Stratagems of HTLV-1 for persistent infection and the resultant oncogenesis: Immune evasion and clonal expansion

Adult T-cell leukemia-lymphoma (ATL) is one of the most severe malignant T-cell leukemia/lymphomas induced by human T-cell leukemia virus type I (HTLV-1). HTLV-1 persists in the host through stratagems of proliferating infected cells and evading host immunity. HTLV-1 encodes two viral oncogenes, tax and HTLV-1 bZIP factor (HBZ), which are related with protection from cell death and promotion of cell proliferation. In addition, HBZ and the somatic mutations in host genes, such as C-C chemokine receptor 4 (CCR4) and CIC, convert HTLV-1-infected cells into regulatory T (Treg)-like cells, leading to evasion of host immunity. A recent study demonstrated the key mechanisms for clonal expansion of HTLV-1-infected cells; the activation of the transforming growth factor (TGF)-β signaling pathway by HBZ not only converts HTLV-1-infected cells into a Treg-like cells through Foxp3 expression, but also contributes to the proliferation of HTLV-1-infected cells themselves. Due to the longevity induced by HTLV-1 infection, somatic mutations and epigenetic aberrations are accumulated in infected clones, contributing to the oncogenesis of ATL. Collectively, the long-term survival of infected cells enabled by the HTLV-1's stratagems for persistent infection ultimately leads to ATL oncogenesis via the accumulation of genetic/epigenetic abnormalities.

Phase I study on neoadjuvant combination immunotherapy with mogamulizumab and nivolumab for solid tumors

BACKGROUND

Effector regulatory T cells expressing C-C chemokine receptor 4 (CCR4) suppress antitumor immune responses. We conducted a phase I clinical trial to evaluate the safety and efficacy of preoperative combination therapy with mogamulizumab (an anti-CCR4 antibody) and nivolumab (an anti-programmed death-1 antibody) in patients with solid tumors.

METHODS

Patients with operable solid tumors were enrolled in a 3+3 design, with preoperative nivolumab (3.0 mg/kg) administered intravenously every 2 weeks three times and mogamulizumab at 0.1 mg/kg (cohort 1), 0.3 mg/kg (cohort 2), or 1.0 mg/kg (cohort 3) every week four times. The primary endpoints were safety and the effects of depleting Forkhead box P3+ (FoxP3+) T cells in the tumor.

RESULTS

16 patients were enrolled between June 2016 and April 2020, including those with renal (n=7), lung (n=5), esophageal (n=3), and oral (n=1) cancers. Grade 3-4 treatment-related adverse events were observed in 6 of 16 patients, with lymphopenia (25%) and maculopapular rash (13%) being the most frequent. Grade 5 interstitial pneumonia was observed in one patient; however, the cause of death was disease progression. There were three partial responses (PRs) (one lung and two esophageal cancers) among clinical responses and one complete response (one lung cancer) and nine PRs (five kidney, two lung, and two esophageal cancers) among pathological responses. CCR4+FoxP3+ T cells were depleted in the tumors of all patients and increases in lymphocytes in tumor tissue according to the tumor immune microenvironment classification were observed in 50% of the patients, which correlated with a better prognosis.

CONCLUSIONS

The preoperative combination of mogamulizumab and nivolumab was safely managed, exerted antitumor effects, and may be an effective option in the preoperative setting.

TRIAL REGISTRATION NUMBER

The present study was registered with ClinicalTrials.gov as NCT02946671 (registration date 2016-10-05).

Low Survival Due to Higher Risk of Relapse and Nonrelapse Mortality After Allogeneic HSCT in ATL Compared with AML and ALL

BACKGROUND

Patients with adult T-cell leukemia/lymphoma (ATL) are considered to have worse outcomes after allogeneic hematopoietic stem cell transplantation (allo-HSCT) than patients with other hematological malignancies, owing to high risk of relapse and immunocompromised status. However, no studies have compared transplant outcomes between patients with ATL and those with other hematological malignancies using a large-scale database.

OBJECTIVES

To compare transplant outcomes between patients with ATL and those with other leukemias and to identify factors contributing to worse transplant outcomes in ATL patients.

STUDY DESIGN

Using Japanese registry data, we retrospectively compared transplant outcomes between patients with ATL and those with acute myeloid leukemia (AML) and acute lymphoblastic leukemia (ALL). As ATL often develops in patients in their 60s or older, patients with ATL, AML, or ALL aged ≥50 years were included in order to compare patients in the same age group. A total of 7764 patients (ATL, n = 1151; AML, n = 5393; ALL, n = 1220) who underwent their first allo-HSCT between January 1, 2006 and December 31, 2017 were included in this study.

RESULTS

Compared with AML, ATL showed significantly worse overall survival (OS) (hazard ratio [HR], 1.24; 95% confidence interval [CI], 1.14 to 1.34; P < .001) and higher risk of relapse (HR, 1.33; 95% CI, 1.2 to 1.47; P < .001), while there were no significant differences between AML and ALL. Among patients in complete remission (CR) at transplantation, ATL showed worse OS (HR, 1.30; 95% CI, 1.08 to 1.56; P = .006), higher risk of relapse (HR, 1.78; 95% CI, 1.48 to 2.14; P < .001), and higher risk of nonrelapse mortality (NRM) (HR, 1.38; 95% CI, 1.14 to 1.33; P = .001) in comparison with AML, whereas there were no significant differences between AML and ALL.

CONCLUSION

We found that ATL patients have poor transplant outcomes compared with AML or ALL patients. In ATL patients, survival is poor, relapse is more frequent, and NRM is significantly higher, especially in cases of CR. These findings suggest that prevention of relapse and transplant-related complications is important for successful allo-HSCT in ATL.

Clinical and therapeutic significance of genetic profiling in adult T-cell leukemia/lymphoma

Adult T-cell leukemia/lymphoma (ATLL) is a highly aggressive T-cell malignancy with a poor prognosis. Several genetic analyses using next-generation sequencing have uncovered recurrent mutations and copy number alterations involved in diverse functional pathways, including T-cell receptor/NF-κB signaling, immune surveillance, transcription factors, chemokine receptors, and CIC-ATXN1 complex. In addition to these alterations, recurrent structural variations, including PD-L1 (CD274) and REL truncations, characterize ATLL genome. Recent clinicogenetic studies have linked several genetic alterations, such as PRKCB mutations, to a worse clinical outcome. Using genetic and clinical factors, novel prognostic models have been developed, which outperform previous models based on only clinical factors in prognostic prediction. Furthermore, genetic and epigenetic events influencing response to molecularly targeted therapies, such as mogamulizumab and valemetostat, have also been identified. Collectively, these insights underscore the clinical importance of assessing genetic alterations. This review highlights the latest insights into the genetic landscape of ATLL and their clinical implications, which will facilitate the development of future strategies for targeted and personalized therapy.

Targeted antibody therapy as a treatment strategy for aggressive adult T-cell leukemia/lymphoma

The standard treatment for aggressive adult T-cell leukemia/lymphoma (ATL) is multi-agent chemotherapy, but the use of more intense cytotoxic anticancer agents is becoming more difficult with the aging of patients at the time of diagnosis. As a means of overcoming this hurdle, antibody drugs, which are supposed to be less toxic, have been developed for ATL. The advent of the anti-CC chemokine receptor 4 (CCR4) antibody mogamulizumab has significantly advanced ATL treatment. Real-world data and a phase 2 clinical trial suggest the efficacy and manageable safety profile of mogamulizumab with combination chemotherapy in elderly patients. Interestingly, mogamulizumab has performed well in cases with CCR4 mutations and cutaneous adverse events. In addition, emerging immunotherapies, including Tax peptide dendritic cell vaccines, immune checkpoint inhibitors, and Chimeric Antigen Receptor-T cell therapy, are under investigation. These innovative approaches aim to enhance immunogenic responses and offer hope for better outcomes in this challenging malignancy.

