Psoralen plus ultraviolet A ± interferon-α treatment resistance in mycosis fungoides: the role of tumour microenvironment, nuclear transcription factor-κB and T-cell receptor pathways

The efficacy of long-term psoralen plus ultraviolet A and low-dose interferon-a combination therapy in mycosis fungoides: A literature review

BACKGROUND/PURPOSE

Interferon (IFN)-a is often used in combination with psoralen plus ultraviolet A (PUVA) in patients with mycosis fungoides (MF) refractory to skin-targeted therapies in early or advanced stages. The main objective is to evaluate the effectiveness of combined PUVA and low-dose IFN-α-2a therapy in patients with early- and advanced-stage MF.

METHODS

Sixty-eight patients who received a combination of PUVA twice or thrice a week and INF-a 3 MU thrice a week for at least 3 months were reviewed retrospectively. The treatment response was evaluated as complete remission (CR), partial remission, stable disease, or progression.

RESULTS

At the initiation, the majority of patients (66.2%) had early-stage disease. In 27.9% of cases, this was the initial treatment administered following the diagnosis of MF. The median duration of combination therapy was 11 months. Complete remission was achieved in 45.6% of the patients with an overall response rate of 60.3%. The mean duration of response was 5 months. Complete remission was statistically significantly higher in early-stage patients (p < .05). No statistically significant correlation was observed between CR and gender, histopathological features, or laboratory parameters. In patients with CR, 80% experienced relapse, significantly higher in early-stage patients (p < .05). However, there was no significant difference in disease-free survival between early and advanced stages (p > .05).

CONCLUSIONS

The study results indicated that PUVA + low-dose INF-a combination therapy was more effective in the early stage than in the advanced stage. Additionally, there was a high relapse rate after the cessation of treatment in patients who achieved CR.

Phototherapy Restores Deficient Type I IFN Production and Enhances Antitumor Responses in Mycosis Fungoides

Transcriptional profiling demonstrated markedly reduced type I IFN gene expression in untreated mycosis fungoides (MF) skin lesions compared with that in healthy skin. Type I IFN expression in MF correlated with antigen-presenting cell-associated IRF5 before psoralen plus UVA therapy and epithelial ULBP2 after therapy, suggesting an enhancement of epithelial type I IFN. Immunostains confirmed reduced baseline type I IFN production in MF and increased levels after psoralen plus UVA treatment in responding patients. Effective tumor clearance was associated with increased type I IFN expression, enhanced recruitment of CD8+ T cells into skin lesions, and expression of genes associated with antigen-specific T-cell activation. IFNk, a keratinocyte-derived inducer of type I IFNs, was increased by psoralen plus UVA therapy and expression correlated with upregulation of other type I IFNs. In vitro, deletion of keratinocyte IFNk decreased baseline and UVA-induced expression of type I IFN and IFN response genes. In summary, we find a baseline deficit in type I IFN production in MF that is restored by psoralen plus UVA therapy and correlates with enhanced antitumor responses. This may explain why MF generally develops in sun-protected skin and suggests that drugs that increase epithelial type I IFNs, including topical MEK and EGFR inhibitors, may be effective therapies for MF.

Harnessing the immune system in the treatment of cutaneous T cell lymphomas

Cutaneous T cell lymphomas are a rare subset of non-Hodgkin's lymphomas with predilection for the skin with immunosuppressive effects that drive morbidity and mortality. We are now appreciating that suppression of the immune system is an important step in the progression of disease. It should come as no surprise that therapies historically and currently being used to treat these cancers have immune modulating functions that impact disease outcomes. By understanding the immune effects of our therapies, we may better develop new agents that target the immune system and improve combinatorial treatment strategies to limit morbidity and mortality of these cancers. The immune modulating effect of therapeutic drugs in use and under development for cutaneous T cell lymphomas will be reviewed.

Phototherapy combined with systemic agents for mycosis fungoides

The choice of tactics for managing a patient with mycosis fungoides is determined by the stage of the disease. In the early stages of mycosis fungoides, a treatment approach using external therapy and various ultraviolet irradiation spectra (UVB-311 nm and PUVA therapy) is preferable. With insufficient efficiency and / or short remissions in some patients, it is possible to use combined methods in the early stages: PUVA therapy or UVB-311 nm therapy. in combination with systemic therapy, including interferon (IFN) 2b preparations, methotrexate and retinoids. The results of original studies demonstrate an increase in the overall response rate when combining PUVA therapy with IFN- or retinoids in patients with stages IB-IIB. The effectiveness of combined treatment regimens using UVB-311 nm remains insufficiently studied.

