Topical bexarotene therapy for patients with refractory or persistent early-stage cutaneous T-cell lymphoma: results of the phase III clinical trial

Validation of the Cutaneous Dermatomyositis Disease Area and Severity Index: characterizing disease severity and assessing responsiveness to clinical change

BACKGROUND

The Cutaneous Dermatomyositis Disease Area and Severity Index (CDASI) was developed for use in clinical trials and longitudinal patient assessment.

OBJECTIVES

To characterize disease severity using the CDASI and assess the responsiveness of this instrument to clinically meaningful changes in disease activity.

METHODS

Patients with cutaneous dermatomyositis at the University of Pennsylvania (UPenn, n = 93) and Stanford University (Stanford, n = 106) were prospectively evaluated using the CDASI, physician global assessment (PGA) Likert scales and a visual analogue scale (VAS). Data was analysed using logistic regression models and receiver operating characteristic curves to select cut-offs.

RESULTS

Baseline CDASI activity scores for the patients evaluated at UPenn ranged from 0 to 47 (median 17), and baseline PGA VAS scores ranged from 0 to 9·6 (median 1·1). At UPenn a CDASI activity score of 19 differentiated mild from moderate and severe disease. At Stanford baseline CDASI scores ranged from 0 to 48 (median 21), baseline PGA VAS scores ranged from 0 to 9·7 (median 4·2) and CDASI activity scores of 14 or less characterized mild disease. When a 2-cm change in the PGA VAS was regarded as a clinically significant improvement, a 4-point (UPenn) or 5-point (Stanford) change in CDASI reflected a minimal clinically significant response.

CONCLUSIONS

The CDASI is a valid and responsive measure that can be used to characterize cutaneous dermatomyositis severity and detect improvement in disease activity. Variations in cut-offs may be due to differences in disease severity between the two populations or inter-rater variations in the use of the external gold measures.

Topical and oral bexarotene

Bexarotene is a retinoid that specifically binds retinoid X receptors and has numerous effects on cellular growth and differentiation. It is approved for the treatment of cutaneous T cell lymphoma both topically and systemically. Adverse effects include hyperlipidemia, central hypothyroidism, and neutropenia with bexarotene capsules, and an irritant dermatitis with bexarotene gel. With aggressive management of these potential side effects, bexarotene is an additional option in the armamentarium for management of cutaneous T cell lymphoma.

Everolimus for angiomyolipoma associated with tuberous sclerosis complex or sporadic lymphangioleiomyomatosis (EXIST-2): a multicentre, randomised, double-blind, placebo-controlled trial

BACKGROUND

Angiomyolipomas are slow-growing tumours associated with constitutive activation of mammalian target of rapamycin (mTOR), and are common in patients with tuberous sclerosis complex and sporadic lymphangioleiomyomatosis. The insidious growth of these tumours predisposes patients to serious complications including retroperitoneal haemorrhage and impaired renal function. Everolimus, a rapamycin derivative, inhibits the mTOR pathway by acting on the mTOR complex 1. We compared the angiomyolipoma response rate on everolimus with placebo in patients with tuberous sclerosis or sporadic lymphanioleiomyomatosis-associated angiomyolipomata.

METHODS

In this double-blind, placebo-controlled, phase 3 trial, patients aged 18 years or older with at least one angiomyolipoma 3 cm or larger in its longest diameter (defined by radiological assessment) and a definite diagnosis of tuberous sclerosis or sporadic lymphangioleiomyomatosis were randomly assigned, in a 2:1 fashion with the use of an interactive web response system, to receive oral everolimus 10 mg per day or placebo. The primary efficacy endpoint was the proportion of patients with confirmed angiomyolipoma response of at least a 50% reduction in total volume of target angiomyolipomas relative to baseline. This study is registered with ClinicalTrials.gov number NCT00790400.