New treatments for adult T-cell leukemia/lymphoma

Adult T cell leukemia lymphoma (ATL) is a mature T cell neoplasm caused by human T-cell lymphotropic virus type 1 (HTLV-1). ATL is endemic in specific geographic regions of the world closely related to areas with high prevalence of HLTV-1 infection, including Southwestern Japan, the Caribbean Basin, Central Africa, South America, Northern and Central Australia. HLTV-1 is primarily transmitted through breastmilk in asymptomatic carriers with a long latency period before transformation into ATL in 3 - 5 % of carriers after acquisition of multiple leukemogenic mutations. The Shimoyama classification established by the Japanese Lymphoma Study Group more than three decades ago remains clinically relevant and practical for guiding treatment. Due to the rarity of this illness, prospective, large prospective clinical are challenging to perform and treatment recommendations are based upon limited evidence. Aggressive disease subtypes have median survival ranging in months and the only curative therapy remains achieving deep remission with induction therapy followed by consolidative allogeneic transplantation. The prognosis for relapsed disease remains dismal due to chemo-refractoriness and limited therapeutic options. Herein, we review the current landscape of novel therapeutic agents with a focus on relapsed and refractory ATL including their mechanisms of action, resistance, and clinical efficacy.

Clinical significance of NOTCH1 and FBXW7 alterations in adult T-cell leukemia/lymphoma

Here, we investigated the clinical significance of NOTCH1 and FBXW7 alterations for adult T-cell leukemia/lymphoma (ATLL) treatment outcomes. NOTCH1 alterations were identified in 37 (14.4%) of 257 patients, of which 33 were single nucleotide variants/insertion-deletions in the PEST domain, and 7 were in the heterodimerization or LIN-12/Notch repeats domains. FBXW7 alterations were observed in nine ATLL patients (3.5%). For patients without allogeneic hematopoietic stem cell transplantation (HSCT), NOTCH1, but not FBXW7, alterations were significantly and independently associated with worse overall survival (median OS 0.5 years, 95% confidence interval [CI] 0.4-0.5 years for 27 patients with NOTCH1 alterations vs 1.8 years, 95% CI 1.3-2.2 years for 170 patients without). Also, for patients receiving mogamulizumab, but not allogeneic-HSCT, NOTCH1, but not FBXW7, alterations were significantly associated with worse survival (median survival from the first dose of mogamulizumab 0.4 years, 95% CI 0.3-0.5 years for 12 patients with NOTCH1 alterations vs 1.4 years, 95% CI 0.9-2.0 years for 87 without). In contrast, NOTCH1 alterations had no significant impact on survival of patients who did receive allogeneic-HSCT. Thus, mogamulizumab-containing treatment was unable to overcome treatment refractoriness of ATLL with NOTCH1 alterations. Therefore, patients with NOTCH1 alterations are recommended for allogeneic-HSCT.

Exploring the Potential of Nanocarriers for Cancer Immunotherapy: Insights into Mechanism, Nanocarriers, and Regulatory Perspectives

Immunotherapy is a cutting-edge approach that leverages sophisticated technology to target tumor-specific antibodies and modulate the immune system to eradicate cancer and enhance patients' quality of life. Bioinformatics and genetic science advancements have made it possible to diagnose and treat cancer patients using immunotherapy technology. However, current immunotherapies against cancer have limited clinical benefits due to cancer-associated antigens, which often fail to interact with immune cells and exhibit insufficient therapeutic targeting with unintended side effects. To surmount this challenge, nanoparticle systems have emerged as a potential strategy for transporting immunotherapeutic agents to cancer cells and activating immune cells to combat tumors. Consequently, this process potentially generates an antigen-specific T cells response that effectively suppresses cancer growth. Furthermore, nanoplatforms have high specificity, efficacy, diagnostic potential, and imaging capabilities, making them promising tools for cancer treatment. However, this informative paper delves into the various available immunotherapies, including CAR T cells therapy and immune checkpoint blockade, cytokines, cancer vaccines, and monoclonal antibodies. Furthermore, the paper delves into the concept of theragnostic nanotechnology, which integrates therapy and diagnostics for a more personalized treatment approach for cancer therapy. Additionally, the paper covers the potential benefits of different nanocarrier systems, including marketed immunotherapy products, clinical trials, regulatory considerations, and future prospects for cancer immunotherapy.

Chemotherapy and allo-HSCT for young patients with aggressive ATL

Adult T-cell leukemia-lymphoma (ATL) is an aggressive malignancy with a poor prognosis, especially for patients with the aggressive subtype. While conventional chemotherapy offers short-term disease control, allogeneic hematopoietic stem cell transplantation (allo-HSCT) remains the most promising curative approach for young, transplant-eligible patients. This review focuses on current treatment strategies for aggressive ATL in this specific population. We discuss the rationale for early upfront allo-HSCT following induction chemotherapy. The advent of allo-HSCT using alternative donors, particularly haploidentical HCT, has broadened the applicability of early upfront allo-HSCT in patients with aggressive ATL worldwide. Finally, we address emerging therapies that may improve outcomes in the context of allo-HSCT, paving the way for further advancements in the treatment of aggressive ATL.

Therapeutic advances for the management of adult T cell leukemia: Where do we stand?

Adult T cell leukemia (ATL) is an aggressive blood malignancy secondary to chronic infection with the human T cell leukemia virus type I (HTLV-1) retrovirus. ATL encompasses four subtypes (acute, lymphoma, chronic, and smoldering), which exhibit different clinical characteristics and respond differently to various treatment strategies. Yet, all four subtypes are characterized by a dismal long-term prognosis and a low survival rate. While antiretroviral therapy improves overall survival outcomes in smoldering and chronic subtypes, survival remains poor in lymphoma subtypes despite their good response to intensive chemotherapy. Nonetheless, acute ATL remains the most aggressive form associated with profound immunosuppression, chemo-resistance and dismal prognosis. Targeted therapies such as monoclonal antibodies, epigenetic therapies, and arsenic/IFN, emerged as promising therapeutic approaches in ATL. Allogeneic hematopoietic cell transplantation is the only potentially curative modality, alas applicable to only a small percentage of patients. The recent findings demonstrating the expression of the viral oncoprotein Tax in primary ATL cells from patients with acute or chronic ATL, albeit at low levels, and their dependence on continuous Tax expression for their survival, position ATL as a virus-addicted leukemia and validates the rationale of anti-viral treatment strategies. This review provides a comprehensive overview on conventional, anti-viral and targeted therapies of ATL, with emphasis on Tax-targeted therapied in the pre-clinical and clinical settings.

Fulminant hepatitis in a hepatitis B surface antigen-positive patient with adult T-cell leukemia-lymphoma after mogamulizumab monotherapy

We report a case of fulminant hepatitis in a hepatitis B surface antigen (HBsAg)-positive patient with aggressive adult T-cell leukemia-lymphoma who received monotherapy with an anti-CCR4 monoclonal antibody, mogamulizumab, with decreased hepatitis B virus (HBV)- DNA levels by entecavir prophylaxis. Although HBV reactivation-related hepatitis was considered in the differential diagnosis, the patient did not meet the conventional criteria for HBV reactivation and was finally diagnosed with drug-induced hepatitis. Considering that the immunoenhancing effects of mogamulizumab can lead to HBV reactivation-related hepatitis in HBsAg-positive patients, we should differentiate drug-induced hepatitis from HBV reactivation, especially in patients receiving immunomodulatory drugs, if HBV-DNA levels are reduced by antiviral prophylaxis.