Interventions for mycosis fungoides

BACKGROUND

Mycosis fungoides (MF) is the most common type of cutaneous T-cell lymphoma, a malignant, chronic disease initially affecting the skin. Several therapies are available, which may induce clinical remission for a time. This is an update of a Cochrane Review first published in 2012: we wanted to assess new trials, some of which investigated new interventions.

OBJECTIVES

To assess the effects of interventions for MF in all stages of the disease.

SEARCH METHODS

We updated our searches of the following databases to May 2019: the Cochrane Skin Specialised Register, CENTRAL, MEDLINE, Embase, and LILACS. We searched 2 trials registries for additional references. For adverse event outcomes, we undertook separate searches in MEDLINE in April, July and November 2017.

SELECTION CRITERIA

Randomised controlled trials (RCTs) of local or systemic interventions for MF in adults with any stage of the disease compared with either another local or systemic intervention or with placebo.

DATA COLLECTION AND ANALYSIS

We used standard methodological procedures expected by Cochrane. The primary outcomes were improvement in health-related quality of life as defined by participants, and common adverse effects of the treatments. Key secondary outcomes were complete response (CR), defined as complete disappearance of all clinical evidence of disease, and objective response rate (ORR), defined as proportion of patients with a partial or complete response. We used GRADE to assess the certainty of evidence and considered comparisons of psoralen plus ultraviolet A (PUVA) light treatment as most important because this is first-line treatment for MF in most guidelines.

MAIN RESULTS

This review includes 20 RCTs (1369 participants) covering a wide range of interventions. The following were assessed as either treatments or comparators: imiquimod, peldesine, hypericin, mechlorethamine, nitrogen mustard and intralesional injections of interferon-α (IFN-α) (topical applications); PUVA, extracorporeal photopheresis (ECP: photochemotherapy), and visible light (light applications); acitretin, bexarotene, lenalidomide, methotrexate and vorinostat (oral agents); brentuximab vedotin; denileukin diftitox; mogamulizumab; chemotherapy with cyclophosphamide, doxorubicin, etoposide, and vincristine; a combination of chemotherapy with electron beam radiation; subcutaneous injection of IFN-α; and intramuscular injections of active transfer factor (parenteral systemics). Thirteen trials used an active comparator, five were placebo-controlled, and two compared an active operator to observation only. In 14 trials, participants had MF in clinical stages IA to IIB. All participants were treated in secondary and tertiary care settings, mainly in Europe, North America or Australia. Trials recruited both men and women, with more male participants overall. Trial duration varied from four weeks to 12 months, with one longer-term study lasting more than six years. We judged 16 trials as at high risk of bias in at least one domain, most commonly performance bias (blinding of participants and investigators), attrition bias and reporting bias. None of our key comparisons measured quality of life, and the two studies that did presented no usable data. Eighteen studies reported common adverse effects of the treatments. Adverse effects ranged from mild symptoms to lethal complications depending upon the treatment type. More aggressive treatments like systemic chemotherapy generally resulted in more severe adverse effects. In the included studies, CR rates ranged from 0% to 83% (median 31%), and ORR ranged from 0% to 88% (median 47%). Five trials assessed PUVA treatment, alone or combined, summarised below. There may be little to no difference between intralesional IFN-α and PUVA compared with PUVA alone for 24 to 52 weeks in CR (risk ratio (RR) 1.07, 95% confidence interval (CI) 0.87 to 1.31; 2 trials; 122 participants; low-certainty evidence). Common adverse events and ORR were not measured. One small cross-over trial found once-monthly ECP for six months may be less effective than twice-weekly PUVA for three months, reporting CR in two of eight participants and ORR in six of eight participants after PUVA, compared with no CR or ORR after ECP (very low-certainty evidence). Some participants reported mild nausea after PUVA but no numerical data were given. One participant in the ECP group withdrew due to hypotension. However, we are unsure of the results due to very low-certainty evidence. One trial comparing bexarotene plus PUVA versus PUVA alone for up to 16 weeks reported one case of photosensitivity in the bexarotene plus PUVA group compared to none in the PUVA-alone group (87 participants; low-certainty evidence). There may be little to no difference between bexarotene plus PUVA and PUVA alone in CR (RR 1.41, 95% CI 0.71 to 2.80) and ORR (RR 0.94, 95% CI 0.61 to 1.44) (93 participants; low-certainty evidence). One trial comparing subcutaneous IFN-α injections combined with either acitretin or PUVA for up to 48 weeks or until CR indicated there may be little to no difference in the common IFN-α adverse effect of flu-like symptoms (RR 1.32, 95% CI 0.92 to 1.88; 82 participants). There may be lower CR with IFN-α and acitretin compared with IFN-α and PUVA (RR 0.54, 95% CI 0.35 to 0.84; 82 participants) (both outcomes: low-certainty evidence). This trial did not measure ORR. One trial comparing PUVA maintenance treatment to no maintenance treatment, in participants who had already had CR, did report common adverse effects. However, the distribution was not evaluable. CR and OR were not assessable. The range of treatment options meant that rare adverse effects consequently occurred in a variety of organs.

