed over an 8-week period with a study extension conducted in two institutions. In the combination therapy group, bexarotene (300 mg/m² body surface area) was administered orally once daily to 22 subjects, followed by treatment with bath-psoralen and ultraviolet A (bath-PUVA) or narrowband UVB. In the bexarotene monotherapy group, bexarotene (300 mg/m²) was administered orally once daily to 24 subjects. Efficacy was assessed using the modified Severity-Weighted Assessment Tool. Among the 39 subjects analyzed for treatment efficacy, the response rate of the combination therapy group was 81.0% (17/21) and that of the monotherapy group was 83.3% (15/18). Differences between the two treatment groups were not statistically significant. Of the 21 subjects in the combination therapy group, 4 had a complete clinical response or complete response, and those with a partial response showed a higher skin lesion resolution rate than in the monotherapy group. The safety analysis revealed no reports of adverse events or adverse drug reactions among the 46 treated subjects (combination therapy group = 22; monotherapy group = 24). Thus, both bexarotene and photo(chemo)therapy combination therapy and bexarotene monotherapy were therapeutically effective and well tolerated in Japanese patients with CTCL. Patients receiving the combined therapy, however, showed a higher rate of skin lesion resolution.

Current treatment strategies and emerging therapies for cutaneous lymphoma

Cutaneous lymphoma is generally treated with skin-directed therapies (SDT) during the early and localized stages. For the refractory or advanced stages, systemic therapies are used. Previously, retinoids and interferons were used for SDT-resistant cases. Only a few chemotherapy options were available for more advanced disease. In recent years, many novel agents have been introduced and the strategy for systemic therapy has changed, especially for cutaneous T-cell lymphoma (CTCL). For SDT, helical tomotherapy, a new radiation modality, has been drawing attention as an option for radiotherapy. Targeted therapies such as histone deacetylase inhibitors, mogamulizumab, brentuximab vedotin, and denileukin diftitox are new treatment options. Chemotherapy agents such as gemcitabine and pralatrexate have been introduced; they are expected to have meaningful efficacy as monotherapy. Allogeneic hematopoietic stem cell transplantation is still considered for young patients with advanced CTCL as the only potentially curative treatment.

Safety and efficacy of bexarotene for Japanese patients with cutaneous T-cell lymphoma: Real-world experience from post-marketing surveillance

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/m² (61.6%) and patients who started with bexarotene at less than 300 mg/m² (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/m² 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/m² than patients who started with bexarotene at less than 300 mg/m² (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/m² 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.

Synthetic Retinoids Beyond Cancer Therapy

While the uses of retinoids for cancer treatment continue to evolve, this review focuses on other therapeutic areas in which retinoids [retinol (vitamin A), all-trans retinoic acid (RA), and synthetic retinoic acid receptor (RAR)α-, β-, and γ-selective agonists] are being used and on promising new research that suggests additional uses for retinoids for the treatment of disorders of the kidneys, skeletal muscles, heart, pancreas, liver, nervous system, skin, and other organs. The most mature area, in terms of US Food and Drug Administration-approved, RAR-selective agonists, is for treatment of various skin diseases. Synthetic retinoid agonists have major advantages over endogenous RAR agonists such as RA. Because they act through a specific RAR, side effects may be minimized, and synthetic retinoids often have better pharmaceutical properties than does RA. Based on our increasing knowledge of the multiple roles of retinoids in development, epigenetic regulation, and tissue repair, other exciting therapeutic areas are emerging. Expected final online publication date for the Annual Review of Pharmacology and Toxicology, Volume 62 is January 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

Alitretinoin in the treatment of cutaneous T-cell lymphoma

INTRODUCTION

In this survey, we analyzed data from patients suffering from the most common cutaneous T-cell lymphomas (CTCLs) subtypes mycosis fungoides (MF) and Sézary syndrome (SS), treated with the retinoid alitretinoin during a 7-year period at our outpatient department between 2015 and 2020.

MATERIALS AND METHODS

We analyzed patient medical records including TNMB stage, side effects under therapy with alitretinoin, time to next treatment (TTNT), and previous photo documentation.

