KIR3DL2 (CD158k) is a potential therapeutic target in primary cutaneous anaplastic large-cell lymphoma

MHC-I upregulation safeguards neoplastic T cells in the skin against NK cell-mediated eradication in mycosis fungoides

Cancer-associated immune dysfunction is a major challenge for effective therapies. The emergence of antibodies targeting tumor cell-surface antigens led to advancements in the treatment of hematopoietic malignancies, particularly blood cancers. Yet their impact is constrained against tumors of hematopoietic origin manifesting in the skin. In this study, we employ a clonality-supervised deep learning methodology to dissect key pathological features implicated in mycosis fungoides, the most common cutaneous T-cell lymphoma. Our investigations unveil the prominence of the IL-32β-major histocompatibility complex (MHC)-I axis as a critical determinant in tumor T-cell immune evasion within the skin microenvironment. In patients' skin, we find MHC-I to detrimentally impact the functionality of natural killer (NK) cells, diminishing antibody-dependent cellular cytotoxicity and promoting resistance of tumor skin T-cells to cell-surface targeting therapies. Through murine experiments in female mice, we demonstrate that disruption of the MHC-I interaction with NK cell inhibitory Ly49 receptors restores NK cell anti-tumor activity and targeted T-cell lymphoma elimination in vivo. These findings underscore the significance of attenuating the MHC-I-dependent immunosuppressive networks within skin tumors. Overall, our study introduces a strategy to reinvigorate NK cell-mediated anti-tumor responses to overcome treatment resistance to existing cell-surface targeted therapies for skin lymphoma.

KIR3DL2 contributes to the typing of acute adult T-cell leukemia and is a potential therapeutic target

Adult T-cell leukemia (ATL) is a lymphoid neoplasm caused by human T-cell leukemia virus type 1 (HTLV-1), which encodes the transcriptional activator Tax, which participates in the immortalization of infected T cells. ATL is classified into 4 subtypes: smoldering, chronic, acute, and lymphoma. We determined whether natural killer receptors (NKRs) were expressed in ATL. NKR expression (KIR2DL1/2DS1, KIR2DL2/2DL3/2DS2, KIR3DL2, NKG2A, NKG2C, and NKp46) was assessed in a discovery cohort of 21 ATL, and KIR3DL2 was then assessed in 71 patients with ATL. KIR3DL2 was the only NKR among those studied frequently expressed by acute-type vs lymphoma- and chronic/smoldering-type ATL (36 of 40, 4 of 16, and 1 of 15, respectively; P = .001), although acute- and lymphoma-type ATL had similar mutation profiles by targeted exome sequencing. The correlation of KIR3DL2 expression with promoter demethylation was determined by microarray-based DNA methylation profiling. To explore the role of HTLV-1, KIR3DL2 and TAX messenger RNA (mRNA) expression levels were assessed by PrimeFlow RNA in primary ATL and in CD4+ T cells infected with HTLV-1 in vitro. TAX mRNA and KIR3DL2 protein expressions were correlated on ATL cells. HTLV-1 infection triggered KIR3DL2 by CD4+ cells but Tax alone did not induce KIR3DL2 expression. Ex vivo, autologous, antibody-dependent cell cytotoxicity using lacutamab, a first-in-class anti-KIR3DL2 humanized antibody, selectively killed KIR3DL2+ primary ATL cells ex vivo. To conclude, KIR3DL2 expression is associated with acute-type ATL. Transcription of KIR3DL2 may be triggered by HTLV-1 infection and correlates with hypomethylation of the promoter. The benefit of targeting KIR3DL2 with lacutamab is being further explored in a randomized phase 2 study in peripheral T-cell lymphoma, including ATL (registered on https://clinicaltrials.gov as #NCT04984837).

Clinical Guidelines and New Molecular Targets for Cutaneous Lymphomas

Primary cutaneous lymphomas are heterogenous lymphoproliferative disorders. Some patients show rapid progression and the need for treatment of advanced disease is still unmet. The frequency of each subtype of cutaneous lymphoma varies among different ethnic groups, as do the medical systems found in different countries. It is important to know the differences in clinical guidelines in different areas of the world. Although current monochemotherapy with gemcitabine or pegylated liposomal doxorubicin is temporarily effective for mycosis funogides (MF) and Sézary syndrome (SS)-representative types of cutaneous lymphomas-the duration of response is usually limited. Therefore, treatment strategies targeting tumor-specific molecules have been developed. Molecular targets for MS/SS are currently CD30, CCR4, CD25, CD52, and histone deacetylases, most of which are surface molecules specifically expressed on tumor cells. As a result of advances in research techniques, different kinds of genomic alterations in MF/SS have been revealed. Molecular targets for MS/SS in the near future would be CD158k, JAK, PIK3, the mammalian target of rapamycin, and microRNAs, most of which mediate intracellular signaling pathways. Personalized therapy based on the detection of the genetic signatures of tumors and inhibition of the most suitable target molecules constitutes a future treatment strategy for MF/SS.