AUTHORS' CONCLUSIONS

​​There is a lack of high-certainty evidence to support decision making in the treatment of MF. Because of substantial heterogeneity in design, missing data, small sample sizes, and low methodological quality, the comparative safety and efficacy of these interventions cannot be reliably established on the basis of the included RCTs. PUVA is commonly recommended as first-line treatment for MF, and we did not find evidence to challenge this recommendation. There was an absence of evidence to support the use of intralesional IFN-α or bexarotene in people receiving PUVA and an absence of evidence to support the use of acitretin or ECP for treating MF. Future trials should compare the safety and efficacy of treatments to PUVA, as the current standard of care, and should measure quality of life and common adverse effects.

Cost of early-stage mycosis fungoides treatments in Spain

AIM

To identify the most common therapeutic options for the treatment of early-stage mycosis fungoides in Spain, quantify their associated healthcare resource use and costs.

METHODS

After reviewing the literature, a panel of 6 Spanish clinical dermatologists validated the treatments and healthcare resource use through a structured questionnaire. Individual responses were collected, analyzed and presented into a face-to-face meeting in order to reach a consensus. Cost categories considered were: drug acquisition and administration, photo/radiotherapy session and maintenance, clinical follow-up visits and laboratory tests. Costs were expressed in euros from 2018. The Spanish National Health System perspective was considered, taking into account direct health costs and time horizons of 1, 3 and 6 months.

RESULTS

Costs for the skin-directed treatments (SDT) assessed at 1, 3 and 6 months, were: Topical carmustine [€6,593.36, €19,780.09 and €27,592.78]; Phototherapy with psoralens and ultraviolet A light (PUVA) [€1,098.68, €2,999.99 and €3,187.60]; Narrow-band ultraviolet B phototherapy [€1,657.47, €4,842.10 and €4,842.10]; Total skin electron beam therapy (TSEBT) [€6,796.45, €7,913.34 and €7,913.34]. Cost for topical corticosteroids, being considered an adjuvant option, were €17.16, €51.49 and €102.97. Costs for the assessed systemic treatments alone or in combination with SDT at 1, 3 and 6 months, were: Systemic retinoids [€2,026.03, €5,206.63 and €7,426.42]; Systemic retinoids + PUVA phototherapy [€3,066.50, €8,271.26 and €10,046.58]; Interferon alfa + PUVA phototherapy [€1,541.09, €5,167.57 and €6,404.55].

CONCLUSION

According to the Spanish clinical practice, phototherapies in monotherapy were the treatments with the lowest associated costs regardless of the time horizon considered. TSEBT turned out as the treatment with the highest associated costs when considering 1 month. However, while considering 3 and 6 months the treatment with the highest associated costs was topical carmustine. The results of this analysis may provide critical information to measure the disease burden, to detect unmet medical needs and to advocate towards better treatments for this rare disease.

The Use of Interferons in the Treatment of Cutaneous T-Cell Lymphoma

Interferons are polypeptides that naturally occur in the human body as a part of the innate immune response. By harnessing these immunomodulatory functions, synthetic interferons have shown efficacy in combating various diseases including cutaneous T-cell lymphoma. This article closely examines the qualities of interferon alfa and interferon gamma and the evidence behind their use in the 2 most common types of cutaneous T-cell lymphomas, namely, mycosis fungoides and Sézary syndrome.