RESULTS

A total of 35 patients with MF (n = 28) and SS (n = 7) were included in the study, of whom 69% were male and 31% were female. The mean age of onset was 56 ± 15 years in MF and 65.4 ± 10.8 years in SS with 51.4% having early stage (IA-IIA) and 48.6% having advanced stage (IIB-IVA) CTCL. Of these patients 37.2% responded to alitretinoin, 28.6% had a stable course, and 34.3% experienced progression. Alitretinoin was administered as a monotherapy (25.7%) or combined with five concomitant therapies (74.2%), most frequently with ECP (31.4%) and PUVA (11.4%). 63% did not report any side effects, most often hypertriglyceridemia (20%) was described.

CONCLUSION

Considering that nearly two thirds of the CTCL patients treated with alitretinoin showed a response or stable disease, together with a low number of side effects and low cost compared to bexarotene, alitretinoin may be a potential alternative in the treatment of less advanced CTCLs. This survey represents the largest number of recorded therapies with the retinoid alitretinoin in CTCLs in a European patient collective.

Oxaprozin Analogues as Selective RXR Agonists with Superior Properties and Pharmacokinetics

The retinoid X receptors (RXR) are ligand-activated transcription factors involved in multiple regulatory networks as universal heterodimer partners for nuclear receptors. Despite their high therapeutic potential in many pathologies, targeting of RXR has only been exploited in cancer treatment as the currently available RXR agonists suffer from exceptional lipophilicity, poor pharmacokinetics (PK), and adverse effects. Aiming to overcome the limitations and to provide improved RXR ligands, we developed a new potent RXR ligand chemotype based on the nonsteroidal anti-inflammatory drug oxaprozin. Systematic structure-activity relationship analysis enabled structural optimization toward low nanomolar potency similar to the well-established rexinoids. Cocrystal structures of the most active derivatives demonstrated orthosteric binding, and in vivo profiling revealed superior PK properties compared to current RXR agonists. The optimized compounds were highly selective for RXR activation and induced RXR-regulated gene expression in native cellular and in vivo settings suggesting them as excellent chemical tools to further explore the therapeutic potential of RXR.

Topical and Systemic Formulation Options for Cutaneous T Cell Lymphomas

Although various anti-cutaneous T-cell lymphoma (CTCL) therapies are available for clinical use, appropriate chemotherapy lines for the treatment of CTCLs have yet to be established. Therefore, to date, various clinical trials for the treatment of advanced CTCLs are ongoing. In this review, we evaluate the therapeutic options that are available in clinical practice for treatment of early- and advanced-stage CTCLs (targeted therapies, histone deacetylase (HDAC) inhibitors, retinoids, interferons, cytotoxic drugs, etc.). We also examine clinical trials of novel regimens for the treatment of CTCLs.

Outlines of the Japanese guidelines for the management of primary cutaneous lymphomas 2020

Since the publication of the Japanese "Guidelines for the management of cutaneous lymphomas" in 2011, the World Health Organization (WHO) classification of hematolymphoid neoplasms and the WHO-European Organisation for Research and Treatment of Cancer classification for primary cutaneous lymphomas were updated and a number of novel systemic drugs for cutaneous T-cell lymphoma had been approved in Japan. In 2020, we revised the Japanese guidelines for the management of cutaneous lymphomas with consideration of the recent advances in the understanding of the pathophysiology and classification of cutaneous lymphomas together with the update of treatment strategies reflecting the advent of novel drugs. In addition to a brief explanation of epidemiology, diagnosis, staging system, prognosis and management of each subtype of cutaneous lymphomas, the recommendations for nine clinical questions regarding treatment options that can vary even among experts are also described. A systematic review process and determination of recommendations in answer to each clinical question have been performed in accordance with the Grading of Recommendations, Assessment, Development and Evaluation scheme by a multidisciplinary expert panel consisting of dermatologists, a hematologist and a radiation oncologist. In this article, we present the outlines of the revised Japanese "Guidelines for the management of cutaneous lymphomas".

