CD5 deletion enhances the antitumor activity of adoptive T cell therapies.

Most patients treated with US Food and Drug Administration (FDA)-approved chimeric antigen receptor (CAR) T cells eventually experience disease progression. Furthermore, CAR T cells have not been curative against solid cancers and several hematological malignancies such as T cell lymphomas, which have very poor prognoses. One of the main barriers to the clinical success of adoptive T cell immunotherapies is CAR T cell dysfunction and lack of expansion and/or persistence after infusion. In this study, we found that CD5 inhibits CAR T cell activation and that knockout (KO) of CD5 using CRISPR-Cas9 enhances the antitumor effect of CAR T cells in multiple hematological and solid cancer models. Mechanistically, CD5 KO drives increased T cell effector function with enhanced cytotoxicity, in vivo expansion, and persistence, without apparent toxicity in preclinical models. These findings indicate that CD5 is a critical inhibitor of T cell function and a potential clinical target for enhancing T cell therapies.

Cutaneous T-cell Lymphoma.

Cutaneous T-cell lymphoma is a group of non-Hodgkin T-cell lymphomas that develop in and affect the skin but can potentially spread to other organs. There are many subtypes, the most common of which are mycosis fungoides, Sezary syndrome, lymphomatoid papulosis, and primary cutaneous anaplastic large cell lymphoma. Cutaneous lymphoma is a common cause of recalcitrant chronic skin rash and notoriously mimics other dermatologic and hematologic conditions, often resulting in diagnostic delays of months to years. This review provides an introduction to cutaneous T-cell lymphoma, with a primary focus on the clinical presentation, diagnosis, immunopathogenesis, and management of the condition.

Immunobiology and treatment of cutaneous T-cell lymphoma.

INTRODUCTION: Primary cutaneous T cell lymphomas (CTCL) are a heterogenous group of non-Hodgkin lymphomas derived from skin-homing T cells. These include mycosis fungoides and its leukemic variant Sezary syndrome, as well as the CD30+ lymphoproliferative disorders. AREAS COVERED: In this review, we provide a summary of the current literature on CTCL, with a focus on the immunopathogenesis and treatment of mycosis fungoides and Sezary syndrome. EXPERT OPINION: Recent advances in immunology have provided new insights into the biology of malignant T cells. This in turn has led to the development of new therapies that modulate the immune system to facilitate tumor clearance or target specific aspects of tumor biology.

Identifying highly active anti-CCR4 CAR T cells for the treatment of T-cell lymphoma.

A challenge when targeting T-cell lymphoma with chimeric antigen receptor (CAR) T-cell therapy is that target antigens are often shared between T cells and tumor cells, resulting in fratricide between CAR T cells and on-target cytotoxicity on normal T cells. CC chemokine receptor 4 (CCR4) is highly expressed in many mature T-cell malignancies, such as adult T-cell leukemia/lymphoma (ATLL) and cutaneous T-cell lymphoma (CTCL), and has a unique expression profile in normal T cells. CCR4 is predominantly expressed by type-2 and type-17 helper T cells (Th2 and Th17) and regulatory T cells (Treg), but it is rarely expressed by other T helper (Th) subsets and CD8+ cells. Although fratricide in CAR T cells is generally thought to be detrimental to anticancer functions, in this study, we demonstrated that anti-CCR4 CAR T cells specifically depleted Th2 and Tregs, while sparing CD8+ and Th1 T cells. Moreover, fratricide increased the percentage of CAR+ T cells in the final product. CCR4-CAR T cells were characterized by high transduction efficiency, robust T-cell expansion, and rapid fratricidal depletion of CCR4-positive T cells during CAR transduction and expansion. Furthermore, mogamulizumab-based CCR4-CAR T cells induced superior antitumor efficacy and long-term remission in mice engrafted with human T-cell lymphoma cells. In summary, CCR4-depleted anti-CCR4 CAR T cells are enriched in Th1 and CD8+ T cells and exhibit high antitumor efficacy against CCR4-expressing T-cell malignancies.

TCRvß-CART therapy mediates high-precision targeting of malignant T-cell clones.