Improved survival among elderly patients with aggressive adult T-cell leukemia/lymphoma: Impact of mogamulizumab-containing chemotherapy

Due to the poor prognosis of adult T-cell leukemia/lymphoma (ATL), new treatments are urgently needed, especially for elderly patients with aggressive ATL. The anti-CCR4 antibody drug mogamulizumab (MOG) has been approved for the treatment of untreated ATL. To analyze the impact of MOG on elderly patients, we conducted a retrospective analysis of patients aged 70 years and older with aggressive ATL diagnosed at our institution between 2015 and 2021. Among 32 patients, including those who received best supportive care, the median survival time (MST) and 2-year overall survival (OS) rate were 14.6 months (range, 0.0-83.7), and 34.7% [95% confidence interval (CI), 18.2-51.9], respectively, which were better than outcomes in our previous study. The MST and 2-year OS for patients treated with MOG-containing chemotherapy were 18.1 months (range, 4.0-83.7) and 45.0% (95%CI, 23.1-64.7), respectively, demonstrating clear improvement. Adverse events observed with MOG-containing treatment, such as myelosuppression and skin rash, were similar to those reported previously. Univariate analysis identified comorbidity as a predictor of poor outcomes, but not intensity of MOG-containing treatment, suggesting a different mechanism of action than that of classical chemotherapy. Our study suggests that MOG-containing treatments are an option for elderly patients with ATL.

RUNX1 expression is regulated by a super-enhancer and is a therapeutic target in adult T-cell leukemia/lymphoma

Super-enhancers (SEs) play an important role in regulating tumor-specific gene expression. JQ1, a Bromodomain-containing protein 4 (BRD4) inhibitor, exerts antitumor effects by disrupting SE-mediated regulation of gene expression. We investigated the anti-adult T-cell leukemia/lymphoma (ATL) effects of JQ1. JQ1 induced apoptosis and inhibited ATL cell proliferation. JQ1 suppressed RUNX1expression through the disruption of SE-mediated gene regulation. In the previous reports, it was shown that IC50s of AI-10-104 and Ro5-3335, RUNX1 inhibitors were 1-10 µM for lymphoblastic leukemia cell lines carrying RUNX1 mutations. In the present study, we demonstrated that IC50s of AI-10-104 and Ro5-3335 were also 1-10 µM or lower for ATL cell lines. Simultaneously, AI-10-104 suppressed MYC proto-oncogene (c-MYC) expression. RUNX1 is a potential therapeutic target for ATL that promotes c-MYC expression. We showed that RUNX1 expression is regulated via SEs in ATL and that RUNX1 may be a novel therapeutic target for ATL.

Allogeneic transplantation for adult T-cell leukemia/lymphoma in adolescent and young adults and young patients: A nationwide retrospective study by the ATL working group of the Japan society for transplantation and cellular therapy

Allogeneic hematopoietic stem cell transplantation (allo-HSCT) provides durable remission for patients with adult T-cell leukemia/lymphoma (ATL); however, few studies have focused on post-transplant outcomes in ATL patients ≤49 years. To clarify prognostic factors in ATL among patients <40 years (adolescents and young adult [AYA]; n = 73) and 40-49 years (Young; n = 330), we conducted a nationwide retrospective study. Estimated 3-year overall survival (OS) rates were 61.8% and 43.1% in AYA and Young patients, respectively (p = 0.005). In the multivariate analysis, Young patients showed worse OS (Hazard ratio (HR) [95% confidential interval] 1.62 [1.10-2.39], p = 0.015), chronic graft-versus-host disease (GVHD)-free and relapse-free survival (CRFS) (HR 1.54 [1.10-2.14], p = 0.011), and GVHD-free and relapse-free survival (GRFS) (HR 1.40 [1.04-1.88], p = 0.026) than AYA patients. No significant differences were observed in OS, CRFS, or GRFS between the myeloablative conditioning (MAC) and reduced-intensity conditioning (RIC) regimens; however, non-relapse mortality was significantly lower in patients with the RIC regimen than those with the MAC regimen (HR 0.46 [0.24-0.86], p = 0.015). In summary, OS was worse in Young patients than in AYA patients in the allo-HSCT setting for ATL. Furthermore, the RIC regimen has potential as an alternative treatment option for ATL patients ≤49 years.

New insights into the biology of T-cell lymphomas

ABSTRACT

Peripheral T-cell lymphomas (PTCLs) encompass a heterogeneous group of postthymic T-cell lymphomas with >30 distinct subtypes associated with varied clinicopathological features. Unfortunately, the overall survival of the major PTCL subtypes is dismal and has not improved for decades; thus, there is an urgent unmet clinical need to improve diagnosis, therapies, and clinical outcomes. The diagnosis is often challenging, requiring a combinatorial evaluation of clinical, morphologic, and immunophenotypic features. PTCL pathobiology is difficult to investigate due to enormous intertumor and intratumor heterogeneity, limited tissue availability, and the paucity of authentic T-cell lymphoma cell lines or genetically faithful animal models. The application of transcriptomic profiling and genomic sequencing has markedly accelerated the discovery of new biomarkers, molecular signatures, and genetic lesions, and some of the discoveries have been included in the revised World Health Organization or International Consensus Classification. Genome-wide investigations have revealed the mutational landscape and transcriptomic profiles of PTCL entities, defined the cell of origin as a major determinant of T-cell lymphoma biology, and allowed for the refinement of biologically and clinically meaningful entities for precision therapy. In this review, we prioritize the discussion on common nodal PTCL subtypes together with 2 virus-associated T-cell and natural killer cell lymphomas. We succinctly review normal T-cell development, differentiation, and T-cell receptor signaling as they relate to PTCL pathogenesis and biology. This review will facilitate a better biological understanding of the different PTCL entities and their stratification for additional studies and target-directed clinical trials.

Current State of Therapeutics for HTLV-1

Human T cell leukaemia virus type-1 (HTLV-1) is an oncogenic retrovirus that causes lifelong infection in ~5-10 million individuals globally. It is endemic to certain First Nations populations of Northern and Central Australia, Japan, South and Central America, Africa, and the Caribbean region. HTLV-1 preferentially infects CD4+ T cells and remains in a state of reduced transcription, often being asymptomatic in the beginning of infection, with symptoms developing later in life. HTLV-1 infection is implicated in the development of adult T cell leukaemia/lymphoma (ATL) and HTLV-1-associated myelopathies (HAM), amongst other immune-related disorders. With no preventive or curative interventions, infected individuals have limited treatment options, most of which manage symptoms. The clinical burden and lack of treatment options directs the need for alternative treatment strategies for HTLV-1 infection. Recent advances have been made in the development of RNA-based antiviral therapeutics for Human Immunodeficiency Virus Type-1 (HIV-1), an analogous retrovirus that shares modes of transmission with HTLV-1. This review highlights past and ongoing efforts in the development of HTLV-1 therapeutics and vaccines, with a focus on the potential for gene therapy as a new treatment modality in light of its successes in HIV-1, as well as animal models that may help the advancement of novel antiviral and anticancer interventions.

Antibody-Based Therapies for Peripheral T-Cell Lymphoma

While antibody-based immunotherapeutic strategies have revolutionized the treatment of B-cell lymphomas, progress in T-cell lymphomas has suffered from suboptimal targets, disease heterogeneity, and limited effective treatment options. Nonetheless, recent advances in our understanding of T-cell biology, the identification of novel targets, and the emergence of new therapies provide hope for the future. In this review, we explore four areas of current and evolving antibody-based strategies for the treatment of peripheral T-cell lymphoma (PTCL): monoclonal antibodies (mAbs), bispecific antibodies (BsAs), chimeric antigen receptor T-cell therapy (CAR-T), and antibody-drug conjugates (ADCs). As part of this discussion, we will also include limitations, lessons learned, and potential future directions.