RESULTS

118 patients (median age 31·0 years; IQR 18·0–61·0) from 24 centres in 11 countries were randomly assigned to receive everolimus (n=79) or placebo (n=39). At the data cutoff, double-blind treatment was ongoing for 98 patients; two main reasons for discontination were disease progression (nine placebo patients) followed by adverse events (two everolimus patients; four placebo patients). The angiomyolipoma response rate was 42% (33 of 79 [95% CI 31–53%]) for everolimus and 0% (0 of 39 [0–9%]) for placebo (response rate difference 42% [24–58%]; one-sided Cochran-Mantel-Haenszel test p<0·0001). The most common adverse events in the everolimus and placebo groups were stomatitis (48% [38 of 79], 8% [3 of 39], respectively), nasopharyngitis (24% [19 of 79] and 31% [12 of 39]), and acne-like skin lesions (22% [17 of 79] and 5% [2 of 39]).

INTERPRETATION

Everolimus reduced angiomyolipoma volume with an acceptable safety profile, suggesting it could be a potential treatment for angiomyolipomas associated with tuberous sclerosis.

FUNDING

Novartis Pharmaceuticals.

Emerging treatment options for early mycosis fungoides

Mycosis fungoides is a candidate for skin-directed therapies in its initial stages. In recent years, therapeutic options outside of the normal treatment recommendations such as topical imiquimod, topical tazarotene, topical methotrexate, excimer light sources, and photodynamic therapy have been published with variable results. These alternatives have been useful in cases of localized mycosis fungoides that do not respond to routine treatments; nevertheless, more studies on these methods are still needed. This article summarizes the literature and data that are known so far about these treatments.

Efficacy and safety of everolimus for subependymal giant cell astrocytomas associated with tuberous sclerosis complex (EXIST-1): a multicentre, randomised, placebo-controlled phase 3 trial

BACKGROUND

Tuberous sclerosis complex is a genetic disorder leading to constitutive activation of mammalian target of rapamycin (mTOR) and growth of benign tumours in several organs. In the brain, growth of subependymal giant cell astrocytomas can cause life-threatening symptoms--eg, hydrocephalus, requiring surgery. In an open-label, phase 1/2 study, the mTOR inhibitor everolimus substantially and significantly reduced the volume of subependymal giant cell astrocytomas. We assessed the efficacy and safety of everolimus in patients with subependymal giant cell astrocytomas associated with tuberous sclerosis complex.

METHODS

In this double-blind, placebo-controlled, phase 3 trial, patients (aged 0-65 years) in 24 centres in Australia, Belgium, Canada, Germany, the UK, Italy, the Netherlands, Poland, Russian Federation, and the USA were randomly assigned, with an interactive internet-response system, in a 2:1 ratio to oral everolimus 4·5 mg/m(2) per day (titrated to achieve blood trough concentrations of 5-15 ng/mL) or placebo. Eligible patients had a definite diagnosis of tuberous sclerosis complex and at least one lesion with a diameter of 1 cm or greater, and either serial growth of a subependymal giant cell astrocytoma, a new lesion of 1 cm or greater, or new or worsening hydrocephalus. The primary endpoint was the proportion of patients with confirmed response--ie, reduction in target volume of 50% or greater relative to baseline in subependymal giant cell astrocytomas. Analysis was by intention to treat. This study is registered with ClinicalTrials.gov, number NCT00789828.

FINDINGS

117 patients were randomly assigned to everolimus (n=78) or placebo (n=39). 27 (35%) patients in the everolimus group had at least 50% reduction in the volume of subependymal giant cell astrocytomas versus none in the placebo group (difference 35%, 95% CI 15-52; one-sided exact Cochran-Mantel-Haenszel test, p<0·0001). Adverse events were mostly grade 1 or 2; no patients discontinued treatment because of adverse events. The most common adverse events were mouth ulceration (25 [32%] in the everolimus group vs two [5%] in the placebo group), stomatitis (24 [31%] vs eight [21%]), convulsion (18 [23%] vs ten [26%]), and pyrexia (17 [22%] vs six [15%]).

INTERPRETATION

These results support the use of everolimus for subependymal giant cell astrocytomas associated with tuberous sclerosis. Additionally, everolimus might represent a disease-modifying treatment for other aspects of tuberous sclerosis.

FUNDING

Novartis Pharmaceuticals.