Peripheral T-cell lymphomas (PTCLs) are a heterogeneous group of lymphoid malignancies associated with poor prognosis due to ineffective treatment options and high rates of relapse. The success of chimeric antigen receptor T-cell (CART) therapy for certain hematologic malignancies makes it an attractive treatment option for PTCLs. However, shared expression of potential target antigens by both malignant and healthy T cells poses a challenge. Current prospective CART approaches cause a high degree of on-target, off-tumor activity, resulting in fratricide during CART expansion, depletion of healthy T cells in vivo, and immune compromise in the patient. To limit off-tumor targeting, we sought to develop a CART platform specific for a given T-cell receptor vß (TCRvß) family that would endow CAR-modified T cells with the ability to mediate lysis of the clonal malignant population while preserving the majority of healthy T cells. Here, CAR constructs specific for multiple TCRvß family members were designed and validated. Our results demonstrate that TCRvß-family-specific CARTs (TCRvß-CARTs) recognize and kill TCRvß-expressing target cells. This includes specific self-depletion of the targeted cell subpopulation in the CART product and lysis of cell lines engineered to express a target TCRvß family. Furthermore, TCRvß-CARTs eliminated the dominant malignant TCRvß clone in 2 patient samples. Finally, in immunodeficient mice, TCRvß-CARTs eradicated malignant cells in a TCRvß-dependent manner. Importantly, the nontargeted TCRvß families were spared in all cases. Thus, TCRvß-CART therapy provides a potential option for high-precision treatment of PTCL with limited healthy T-cell depletion.

Efficacy and Safety of Topical Hypericin Photodynamic Therapy for Early-Stage Cutaneous T-Cell Lymphoma (Mycosis Fungoides): The FLASH Phase 3 Randomized Clinical Trial.

Importance: Given that mycosis fungoides-cutaneous T-cell lymphoma (MF/CTCL) is chronic, there is a need for additional therapies with minimal short- and long-term adverse effects. Topical synthetic hypericin ointment, 0.25%, activated with visible light is a novel, nonmutagenic photodynamic therapy (PDT). Objectives: To determine the efficacy and safety of topical synthetic hypericin ointment, 0.25%, activated with visible light as a nonmutagenic PDT in early-stage MF/CTCL. Design, Settings, and Participants: This was a multicenter, placebo-controlled, double-blinded, phase 3 randomized clinical trial (FLASH study) conducted from December 2015 to November 2020 at 39 academic and community-based US medical centers. Participants were adults (≥18 years) with early-stage (IA-IIA) MF/CTCL. Interventions: In cycle 1, patients were randomized 2:1 to receive hypericin or placebo to 3 index lesions twice weekly for 6 weeks. In cycle 2, all patients received the active drug for 6 weeks to index lesions. In cycle 3 (optional), both index and additional lesions received active drug for 6 weeks. Main Outcomes and Measures: The primary end point was index lesion response rate (ILRR), defined as 50% or greater improvement in modified Composite Assessment of Index Lesion Severity (mCAILS) score from baseline after 6 weeks of therapy for cycle 1. For cycles 2 and 3, open label response rates were secondary end points. Adverse events (AEs) were assessed at each treatment visit, after each cycle, and then monthly for 6 months. Data analyses were performed on December 21, 2020. Results: The study population comprised 169 patients (mean [SD] age, 58.4 [16.0] years; 96 [57.8%] men; 120 [72.3%] White individuals) with early-stage MF/CTCL. After 6 weeks of treatment, hypericin PDT was more effective than placebo (cycle 1 ILRR, 16% vs 4%; P = .04). The ILRR increased to 40% in patients who received 2 cycles of hypericin PDT (P < .001 vs cycle 1 hypericin) and to 49% after 3 cycles (P < .001 vs cycle 1 hypericin). Significant clinical responses were observed in both patch and plaque type lesions and were similar regardless of age, sex, race, stage IA vs IB, time since diagnosis, and number of prior therapies. The most common treatment-related AEs were mild local skin (13.5%-17.3% across cycles 1-3 vs 10.5% for placebo in cycle 1) and application-site reactions (3.2%-6.9% across cycles 1-3 vs 4% for placebo in cycle 1). No drug-related serious AEs occurred. Conclusion and Relevance: The findings of this randomized clinical trial indicate that synthetic hypericin PDT is effective in early-stage patch and plaque MF/CTCL and has a favorable safety profile. Trial Registration: ClinicalTrials.gov Identifier: NCT02448381.

The Robust Tumoricidal Effects of Combined BET/HDAC Inhibition in Cutaneous T-Cell Lymphoma Can Be Reproduced by ΔNp73 Depletion.