CCL17, CCL22 and their receptor CCR4 in hematologic malignancies

Hematological malignancies (HM) are common malignant tumors with high morbidity and mortality rates, and are malignant diseases that seriously affect human health, with chemotherapy prone to recurrence and toxic side effects. Therefore, the development of precise, effective, and safe targeted therapeutic agents has become a hotspot in the current research of antitumor technology. More and more studies have shown that the interaction of C-C chemokine ligand 17 (CCL17) and C-C chemokine ligand 22 (CCL22) with the receptor C-C chemokine receptor type 4 (CCR4) promotes the immune escape of tumors and is closely related to the occurrence, development, and prognosis of hematological tumors. In this regard, we present a review on the expression and role of the CCL17/CCL22-CCR4 axis in HM, including lymphoma, leukemia, and multiple myeloma, with the aim of providing latest ideas and directions for the diagnosis and treatment of HM. In addition, we discuss the role and related mechanisms of HM therapeutic agents targeting the CCL17/CCL22-CCR4 axis and the potential of humanized anti-CCR4 antibodies for the treatment of HM.

Immune-related adverse events associated with mogamulizumab: a comprehensive review of the literature

INTRODUCTION

Mogamulizumab is an anti-C-C chemokine receptor 4 antibody that is increasingly being used to treat T-cell malignancies such as cutaneous T-cell lymphoma, adult T-cell leukemia-lymphoma, and peripheral T-cell lymphoma. Because CCR4 is expressed on both malignant T-cells and regulatory T-cells (Tregs), mogamulizumab can be associated with increased immune-related adverse events (irAEs). While there is abundant literature on mogamulizumab-associated rash (MAR) and graft-versus-host disease (GVHD), other reported irAEs have not been collated into a single review.

AREAS COVERED

This narrative review covers irAEs associated with mogamulizumab in patients with T-cell lymphomas, focusing on events other than MAR and GVHD. We searched PubMed and Google Scholar for case reports, case series, chart reviews, and clinical trials published from inception to March 2024. Identified events include alopecia, vitiligo, arthritis, psoriasis, myocarditis, myositis/polymyositis, hepatitis, and others.

EXPERT OPINION

Mogamulizumab's ability to augment the host immune response through Treg depletion adds to its efficacy but has wide-ranging implications for autoimmunity across multiple organ systems, similar to immune checkpoint inhibitor therapy. Occurrence of irAEs may be associated with improved overall clinical response, although long-term follow-up studies are needed.

Atypical Presentation of Invasive Aspergillosis during Treatment with Mogamulizumab

Treatment with CCR-4 antagonists has been shown to be protective against the development of invasive pulmonary aspergillosis in animal models. Herein, we present a case of fatal invasive pulmonary aspergillosis in a patient receiving Mogamulizumab. A 64-year-old man with refractory mycosis fungoides was found to have diffuse bilateral pulmonary nodules during a chest CT in June 2022. Bronchoalveolar lavage (BAL) fungal and bacterial cultures and galactomannan were negative, as well as serum beta-glucan and galactomannan. Histology showed a lymphoid infiltrate with a negative fungal stain, so a presumptive diagnosis of lymphoma infiltration was made, and the patient started the CCR-4 antagonist Mogamulizumab treatment in August 2022. He had no symptoms until November when he presented to the hematology clinic reporting dyspnea. He had neutrophilic leukocytosis (18.610 cells/µL), his c-reactive protein was 27 mg/dL, and his skin lesions from mycosis fungoides were just starting to improve. A CT scan showed large diffuse bilateral severely necrotic cavitated lesions with thick walls and apparently synchronous evolution. Beta-glucan was 31 pg/mL (wako method), while serum galactomannan 3.6. BAL was positive for Aspergillus fumigatus culture and galactomannan. Patient started voriconazole but, despite being in a stable condition, he suddenly died after two days. Discussion: Paradoxically, worsening of the chronic pulmonary aspergillosis has been reported after nivolumab treatment, and immune reconstitution syndromes are usually seen during neutrophil recovery after intensive chemotherapy. Our patient already presented indolent lung lesions from 5 months before and he remained completely asymptomatic until the aspergillosis diagnosis when he quickly passed away. Even if a progression of the lesions was expected in 5 months, this case had an atypical presentation. During the 5-month period, he had no pulmonary symptoms, and his c-reactive protein was negative. Furthermore, in the setting of the natural progression of subacute/chronic aspergillosis, a different radiological picture was expected with a less severe and probably asynchronous evolution. We think that the immune restoration associated with Mogamulizumab (also supported by the concurrent clinical response of the skin lesions) could have been detrimental in this case, exacerbating a catastrophic immune response or alternatively masquerading the clinical progression of aspergillosis. Clinicians should be aware of immune reconstitution syndromes possibly leading to fatal outcomes in immunocompromised patients starting CCR-4 antagonists.

Flow cytometric profiles with CD7 and CADM1 in CD4+ T cells are promising indicators for prognosis of aggressive ATL

ABSTRACT

Adult T-cell leukemia/lymphoma (ATL) is a poor prognosis hematological malignancy originating from human T-cell leukemia virus 1 (HTLV-1)-infected CD4+ T cells. Flow cytometric plots of CADM1 and CD7 in CD4+ T cells are useful for separating HTLV-1-uninfected T cells and ATL cells. They are indicators of clonal evolution of HTLV-1-infected cells and disease progression of asymptomatic carriers or indolent ATL. However, the impacts of the plots on the clinical course or prognosis of ATL, especially in aggressive ATL, remain unclear. We focused on the N fraction (CD4+ CADM1+ CD7-) reflecting ATL cells and analyzed the flow cytometric profiles and clinical course of 497 samples from 92 HTLV-1-infected patients who were mainly aggressive ATL. The parameters based on N fractions showed significant correlations with known indicators of ATL disease status (soluble interleukin-2 receptor, lactate dehydrogenase, abnormal lymphocytes, etc.) and sensitively reflected the treatment response of aggressive ATL. The parameters based on N fractions significantly stratified the prognosis of aggressive ATL at 4 different time points: before treatment, after 1 course of chemotherapy, at the best response after chemotherapy, and before allogeneic hematopoietic cell transplantation. Even after mogamulizumab administration, which shows potent effects for peripheral blood lesions, the N fraction was still a useful indicator for prognostic estimation. In summary, this report shows that CADM1 vs CD7 plots in CD4+ T cells are useful indicators of the clinical course and prognosis of aggressive ATL. Therefore, this CADM1 and CD7 profile is suggested to be a useful prognostic indicator consistently from HTLV-1 carriers to aggressive ATL.

Safety and effectiveness of mogamulizumab in relapsed or refractory CC chemokine receptor 4-positive peripheral T-cell lymphoma and relapsed or refractory cutaneous T-cell lymphoma: A post-marketing surveillance in Japan

Mogamulizumab is a humanized antibody targeting CC chemokine receptor 4 (CCR4). This post-marketing surveillance was conducted in Japan as a regulatory requirement from 2014 to 2020 to ensure the safety and effectiveness of mogamulizumab in patients with relapsed or refractory (r/r) CCR4-positive peripheral T-cell lymphoma (PTCL) or r/r cutaneous T-cell lymphoma (CTCL). Safety and effectiveness data were collected for up to 31 weeks after treatment initiation. A total of 142 patients were registered; safety was evaluated in 136 patients. The median number of doses was 8.0 (range, 1-18). The main reasons for treatment termination were insufficient response (22.1%) and adverse events (13.2%). The frequency of any grade adverse drug reaction was 57.4%, including skin disorders (26.5%), infections and immune system disorders (16.2%), and infusion-related reactions (13.2%). Graft-versus-host disease, grade 2, developed in one of two patients who underwent allogeneic-hematopoietic stem cell transplantation after receiving mogamulizumab. Effectiveness was evaluated in 131 patients (103 with PTCL; 28 with CTCL). The best overall response rate was 45.8% (PTCL, 47.6%; CTCL, 39.3%). At week 31, the survival rate was 69.0% (95% confidence interval, 59.8%-76.5%) [PTCL, 64.4% (54.0%-73.0%); CTCL, 90.5% (67.0%-97.5%)]. Safety and effectiveness were comparable between patients <70 and ≥ 70 years old and between those with relapsed and refractory disease. The safety and effectiveness of mogamulizumab for PTCL and CTCL in the real world were comparable with the data reported in previous clinical trials. Clinical Trial Registration.