Topical chemotherapy in cutaneous T-cell lymphoma: positive results of a randomized, controlled, multicenter trial testing the efficacy and safety of a novel mechlorethamine, 0.02%, gel in mycosis fungoides

OBJECTIVE

To evaluate the efficacy and safety of a novel mechlorethamine hydrochloride, 0.02%, gel in mycosis fungoides. DESIGN Randomized, controlled, observer-blinded, multicenter trial comparing mechlorethamine, 0.02%, gel with mechlorethamine, 0.02%, compounded ointment. Mechlorethamine was applied once daily for up to 12 months. Tumor response and adverse events were assessed every month between months 1 and 6 and every 2 months between months 7 and 12. Serum drug levels were evaluated in a subset of patients.

SETTING

Academic medical or cancer centers.

PATIENTS

In total, 260 patients with stage IA to IIA mycosis fungoides who had not used topical mechlorethamine within 2 years and were naive to prior use of topical carmustine therapy.

MAIN OUTCOME MEASURES

Response rates of all the patients based on a primary clinical end point (Composite Assessment of Index Lesion Severity) and secondary clinical end points (Modified Severity-Weighted Assessment Tool and time-to-response analyses).

RESULTS

Response rates for mechlorethamine gel vs ointment were 58.5% vs 47.7% by the Composite Assessment of Index Lesion Severity and 46.9% vs 46.2% by the Modified Severity-Weighted Assessment Tool. By the Composite Assessment of Index Lesion Severity, the ratio of gel response rate to ointment response rate was 1.23 (95% CI, 0.97-1.55), which met the prespecified criterion for noninferiority. Time-to-response analyses demonstrated superiority of mechlorethamine gel to ointment (P< .01). No drug-related serious adverse events were seen. Approximately 20.3% of enrolled patients in the gel treatment arm and 17.3% of enrolled patients in the ointment treatment arm withdrew because of drug-related skin irritation. No systemic absorption of the study medication was detected.

CONCLUSION

The use of a novel mechlorethamine, 0.02%, gel in the treatment of patients with mycosis fungoides is effective and safe.

TRIAL REGISTRATION

clinicaltrials.gov Identifier:NCT00168064.

Panobinostat activity in both bexarotene-exposed and -naïve patients with refractory cutaneous T-cell lymphoma: results of a phase II trial

BACKGROUND

Panobinostat is a potent, oral pan-deacetylase inhibitor (pan-DACi) that increases the acetylation of proteins involved in multiple oncogenic pathways. Here, panobinostat is studied in bexarotene-exposed and -naïve patients with refractory cutaneous T-cell lymphoma (CTCL).

PATIENTS AND METHODS

Patients with CTCL subtypes mycosis fungoides and Sézary syndrome who received ⩾2 prior systemic therapy regimens received panobinostat (20mg) three times every week. The primary objective was overall response rate (ORR) as determined by a combined evaluation of skin disease and involvement of lymph node and viscera. Disease progression was defined as an unconfirmed, ⩾25% increase in modified Severity Weighted Assessment Tool (mSWAT) compared with nadir.

RESULTS

Seventy-nine bexarotene-exposed and 60 bexarotene-naïve patients were enrolled. Reductions in baseline mSWAT scores were observed in 103 patients (74.1%). The ORR was 17.3% in all patients in the primary analysis (15.2% and 20.0% in the bexarotene-exposed and -naïve groups, respectively). The median progression-free survival was 4.2 and 3.7 months in the bexarotene-exposed and -naïve groups, respectively. The median duration of response was 5.6 months in the bexarotene-exposed patients and was not reached at data cutoff in the bexarotene-naïve patients. Additional responses were observed when less-stringent progression criteria were used. The most common adverse events were thrombocytopenia, diarrhoea, fatigue and nausea. Thrombocytopenia and neutropenia were the only grade 3/4 adverse events in >5% of patients and were manageable.

CONCLUSION

Despite a very conservative definition of disease progression, panobinostat demonstrated activity with a manageable safety profile in bexarotene-exposed and -naïve CTCL patients. ClinicalTrials.gov Identifier: NCT00425555.