Combined BET inhibitor/histone deacetylase inhibitor treatment induces marked apoptosis of cutaneous T-cell lymphoma (CTCL) with minimal normal T-cell toxicity. At 96 hours when apoptosis was extensive, a majority of CTCL lines showed ≥2-fold suppression of T-cell survival factors (e.g., AKT1, BCL2 antiapoptotic factors, BIRC5, CD40, CD70, GADD45A, PRKCA, TNFRSF1B, ΔNp73) and ≥2-fold upregulation of proapoptotic factors and tumor suppressors (e.g., ATM, BAK, BIM, multiple caspases, FHIT, HIC1, MGMT, NOD1) (P < 0.05). The largest alterations were in TP73 isoform expression, resulting in increased TAp73/ΔNp73 ratios in CTCL lines and leukemic Sézary cells. Targeted ΔNp73 inhibition by small interfering RNA knockdown resulted in robust CTCL apoptosis comparable with that induced by BET inhibitor/histone deacetylase inhibitor with minimal normal T-cell toxicity. Chromatin immunoprecipitation analysis showed that BET inhibitor/histone deacetylase inhibitor treatment reduced RNA polymerase II binding to ΔNp73, MYC, and AKT1 while increasing its binding to TAp73. CTCL skin lesions expressed both TAp73 and ΔNp73 isoforms in situ. In aggregate, these findings implicate TAp73/ΔNp73 balance as a major factor governing CTCL survival, show that the expression of p73 isoforms can be altered by molecular biological and pharmaceutical means, show that p73 isoforms are expressed across the entire CTCL clinical spectrum, and identify the p73 pathway as a potential target for therapeutics.

Management of relapsed cutaneous T-Cell lymphoma following allogeneic hematopoietic stem cell transplantation: Review with representative patient case.

Allogeneic hematopoietic stem cell transplantation (allo-HSCT) is a potentially curative treatment option for patients with refractory cutaneous T-cell lymphoma (CTCL) through replacement of the bone marrow responsible for lymphoma cells and possibly induction of a graft-versus-lymphoma effect. However, allo-HSCT is not always curative; relapse of CTCL occurs in about half of patients post-transplant. Treatment of relapsed CTCL after allo-HSCT is challenging because post-transplant patients are at high risk of graft-versus-host disease, and this condition may be precipitated or exacerbated by standard CTCL therapies. The benefit of each potential therapy must therefore be weighed against its risk of graft versus host disease (GVHD). In this article, we review the management of relapsed CTCL after allo-HSCT. We begin with an exemplative patient whose relapsed Sezary syndrome was successfully treated without development of GVHD. We also report high-throughput T-cell receptor sequencing data obtained during the patient's disease relapse and remission. We then review general guidelines for management of relapsed CTCL and summarize all reported cases and outcomes of relapsed CTCL after transplant. We conclude by reviewing the current CTCL therapies and their risk of GVHD.

Resistance to mogamulizumab is associated with loss of CCR4 in cutaneous T-cell lymphoma.

Mogamulizumab is a humanized anti-CC chemokine receptor 4 (CCR4) antibody approved for the treatment of mycosis fungoides and Sézary syndrome. Despite almost universal expression of CCR4 in these diseases, most patients eventually develop resistance to mogamulizumab. We tested whether resistance to mogamulizumab is associated with loss of CCR4 expression. We identified 17 patients with mycosis fungoides or Sézary syndrome who either were intrinsically resistant or acquired resistance to mogamulizumab. Low expression of CCR4 by immunohistochemistry or flow cytometry was found in 65% of patients. Novel emergent CCR4 mutations targeting the N-terminal and transmembrane domains were found in 3 patients after disease progression. Emerging CCR4 copy number loss was detected in 2 patients with CCR4 mutations. Acquisition of CCR4 genomic alterations corresponded with loss of CCR4 antigen expression. We also report on outcomes of 3 cutaneous T-cell lymphoma (CTCL) patients with gain-of-function CCR4 mutations treated with mogamulizumab. Our study indicates that resistance to mogamulizumab in CTCL frequently involves loss of CCR4 expression and emergence of CCR4 genomic alterations. This finding has implications for management and monitoring of CTCL patients on mogamulizumab and development of future CCR4-directed therapies.

Dermatologic Events Associated with the Anti-CCR4 Antibody Mogamulizumab: Characterization and Management.

The CCR4-directed monoclonal antibody mogamulizumab has been shown to significantly improve progression-free survival and overall response rate compared with vorinostat in adults with relapsed/refractory mycosis fungoides (MF) and Sézary syndrome (SS). One of the most common adverse events seen with mogamulizumab in MF/SS patients is rash. Because of the protean nature of MF/SS and the variable clinical and histopathological features of mogamulizumab-associated rash, healthcare providers may have difficulty distinguishing rash from disease, and may not be aware of appropriate treatment strategies for this generally manageable adverse event. The objective of this report was to combine results from published literature with experiences and recommendations from multiple investigators and institutions into clinical best practice recommendations to assist healthcare providers in identifying and managing mogamulizumab-associated rash. Optimal management, which includes biopsy confirmation and steroid treatment, requires a multidisciplinary approach among oncology, dermatology, and pathology practitioners. INFOGRAPHIC.

