Impact of body mass index on the severity of bexarotene-associated hypertriglyceridemia: A post hoc analysis of an open-labeled clinical study of combined bexarotene and phototherapy in Japanese patients with cutaneous T-cell lymphoma.

Bexarotene is an effective oral drug for the treatment of cutaneous T-cell lymphoma, but careful management is required due to its various side effects. In particular, hypertriglyceridemia often requires a reduction or even suspension of bexarotene therapy. The risk factors of bexarotene-associated severe hypertriglyceridemia are not clear. Here, we conducted a post hoc analysis of the data from our previous clinical trial, which confirmed the efficacy and safety of combined bexarotene and phototherapy, to evaluate the effect of body mass index on bexarotene-associated hypertriglyceridemia. Twenty-five subjects were divided into two subgroups: normal and underweight (body mass index [BMI] <25 kg/m2 group) and overweight and obese (BMI ≥25 kg/m2 group) patients. The overall incidence of hypertriglyceridemia was 81.3% (13/16) in the BMI <25 kg/m2 group and 88.9% (8/9) in the BMI ≥25 kg/m2 group. The incidence of grade ≥3 hypertriglyceridemia (≥500 mg/dL) was 7.7% (1/13) in the BMI <25 kg/m2 group and 7/8 (87.5%) in the BMI ≥25 kg/m2 group (P < 0.001). Consequently, dose reduction in the BMI ≥25 kg/m2 group was larger than that in the BMI <25 kg/m2 group. The bexarotene-induced change in the serum triglyceride concentration was significantly increased in cutaneous T-cell lymphoma patients with a higher body mass index (ρ = 0.508, P = 0.009). The area under the curve was 0.886 (95% confidence interval 0.748-1.000, P = 0.002). With a body mass index cut-off of 24.85 kg/m2 , the sensitivity and specificity for identifying grade ≥3 hypertriglyceridemia were 0.875 and 0.882, respectively. The present findings suggest that BMI ≥25 kg/m2 is a risk factor for bexarotene-associated severe hypertriglyceridemia, therefore overweight and obese patients treated with bexarotene should receive lipid-lowering drugs prophylactically. Further studies for optimizing the initial bexarotene dose in such patients are required.

Omega-3 fatty acids as adjunctive treatment for bexarotene-induced hypertriglyceridaemia in patients with cutaneous T-cell lymphoma.

BACKGROUND: Bexarotene is an oral retinoid approved for treating cutaneous T-cell lymphoma (CTCL) in patients resistant to first-line systemic treatment. Hypertriglyceridaemia is an unavoidable adverse effect of bexarotene therapy, and requires monitoring because of the risk of developing pancreatitis. Therefore, prophylactic hypolipidaemic therapy, usually with a fibrate alone, is required for preventing bexarotene-induced hypertriglyceridaemia. Despite these measures, a large number of patients develop very severe hypertriglyceridaemia. AIM: To assess the lipid metabolism changes before and after the use of a combination of omega-3 fatty acids (n-3 FA) plus fenofibrate compared with fenofibrate alone as a more effective lipid-lowering therapy in patients with CTCL treated with bexarotene. METHODS: From January 2005 to January 2013, we analysed all 25 patients with CTCL treated with bexarotene. The first 18 consecutively enrolled patients received fenofibrate alone as a lipid-lowering therapy, and the next 7 consecutively enrolled patients received a combination of fenofibrate and n-3 FA. RESULTS: Data for all 25 consecutive patients with CTCL treated with bexarotene were evaluated. Of these, 24 patients (96%) developed hypertriglyceridaemia despite the hypolipidaemic therapy, with this being very severe (> 11.2 mmol/L) in 20% of the cases. Of the 18 patients receiving fenofibrate alone, 5 (28%) developed very severe hypertriglyceridaemia, compared with none of the 7 patients treated with the n-3 FA combination. CONCLUSIONS: Our results suggest that the n-3 FA combination may be more effective than fibrate alone for preventing bexarotene-induced hypertriglyceridaemia.

[Thyroid and lipidic dysfunction associated with bexarotene in cutaneous T-cell lymphoma]. / Disfunción tiroidea y lipídica asociada a bexaroteno en el linfoma cutáneo de células T.