The tyrosine kinase KDR is essential for the survival of HTLV-1-infected T cells by stabilizing the Tax oncoprotein

Human T-cell leukemia virus type 1 (HTLV-1) infection is linked to the development of adult T-cell leukemia/lymphoma (ATLL) and the neuroinflammatory disease, HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP). The HTLV-1 Tax oncoprotein regulates viral gene expression and persistently activates NF-κB to maintain the viability of HTLV-1-infected T cells. Here, we utilize a kinome-wide shRNA screen to identify the tyrosine kinase KDR as an essential survival factor of HTLV-1-transformed cells. Inhibition of KDR specifically induces apoptosis of Tax expressing HTLV-1-transformed cell lines and CD4 + T cells from HAM/TSP patients. Furthermore, inhibition of KDR triggers the autophagic degradation of Tax resulting in impaired NF-κB activation and diminished viral transmission in co-culture assays. Tax induces the expression of KDR, forms a complex with KDR, and is phosphorylated by KDR. These findings suggest that Tax stability is dependent on KDR activity which could be exploited as a strategy to target Tax in HTLV-1-associated diseases.

Pooled analysis of pralatrexate single-agent studies in patients with relapsed/refractory peripheral T-cell lymphoma

ABSTRACT

Patients with relapsed or refractory (R/R) mature natural killer cell and T-cell lymphoma have limited treatment options. To evaluate pralatrexate's performance and factors influencing its safety and efficacy in R/R peripheral T-cell lymphoma (PTCL), we performed a pooled analysis of data from 4 similarly designed, regulatory-mandated prospective clinical trials. Of 221 patients (median age, 59 years; 67.0% male) in the study population, 48.9% had PTCL not otherwise specified (PTCL-NOS), 21.3% angioimmunoblastic T-cell lymphoma, and 11.8% ALK-negative anaplastic large cell lymphoma (ALCL). Patients received pralatrexate for a median of 2.56 months (range, 0.03-24.18) and had a 40.7% objective response rate with a median duration of response of 9.1 months, progression-free survival 4.6 months, and overall survival 16.3 months. The most common treatment-related all-grade adverse events were stomatitis, thrombocytopenia, white blood cell count decrease, pyrexia, and vomiting. Subgroup exploratory analyses suggest improved efficacy with 1 prior line of chemotherapy vs 2 or ≥4 prior lines; PTCL-NOS or ALCL vs transformed mycosis fungoides; chemotherapy and transplant before pralatrexate vs chemotherapy alone or chemotherapy with other nontransplant treatments. In conclusion, these pooled analysis results further support using pralatrexate in patients with R/R PTCL. Prospective studies are needed to confirm the findings of subgroups analyses.

Allogeneic hematopoietic stem cell transplantation after mogamulizumab in T-cell lymphoma patients: a retrospective analysis

Allogeneic hematopoietic stem cell transplantation (allo-HSCT) is an important therapy for patients with T-cell lymphomas, including cutaneous T-cell lymphoma (CTCL), adult T-cell lymphoma (ATL), and peripheral T-cell lymphoma (PTCL). Mogamulizumab is an anti-CCR4 antibody that has been associated with an increased risk of transplant-related complications in retrospective analyses of ATL, particularly when administered within 50 days before transplantation. This post hoc analysis of 3 clinical trials examined safety and outcome data for 32 patients with CTCL (n = 23), ATL (n = 7), or PTCL (n = 2) who underwent allo-HSCT after mogamulizumab treatment. Overall, 22 patients (69%) were known to have graft-versus-host disease (GVHD), 8 patients (25%) did not report GVHD, and 2 patients (6%) had unknown GVHD status. Fourteen patients with known GVHD underwent transplantation between 50 and 365 days after their last dose of mogamulizumab, while 2 underwent transplantation within 50 days after treatment. Based on this limited evidence, GVHD was not associated with the time interval from last mogamulizumab dose to transplantation.

Regulatory T-cells activated in metastatic draining lymph nodes possibly suppress cancer immunity in cancer tissues of head and neck squamous cell cancer

Regulatory T cells (Tregs) play an important role in creating an immunosuppressive microenvironment in cancer tissues. However, the mechanisms by which Tregs are activated and suppress cancer immunity remain unclear. To elucidate these mechanisms, we performed a T cell receptor (TCR) repertoire analysis of Tregs and conventional T cells in peripheral blood, draining lymph nodes (DLNs), and cancer tissues of patients with head and neck squamous cell cancer (HNSCC). We found that the TCR repertoire was skewed in cancer tissue and metastatic DLNs (M-DLNs) compared with non-metastatic DLNs, and TCR repertoire similarities in Tregs and CD8+ T cells between M-DLNs and cancer tissue were high compared with those at other sites. These results suggest that Tregs and CD8+ T cells are activated in M-DLNs and cancer tissues by cancer antigens, such as neoantigens, and shared antigens and Tregs suppress CD8+ T cell function in a cancer antigen-specific manner in M-DLNs and cancer tissue. Moreover, M-DLNs might be a source of Tregs and CD8+ T cells recruited into the cancer tissue. Therefore, targeting Tregs in M-DLNs in an antigen-specific manner is expected to be a novel immunotherapeutic strategy for HNSCCs.

Multicenter, randomized, double-blind, placebo-controlled phase 3 study of mogamulizumab with open-label extension study in a minimum number of patients with human T-cell leukemia virus type-1-associated myelopathy

Human T-cell leukemia virus type 1 (HTLV-1)-associated myelopathy/tropical spastic paraparesis (HAM/TSP) is a chronic neurodegenerative disease. This multicenter, randomized phase 3 study evaluated the efficacy and safety of 0.3 mg/kg intravenous mogamulizumab, a monoclonal antibody targeting-CC chemokine receptor 4, every 12 weeks in HAM/TSP patients. This study comprised a 24-week double-blind, placebo-controlled period, 24-week open-label period, and extension treatment period. The primary endpoint was the proportion of patients with a ≥ 1-grade improvement in the Osame motor disability score (OMDS). Secondary endpoints were changes in HTLV-1 proviral load, 10-m timed walk, cerebrospinal fluid (CSF) neopterin levels, and safety. The exploratory endpoint was CSF chemokine C-X-C motif ligand 10 (CXCL10) levels. Thirty-four and 33 patients were randomized to mogamulizumab and placebo arms, respectively. At the end of the double-blind period, no significant difference was found in the OMDS improvement rate or other secondary efficacy endpoints assessing motor activities. However, the mogamulizumab arm showed a significant decrease in HTLV-1 proviral load (- 59.39 ± 29.91% vs. placebo 2.32 ± 36.31%) and CSF neopterin (p < 0.001)/CXCL10 levels (p = 0.004). The baseline OMDS pattern and the 60-80% HTLV-1 proviral load reduction were sustained through the open-label and extension treatment periods. Although a higher incidence of rash (69.2%) was reported, the safety profile was similar compared with a previous phase 1/2a study. We found no significant difference in clinical benefit; however, mogamulizumab may provide long-term clinical benefit by preventing disease progression, as CSF neopterin/CXCL10 levels are associated with long-term prognosis in HAM/TSP.Clinical Trial Registration Number: NCT03191526 (registered date: 6-June-2017).