Dietary Glucose Consumption Promotes RALDH Activity in Small Intestinal CD103+CD11b+ Dendritic Cells

Retinal dehydrogenase (RALDH) enzymatic activities catalyze the conversion of vitamin A to its metabolite Retinoic acid (RA) in intestinal dendritic cells (DCs) and promote immunological tolerance. However, precise understanding of the exogenous factors that act as initial trigger of RALDH activity in these cells is still evolving. By using germ-free (GF) mice raised on an antigen free (AF) elemental diet, we find that certain components in diet are critically required to establish optimal RALDH expression and activity, most prominently in small intestinal CD103⁺CD11b⁺ DCs (siLP-DCs) right from the beginning of their lives. Surprisingly, systematic screens using modified diets devoid of individual dietary components indicate that proteins, starch and minerals are dispensable for this activity. On the other hand, in depth comparison between subtle differences in dietary composition among different dietary regimes reveal that adequate glucose concentration in diet is a critical determinant for establishing RALDH activity specifically in siLP-DCs. Consequently, pre-treatment of siLP-DCs, and not mesenteric lymph node derived MLNDCs with glucose, results in significant enhancement in the in vitro generation of induced Regulatory T (iTreg) cells. Our findings reveal previously underappreciated role of dietary glucose concentration in establishing regulatory properties in intestinal DCs, thereby extending a potential therapeutic module against intestinal inflammation.

Case series of cutaneous T-cell lymphomas treated with bexarotene-based therapy

Bexarotene is useful for both early and advanced cutaneous T-cell lymphoma (CTCL), and is sometimes applied to ultraviolet-tolerant early CTCL patients as one of the first-line therapies in the real world. However, continuous administration of bexarotene is sometimes difficult because of its adverse events (AE). Development of an appropriate protocol for bexarotene that can induce a consistent response for CTCL without severe AE (SAE) is needed. We retrospectively investigated 29 Japanese cases of CTCL and evaluated the efficacy of treatment and incident ratios of all AE and SAE. Objective response rate (ORR) for the overall cohort was 65.5%. ORR of the 300 mg/m² cohort (conventional dose) was 76.2%, while that of the 150-300 mg/body (low dose) with narrowband ultraviolet B light (NBUVB) cohort was 37.5%. Mean event-free survival was 10.0 months for all patients, 6.7 months for the bexarotene conventional-dose cohort and 19.1 months for the low-dose with NBUVB cohort. The incident ratio of total SAE for all patients was 20.7%. The incident ratio of total SAE was 23.8% for the conventional-dose cohort and 12.5% for the low-dose with NBUVB cohort. Our present study suggests that low-dose bexarotene plus NBUVB therapy is well-tolerated and could be one of the optimal therapies for advanced CTCL.

Efficacy and safety of bexarotene combined with photo(chemo)therapy for cutaneous T-cell lymphoma

Cutaneous T‐cell lymphoma (CTCL) is a chronic condition with low malignancy. International treatment guidelines for CTCL are widely followed in Europe and the USA. Combination therapy with therapeutic agents for CTCL and phototherapy is effective on the basis of European data. The efficacy and safety of combination therapy for Japanese CTCL patients are not established. We investigated the efficacy and safety of combination therapy with photo(chemo)therapy and bexarotene in Japanese CTCL patients. Twenty‐five patients received daily oral bexarotene (300 mg/m² body surface), followed by bath‐psoralen plus ultraviolet (UV)‐A (PUVA) or narrowband UV‐B. Treatment results were evaluated using the modified Severity‐Weighted Assessment Tool (mSWAT) and the Physician Global Assessment of Clinical Condition (PGA) up to week 24. Safety was also assessed. Twenty‐four weeks after initiating treatment, the total response rate was 80.0% (mSWAT) and 84.0% (PGA). Response rates did not differ when stratified by disease stage. Number of days (mean ± standard deviation) for time to response, duration of response and time to progression determined by the mSWAT were 20.7 ± 9.62, 117.0 ± 43.0 and 163.6 ± 28.8, respectively. T‐helper 2 chemokine levels in patients at stage IIA or more decreased significantly at weeks 12 and 24. All patients experienced adverse events and adverse drug reactions. Serious adverse drug reactions included sepsis, anemia and congestive cardiac insufficiency (n = 1 each). Other adverse drug reactions were of mild to moderate severity. Combination therapy with bexarotene and PUVA was safe and effective in Japanese CTCL patients.