Systematic review of combination therapies for mycosis fungoides

BACKGROUND

A variety of therapeutic options are available for mycosis fungoides, the most prevalent subtype of cutaneous T cell lymphomas, but thus far, no regimen has been proven to be curative. A combination of treatments is a well-established strategy to increase the therapeutic efficacy. However, data from clinical trials analyzing such combinations for the treatment of mycosis fungoides are scarce.

OBJECTIVE

To analyze the available evidence on combination therapies with emphasis on the combination of psoralen with UVA phototherapy (PUVA), interferon-alpha and bexarotene with another treatment.

METHODS

Systematic literature review of the databases Embase, Cochrane, Medline, and Medline in Process.

RESULTS

Combination of PUVA with interferon-alpha or retinoids did not result in an increased overall response rate. Addition of methotrexate but not retinoids to interferon-alpha may increase the overall response rate. Bexarotene was investigated in one trial each with vorinostat, methotrexate or gemcitabine, whereby only methotrexate possibly enhanced the effect of bexarotene.

CONCLUSION

For mycosis fungoides, no combination treatment has been demonstrated to be superior to monotherapy. Based on our analysis, we conclude that in certain clinical situations, patients may benefit from a combination of PUVA with interferon-alpha or a retinoid or a combination of the latter two. Furthermore, patients in advanced stages may benefit from the combination of methotrexate and interferon-alpha or bexarotene. Finally, the combination of bexarotene with either vorinostat or gemcitabine did not increase the overall response rate but resulted in more pronounced side effects and cannot be recommended.

Proteasome inhibition as a novel mechanism of the proapoptotic activity of γ-secretase inhibitor I in cutaneous T-cell lymphoma

BACKGROUND

We have previously discovered that Notch1 is expressed on malignant T cells in cutaneous T-cell lymphoma (CTCL), and is required for survival of CTCL cell lines. Notch can be inhibited by γ-secretase inhibitors (GSIs), which differ widely in their ability to induce apoptosis in CTCL.

OBJECTIVES

To investigate whether GSI-I, in addition to inhibiting Notch, induces apoptosis in CTCL by proteasome inhibition, as GSI-I is very potent and has structural similarity to the proteasome inhibitor MG-132.

METHODS

Cell lines derived from CTCL (MyLa, SeAx, JK, Mac1 and Mac2a) were treated with GSI-I and two other proteasome inhibitors (MG-132 and bortezomib). The effects on cell viability, apoptosis and proteasome activity were measured, as was the impact on the prosurvival, nuclear factor κB (NF-κB) pathway.

RESULTS

In CTCL, GSI-I had proteasome-blocking activity with a potency comparable to the proteasome inhibitors MG-132 and bortezomib. Proteasome inhibition was the main mechanism responsible for GSI-I-induced cell death, as tiron, a compound known to reverse the effect of MG-132, restored proteasome activity and largely abrogated the cytotoxic effect of GSI-I. Although inactivation of NF-κB is an important mechanism of action for proteasome inhibitors, we demonstrated an apparent activation of NF-κB. Furthermore, we showed that while the tumour suppressor protein p53 was induced during proteasome inhibition, it was dispensable for CTCL apoptosis, as both SeAx cells, which harbour p53 mutations that attenuate the apoptotic capacity, and HuT-78 cells, which have a deleted p53 gene, demonstrated potent apoptotic response.

CONCLUSIONS

GSI-I represents an interesting drug with a dual mechanism of action comprising inhibition of both Notch and the proteasome.

Interventions for mycosis fungoides

BACKGROUND

Mycosis fungoides is the most common type of cutaneous T-cell lymphoma, a malignant, chronic disease initially affecting the skin. Several therapies are available, which may induce clinical remission for a time.

OBJECTIVES

To assess the effects of interventions for mycosis fungoides in all stages of the disease.

SEARCH METHODS

We searched the following databases up to January 2011: the Cochrane Skin Group Specialised Register, CENTRAL in The Cochrane Library, MEDLINE (from 2005), EMBASE (from 2010), and LILACS (from 1982). We also checked reference lists of included studies for further references to relevant RCTs. We searched online trials registries for further references to unpublished trials and undertook a separate search for adverse effects of interventions for mycosis fungoides in non-RCTs in MEDLINE in May 2011.