Cytokines, Genetic Lesions and Signaling Pathways in Anaplastic Large Cell Lymphomas

ALCL is a tumor of activated T cells and possibly innate lymphoid cells with several subtypes according to clinical presentation and genetic lesions. On one hand, the expression of transcription factors and cytokine receptors triggers signaling pathways. On the other hand, ALCL tumor cells also produce many proteins including chemokines, cytokines and growth factors that affect patient symptoms. Examples are accumulation of granulocytes stimulated by IL-8, IL-17, IL-9 and IL-13; epidermal hyperplasia and psoriasis-like skin lesions due to IL-22; and fever and weight loss in response to IL-6 and IFN-γ. In this review, we focus on the biology of the main ALCL subtypes as the identification of signaling pathways and ALCL-derived cytokines offers opportunities for targeted therapies.

Novel targeted therapies of T cell lymphomas

T cell lymphomas (TCL) comprise a heterogeneous group of non-Hodgkin lymphomas (NHL) that often present at an advanced stage at the time of diagnosis and that most commonly have an aggressive clinical course. Treatment in the front-line setting is most often cyclophosphamide, doxorubicin, vincristine, and prednisone (CHOP) or CHOP-like regimens, which are effective in B cell lymphomas, but in TCL are associated with a high failure rate and frequent relapses. Furthermore, in contrast to B cell NHL, in which substantial clinical progress has been made with the introduction of monoclonal antibodies, no comparable advances have been seen in TCL. To change this situation and improve the prognosis in TCL, new gene-targeted therapies must be developed. This is now possible due to enormous progress that has been made in the last years in the understanding of the biology and molecular pathogenesis of TCL, which enables the implementation of the research findings in clinical practice. In this review, we present new therapies and current clinical and preclinical trials on targeted treatments for TCL using histone deacetylase inhibitors (HDACi), antibodies, chimeric antigen receptor T cells (CARTs), phosphatidylinositol 3-kinase inhibitors (PI3Ki), anaplastic lymphoma kinase inhibitors (ALKi), and antibiotics, used alone or in combinations. The recent clinical success of ALKi and conjugated anti-CD30 antibody (brentuximab-vedotin) suggests that novel therapies for TCL can significantly improve outcomes when properly targeted.

The potentials of immune checkpoints for the treatment of blood malignancies

Immune checkpoints are the regulators of the immune system, which include stimulatory and inhibitory receptors. They play substantial roles in the maintenance of immune system homeostasis and the prevention of autoimmunity and cancer. In the current review, immune checkpoints roles are surveyed in the initiation, progression, and treatment of blood malignancies. The significant roles of immune checkpoints are discussed as clinical markers in the diagnosis and prognosis of a plethora of blood malignancies and also as potential targets for the treatment of these malignancies. It could be concluded that the regulation of immune checkpoints in various blood cancers can be employed as a novel strategy to obtain effective results in leukemia treatment and introduce immune checkpoint inhibitors as sufficient weapons against blood cancers in the future.

Advances in targeted therapy for malignant lymphoma

The incidence of lymphoma has gradually increased over previous decades, and it ranks among the ten most prevalent cancers worldwide. With the development of targeted therapeutic strategies, though a subset of lymphoma patients has become curable, the treatment of refractory and relapsed diseases remains challenging. Many efforts have been made to explore new targets and to develop corresponding therapies. In addition to novel antibodies targeting surface antigens and small molecular inhibitors targeting oncogenic signaling pathways and tumor suppressors, immune checkpoint inhibitors and chimeric antigen receptor T-cells have been rapidly developed to target the tumor microenvironment. Although these targeted agents have shown great success in treating lymphoma patients, adverse events should be noted. The selection of the most suitable candidates, optimal dosage, and effective combinations warrant further investigation. In this review, we systematically outlined the advances in targeted therapy for malignant lymphoma, providing a clinical rationale for mechanism-based lymphoma treatment in the era of precision medicine.