Cutaneous T-cell lymphomas: a review of new discoveries and treatments

Treatment regimens of patients with CTCL vary widely based on clinician preference and patient tolerance. Skin directed therapies are recommended for patients with early stage IA and IB MF, with combinations used in refractory cases. While no regimen has been proven to prolong survival in advanced stages, immunomodulatory regimens should be used initially to reduce the need for cytotoxic therapies. In more advanced stages of disease, treatment efforts should strive for palliation and improvement of quality of life. With many new therapies and strategies on the horizon, the future looks promising for CTCL patients. Unfortunately, other than allogeneic HCT, there are no potential curative therapies for CTCL. Clinical trials are currently underway to identify new therapies to improve quality of life for patients, and researchers are hard at work to identify novel pathways and genes for prognostication and as targets for therapies. Importantly, collaborative clinical trials to enhance rates of accrual need to be conducted, and improved interpretation of data via standardizing end points and response criteria should be an emphasis. Recently, the International Society for Cutaneous Lymphomas (ISCL), the United States Cutaneous Lymphoma Consortium (USCLC), and the Cutaneous Lymphoma Task Force of the European Organisation for Research and Treatment of Cancer (EORTC) met to develop consensus guidelines to facilitate collaboration on clinical trials. These proposed guidelines consist of: recommendations for standardizing general protocol design; a scoring system for assessing tumor burden in skin, lymph nodes, blood, and viscera; definition of response in skin, nodes, blood, and viscera; a composite global response score; and a definition of end points. Although these guidelines were generated by consensus panels, they have not been prospectively or retrospectively validated through analysis of large patient cohorts.

Management of cutaneous T cell lymphoma: new and emerging targets and treatment options

Cutaneous T cell lymphomas (CTCL) clinically and biologically represent a heterogeneous group of non-Hodgkin lymphomas, with mycosis fungoides and Sézary syndrome being the most common subtypes. Over the last decade, new immunological and molecular pathways have been identified that not only influence CTCL phenotype and growth, but also provide targets for therapies and prognostication. This review will focus on recent advances in the development of therapeutic agents, including bortezomib, the histone deacetylase inhibitors (vorinostat and romidepsin), and pralatrexate in CTCL.

Menus for managing patients with cutaneous T-cell lymphoma

In the management of patients with cutaneous T-cell lymphoma (CTCL), there are numerous distinct therapy options. Each of these therapies is discussed in terms of when to use it, what factors limit the success of the treatment, and what to expect. A menu is defined as a list of items from which to choose. The treatments for CTCL are presented in various menus where they are options for a particular goal in a particular setting of CTCL. The best recognized clinical scenarios of CTCL are those recognized by the staging system: limited patch plaque (T1), disseminated patch plaque (T2), erythroderma (T4), and tumor (T3). Each phase of the disease will have the menu of therapy options presented for a given goal of management.

Reliability and convergent validity of two outcome instruments for pemphigus

A major obstacle in performing multicenter controlled trials for pemphigus is the lack of a validated disease activity scoring system. Here, we assess the reliability and convergent validity of the PDAI (pemphigus disease area index). A group of 10 dermatologists scored 15 patients with pemphigus to estimate the inter- and intra-rater reliability of the PDAI and the recently described ABSIS (autoimmune bullous skin disorder intensity score) instrument. To assess convergent validity, these tools were also correlated with the Physician's Global Assessment (PGA). Reliability studies demonstrated an intra-class correlation coefficient (ICC) for inter-rater reliability of 0.76 (95% confirdence interval (CI)=0.61-0.91) for the PDAI and 0.77 (0.63-0.91) for the ABSIS. The tools differed most in reliability of assessing skin activity, with an ICC of 0.39 (0.17-0.60) for the ABSIS and 0.86 (0.76-0.95) for the PDAI. Intra-rater test-retest reliability demonstrated an ICC of 0.98 (0.96-1.0) for the PDAI and 0.80 (0.65-0.96) for the ABSIS. The PDAI also correlated more closely with the PGA. We conclude that the PDAI is more reproducible and correlates better with physician impression of extent. Subset analysis suggests that for this population of mild-to-moderate disease activity, the PDAI captures more variability in cutaneous disease than the ABSIS.