Potential therapeutic roles of retinoids for prevention of neuroinflammation and neurodegeneration in Alzheimer's disease

All retinoids, which can be natural and synthetic, are chemically related to vitamin A. Both natural and synthetic retinoids use specific nuclear receptors such as retinoic acid receptors and retinoid X receptors to activate specific signaling pathways in the cells. Retinoic acid signaling is extremely important in the central nervous system. Impairment of retinoic acid signaling pathways causes severe pathological processes in the central nervous system, especially in the adult brain. Retinoids have major roles in neural patterning, differentiation, axon outgrowth in normal development, and function of the brain. Impaired retinoic acid signaling results in neuroinflammation, oxidative stress, mitochondrial malfunction, and neurodegeneration leading to progressive Alzheimer's disease, which is pathologically characterized by extra-neuronal accumulation of amyloid plaques (aggregated amyloid-beta) and intra-neurofibrillary tangles (hyperphosphorylated tau protein) in the temporal lobe of the brain. Alzheimer's disease is the most common cause of dementia and loss of memory in old adults. Inactive cholinergic neurotransmission is responsible for cognitive deficits in Alzheimer's disease patients. Deficiency or deprivation of retinoic acid in mice is associated with loss of spatial learning and memory. Retinoids inhibit expression of chemokines and neuroinflammatory cytokines in microglia and astrocytes, which are activated in Alzheimer's disease. Stimulation of retinoic acid receptors and retinoid X receptors slows down accumulation of amyloids, reduces neurodegeneration, and thereby prevents pathogenesis of Alzheimer's disease in mice. In this review, we described chemistry and biochemistry of some natural and synthetic retinoids and potentials of retinoids for prevention of neuroinflammation and neurodegeneration in Alzheimer's disease.

Two distinct variants of mycosis fungoides (MF): Folliculotropic MF and erythrodermic MF

Mycosis fungoides (MF) is the most frequent type of cutaneous T-cell lymphoma. Folliculotropic MF (fMF) and erythrodermic MF (eMF) are two distinct variants of MF. Both variants have been considered aggressive and most cases are less responsive to standard skin-directed therapies than classical MF. We, however, experienced many cases with fMF or eMF who showed indolent clinical courses. In this article, we reviewed 10 cases with fMF and 13 cases with eMF who came to our department between 2005 and 2017. In patients with fMF, monotherapy with topical corticosteroid was effective in two cases (20%) and ultraviolet phototherapy with oral retinoid controlled disease activity in two cases (20%). Five patients with eMF (38%) responded well to ultraviolet phototherapy. In conclusion, patients with early fMF and a subgroup of eMF patients have an indolent disease course, as was proposed among the specialists. Skin-directed therapies are preferable rather than aggressive treatment in those cases.

Bexarotene-induced hypothyroidism: Characteristics and therapeutic strategies

OBJECTIVE

Central hypothyroidism (CH) is a well-known adverse effect of bexarotene treatment for cutaneous T-cell lymphoma (CTCL). While concomitant levothyroxine therapy is recommended in these cases, associations between ethnic variation or susceptibility and bexarotene-induced CH have not yet been reported. This study aimed to characterize the kinetics and dose dependency of bexarotene-induced CH in Japanese patients.

DESIGN AND PATIENTS

Sixty-six Japanese patients with CTCL were retrospectively investigated by evaluating thyroid function during the early phase of bexarotene therapy.

RESULTS

At one week after bexarotene initiation, TSH and FT4 values significantly declined. However, this effect was not bexarotene dose-dependent at least at the dose of 96-320 mg/m² . Approximately 1 month later, 61 patients exhibited hypothyroidism at a relatively low dose of bexarotene (average 251 mg/m² /day). Forty-five study cases showed this effect at 1 week. Simple regression analyses indicated that higher pretreatment TSH values (at a cut-off value of 1.30:73% sensitivity, 57% specificity) or lower normal (within the lower half of the reference range) pretreatment FT4 values (84% sensitivity, 57% specificity) were predictive of hypothyroidism at 1 week. The remaining 21 cases showed euthyroidism at 1 week, at which TSH values may roughly predict their thyroid function at 1 month (at a cut-off value of 0.05:100% sensitivity, 80% specificity).

CONCLUSIONS

Preventive treatment with levothyroxine is recommended for Japanese CTCL patients prior to bexarotene therapy. Minimally, it should be considered for patients with a pretreatment TSH above 1.30, a lower normal pretreatment FT4, or a TSH below 0.05 at 1 week.