Stem cell therapy for HTLV-1 induced adult T-cell leukemia/lymphoma (ATLL): A comprehensive review

Adult T-cell leukemia/lymphoma (ATLL) is a rare and aggressive form of cancer associated with human T-cell lymphotropic virus type 1 (HTLV-1) infection. The emerging field of stem cell therapies for ATLL is discussed, highlighting the potential of hematopoietic stem cell transplantation (HSCT) and genetically modified stem cells. HSCT aims to eradicate malignant T-cells and restore a functional immune system through the infusion of healthy donor stem cells. Genetically modified stem cells show promise in enhancing their ability to target and eliminate ATLL cells. The article presents insights from preclinical studies and limited clinical trials, emphasizing the need for further research to establish the safety, efficacy, and long-term outcomes of stem cell therapies for ATLL and challenges associated with these innovative approaches are also explored. Overall, stem cell therapies hold significant potential in revolutionizing ATLL treatment, and ongoing clinical trials aim to determine their benefits in larger patient populations.

Clinical and Real-World Effectiveness of Mogamulizumab: A Narrative Review

Mogamulizumab (MOG) is an antibody targeting the CCR4 receptor, authorized for relapsed or refractory peripheral T-cell (PTCL) and cutaneous T-cell lymphomas (CTCL). Its adoption in guidelines and endorsement by FDA and EMA established it as a systemic treatment, especially for advanced disease stages due to its comparatively lower toxicity. Clinical trials and real-world evidence have underscored its efficacy in advanced CTCLs, including mycosis fungoides and Sézary syndrome; PTCLs; and adult T-cell leukemia/lymphoma (ATLL), showcasing positive outcomes. Notably, the drug has demonstrated significant response rates, disease stability, and extended periods of progression-free survival, suggesting its applicability in cases with multiple treatment lines. Its safety profile is generally manageable, with adverse events (AEs) primarily related to the skin, infusion-related reactions, drug eruptions, autoimmune diseases, and skin disorders. The latter seem to appear as CCR4 can promote the skin-specific homing of lymphocytes, and MOG is directed against this receptor. While combination with immunostimulatory agents like interferon alpha and interleukin 12 has shown promising results, caution is urged when combining with PD1 inhibitors due to the heightened risk of immune-mediated AEs. The introduction of MOG as a systemic treatment implies a significant advancement in managing these diseases, supported by its favorable safety profile and complementary mechanisms.

SOHO State-of-the-Art Updates and Next Questions: Treatment for Newly Diagnosed Peripheral T-Cell Lymphomas

Although a rare subset of non-Hodgkin lymphomas, peripheral T-cell lymphomas (PTCL) account for a disproportionate proportion of patient mortality. Conventional therapies are derived from experience treating aggressive B-cell lymphomas and center around CHOP-based chemotherapy. However, due to the unique biology and diverse subtypes of PTCL, most patients fail to durably respond to this approach and 5-year survival is only 20% to 30%. There have been multiple attempts to improve outcomes for patients with PTCL. Among the more successful strategies are the use of consolidative autologous stem cell transplant, the augmentation of CHOP with etoposide (CHOEP), and the use of brentuximab vedotin in CD30-positive PTCL. Advances in the understanding of histology-specific biology has cultivated enthusiasm to evaluate hypomethylating agents, histone deacetylate inhibitors, and phosphoinositol-3-kinase inhibitors in the frontline setting. Improvements in monitoring disease response and prognostication including the use of cell-free DNA, mutational profiling, and interim PET/CT imaging are also on the horizon. For patients with acute T-cell leukemia/lymphoma, the use of mogamulizumab-based therapy in the frontline setting may lead to advances in care. The true impact of these new-era therapies will only be elucidated as clinical practices incorporate the rapidly changing evidence.

Approaches for Increasing Cerebral Efflux of Amyloid-β in Experimental Systems

Amyloid protein-β (Aβ) concentrations are increased in the brain in both early onset and late onset Alzheimer's disease (AD). In early onset AD, cerebral Aβ production is increased and its clearance is decreased, while increased Aβ burden in late onset AD is due to impaired clearance. Aβ has been the focus of AD therapeutics since development of the amyloid hypothesis, but efforts to slow AD progression by lowering brain Aβ failed until phase 3 trials with the monoclonal antibodies lecanemab and donanemab. In addition to promoting phagocytic clearance of Aβ, antibodies lower cerebral Aβ by efflux of Aβ-antibody complexes across the capillary endothelia, dissolving Aβ aggregates, and a "peripheral sink" mechanism. Although the blood-brain barrier is the main route by which soluble Aβ leaves the brain (facilitated by low-density lipoprotein receptor-related protein-1 and ATP-binding cassette sub-family B member 1), Aβ can also be removed via the blood-cerebrospinal fluid barrier, glymphatic drainage, and intramural periarterial drainage. This review discusses experimental approaches to increase cerebral Aβ efflux via these mechanisms, clinical applications of these approaches, and findings in clinical trials with these approaches in patients with AD or mild cognitive impairment. Based on negative findings in clinical trials with previous approaches targeting monomeric Aβ, increasing the cerebral efflux of soluble Aβ is unlikely to slow AD progression if used as monotherapy. But if used as an adjunct to treatment with lecanemab or donanemab, this approach might allow greater slowing of AD progression than treatment with either antibody alone.

An update on the developments in the treatment of adult T-cell leukemia-lymphoma: current knowledge and future perspective

Adult T-cell leukemia-lymphoma is defined as peripheral T-cell lymphoma caused by the human T-cell leukemia virus type I. Adult T-cell leukemia-lymphoma is classified into indolent (favorable chronic or smoldering) or aggressive (acute, lymphoma or unfavorable chronic) types. This review discusses the therapeutic developments for patients with adult T-cell leukemia-lymphoma and unmet issues in treating adult T-cell leukemia-lymphoma. For indolent adult T-cell leukemia-lymphoma, a watchful waiting strategy is recommended until the disease progresses to aggressive adult T-cell leukemia-lymphoma. For aggressive adult T-cell leukemia-lymphoma, multi-agent chemotherapy with or without allogeneic hematopoietic stem cell transplantation has been recommended. However, many patients with adult T-cell leukemia-lymphoma relapse, and their prognosis is poor. Recently, novel agents, including mogamulizumab, lenalidomide, brentuximab vedotin, tucidinostat and valemetostat, have been approved for patients with relapsed or refractory aggressive adult T-cell leukemia-lymphoma, and the combination of mogamulizumab with multi-agent chemotherapy or brentuximab vedotin with cyclophosphamide, doxorubicin and prednisone has been approved for patients with untreated aggressive adult T-cell leukemia-lymphoma in Japan. Importantly, the aging of patients with adult T-cell leukemia-lymphoma has recently been reported, and no standard of care for elderly patients with adult T-cell leukemia-lymphoma has been established. New evidence must be obtained from prospective clinical trials to improve the prognosis of patients with adult T-cell leukemia-lymphoma.

Advancements in the treatment of mycosis fungoides and Sézary syndrome: monoclonal antibodies, immunotherapies, and Janus kinase inhibitors

Mycosis fungoides (MF) and Sézary syndrome (SS) are forms of cutaneous T cell lymphoma (CTCL) that pose significant challenges in their clinical management, particularly in refractory and advanced-stage disease. With the emergence of novel therapeutic modalities however, there are increasing opportunities to exploit the current understanding of pathophysiologic mechanisms of MF/SS for treatment. This review summarizes recent advances in the treatment of MF/SS, with a focus on monoclonal antibodies, immunotherapies, and Janus kinase (JAK) inhibitors, including ongoing clinical trials.