CD8+ cutaneous T-cell lymphoma successfully treated with bexarotene: a case report and review of the literature

CD8+ cutaneous T-cell lymphoma (CTCL) is a relatively rare subset of the non-Hodgkins lymphomas. Bexarotene has been FDA-approved for the treatment of CTCL, but previous studies have been conducted on CD4+ CTL and there have been no reports about its use in CD8+ CTCL. Herein, we report on a patient whose CD8+ CTCL completely responded to treatment with bexarotene.

Mycosis fungoides

Mycosis fungoides (MF) constitutes the most frequent cutaneous T-cell lymphoma. Sezary syndrome is considered by some authors to be an erythrodermic leukemic variant of MF, but is classified separately in the new WHO-EORT classification of cutaneous lymphomas. MF usually occurs in old adults with a 2:1 male to female ratio. Its prognosis is variable and strongly conditioned by the extent and type of skin involvement and presence of extracutaneous disease. Patients with stage IA-disease have an excellent prognosis with an overall long-term life expectancy that is similar to an age-, sex-, and race-matched control population. Almost all patients with stage IA MF will die from causes other than MF, with a median survival >33 years. Only 9% of these patients will progress to more extended disease. Patients with stage IB or IIA have a median survival greater than 11 years. These patients with T2 disease have a likelihood of disease progression of 24% and nearly 20% die of MF. Subgroups with stage IB or IIA have similar prognosis. Patients with cutaneous tumors or generalized erythroderma have a median survival of 3 and 4.5 years, respectively. The majority of these patients will die of MF. Extracutaneous dissemination is observed in less than 10% of patients with patch or plaque disease and in 30-40% of patients with tumors or generalized erythrodermatous involvement. Extracutaneous involvement is directly correlated to the extent of cutaneous disease. The most commonly involved organs are lung, spleen, liver, and gastrointestinal tract. Patients with extracutaneous disease at presentation involving either lymph nodes or viscera have a median survival of <1.5 years. Patients with plaque-type or erythrodermic MF may develop cutaneous tumors with large cell histology, often expressing CD30, which share a common clonal origin as observed in their preexisting MF and are associated with a less favourable outcome.

Subchronic toxicity and toxicogenomic evaluation of tamoxifen citrate + bexarotene in female rats

Tamoxifen (TAM) is a nonsteroidal antiestrogen that prevents estrogen receptor-positive breast cancer in rodents and humans. Bexarotene (BEX), a selective agonist for retinoid X receptors, inhibits mammary carcinogenesis in rodents. The present study was conducted to support the preclinical development of TAM (tamoxifen citrate) + BEX for use in breast cancer chemoprevention, and to investigate the influence of these agents on hepatic gene expression. Female CD rats (20 per group) received daily oral (gavage) exposure to TAM (0 or 60 microg/kg/day) and/or BEX (0, 5, 15, or 45 mg/kg/day) for a minimum of 90 days. BEX induced mild, dose-related anemia and dose-related increases in serum alkaline phosphatase, cholesterol, triglycerides, and calcium levels, and increased platelet counts. TAM had no biologically significant effect on any clinical pathology parameter and did not alter the effects of BEX on these endpoints. Microscopic alterations induced by BEX included epidermal hyperplasia, hyperkeratosis (stomach), and cytoplasmic clearing (liver). Microscopic changes in TAM-treated rats were limited to mucous cell hypertrophy in the cervix and vagina. The toxicity of administration of the combination of TAM + BEX can generally be predicted on the basis of the toxicity of each drug as a single agent. BEX induced dose-related alterations in the expression of several genes involved in steroid, drug, and/or fatty acid metabolism; TAM did not alter these effects of BEX. Differential expression of genes involved in drug and lipid metabolism may underlie the observed effects of BEX on cholesterol and triglyceride levels and its effects on liver histology.