Interleukin-31, a Potent Pruritus-Inducing Cytokine and Its Role in Inflammatory Disease and in the Tumor Microenvironment.

Substantial new information has emerged supporting the fundamental role of the cytokine interleukin-31 (IL-31) in the genesis of chronic pruritus in a broad array of clinical conditions. These include inflammatory conditions, such as atopic dermatitis and chronic urticaria, to autoimmune conditions such as dermatomyositis and bullous pemphigoid, to the lymphoproliferative disorders of Hodgkin's disease and cutaneous T-cell lymphoma. IL-31 is produced in greatest quantity by T-helper type 2 (Th2) cells and upon release, interacts with a cascade of other cytokines and chemokines to lead to pruritus and to a proinflammatory environment, particularly within the skin. Antibodies which neutralize IL-31 or which block the IL-31 receptor may reduce or eliminate pruritus and may diminish the manifestations of chronic cutaneous conditions associated with elevated IL-31. The role of IL-31 in these various conditions will be reviewed.

Brentuximab Vedotin for Relapsed or Refractory Sézary Syndrome.

Importance: Treatment options for Sézary syndrome (SS) are limited and associated with low response rates. Brentuximab vedotin is a CD30-directed antibody-drug conjugate approved for refractory CD30-positive cutaneous T-cell lymphoma. However, limited data exist on its efficacy in SS, including in the pivotal phase 3 ALCANZA (A Phase 3 Trial of Brentuximab Vedotin (SGN-35) Versus Physician's Choice [Methotrexate or Bexarotene] in Participants With CD30-Positive Cutaneous T-Cell Lymphoma) trial. Objective: To assess the preliminary efficacy and tolerability of brentuximab vedotin for SS. Design, Setting, and Participants: From January 1, 2017, to July 31, 2020, a total of 13 patients with SS received brentuximab vedotin and were analyzed as part of a retrospective case series. Median follow-up was 10.4 months (range, 1.4-34.6 months). All patients were 18 years or older with a diagnosis of SS and with B2 blood involvement at the time brentuximab vedotin therapy was initiated. This single-center study was conducted at a major academic referral center. Interventions: Intravenous brentuximab vedotin administration approximately every 3 weeks. Main Outcomes and Measures: The primary end point was the global response rate. Outcomes were assessed in the skin and lymph nodes per the 2011 European Organization for Research and Treatment of Cancer-International Society of Cutaneous Lymphoma response criteria and in the blood per the 2018 Prospective Cutaneous Lymphoma International Prognostic Index revised blood response criteria. Results: The study included 13 patients (8 [62%] male; mean [SD] age, 68.2 [8.6] years). Of these 13 patients, 5 (38%) achieved a global response after a median of 6 cycles, including 1 complete response. Response rates by disease compartment were 38% in the skin, 63% in the blood, and 50% in the lymph nodes. Three of 11 patients (27%) with pruritus reported improvement. Skin CD30 positivity (>10%) was detected in 9 patients but was not associated with responses. Among responders, the median time to response was 6 weeks (range, 6-9 weeks), and the median duration of response was 5.5 months (range, 2.5-28.9 months). The median time to next treatment was 3.2 months (range, 1.5-36.7 months). Peripheral neuropathy occurred in 4 patients but resolved in 2 patients. Grade 2 adverse events were neuropathy (n = 2), constipation (n = 1), and hand-foot syndrome (n = 1). Conclusions and Relevance: In this case series, brentuximab vedotin use was associated with some efficacy in SS across multiple disease compartments and in the setting of refractory disease or low CD30 skin expression. Brentuximab vedotin may offer a manageable treatment schedule and low incidence of significant toxic effects.

The immunopathogenesis and immunotherapy of cutaneous T cell lymphoma: Pathways and targets for immune restoration and tumor eradication.

Cutaneous T cell lymphomas (CTCLs) are malignancies of skin-trafficking T cells. Patients with advanced CTCL manifest immune dysfunction that predisposes to infection and suppresses the antitumor immune response. Therapies that stimulate immunity have produced superior progression-free survival compared with conventional chemotherapy, reinforcing the importance of addressing the immune deficient state in the care of patients with CTCL. Recent research has better defined the pathogenesis of these immune deficits, explaining the mechanisms of disease progression and revealing potential therapeutic targets. The features of the malignant cell in mycosis fungoides and Sézary syndrome are now significantly better understood, including the T helper 2 cell phenotype, regulatory T cell cytokine production, immune checkpoint molecule expression, chemokine receptors, and interactions with the microenvironment. The updated model of CTCL immunopathogenesis provides understanding into clinical progression and therapeutic response.