BACKGROUND AND OBJECTIVE: Bexarotene is a synthetic selective X receptor rexinoide approved for the systemic treatment of cutaneous T-cell lymphoma. During treatment is very frequent the occurrence of hypothyroidism and severe mixed hyperlipidemia, both are reversibles and dose-dependent adverse events. Increase of triglycerides and LDL-cholesterol level (up to even higher levels have been associated with pancreatitis in some cases) is widely described (as is the case with other retinoids) but decrease in HDL-cholesterol is poored know. We review our experience with the use of bexarotene. MATERIAL AND METHODS: We present a serie of 3 clinical report of patients treated with bexarotene in whose, in addition to these well-known adverse event, a serious lowering of HDL-cholesterol was observed. RESULTS: The 3 patients studied had metabolic complications like central hypothyroidism and severe mixed hyperlipidemia; with special emphasis on the sharp fall (mean decrease>83%) in the HDL-cholesterol level. Cholesterol lowering medication and substitutive hormonal replacement with levotiroxine resulted in an improvement of the biochimical parameters without reaching the correct goals. CONCLUSIONS: Bexarotene produce as predictable side effects severe mixed hyperlipidemia with marked decrease in HDL-cholesterol levels and central hypothyroidism, being the both reversible and dose-dependent. A reflection on the possible aetiological mechanisms and implications of this phenomenon are included.

Marked lowering of high-density lipoprotein cholesterol levels due to high dose bexarotene therapy.

CONTEXT: Bexarotene is a retinoid X receptor agonist, which is currently used for the treatment of cutaneous T-cell lymphoma (CTCL). It is known to induce central hypothyroidism as well as dyslipidemia including elevation of triglycerides (TG) and low-density lipoprotein cholesterol along with slight lowering of high-density lipoprotein cholesterol (HDL-C). Marked lowering of HDL-C has never been previously reported in bexarotene-treated patients and whether it is related to hypothyroidism remains unclear. CASE REPORT: A 49-year-old African female with a history of CTCL on treatment with bexarotene of 300 mg/d, presented with serum total cholesterol level of 249 mg/dL (6.4 mmol/L), TG level of 92 mg/dL (1.03 mmol/L), HDL-C level of 78 mg/dL (2.02 mmol/L), thyroid stimulating hormone (TSH) of 0.68 µIU/mL, and free thyroxine level of 0.5 ng/dL. Six months later, on increasing the bexarotene dose to 600 mg daily, serum TG increased to 310 mg/dL (3.5 mmol/L) and HDL-C dropped to 3 to 5 mg/dL (0.077-0.13 mmol/L), whereas the TSH was undetectable (0.01 µIU/mL). Despite adequate levothyroxine replacement to 225 µg daily resulting in free thyroxine levels up to 1.5 ng/dL, HDL-C remained extremely low of 4 to 9 mg/dL (0.103-0.233 mmol/L). Bexarotene was discontinued due to poor response of CTCL, 3 months after which her HDL-C levels returned to baseline of 80 to 90 mg/dL (2.07-2.33 mmol/L). CONCLUSIONS: High dose bexarotene can markedly lower HDL-C levels, which normalize on discontinuation of the drug. Lowering of HDL-C with bexarotene may be due to an increase in cholesterol ester transfer protein activity and appears to be independent of central hypothyroidism.

The Role of Systemic Retinoids in the Treatment of Cutaneous T-Cell Lymphoma.

Retinoids are natural and synthetic vitamin A analogs with effects on cell proliferation, differentiation, and apoptosis. They have significant activity in hematologic malignancies and have been studied extensively in cutaneous T-cell lymphoma. Retinoids bind to nuclear receptors and exert their effects through moderation of gene expression. Retinoic acid receptor and retinoic X receptor exert regulatory activity in vivo, binding to distinct ligands. Studies investigating systemic retinoids as monotherapy and in combination with other agents active against cutaneous lymphoma are reviewed. Side effects associated with retinoids include teratogenicity, dyslipidemias, and hypothyroidism, which should be carefully monitored in patients receiving treatment.

Amyloid-ß pathology and APOE genotype modulate retinoid X receptor agonist activity in vivo.