Management of refractory early-stage cutaneous T-cell lymphoma

Cutaneous T-cell lymphoma (CTCL) is a heterogeneous group of non-Hodgkin's lymphomas that manifest primarily in the skin. Mycosis fungoides is recognized as the most common type of CTCL. Patients with early-stage CTCL usually have a benign and chronic disease course. However, although there is a wide array of therapeutic options for early-stage CTCL, not all patients respond to these individual therapies, resulting in refractory cutaneous disease over time. Refractory early-stage CTCL poses an important therapeutic challenge, as one of the principal treatment goals is to keep the disease confined to the skin, thereby preventing disease progression. Much of the focus of current research has been on the evaluation of already available skin-directed therapies and biologic response modifiers and combination regimens thereof, such as the combination of psoralen and UVA (PUVA) with interferon-alpha or retinoids. Recent novel developments include oral bexarotene, a retinoid X receptor-selective retinoid that has activity in all stages of CTCL and has been shown to be effective in patients with refractory early-stage disease as well as advanced-stage disease. Likewise, the topical gel formulation of bexarotene has proved to be an important therapeutic option in patients with refractory or relapsed lesions. Oral bexarotene and topical bexarotene have been approved by the US FDA for the treatment of refractory CTCL. Systemic chemotherapy is typically reserved for advanced-stage CTCL and is usually not recommended for early-stage, skin-limited disease. However, recent exploratory studies indicate that low-dose methotrexate may represent an overall well tolerated therapy in a subset of patients with refractory early-stage CTCL, as may pegylated liposomal doxorubicin, which is currently being investigated in this specific clinical setting. Another recently FDA-approved therapy is the interleukin-2 fusion toxin denileukin diftitox, which is now well established to play a role in the treatment of refractory CTCL, including early-stage extensive plaque disease. The value of other agents, such as topical tazarotene, topical methotrexate, and topical imiquimod, and of novel immunomodulatory approaches including monoclonal antibodies, still needs to be assessed for refractory early-stage CTCL.

Treatment of cutaneous T-cell lymphoma with retinoids

Retinoids are biologic regulators of differentiation, proliferation, apoptosis, and immune response. Retinoids (all-trans retinoic acid, 13-cis-retinoic acid, and the synthetic analogs isotretinoin, etretinate, and acitretin) have been used for years as monotherapy and/or in combination for treatment of cutaneous T-cell lymphomas (CTCL). Orally administered bexarotene, the first synthetic highly selective retinoid X receptor retinoid to be approved by the Food and Drug Administration for CTCL, was shown to be active against the cutaneous manifestations of all stages of CTCL. The topical gel formulation was also effective for early cutaneous manifestations of CTCL or as an adjunct to systemic or phototherapy. Use of retinoids in future long-term clinical trials and their eventual application in CTCL regiments will require strategies to decrease the side effects of existing retinoids, identify novel receptor subtype-selective retinoids with better therapeutic index, and explore biologically based synergistic combination therapies with other active agents.

Bexarotene in the treatment of cutaneous T-cell lymphoma

Primary cutaneous T-cell lymphomas encompass a spectrum of non-Hodgkin's lymphomas that are characterised by clonal proliferation of skin-homing malignant T lymphocytes. Mycosis fungoides and the leukaemic variant Sézary syndrome, collectively referred to as cutaneous T-cell lymphomas, are the most common entities. No curative therapy exists and patients ultimately develop advanced or relapsed disease that is refractory to standard treatment options. Therefore, there is a great need for the development of novel emerging therapies. Bexarotene is the first synthetic nuclear retinoid X receptor-selective retinoid approved by the FDA for the treatment of refractory cutaneous T-cell lymphoma in all stages, as both an oral capsule and a topical gel formulation. Bexarotene was found to induce apoptosis in a variety of preclinical in vitro and in vivo models including cutaneous T-cell lymphoma cells, and has shown efficacy in two multi-centre, open-label Phase II - III clinical trials for early and advanced stages of cutaneous T-cell lymphoma in patients who have failed or were refractory to standard therapies. New insights into the immunomodulatory function of bexarotene have indicated opportunities for combined treatment with IFN-alpha, denileukin diftitox or phototherapy. This article reviews the biological properties, pharmacokinetics, clinical efficacy, safety and role of bexarotene in the treatment of cutaneous T-cell lymphoma.