An Update on Molecular Biology of Cutaneous T Cell Lymphoma

Cutaneous T cell lymphomas represent a heterogenous group of lymphoproliferative disorders defined by clonal proliferation of T cells present in the skin. The latest WHO classification in 2016 and WHO-EORTC classification in 2018 has updated the classification of these entities based on the molecular profile. Research in the field of molecular genetics of CTCL has allowed a better understanding of the biology of these tumors and has helped to identify potential targets for therapy that can be tailored to individual patients. In this review, we discuss the latest developments in the molecular profile of CTCLs including biomarkers for diagnosis, prognosis, and potential therapeutic targets. We have also touched upon the utility of various molecular diagnostic modalities. For the purpose of this review, we researched papers in PubMed indexed journals in English literature published in the past 20 years using keywords CTCL, mycosis fungoides, molecular profile, molecular diagnosis, whole genome profile, genomic landscape, TCR clonality.

Low-dose total skin electron beam therapy: Quality of life improvement and clinical impact of maintenance and adjuvant treatment in patients with mycosis fungoides or Sezary syndrome

PURPOSE

Total skin electron beam therapy (TSEBT) has proved to be a safe and effective treatment for cutaneous T‑cell lymphomas. Here, we examined the impact of this treatment on patient quality of life and outcome.

PATIENTS AND METHODS

Forty-four patients with mycosis fungoides (MF) or Sezary syndrome (SS) received 48 TSEBT courses with a median dose of 12 Gy within the past 8 years at our institute. Patient and treatment characteristics for these cases as well as the impact of TSEBT on quality of life and duration of response were retrospectively analyzed and compared.

RESULTS

The median modified Severity-Weighted Assessment Tool score before the start of TSEBT was 44. The overall response rate was 88%, with a complete response (CR) rate of 33%. The median follow-up period was 13 months. The median duration of response (DOR) and progression-free survival (PFS) for the entire cohort were 10 months and 9 months, respectively. Patient-reported symptom burden was measured with the Dermatological Life Quality Index and Skindex-29 questionnaires. The mean symptom reductions were 6 ± 8 (P = 0.005) and 21 ± 24 (P = 0.002), respectively. In the Functional Assessment of Cancer Therapy-General Assessment, significant improvements in the emotional (P = 0.03) domains were observed after TSEBT. Patients who received maintenance or adjuvant treatments had a longer PFS (P = 0.01).

CONCLUSION

TSEBT improved disease symptoms and significantly improved emotional domains of patients' quality of life in patients with MF or SS. In addition, our results indicate that maintenance or adjuvant therapy after TSEBT may improve the PFS.

[Primary skin lymphomas: Current therapy]

Therapeutic progress in primary cutaneous lymphomas continues to be largely dominated by the T-cell lymphomas, towards which the great majority of recent therapeutic innovations have been directed. The latter include local treatments consisting either of relatively classical but "revamped" approaches involving different pharmaceutical forms (example: chlormethine gel) or else lower but seemingly equally effective dosages (electron therapy), or of more innovative approaches (example: UVA-1, dynamic phototherapy, imiquimod, resimiquimod). However, significant progress has been made chiefly in terms of systemic treatments with the emergence of "targeted" drugs that directly and specifically target tumour cells (monoclonal antibodies directed against CD30, CCR4 or CD158k) and the further development of "small" molecules such as histone deacetylase inhibitors and new cytostatics. Immunotherapies, which have proven so effective in other areas of oncodermatology, are also of great interest, while allogeneic haematopoietic stem-cell transplantation has clearly shown its superiority over autologous transplantation and now constitutes a significant component of the therapeutic arsenal in advanced disease. While the innovations in terms of B-cell lymphomas are certainly less significant, mention must also be made of the value of rituximab combined with polychemotherapy (CHOP) and of lenalidomide (as second-line therapy) in primary cutaneous diffuse large B-cell lymphoma, leg type, along with the development of localized (very) low-dose radiotherapy in unilesional or paucilesional indolent forms.

CD30-positive primary cutaneous lymphoproliferative disorders: molecular alterations and targeted therapies

Primary cutaneous CD30-positive T-cell lymphoproliferative disorders are the second most common subgroup of cutaneous T-cell lymphomas. They include two clinically different entities with some overlapping features and borderline cases: lymphomatoid papulosis and primary cutaneous anaplastic large cell lymphoma. Molecular studies of primary cutaneous anaplastic large cell lymphoma reveal an increasing level of heterogeneity that is associated with histological and immunophenotypic features of the cases and their response to specific therapies. Here, we review the most significant genetic, epigenetic and molecular alterations described to date in primary cutaneous CD30-positive T-cell lymphoproliferative disorders, and their potential as therapeutic targets.