Previous data demonstrate that bexarotene (Bex), retinoid X receptor (RXR) agonist, reduces soluble and insoluble amyloid-ß (Aß) in Alzheimer disease (AD)-transgenic mice either by increasing the levels of mouse apolipoprotein E (apoE) or increasing ABCA1/ABCG1-induced apoE lipoprotein association/lipidation. However, although the mechanism of action of RXR agonists remains unclear, a major concern for their use is human (h)-APOE4, the greatest AD genetic risk factor. If APOE4 imparts a toxic gain-of-function, then increasing apoE4 may increase soluble Aß, likely the proximal AD neurotoxin. If the APOE4 loss-of-function is lipidation of apoE4, then induction of ABCA1/ABCG1 may be beneficial. In novel EFAD-Tg mice (overexpressing h-Aß42 with h-APOE), levels of soluble Aß (Aß42 and oligomeric Aß) are highest in E4FAD hippocampus (HP) > E3FAD-HP > E4FAD cortex (CX) > E3FAD-CX, whereas levels of lipoprotein-associated/lipidated apoE have the opposite pattern (6 months). In E4FAD-HP, short-term RXR agonist treatment (Bex or LG100268; 5.75-6 months) increased ABCA1, apoE4 lipoprotein-association/lipidation, and apoE4/Aß complex, decreased soluble Aß, and increased PSD95. In addition, hydrogel delivery, which mimics low sustained release, was equally effective as gavage for Bex and LG100268. RXR agonists induced no beneficial effects in the E4FAD-HP in a prevention protocol (5-6 months) and actually increased soluble Aß levels in E3FAD-CX and E4FAD-CX with the short-term protocol, possibly the result of systemic hepatomegaly. Thus, RXR agonists address the loss-of-function associated with APOE4 and exacerbated by Aß pathology, i.e. low levels of apoE4 lipoprotein association/lipidation. Further studies are vital to address whether RXR agonists are an APOE4-specific AD therapeutic and the systemic side effects that limit translational application.

Effects of rotigotine on Parkinson's disease-related sleep disturbances.

INTRODUCTION: Sleep abnormalities are a frequent non-motor symptom and a prominent cause of disability in patients with Parkinson's disease (PD). AREAS COVERED: This review discusses what is currently known about the characteristics of sleep disturbances in PD patients and attempts to clarify the role of dopaminergic pathways in their pathogenesis as well as the beneficial effect of dopaminergic agents in their treatment. In particular, this review will focus on the effects of transdermal rotigotine on improving PD-related sleep disorders. EXPERT OPINION: Sleep disturbances are common in PD, and these disturbances can be reduced or resolved, in large part, by preventing or attenuating nocturnal and early morning motor and non-motor symptoms of PD. The studies discussed within this review suggest that sleep disorders are not just a consequence of motor impairment and dopaminergic therapy but are an integral part of the neurodegenerative process of PD. This is supported by the appearance of specific sleep disturbances, which are related to degeneration of the brainstem areas involved in the regulation of sleep/wake states in advance of typical PD symptoms. Development of more detailed diagnostic tools aimed at detecting sleep disturbances and at defining the main causative factors of sleep disturbances in PD will lead to improved treatment of these disturbances.

Case experience of 308-nm excimer laser therapy compatibility with PUVA and oral bexarotene for the treatment of cutaneous lesions in mycosis fungoides.

Little is known about the safety and effectiveness of excimer laser therapy when used in conjunction with other therapies in the treatment of mycosis fungoides (MF) lesions. We describe the use of adjunctive excimer laser therapy in combination with psoralen plus ultraviolet A (PUVA) and oral bexarotene for the treatment of recalcitrant and sanctuary plaques in a patient with MF. In our patient, this regimen successfully induced clinical and histologic resolution in MF plaques with minimal side effects limited to mild, short-lived tenderness and, rarely, local erythema. Our experience suggests that adjunctive excimer laser therapy with PUVA and oral bexarotene has the potential to be a safe, well-tolerated, and effective focal treatment regimen for cutaneous MF lesions.

[Third generation selective estrogen receptor modulators: benefits beyond bone. II, endometrial action]. / Beneficio extraóseo de los moduladores selectivos del receptor estrogénico de tercera generación: II, acción en el endometrio.