Emerging drugs in cutaneous T-cell lymphomas

Cutaneous T-cell lymphomas are a heterogeneous group of rare lympho-proliferative disorders. In most cases, they are characterised by the accumulation of clonal CD4+ lymphocytes in the skin. Extracutaneous involvement is present in late stages only. Unfortunately, only few drugs are registered for these disfiguring diseases. Skin-directed therapies using topical formulations are the preferred first-line modalities for cutaneous lesions in early stages. In this field there are interesting developments using topical retinoids and gene therapy products, such as adeno-IFN-gamma. Systemic treatment uses biologicals, such as fusion molecules, monoclonal antibodies and immune response modifiers (IFNs, retinoids), and well-tolerated antiproliferative drugs, such as histone deacetylase inhibitors or liposomal doxorubicin.

Combination Treatment Modalities in Cutaneous T-Cell Lymphoma (CTCL)

A wide variety of cutaneous T-cell lymphoma therapies are now used in clinical practice. Treatment options include phototherapy, radiation, topical therapy, systemic mono-chemotherapy, combination chemotherapy, and combined modalities. Many patients fail or develop resistance to monotherapy, resulting in a need for combined treatment modalities to improve therapeutic results in terms of quality of life and duration of response. Recently, bexarotene, a selective antagonist of the retinoid X receptor, has been approved in the treatment of patients with cutaneous T-cell lymphoma. Bexarotene offers new opportunities for combination treatment strategies because of its novel and unique mechanism of action. In this article we review the rationale and examine key published evidence on combining these new treatment modalities.

Therapeutic Advances in Cutaneous T-Cell Lymphoma (CTCL): From Retinoids to Rexinoids

Retinoids comprise a family of polyisoprenoid lipids that include vitamin A (retinol) and its various natural and synthetic analogues. Retinoids are compounds with multiple actions. They are involved in the control of cell proliferation, cell differentiation, and embryonic development. Each retinoid has its own profile of pharmacologic properties that determines its usefulness in clinical dermatology or oncology. Although numerous synthetic retinoids have been synthesized, their biological activities are usually associated with clinical disadvantages such as toxicity and teratogenicity. Retinoids that bind to both the retinoic acid receptor and retinoid X receptor subtypes have shown clinical activity in hematologic malignancies and can mediate genes associated with both growth and differentiation. Retinoid X receptor-specific rexinoids have also shown efficacy in the treatment of cutaneous T-cell lymphomas, but their exact mechanism of action is unclear. This article summarizes the clinical relevance of both groups of compounds in this important patient population.

Therapy for mycosis fungoides

Treatment of mycosis fungoides (MF) is indicated to reduce symptoms, improve clinical appearance, prevent secondary complications, and prevent progression of disease, all of which may have an impact on survival. Treatment of MF includes topical and systemic therapies, which can be administered alone or in combination. Psoralen and ultraviolet A radiation is effective in early-stage MF, inducing complete remissions in most patients. Psoralen and ultraviolet A radiation may also be combined with low doses of interferon (IFN)-alpha to treat stage I/II disease. However, early aggressive therapy with radiation and chemotherapy does not improve the prognosis. Local radiotherapy or total skin electron beam irradiation has been used with success to control advanced skin disease. Extracorporeal photopheresis may also be used successfully, but it is not generally available. Once the disease becomes refractory to topical therapy, IFN-alpha single-agent or combination chemotherapy may be administered, but the duration of response is often less than 1 year and ultimately all patients will relapse and become refractory. Among chemotherapeutic agents, pentostatin, gemcitabine, and liposomal doxorubicin seem to be particularly effective. Response rates after combined modality therapy with total skin electron beam irradiation and chemotherapy/IFN-alpha appear similar to response rates of chemotherapy alone. Therefore, there is a great need for the further development of novel emerging treatment modalities, such as retinoids (ie, bexarotene) and immunotherapeutic agents (ie, cytokines, tumor vaccines, and monoclonal antibodies), all of which appear to have significant therapeutic potential in patients with MF. Biologically based therapies may reduce the need for genotoxic therapies, such as cytostatics and radiotherapy.