New Perspectives about Drug Candidates Targeting HTLV-1 and Related Diseases

Among the human T-lymphotropic virus (HTLV) types, HTLV-1 is the most prevalent, and it has been linked to a spectrum of diseases, including HAM/TSP, ATLL, and hyperinfection syndrome or disseminated strongyloidiasis. There is currently no globally standard first-line treatment for HTLV-1 infection and its related diseases. To address this, a comprehensive review was conducted, analyzing 30 recent papers from databases PubMed, CAPES journals, and the Virtual Health Library (VHL). The studies encompassed a wide range of therapeutic approaches, including antiretrovirals, immunomodulators, antineoplastics, amino acids, antiparasitics, and even natural products and plant extracts. Notably, the category with the highest number of articles was related to drugs for the treatment of ATLL. Studies employing mogamulizumab as a new perspective for ATLL received greater attention in the last 5 years, demonstrating efficacy, safe use in the elderly, significant antitumor activity, and increased survival time for refractory patients. Concerning HAM/TSP, despite corticosteroid being recommended, a more randomized clinical trial is needed to support treatment other than corticoids. The study also included a comprehensive review of the drugs used to treat disseminated strongyloidiasis in co-infection with HTLV-1, including their administration form, in order to emphasize gaps and facilitate the development of other studies aiming at better-directed methodologies. Additionally, docking molecules and computer simulations show promise in identifying novel therapeutic targets and repurposing existing drugs. These advances are crucial in developing more effective and targeted treatments against HTLV-1 and its related diseases.

Serum immunoglobulin and the threshold of Fc receptor-mediated immune activation

Antibodies can mediate immune recruitment or clearance of immune complexes through the interaction of their Fc domain with cellular Fc receptors. Clustering of antibodies is a key step in generating sufficient avidity for efficacious receptor recognition. However, Fc receptors may be saturated with prevailing, endogenous serum immunoglobulin and this raises the threshold by which cellular receptors can be productively engaged. Here, we review the factors controlling serum IgG levels in both healthy and disease states, and discuss how the presence of endogenous IgG is encoded into the functional activation thresholds for low- and high-affinity Fc receptors. We discuss the circumstances where antibody engineering can help overcome these physiological limitations of therapeutic antibodies. Finally, we discuss how the pharmacological control of Fc receptor saturation by endogenous IgG is emerging as a feasible mechanism for the enhancement of antibody therapeutics.

The Novel Link between Gene Expression Profiles of Adult T-Cell Leukemia/Lymphoma Patients' Peripheral Blood Lymphocytes and Ferroptosis Susceptibility

Ferroptosis, a regulated cell death dependent on iron, has garnered attention as a potential broad-spectrum anticancer approach in leukemia research. However, there has been limited ferroptosis research on ATL, an aggressive T-cell malignancy caused by HTLV-1 infection. Our study employs bioinformatic analysis, utilizing dataset GSE33615, to identify 46 ferroptosis-related DEGs and 26 autophagy-related DEGs in ATL cells. These DEGs are associated with various cellular responses, chemical stress, and iron-related pathways. Autophagy-related DEGs are linked to autophagy, apoptosis, NOD-like receptor signaling, TNF signaling, and the insulin resistance pathway. PPI network analysis revealed 10 hub genes and related biomolecules. Moreover, we predicted crucial miRNAs, transcription factors, and potential pharmacological compounds. We also screened the top 20 medications based on upregulated DEGs. In summary, our study establishes an innovative link between ATL treatment and ferroptosis, offering promising avenues for novel therapeutic strategies in ATL.

Human T-Cell Leukemia Virus Type 1 Oncogenesis between Active Expression and Latency: A Possible Source for the Development of Therapeutic Targets

The human T-cell leukemia virus type 1 (HTLV-1) is the only known human oncogenic retrovirus. HTLV-1 can cause a type of cancer called adult T-cell leukemia/lymphoma (ATL). The virus is transmitted through the body fluids of infected individuals, primarily breast milk, blood, and semen. At least 5-10 million people in the world are infected with HTLV-1. In addition to ATL, HTLV-1 infection can also cause HTLV-I-associated myelopathy (HAM/TSP). ATL is characterized by a low viral expression and poor prognosis. The oncogenic mechanism triggered by HTLV-1 is extremely complex and the molecular pathways are not fully understood. However, viral regulatory proteins Tax and HTLV-1 bZIP factor (HBZ) have been shown to play key roles in the transformation of HTLV-1-infected T cells. Moreover, several studies have shown that the final fate of HTLV-1-infected transformed Tcell clones is the result of a complex interplay of HTLV-1 oncogenic protein expression with cellular transcription factors that subvert the cell cycle and disrupt regulated cell death, thereby exerting their transforming effects. This review provides updated information on the mechanisms underlying the transforming action of HTLV-1 and highlights potential therapeutic targets to combat ATL.

Targeting Monocyte Derived CCL17 Attenuates Murine Crescentic Glomerulonephritis by Affecting Renal CCR4+ Regulatory T-Cell Recruitment

INTRODUCTION

The chemokine receptor CCR4 is expressed by diverse CD4+ T cell subsets including regulatory T cells (Tregs) but its functional importance for leukocyte recruitment and the relevance of its two corresponding chemokines CCL17 and CCL22 have not been studied in immune-mediated crescentic glomerulonephritis (cGN).

METHODS

Utilizing the single-cell RNA sequencing (scRNAseq) data in analyzing leukocytes isolated from both human and murine nephritic kidneys, we identified CCL17 as a potential therapeutic target in immune-mediated renal disease. Using a mouse model of murine cGN, we then delineated the effects of targeting CCL17 by neutralizing antibodies and in Ccl17 gene-deficient mice.

RESULTS

Unsupervised scRNAseq analyses identified the CCL17-CCR4 axis as a mechanism potentially involved in renal T-cell migration. Analyses of functional kidney impairment and histopathological kidney damage revealed an attenuation of crescentic GN in anti-CCL17 antibody-treated mice which was corroborated using in Ccl17 gene-deficient mice. Immunohistochemical analyses revealed that these changes were accompanied by an affected renal Treg recruitment in both experimental approaches.

CONCLUSION

The chemokine receptor CCR4 and its corresponding chemokine CCL17 are expressed in human and murine cGN and targeting the CCR4-CCL17 axis by neutralizing antibodies as well as Ccl17 gene deficiency led to increased renal Treg recruitment and reduced histological and functional kidney damage in murine cGN.

Integrated analysis of phase 1a and 1b randomized controlled trials; Treg-targeted cancer immunotherapy with the humanized anti-CCR4 antibody, KW-0761, for advanced solid tumors

INTRODUCTION

Regulatory T cells (Tregs) have attracted attention as a novel therapeutic target to augment the clinical efficacy of immunotherapy. We conducted phase Ia and Ib trials to examine the safety and efficacy of the anti-CCR4 antibody, KW-0761 (mogamulizumab), which may eliminate effector Tregs (eTregs). We herein overviewed the results of these trials, presented cases with a durable clinical response, and investigated factors associated with the clinical effects of KW-0761.

METHODS

Forty-nine patients with CCR4-negative solid cancers were enrolled in the phase Ia and Ib trials on KW-0761. An integral analysis of safety, clinical responses, prognosis, blood laboratory data, and cancer testis antigen-specific immune responses was performed.

RESULTS

Grade 3-4 treatment-related adverse events were reported in 21 (42.9%) out of 49 patients, all of which were manageable. A partial response and stable disease were observed in 1 and 9 patients, respectively. A durable clinical response was noted in 2 esophageal and 2 lung cancer patients. eTreg depletion in peripheral blood was confirmed in most patients, and eTreg depletion was sustained during the KW-0761 treatment. High lymphocyte levels at baseline and 2 weeks after the initiation of KW-0761 were associated with a favorable clinical outcome.

CONCLUSIONS

A durable clinical response was noted in some patients, and high lymphocyte levels before treatment initiation may be a biomarker for the efficacy of KW-0761. The synergistic effect of KW-0761 for depleting Tregs and other immunotherapies is expected in the future.