The selective estrogen receptor modulators (SERMs) are substances with estrogenic/anti-estrogen effect that act differently depending on the tissue and composition. Since the discovery that tamoxifen and raloxifene (RLX) had a breast cancer preventive effect, the search for the perfect SERM has been the goal. The evidence that tamoxifen significantly increased the risk of endometrial cancer as compared to placebo made this tissue the center of interest in developing new SERMs. Thus, ospemifen, arzoxifene, lasofoxifene (LFX) and bazedoxifene (BZA) appeared as third-generation SERMs but only BZA reached the stage of clinical use. Both experimental and clinical data available on the effects of RLX or third-generation SERMs reaching clinical stage (LFX and BZA) show either neutrality or anti-estrogenic effects at endometrial level. BZA has shown to be equivalent to vehicle in several experimental conditions and acts as anti-estrogen in models were estrogens (conjugated equine estrogens [CEE] or E2) were co-administered. In a 7 years pivotal study the incidence of endometrial adenocarcinoma has been significantly lower in the BZA than in the placebo group. Moreover, in a clinical trial to evaluate the ability of a combination of BZA and CEE to prevent hot flushes in symptomatic postmenopausal women, doses of 20mg or higher of BZA have significantly decreased the risk of presenting endometrial hyperplasia when co-administered with either 0.650 or 0.450mg of CEE.

The retinoid X receptor agonist bexarotene relieves positive symptoms of schizophrenia: a 6-week, randomized, double-blind, placebo-controlled multicenter trial.

OBJECTIVE: The limitations of antipsychotic therapy in schizophrenia and schizoaffective disorder led to the investigation of the putative utility of pharmacologic augmentation strategies. The antitumor agent bexarotene via nuclear retinoid X receptor (RXR) activation might modulate numerous metabolic pathways involved in the pathogenesis of schizophrenia and schizoaffective disorder. This trial aimed to investigate efficacy and safety of add-on bexarotene to ongoing antipsychotic treatment of patients with schizophrenia or schizoaffective disorder. METHOD: Ninety inpatients and outpatients that met DSM-IV-TR criteria for schizophrenia or schizoaffective disorder participated in a 6-week, double-blind, randomized, placebo-controlled multicenter study. Bexarotene (75 mg/d) was added to ongoing antipsychotic treatment from October 2008 to December 2010. The reduction in the severity of symptoms on the Positive and Negative Syndrome Scale (PANSS) was a primary outcome. Secondary outcomes included general functioning, quality of life, and side effect scales. RESULTS: Seventy-nine participants (88%) completed the protocol. Controlling for antipsychotic agents, a mixed model showed that patients who received adjunctive bexarotene had significantly lower PANSS positive scale scores compared to patients who received placebo (F = 8.6, P = .003; treatment arms × time, F = 2.7, P = .049), with moderate effect size (d = 0.48; 95% CI,0.04-0.93). Patients with mean or higher baseline PANSS positive scale scores and patients who did not take lipid-reducing agents revealed greater amelioration of positive symptoms (F = 7.4, P = .008). Other symptoms and secondary outcome measures were not affected by adjunctive bexarotene. Bexarotene was well tolerated, though 2 reversible side effects were reported: a significant increase in total cholesterol levels (P < .001) and a decrease in total thyroxine levels (P < .001). CONCLUSIONS: Bexarotene might potentially be a novel adjuvant therapeutic strategy for schizophrenia, particularly for the reduction of positive symptoms. The potential benefits and risks of ongoing administration of bexarotene warrant further evaluation. TRIAL REGISTRATION: ClinicalTrials.gov identifier: NCT00535574.

Acitretin for the treatment of cutaneous T-cell lymphoma.