Interactions Between KIR3DS1 and HLA-F Activate Natural Killer Cells to Control HCV Replication in Cell Culture

Killer-cell immunoglobulin-like receptors (KIRs) are transmembrane glycoproteins expressed by natural killer (NK) cells. Binding of KIR3DS1 to its recently discovered ligand, HLA-F, activates NK cells and has been associated with resolution of hepatitis C virus (HCV) infection. We investigated the mechanisms by which KIR3DS1 contributes to the antiviral immune response. Using cell culture systems, mice with humanized livers, and primary liver tissue from HCV-infected individuals, we found that the KIR3DS1 ligand HLA-F is up-regulated on HCV-infected cells, and that interactions between KIR3DS1 and HLA-F contribute to NK cell-mediated control of HCV. Strategies to promote interaction between KIR3DS1 and HLA-F might be developed for treatment of infectious diseases and cancer.

Systemic Treatment Options for Advanced-Stage Mycosis Fungoides and Sézary Syndrome

PURPOSE OF REVIEW

Cutaneous T-cell lymphoma (CTCL) is a rare form of non-Hodgkin lymphoma. Globally, the most common subtypes of CTCL are mycosis fungoides and Sézary syndrome. CTCL can confer significant morbidity and even mortality in advanced disease. Here we review the current and potential future treatments for advanced-stage CTCL.

RECENT FINDINGS

Heterogeneity of treatment choice has been demonstrated both in US and non-US centers. Systemic treatment choice is currently guided by prognostic features, incorporating stage, immunophenotypic and molecular findings, and patient-specific factors such as age and comorbidities. Randomized controlled studies are uncommon, and the literature is composed predominantly of retrospective, cohort, and early-phase studies. International consensus guidelines are available; however, the lack of comparative trials means that there is no clear algorithmic approach to treatment. This review article reports on the systemic treatment options in current use for advanced CTCL, and on the possible future therapies, acknowledging that an algorithmic approach is not yet forthcoming to guide treatment prioritization.

Current systemic therapeutic options for advanced mycosis fungoides and Sézary syndrome

Mycosis fungoides (MF) and Sézary syndrome (SS) are the most common cutaneous T-cell lymphomas (CTCLs). Both lack curative options, and advanced-stage carries a poor prognosis. Whilst there are a number of treatments available, achieving and maintaining a durable remission remains challenging. We review current systemic treatment options as monotherapy for advanced-stage MF (IIB-IV), appraising their mechanism of action, analyzing their efficacy, and describing toxicities. Individually, reported overall response rates (ORR) vary widely in the literature and duration of responses are typically short, ranging from 7.5 to 22.4 months. Combined therapy is frequently used in an effort to boost responses, although prospective studies comparing combinations to single agent therapies are rarely conducted. While recent translational research has led to increased understanding of the immunopathogenesis of MF and SS and the development of new treatments, current standard of care therapies are not curative and have low ORR for advanced-stage disease.

Recombinant Antibodies to Arm Cytotoxic Lymphocytes in Cancer Immunotherapy

Immunotherapy has the potential to support and expand the body's own armamentarium of immune effector functions, which have been circumvented during malignant transformation and establishment of cancer and is presently considered to be the most promising treatment option for cancer patients. Recombinant antibody technologies have led to a multitude of novel antibody formats, which are in clinical development and hold great promise for future therapies. Among these formats, bispecific antibodies are extremely versatile due to their high efficacy to recruit and activate anti-tumoral immune effector cells, their excellent safety profile, and the opportunity for use in combination with cellular therapies. This review article summarizes the latest developments in cancer immunotherapy using immuno-engagers for recruiting T cells and NK cells to the tumor site. In addition to antibody formats, malignant cell targets, and immune cell targets, opportunities for combination therapies, including check point inhibitors, cytokines and adoptive transfer of immune cells, will be summarized and discussed.