Oncoviruses: How do they hijack their host and current treatment regimes

Viruses have the ability to modulate the cellular machinery of their host to ensure their survival. While humans encounter numerous viruses daily, only a select few can lead to disease progression. Some of these viruses can amplify cancer-related traits, particularly when coupled with factors like immunosuppression and co-carcinogens. The global burden of cancer development resulting from viral infections is approximately 12%, and it arises as an unfortunate consequence of persistent infections that cause chronic inflammation, genomic instability from viral genome integration, and dysregulation of tumor suppressor genes and host oncogenes involved in normal cell growth. This review provides an in-depth discussion of oncoviruses and their strategies for hijacking the host's cellular machinery to induce cancer. It delves into how viral oncogenes drive tumorigenesis by targeting key cell signaling pathways. Additionally, the review discusses current therapeutic approaches that have been approved or are undergoing clinical trials to combat malignancies induced by oncoviruses. Understanding the intricate interactions between viruses and host cells can lead to the development of more effective treatments for virus-induced cancers.

Lenalidomide treatment for recurrent adult T-cell leukemia/lymphoma after allogeneic hematopoietic cell transplantation

Patients with recurrent adult T-cell leukemia/lymphoma (ATL) after allogeneic hematopoietic cell transplantation (allo-HCT) have a dismal prognosis. We retrospectively evaluated the safety and efficacy of lenalidomide (LEN) in 11 consecutive patients with recurrent ATL after allo-HCT. The median time from allo-HCT to ATL recurrence was 111 days (range, 20-1476), and that from allo-HCT to the initiation of LEN was 162 days (range, 43-1560). The median initial daily dose of LEN was 10 mg (range, 5-25), and the median duration of LEN treatment was 37 days (range, 3-1078). Three patients (27%) achieved complete response and two (18%) achieved partial response (PR). The rates of complete or PR according to the involved site were 57% for skin and 50% for nodal or extranodal lesions. With a median follow-up of 1033 days (range, 601-1465) among survivors, the 1-year probability of overall survival (OS) after ATL recurrence was 55%. Grade ≥3 toxicities included cytopenia (n = 4), superficial vein thrombosis (n = 1), and deep vein thrombosis (n = 1). Graft-versus-host disease (GVHD) newly developed in five patients (45%) and worsened in four patients (36%). The median duration from the initiation of LEN to GVHD onset or worsening was 5 days (range, 1-9). GVHD was manageable in all patients. Seven patients received mogamulizumab (MOG) for recurrent ATL before LEN treatment. The overall response rates to LEN were 57% in patients who had previously received MOG and 25% in those who had not. The 1-year probabilities of OS after recurrent ATL were 71% in patients who had previously received MOG and 25% in those who had not. Although cytopenia and GVHD are common among patients with recurrent ATL after allo-HCT, LEN may improve survival. Administering MOG before LEN may augment treatment efficacy in the allo-HCT population.

Treatment of Adult T-Cell Leukemia/Lymphoma: Established Paradigms and Emerging Directions

OPINION STATEMENT

Adult T-cell leukemia/lymphoma (ATL) is a rare, aggressive subtype of peripheral T-cell lymphoma developing after many years of chronic, asymptomatic infection with the retrovirus human T-cell lymphotropic virus type 1 (HTLV-1). HTLV-1 is endemic to certain geographic areas of the world, and primary infection generally occurs in infancy through mother-to-child transmission via breastfeeding. In less than 5% of infected individuals, a decades-long pathogenic process culminates in the development of ATL. Aggressive subtypes of ATL are life-threatening and challenging to treat, with median overall survival typically less than 1 year in the absence of allogeneic hematopoietic cell transplantation (alloHCT). Owing to the rarity of this illness, prospective large-scale clinical trials have been challenging to perform, and treatment recommendations are largely founded upon limited evidence. Herein, we review the current therapeutic options for ATL, providing a broad literature overview of the foremost clinical trials and reports of this disease. We emphasize our own treatment paradigm, which is broadly based upon disease subtype, patient fitness, and intent to perform alloHCT. Finally, we highlight recent advances in understanding ATL disease biology and important ongoing clinical trials that we foresee as informative and potentially practice-changing.

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.

Mouse Models for HTLV-1 Infection and Adult T Cell Leukemia

Adult T cell leukemia (ATL) is an aggressive hematologic disease caused by human T cell leukemia virus type 1 (HTLV-1) infection. Various animal models of HTLV-1 infection/ATL have been established to elucidate the pathogenesis of ATL and develop appropriate treatments. For analyses employing murine models, transgenic and immunodeficient mice are used because of the low infectivity of HTLV-1 in mice. Each mouse model has different characteristics that must be considered before use for different HTLV-1 research purposes. HTLV-1 Tax and HBZ transgenic mice spontaneously develop tumors, and the roles of both Tax and HBZ in cell transformation and tumor growth have been established. Severely immunodeficient mice were able to be engrafted with ATL cell lines and have been used in preclinical studies of candidate molecules for the treatment of ATL. HTLV-1-infected humanized mice with an established human immune system are a suitable model to characterize cells in the early stages of HTLV-1 infection. This review outlines the characteristics of mouse models of HTLV-1 infection/ATL and describes progress made in elucidating the pathogenesis of ATL and developing related therapies using these mice.

Prospects of early therapeutic interventions for indolent adult T-cell leukemia/lymphoma based on the chronic lymphocytic leukemia progression model

Adult T-cell leukemia/lymphoma (ATLL) has aggressive clinical behaviors, and improving its prognosis is a great challenge. A disease progression model from asymptomatic human T-cell leukemia virus type 1 carrier to aggressive-type ATLL has been proposed, and indolent ATLL comprising a smoldering or favorable chronic type is located at the midpoint. Even the most favorable smoldering type has a 4-year overall survival rate of <60%. Although watchful waiting is pervasive in patients with indolent ATLL, early therapeutic intervention is discussed among hematologists. Indolent ATLL was once termed T-cell-derived chronic lymphocytic leukemia (CLL). Unlike indolent ATLL, several molecular-targeted agents at the initial treatment have dramatically improved CLL prognosis. Recent studies on CLL have revealed a similar progression model involving premalignant monoclonal B-cell lymphocytosis (MBL). In particular, individuals with high-count MBL have an increased lymphoma risk. Considering the unsatisfactory long-term prognosis of indolent ATLL, further treatment strategies, including precision medicine, are warranted.

Integrated molecular and immunological features of human T-lymphotropic virus type 1 infection and disease progression to adult T-cell leukaemia or lymphoma

The human T-lymphotropic virus type 1 (HTLV-1) retrovirus infects 10-20 million people globally, with endemic regions in southwestern Japan, the Caribbean basin, Africa, and central Australia. HTLV-1 is associated with lifelong infection and immune suppression, resulting in a range of serious sequalae, including adult T-cell leukaemia or lymphoma (ATLL) in 5% of cases. To date, there are no preventive or curative treatments for HTLV-1 and treatment outcomes for ATLL remain generally poor. Depending on the disease subtype, overall survival is 8-55 months. Recent advancements in the past decade have identified genetic, molecular, and immunological events occurring throughout the lives of individuals infected with HTLV-1 and of those who progress to ATLL. In addition, updated guidelines for clinical management have been published. With the aim of focusing research efforts on the development of treatments for both HTLV-1 infections and ATLL, we have conceptualised a four-step disease model for HTLV-1-associated ATLL: (1) viral exposure, (2) establishment of chronic infection, (3) cellular transformation and evolution, and (4) disease presentation and management. For each stage we describe the clinical features, molecular and immunological factors involved, potential biomarkers of disease progression, and the therapeutic applicability of individual targets. We also discuss emerging concepts and novel treatment approaches. Our hope is that this model will promote research interest and guide the testing of new treatments for this neglected virus and its associated rare cancer.