BACKGROUND: Bexarotene is the only Food and Drug Administration-approved retinoid for the treatment of cutaneous T-cell lymphoma (CTCL) and is associated with a relatively high frequency of adverse effects. Acitretin has anecdotally been reported to be effective for CTCL. OBJECTIVE: We sought to determine the effectiveness and tolerability of acitretin as primary or adjuvant therapy for CTCL. METHODS: We conducted a retrospective chart review of patients with CTCL treated with acitretin at a single tertiary care center. RESULTS: A total of 32 patients with CTCL were included: 29 had mycosis fungoides, 2 had Sézary syndrome, and 1 had CTCL not otherwise specified. Median patient age was 55 years; 56% were male; 47% were white, 47% black, and 6% other. In all, 3% of patients were stage IA, 69% stage IB/IIA, 16% stage IIB, 6% stage III, and 6% stage IV. Six patients received acitretin alone; 26 received acitretin in addition to another CTCL therapy. The overall response rate was 59%. In all, 25% of patients had stable disease and 16% had progressive disease. Median duration of response was 28 months. Adverse effects were generally mild with 5 patients discontinuing therapy because of these. LIMITATIONS: In this small retrospective chart review, many patients were on other CTCL therapies while on acitretin; therefore precise assessment of response to acitretin alone was difficult. CONCLUSIONS: Acitretin is well tolerated and potentially effective for early-stage CTCL. Response to acitretin, either as adjuvant therapy monotherapy, is comparable with the response to oral agents currently approved for this disease.

Efficacy and safety of bexarotene combined with psoralen-ultraviolet A (PUVA) compared with PUVA treatment alone in stage IB-IIA mycosis fungoides: final results from the EORTC Cutaneous Lymphoma Task Force phase III randomized clinical trial (NCT00056056).

BACKGROUND: Psoralen plus ultraviolet A (PUVA) is the standard treatment for early stages of mycosis fungoides. There have been no adequate randomized controlled trials with sufficient power comparing this modality with other therapies. OBJECTIVE: To assess disease response and to compare the response rates of patients treated with PUVA alone or PUVA and bexarotene. METHODS: EORTC 21011 (NCT 00056056) was a randomized phase III study comparing combined bexarotene (Targretin(®) ) and PUVA vs. PUVA alone in patients with stage IB and IIA mycosis fungoides (MF). The primary endpoint was the overall response rate [complete clinical response (CCR) plus partial response (PR)]. RESULTS: The study was prematurely closed due to low accrual after 93 of 145 required patients (65%) were randomized. Of the 93 randomized patients, 87 started treatment, 41 received PUVA and 46 received PUVA + bexarotene. Total UVA doses received were 107 J cm(-2) (range 1·4-489·9) in the PUVA arm vs. 101·7 J cm(-2) (0·2-529·9) in the combination arm. The safety profile was acceptable with few grade 3-4 toxicities observed in either arm. More drop-outs due to toxicity were observed in the combination arm compared with the PUVA-alone arm. The best overall response (CCR + PR) rate was 71% for PUVA alone and 77% for the combination arm (P = 0·57). The median duration of response was 9·7 months for PUVA vs. 5·8 months for the combination arm (P = 0·33). CCR was seen in 25 patients of whom 10 received PUVA alone (CCR 22%) and 15 received combination therapy (CCR 31%) (P = 0·45). CCR was sustained in 25% of patients regardless of therapy. There was a trend towards fewer PUVA sessions needed to achieve CCR in the combination arm (median 22) compared with the PUVA arm (median 27·5) (P = 0·11). Similarly, a trend towards lower UVA dose required to achieve CCR in the combination arm (median 55·8 J cm(-2) ) compared with the PUVA arm alone (median 117·5 J cm(-2) ) (P = 0·5) was observed. CONCLUSIONS: No significant difference in response rate or response duration was observed in this study. However, there was a trend towards fewer PUVA sessions and lower UVA dose required to achieve CCR in the combination arm (PUVA + bexarotene) but this did not achieve statistical significance due to insufficient power.

Hypertriglyceridaemia with bexarotene in cutaneous T cell lymphoma: the role of omega-3 fatty acids.

Bexarotene is approved for the treatment of cutaneous T cell lymphomas in patients refractory to at least one prior systemic therapy. Associated hypertriglyceridaemia requires monitoring, but can readily be managed with concomitant medication, such as fenofibrate. Here we report three cases of hypertriglyceridaemia secondary to bexarotene assumption, which was adequately managed with omega-3 fatty acids. If fenofibate-related side effects occur, or a statin is required to control low-density lipoprotein-cholesterol, omega-3 fatty acids should be considered as a good alternative therapy to lower lipid levels during bexarotene treatment.

Bexarotene induces dyslipidemia by increased very low-density lipoprotein production and cholesteryl ester transfer protein-mediated reduction of high-density lipoprotein.