Therapeutic Antibodies to KIR3DL2 and Other Target Antigens on Cutaneous T-Cell Lymphomas

KIR3DL2 is a member of the killer cell immunoglobulin-like receptor (KIR) family that was initially identified at the surface of natural killer (NK) cells. KIR3DL2, also known as CD158k, is expressed as a disulfide-linked homodimer. Each chain is composed of three immunoglobulin-like domains and a long cytoplasmic tail containing two immunoreceptor tyrosine-based inhibitory motifs. Beside its expression on NK cells, it is also found on rare circulating T lymphocytes, mainly CD8⁺. Although the KIR gene number varies between haplotype, KIR3DL2 is a framework gene present in all individuals. Together with the presence of genomic regulatory sequences unique to KIR3DL2, this suggests some particular functions for the derived protein in comparison with other KIR family members. Several ligands have been identified for KIR3DL2. As for other KIRs, binding to HLA class I molecules is essential for NK development by promoting phenomena such as licensing and driving NK cell maturation. For KIR3DL2, this includes binding to HLA-A3 and -A11 and to the free heavy chain form of HLA-B27. In addition, KIR3DL2 binds to CpG oligonucleotides (ODN) and ensures their transport to endosomal toll-like receptor 9 that promotes cell activation. These characteristics have implicated KIR3DL2 in several pathologies: ankylosing spondylitis and cutaneous T-cell lymphomas such as Sézary syndrome, CD30⁺ cutaneous lymphoma, and transformed mycosis fungoides. Consequently, a new generation of humanized monoclonal antibodies (mAbs) directed against KIR3DL2 has been helpful in the diagnosis, follow-up, and treatment of these diseases. In addition, preliminary clinical studies of a novel targeted immunotherapy for cutaneous T-cell lymphomas using the anti-KIR3DL2 mAb IPH4102 are now underway. In this review, we discuss the various aspects of KIR3DL2 on the functions of CD4⁺ T cells and how targeting this receptor helps to develop innovative therapeutic strategies.

Reduction of Relapse after Unrelated Donor Stem Cell Transplantation by KIR-Based Graft Selection

Besides donor T cells, natural killer (NK) cells are considered to have a major role in preventing relapse after allogeneic hematopoietic stem cell transplantation (HSCT). After T-cell-depleted haploidentical HSCT, a strong NK alloreactivity has been described. These effects have been attributed to killer-cell immunoglobulin-like receptors (KIR). Abundant reports suggest a major role of KIR not only on outcome after haploidentical HSCT but also in the unrelated donor setting. In this review, we give a brief overview of the mechanism of NK cell activation, nomenclature of KIR haplotypes, human leukocyte antigen (HLA) groups, and distinct models for prediction of NK cell alloreactivity. It can be concluded that KIR-ligand mismatch seems to provoke adverse effects in unrelated donor HSCT with reduced overall survival and increased risk for high-grade acute graft-versus-host disease. The presence of activating KIR, as seen in KIR haplotype B, as well as the patient’s HLA C1/x haplotype might reduce relapse in myeloid malignancies.

Deciphering the killer-cell immunoglobulin-like receptor system at super-resolution for natural killer and T-cell biology

Killer-cell immunoglobulin-like receptors (KIRs) are components of two fundamental biological systems essential for human health and survival. First, they contribute to host immune responses, both innate and adaptive, through their expression by natural killer cells and T cells. Second, KIR play a key role in regulating placentation, and hence reproductive success. Analogous to the diversity of their human leucocyte antigen class I ligands, KIR are extremely polymorphic. In this review, we describe recent developments, fuelled by methodological advances, that are helping to decipher the KIR system in terms of haplotypes, polymorphisms, expression patterns and their ligand interactions. These developments are delivering deeper insight into the relevance of KIR in immune system function, evolution and disease.

A new era for cutaneous CD30-positive T-cell lymphoproliferative disorders

Cutaneous CD30+ T-cell lymphoproliferative disorders (CD30+ T-LPD) represent a spectrum encompassing lymphomatoid papulosis (LyP), primary cutaneous anaplastic large-cell lymphoma (pcALCL) and borderline lesions. They share the expression of CD30 as a common phenotypic marker. They differ however in their clinical presentation, the histological features and clinical course. Moreover, LyP and PcALCL show numerous clinical, histological and phenotypic variants. Overlapping features of LyP and pcALCL with themselves and with other cutaneous and systemic lymphomas emphasize the importance of careful clinicopathologic correlation and staging in the diagnosis of CD30+ T-LPD. Furthermore, an increasing number of inflammatory and infectious skin disorders harboring medium-sized to large CD30+ cells have to be considered in the differential diagnosis. Whereas the expression of CD30 in cutaneous CD30+ T-LPD stands for a favourable prognosis, its expression in other cutaneous and systemic lymphomas has a divergent impact. The assessment of CD30 expression does not only provide prognostic information, but is of potential therapeutic relevance as CD30 can serve as a therapeutic target. This review focuses on the clinicopathological and phenotypic spectrum of CD30+ T-LPD, its differential diagnoses and the role of CD30 as a diagnostic, prognostic and therapeutic marker.