Long-term efficacy and safety of bexarotene for Japanese patients with cutaneous T-cell lymphoma: The results of a phase 2 study (B-1201)

The present study (B‐1201 clinical trial) was conducted as a multicenter, open‐label, single‐arm phase II study to evaluate the long‐term safety, tolerability and efficacy of bexarotene. This study enrolled 10 Japanese adults aged more than 20 years with cutaneous T‐cell lymphoma (CTCL) who completed the 24‐week study period of the B‐1101 trial. The objective response rate (ORR) was 53.8% (95% confidence interval, 25.1–80.8). In the early stage (IB), the ORR was 60% (3/5 cases). In the advanced stage (IIB and IIIA), the ORR was 57.1% (4/7 cases). The median time to response was 58 days (range, 27–168). The median treatment duration was 380 days (range, 33–1674). The median duration of response (DOR) could not be reached during the study period. The longest DOR reached 1618 days at the end of the B‐1201 trial. Nine patients (56.3%) in the full analysis set (FAS) population experienced dose reduction of bexarotene. Common drug‐related adverse events in the FAS population included hypothyroidism (93.8%), hypertriglyceridemia (81.3%), hypercholesterolemia (81.3%), leukopenia (68.8%) and neutropenia (56.3%). Dose‐limiting toxicity (DLT) was present in five (38.5%) of the 13 patients in the 300 mg/m² cohort. Of the five patients, four developed grade 3 neutropenia and one developed grade 4 hypertriglyceridemia. All DLT cases recovered after the discontinuation of bexarotene. None of the five patients discontinued this trial because of DLT. The B‐1201 trial shows the long‐term safety of oral bexarotene for Japanese patients with CTCL, despite frequent dose reduction.

CD4/CD8 Double-negative Mycosis Fungoides: A Case Report and Literature Review

Mycosis fungoides, the most common subtype of cutaneous T-cell lymphoma, displays a broad spectrum of clinical, histological and phenotypic variants with different prognostic impacts. The classic immunophenotype is CD3+/CD4+/CD45RO+memory T cells. CD4/CD8 double-negative mycosis fungoides is rare. Here we describe the clinicopathological features of CD4/CD8 double-negative mycosis fungoides in a 55-year-old female with a review of the literature. Although the CD4/CD8 double-negative phenotype appears to be associated with an unusual clinical presentation, it does not appear to confer prognostic significance.

Successful Treatment of Advanced Primary Cutaneous Peripheral T-Cell Lymphoma with Oral Bexarotene Monotherapy

Bexarotene is a third-generation retinoid X receptor-selective retinoid that is widely used for the early treatment of advanced-stage cutaneous T-cell lymphomas. In this report, we describe a case of successful treatment of advanced primary cutaneous peripheral T-cell lymphoma not otherwise specified (PTCL-NOS) with oral bexarotene monotherapy. After the administration of oral bexarotene at a dose of 300 mg/m²/day, all skin lesions and lymph nodes regressed, and complete remission was achieved for 1 year. Our case suggested that bexarotene monotherapy could be one of the possible therapies for the treatment of primary cutaneous PTCL-NOS.

Bexarotene attenuates early brain injury via inhibiting micoglia activation through PPARγ after experimental subarachnoid hemorrhage

Objectives Early brain injury (EBI) is considered to be one of the main causes of poor outcome in subarachnoid hemorrhage (SAH) patients. Bexarotene is an agonist of retinoid X receptor and plays a protective role in central nervous system diseases. However, the exact role of bexarotene in SAH has not been reported. Therefore, the present study was to determine whether bexarotene administration attenuate EBI after SAH in mice and to explore the underlying mechanism. Methods SAH was induced in C57BL/6 mice by endovascular perforation. Bexarotene was administrated intraperitoneally. Neurological score, cell death, microglia activation, and pro-inflammatory cytokines were detected at 24 h after SAH. The expression of PPARγ was measured by Western blot. Results Results showed that bexarotene significantly improved neurological score after SAH. In addition, the number of cell death and activated microglia were significantly reduced by bexarotene administration. Compared with vehicle-treated mice, bexarotene-treated mice showed reduced pro-inflammatory cytokines after SAH. The expression of PPARγ was significantly increased with bexarotene treatment compared with vehicle-treated controls. Discussion The present study demonstrats that bexarotene administration protects against EBI after SAH, inhibiting cell death, attenuating microglia activation, and alleviating neuroinflammation. The underlying mechanism may partially involve the activation of PPARγ.