A common dose-limiting side effect of treatment with the retinoid X receptor agonist bexarotene is dyslipidemia. We evaluated the effects of bexarotene on plasma lipid metabolism in patients with metastatic differentiated thyroid carcinoma and investigated the underlying mechanism(s) in apolipoprotein (APO) E*3-Leiden mice without (E3L) and with human cholesteryl ester transfer protein (CETP; E3L.CETP). To this end, 10 patients with metastatic differentiated thyroid carcinoma were treated with bexarotene (300 mg/d) for 6 wk. Bexarotene increased plasma triglyceride (TG; +150%), primarily associated with very low-density lipoprotein (VLDL), and raised plasma total cholesterol (+50%). However, whereas bexarotene increased VLDL-cholesterol (C) and low-density lipoprotein (LDL)-C (+63%), it decreased high-density lipoprotein (HDL)-C (-30%) and tended to decrease apoAI (-18%) concomitant with an increase in endogenous CETP activity (+44%). To evaluate the cause of the bexarotene-induced hypertriglyceridemia and the role of CETP in the bexarotene-induced shift in cholesterol distribution, E3L and E3L.CETP mice were treated with bexarotene through dietary supplementation [0.03% (wt/wt)]. Bexarotene increased VLDL-associated TG in both E3L (+47%) and E3L.CETP (+29%) mice by increasing VLDL-TG production (+68%). Bexarotene did not affect the total cholesterol levels or distribution in E3L mice but increased VLDL-C (+11%) and decreased HDL-C (-56%) as well as apoAI (-31%) in E3L.CETP mice, concomitant with increased endogenous CETP activity (+41%). This increased CETP activity by bexarotene-treatment is likely due to the increase in VLDL-TG, a CETP substrate that drives CETP activity. In conclusion, bexarotene causes combined dyslipidemia as reflected by increased TG, VLDL-C, and LDL-C and decreased HDL-C, which is the result of an increased VLDL-TG production that causes an increase of the endogenous CETP activity.

Complete clinical remission of tumor-stage mycosis fungoides after acute extensive skin necroses, granulomatous reaction, and fever under treatment with bexarotene, vorinostat, and high-dose fenofibrate.

Mycosis fungoides and its variants are a distinct entity with a variable, but well-characterized clinical course. We report on a 51-year-old patient with tumor-stage mycosis fungoides who developed several unusual features such as extensive necrosis of lymphoma lesions, granulomatous reaction, and venular thromboses while under treatment with bexarotene, vorinostat, and high-dose fenofibrate. After surgical removal of skin necroses, the patient recovered and was in complete clinical remission. Possible causal factors such as blastic transformation; hematophagic syndrome; or bacterial, fungal, or viral infection could be excluded. We hypothesize that combination of the high-dose fenofibrate (400 mg) with the retinoid X receptor ligand bexarotene and vorinostat might have induced an increased rate of apoptosis in lymphoma cells in our patient resulting in an extensive release of lymphoma antigens. Augmented antigen release along with changes in local cytokine milieu might have induced macrophage activation and granuloma formation.

Safety and efficacy of low-dose bexarotene and PUVA in the treatment of patients with mycosis fungoides.

BACKGROUND: The new rexinoid bexarotene is a retinoid X receptor antagonist and immune response modifier. Although combinations of oral bexarotene and psoralen plus UVA (PUVA) have been tried in patients with all stages of mycosis fungoides (MF), the dosage of bexarotene used in these combination regimens has been variable. OBJECTIVE: To assess the efficacy and safety of low-dose oral bexarotene and PUVA in patients with relapsed or treatment-refractory MF following monotherapy with multiple agents including PUVA, narrow-band UVB, interferon-alpha, oral bexarotene, and topical corticosteroids. METHOD: Combination therapy with PUVA three times weekly and low-dose oral bexarotene (150 or 300 mg/day, depending on physicians' preference) was administered to 14 patients, seven men and seven women (median age 49.5 years, range 30-75 years), with relapsed or refractory MF stages I-III. All responders received maintenance treatment at the same bexarotene dose that induced remission until progression or unacceptable toxicity. RESULTS: Low-dose oral bexarotene combined with PUVA was associated with an overall response rate (complete response or partial response) in 67% of the nine patients with refractory MF who completed the treatment course. Of these nine patients, four had a complete response, two had a partial response, one had stable disease, and two had progressive disease. Five patients withdrew because of hyperlipidemia. Oral bexarotene was continued as maintenance therapy in three of the four complete responders (one refused); two of these patients relapsed 2-10 months after PUVA discontinuation. Patients with partial response or stable disease received the combination for 3-5 months and were switched to another treatment regimen because of lack of further response. Therapy was fairly well tolerated. CONCLUSION: In a select population of patients who had not responded to at least one monotherapy for early-stage MF, a combination of low-dose oral bexarotene and PUVA was successful in achieving a satisfactory overall response rate in 67% of patients who completed the treatment course and was fairly well tolerated. Limitations of the study include the small number of patients evaluated, its retrospective nature, and the fact that patients were commenced on different bexarotene starting doses (150 or 300 mg/day), depending on physicians' preference.