SELECTION CRITERIA

Randomised controlled trials (RCTs) of interventions for mycosis fungoides in people with any stage of the disease. At least 90% of participants in the trials must have been diagnosed with mycosis fungoides (Alibert-Bazin-type).

DATA COLLECTION AND ANALYSIS

Two authors independently assessed eligibility and methodological quality for each study and carried out data extraction. We resolved any disagreement by discussion. Primary outcomes were the impact on quality of life and the safety of interventions. When available, we reported on our secondary outcomes, which were the improvement or clearance of skin lesions, disease-free intervals, survival rates, relapse rates, and rare adverse effects. When possible, we combined homogeneous studies for meta-analysis. We used The Cochrane Collaboration's 'Risk of bias' tool to assess the internal validity of all included studies in six different domains.

MAIN RESULTS

The review included 14 RCTs involving 675 participants, covering a wide range of interventions. Eleven of the included trials assessed participants in clinical stages IA to IIB only (please see Table 1 for definitions of these stages).Internal validity was considerably low in studies with a high or unclear risk of bias. The main reasons for this were low methodological quality or missing data, even after we contacted the study authors, and a mean dropout rate of 26% (0% to 72%). Study size was generally small with a minimum of 4 and a maximum of 103 participants. Only one study provided a long enough follow-up for reliable survival analysis.Included studies assessed topical treatments, such as imiquimod, peldesine, hypericin, nitrogen mustard, as well as intralesional injections of interferon-α (IFN-α). The light therapies investigated included psoralen plus ultraviolet A light (PUVA), extracorporeal photopheresis (photochemotherapy), and visible light. Oral treatments included acitretin, bexarotene, and methotrexate. Treatment with parenteral systemic agents consisted of denileukin diftitox; a combination of chemotherapy and electron beam radiation; and intramuscular injections of active transfer factor. Nine studies evaluated therapies by using an active comparator; five were placebo-controlled RCTs.Twelve studies reported on common adverse effects, while only two assessed quality of life. None of these studies compared the health-related quality of life of participants undergoing different treatments. Most of the reported adverse effects were attributed to the interventions. Systemic treatments, and here in particular a combined therapeutic regimen of chemotherapy and electron beam, bexarotene, or denileukin diftitox, showed more adverse effects than topical or skin-directed treatments.In the included studies, clearance rates ranged from 0% to 83%, and improvement ranged from 0% to 88%. The meta-analysis combining the results of 2 trials comparing the effect of IFN-α and PUVA versus PUVA alone showed no significant difference in the relative risk of clearance: 1.07 (95% confidence interval 0.87 to 1.31). None of the included studies demonstrated a significant increase in disease-free intervals, relapse, or overall survival.

AUTHORS' CONCLUSIONS

This review identified trial evidence for a range of different topical and systemic interventions for mycosis fungoides. Because of substantial heterogeneity in design, small sample sizes, and low methodological quality, the comparative safety and efficacy of these interventions cannot be established on the basis of the included RCTs. Taking into account the possible serious adverse effects and the limited availability of efficacy data, topical and skin-directed treatments are recommended first, especially in the early stages of disease. More aggressive therapeutic regimens may show improvement or clearance of lesions, but they also result in more adverse effects; therefore, they are to be considered with caution. Larger studies with comparable, clearly-defined end points for all stages of mycosis fungoides, and a focus on safety, quality of life, and duration of remission as part of the outcome measures, are necessary.

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.

Evolving insights in the pathogenesis and therapy of cutaneous T-cell lymphoma (mycosis fungoides and Sezary syndrome)

Cutaneous T-cell lymphomas (CTCL) are a heterogeneous group of malignancies derived from skin-homing T cells. The most common forms of CTCL are Mycosis Fungoides (MF) and Sezary Syndrome (SS). Accurate diagnosis remains a challenge due to the heterogeneity of presentation and the lack of highly characteristic immunophenotypical and genetic markers. Over the past decade molecular studies have improved our understanding of the biology of CTCL. The identification of gene expression differences between normal and malignant T-cells has led to promising new diagnostic and prognostic biomarkers that now need validation to be incorporated into clinical practice. These biomarkers may also provide insight into the mechanism of development of CTCL. Additionally, treatment options have expanded with the approval of new agents, such as histone deacetylase inhibitors. A better understanding of the cell biology, immunology and genetics underlying the development and progression of CTCL will allow the design of more rational treatment strategies for these malignancies. This review summarizes the clinical epidemiology, staging and natural history of MF and SS; discusses the immunopathogenesis of MF and the functional role of the malignant T-cells; and reviews the latest advances in MF and SS treatment.

