Bispecific human IL2-CCR4 immunotoxin targets human cutaneous T-cell lymphoma

"Next top" mouse models advancing CTCL research

This review systematically describes the application of in vivo mouse models in studying cutaneous T-cell lymphoma (CTCL), a complex hematological neoplasm. It highlights the diverse research approaches essential for understanding CTCL's intricate pathogenesis and evaluating potential treatments. The review categorizes various mouse models, including xenograft, syngeneic transplantation, and genetically engineered mouse models (GEMMs), emphasizing their contributions to understanding tumor-host interactions, gene functions, and studies on drug efficacy in CTCL. It acknowledges the limitations of these models, particularly in fully replicating human immune responses and early stages of CTCL. The review also highlights novel developments focusing on the potential of skin-targeted GEMMs in studying natural skin lymphoma progression and interactions with the immune system from onset. In conclusion, a balanced understanding of these models' strengths and weaknesses are essential for accelerating the deciphering of CTCL pathogenesis and developing treatment methods. The GEMMs engineered to target specifically skin-homing CD4+ T cells can be the next top mouse models that pave the way for exploring the effects of CTCL-related genes.

Toxicology, pharmacokinetics, and immunogenicity studies of CCR4-IL2 bispecific immunotoxin in rats and minipigs

We have developed a diphtheria toxin-based recombinant human CCR4-IL2 bispecific immunotoxin (CCR4-IL2-IT) for targeted therapy of cutaneous T-cell lymphoma (CTCL). CCR4-IL2-IT demonstrated superior efficacy in an immunodeficient mouse CTCL model. Recently, we have compared the in vivo efficacy of CCR4-IL2-IT versus Brentuximab (FDA approved leading drug in CTCL market) in the same immunodeficient mouse CTCL model. The comparison demonstrated that CCR4-IL2-IT was significantly more effective than Brentuximab. In this study, we have performed non-GLP (Good Laboratory Practice) toxicology, pharmacokinetics, immunogenicity studies of CCR4-IL2-IT in both rats and minipigs. CCR4-IL2-IT demonstrated excellent safety profiles in both rats and minipigs. The maximum tolerated dose of CCR4-IL2-IT was determined as 0.4 mg/kg in both rats and minipigs. Complete blood count and chemistry analysis did not show significant difference for all measured parameters between the blood samples of pre-injection versus post-injection from the five-day toxicology studies of CCT4-IL2-IT in both rats and minipigs. Histology analysis did not show difference between the PBS treatment group versus CCR4-IL2-IT treatment group at 50 μg/kg in both rats and minipigs. The half-life of CCR4-IL2-IT was determined as about 45 min in rats and 30 min in minipigs. The antibodies against CCR4-IL2-IT were detected in about two weeks after CCR4-IL2-IT treatment. CCR4-IL2-IT did not induce cytokine release syndrome in a peripheral blood mononuclear cell derived humanized mouse model. The depletion of CCR4+ cell and CD25+ cell (two target cell populations of CCR4-IL2-IT) was observed in minipigs. The excellent safety profile promoted us to further develop CCR4-IL2-IT towards clinical trials.

Drug conjugates for targeting regulatory T cells in the tumor microenvironment: guided missiles for cancer treatment

Within the tumor microenvironment (TME), regulatory T cells (Tregs) play a key role in suppressing anticancer immune responses; therefore, various strategies targeting Tregs are becoming important for tumor therapy. To prevent the side effects of nonspecific Treg depletion, such as immunotherapy-related adverse events (irAEs), therapeutic strategies that specifically target Tregs in the TME are being investigated. Tumor-targeting drug conjugates are efficient drugs in which a cytotoxic payload is assembled into a carrier that binds Tregs via a linker. By allowing the drug to act selectively on target cells, this approach has the advantage of increasing the therapeutic effect and minimizing the side effects of immunotherapy. Antibody-drug conjugates, immunotoxins, peptide-drug conjugates, and small interfering RNA conjugates are being developed as Treg-targeting drug conjugates. In this review, we discuss key themes and recent advances in drug conjugates targeting Tregs in the TME, as well as future design strategies for successful use of drug conjugates for Treg targeting in immunotherapy.

Truncated Diphtheria Toxin DT390 Enhances the Humoral Immunogenicity of Porcine Circovirus Type 2 Capsid Antigen in Mice

Porcine circovirus type 2 (PCV2) is the causative agent of PCV-associated disease, which harms the swine industry worldwide. Open reading frame 2 of PCV2 encodes the principal immunogenic capsid (Cap) protein, which induces neutralizing antibodies and protective immunity. Cap has been developed as a subunit vaccine against PCV2 infection, although its use is hindered by low immunogenicity. Here, we hypothesized that the truncated diphtheria toxin DT390 might enhance the immunogenicity of Cap. To verify this hypothesis, we fused Cap with DT390, which was expressed using the unique diphtheria toxin-resistant Pichia pastoris expression system. We assessed the immunogenicity of DT390-Cap using BALB/c mice. DT390-Cap induced significantly higher Cap-specific and neutralizing antibodies than Cap alone with or without the ISA201 adjuvant. DT390-Cap with ISA201 adjuvant induced production of more Cap-specific antibodies and neutralizing antibodies than Ingelvac CircoFLEX (positive control). DT390-Cap induced slightly higher Th2-associated interleukin-4 production than Cap alone but did not affect Th1-associated interferon-γ production. The protection study demonstrated that DT390-Cap induced more effective protective immunity than Cap alone, when challenged with PCV2. The viral loads in the lungs, liver, and thymus in mice immunized using DT390-Cap were significantly lower than in those immunized with the corresponding Cap with or without the ISA201 adjuvant. Taken together, the engineered DT390 effectively enhanced the immunogenicity and protective immunity of Cap in mice. Thus, DT390-Cap is a promising novel vaccine candidate against PCV2 infection.

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.