Tamibarotene.

Tamibarotene is a new synthetic retinoid drug recently approved for relapsed or refractory acute promyelocytic leukemia (APL) in Japan. It is a specific agonist for retinoic acid receptor alpha/beta. Compared to all-trans retinoic acid (ATRA), a natural retinoid indicated for a first-line treatment of APL, tamibarotene is chemically more stable and several times more potent as an inducer of differentiation in promyelocytic leukemia cells. In contrast to ATRA, whose plasma concentration declines considerably during daily administration, tamibarotene sustains plasma level probably due to a lower affinity for cellular retinoic acid binding protein. Furthermore, adverse side effects were milder than those of ATRA in clinical trials. Clinical trials held in Japan showed that tamibarotene had efficacy in APL patients who had relapsed from ATRA-induced complete remission. Recently, better understanding of the various mechanisms of action of retinoids has stimulated great interest in its potential use for treatment of various diseases. Tamibarotene is being investigated for treatment of multiple myeloma and Crohn's disease in clinical trials. This review focuses on tamibarotene's mechanisms of action, chemical properties, pharmacokinetics and its use in APL as well as its potential use in various disorders.

Bexarotene-induced hypothyroidism: bexarotene stimulates the peripheral metabolism of thyroid hormones.

OBJECTIVE: Therapy with the retinoid X receptor agonist bexarotene is associated with hypothyroidism caused by decreased pituitary TSH secretion. To evaluate the effects of bexarotene on peripheral thyroid hormone metabolism, we performed a study in athyreotic subjects on a fixed substitution dose with L-T4. DESIGN: The design was an open prospective 6-wk intervention study. METHODS: Ten athyreotic patients with pulmonary metastases of differentiated thyroid carcinoma received 6-wk redifferentiation treatment with 300 mg bexarotene/d. L-T4 doses were kept stable. Before and in the sixth week of therapy, serum levels of total T4, free T4 (FT4), T3, reverse T3 (rT3), and TSH were measured. To study nondeiodinase-mediated thyroid hormone degradation, serum levels of T4 sulfate (T4S) were measured. Recombinant human TSH was administered before and in the sixth week of bexarotene therapy. RESULTS: Bexarotene induced profound decreases in total T4 (56% of baseline), FT4 (47%), T3 (69%), rT3 (51%), and T4S (70%) in all patients, whereas TSH levels were not affected. The T3/rT3 ratio increased by 43%, and the T4S/FT4 ratio increased by 48%. Serum TSH levels before and after recombinant human TSH were unaffected by bexarotene. CONCLUSIONS: In the present study, we demonstrate that increased peripheral degradation of thyroid hormones by a nondeiodinase-mediated pathway contributes to bexarotene induced-hypothyroidism.

[Central hypothyroidism associated with bexarotene therapy]. / Une étiologie d'hypothyroïdie à ne pas méconnaître: l'hypothyroïdie centrale associée au traitement par bexarotène Targretin.

We report the case of a patient with cutaneous T-cell lymphoma treated by bexaroten Targretin, a synthetic retinoid analog with specific affinity for retinoid X receptor. The treatment induced mixed hyperlipidemia and severe central hypothyroidism characterized by reduced TSH and thyroxine serum levels. Only the pituitary thyreotrope function was affected. Targretin therapy can be maintained. Adverse drug events may be managed by fenofibrate Lipanthyl for dyslipidemia and high dose L-thyroxin Lévothyrox requiring serum free thyroxin level measurement for central hypothyroidism.