Drug-loaded, bivalent-bottle-brush polymers by graft-through ROMP

Graft-through ring-opening metathesis polymerization (ROMP) using ruthenium N-heterocyclic carbene catalysts has enabled the synthesis of bottle-brush polymers with unprecedented ease and control. Here we report the first bivalent-brush polymers; these materials were prepared by graft-through ROMP of drug-loaded polyethylene-glycol (PEG) based macromonomers (MMs). Anticancer drugs doxorubicin (DOX) and camptothecin (CT) were attached to a norbornene-alkyne-PEG MM via a photocleavable linker. ROMP of either or both drug-loaded MMs generated brush homo- and co-polymers with low polydispersities and defined molecular weights. Release of free DOX and CT from these materials was initiated by exposure to 365 nm light. All of the CT and DOX polymers were at least 10-fold more toxic to human cancer cells after photoinitiated drug release while a copolymer carrying both CT and DOX displayed 30-fold increased toxicity upon irradiation. Graft-through ROMP of drug-loaded macromonomers provides a general method for the systematic study of structure-function relationships for stimuli-responsive polymers in biological systems.

NF-kappaB activation mediates resistance to IFN beta in MLL-rearranged acute lymphoblastic leukemia

Acute lymphoblastic leukemia (ALL) harboring the t(4;11) translocation is associated with a very poor prognosis; innovative treatment strategies are required to improve the current 5-year survival rate of 30-40%. Interferon beta (IFN beta) has shown promise in the treatment of both solid and hematologic malignancies, although the short half-life and toxicity associated with high doses have limited its clinical utility. To overcome these limitations, we investigated the effect of continuous, gene transfer-mediated delivery of IFN beta using adeno-associated virus (AAV)-mediated expression, on ALL cells with the t(4;11) translocation. We found that this method of IFN beta delivery resulted in complete remission of leukemia in a murine model. However, leukemic cells eventually became resistant to IFN beta and relapse was observed. Activation of NF-kappaB was identified as a mechanism for IFN beta resistance, and inhibition of NF-kappaB activity in resistant cells sensitized cells to IFN beta. IFN beta combined with agents that inhibit NF-kappaB could have therapeutic potential in the treatment of children with mixed lineage leukemia subtype ALL.

Vorinostat interferes with the signaling transduction pathway of T-cell receptor and synergizes with phosphoinositide-3 kinase inhibitors in cutaneous T-cell lymphoma

BACKGROUND

Vorinostat (suberoylanilide hydroxamic acid, SAHA), an inhibitor of class I and II histone deacetylases, has been approved for the treatment of cutaneous T-cell lymphoma. In spite of emerging information on the effect of vorinostat in many types of cancer, little is yet known about this drug's mechanism of action, which is essential for its proper use in combination therapy. We investigated alterations in gene expression profile over time in cutaneous T-cell lymphoma cells treated with vorinostat. Subsequently, we evaluated inhibitors of PI3K, PIM and HSP90 as potential combination agents in the treatment of cutaneous T-cell lymphoma.

DESIGN AND METHODS

The genes significantly up- or down-regulated by vorinostat over different time periods (2-fold change, false discovery rate corrected P value<0.05) were selected using the short-time series expression miner. Cell viability was assessed in vitro in cutaneous T-cell lymphoma cells through measuring intracellular ATP content. Drug interactions were analyzed by the combination index method with CalcuSyn software.

RESULTS

The functional analysis suggests that vorinostat modifies signaling of T-cell receptor, MAPK, and JAK-STAT pathways. The phosphorylation studies of ZAP70 (Tyr319, Tyr493) and its downstream target AKT (Ser473) revealed that vorinostat inhibits phosphorylation of these kinases. With regards to effects on cutaneous T-cell lymphoma cells, combining vorinostat with PI3K inhibitors resulted in synergy while cytotoxic antagonism was observed when vorinostat was combined with HSP90 inhibitor.

CONCLUSIONS

These results demonstrate the potential targets of vorinostat, underlining the importance of T-cell receptor signaling inhibition following vorinostat treatment. Additionally, we showed that combination therapies involving histone deacetylase inhibitors and inhibitors of PI3K are potentially efficacious for the treatment of cutaneous T-cell lymphoma.