New Orders to an Old Soldier: Optimizing NK Cells for Adoptive Immunotherapy in Hematology

The Role of NK Cells in Cancer Immunotherapy: Mechanisms, Evasion Strategies, and Therapeutic Advances

Background/Objectives: Natural killer (NK) cells play a crucial role in tumor surveillance by exerting cytotoxic activity and modulating immune responses. However, tumors employ diverse evasion strategies that limit NK cell effectiveness. This review aims to explore the molecular mechanisms of NK cell activation and inhibition in cancer, the influence of the tumor microenvironment, and the latest advancements in NK cell-based immunotherapies, including adoptive NK cell transfer and Chimeric Antigen Receptor-Natural Killer (CAR-NK) cell therapies. Methods: A comprehensive literature review was conducted, prioritizing peer-reviewed studies from the last decade on NK cell biology, tumor immune evasion, and immunotherapeutic applications. The analysis includes data from preclinical models and clinical trials evaluating NK cell expansion strategies, cytokine-based stimulation, and CAR-NK cell therapy developments. Results: NK cells eliminate tumors through cytotoxic granule release, death receptor pathways, and cytokine secretion. However, tumor cells evade NK-mediated immunity by downregulating activating ligands, secreting immunosuppressive molecules, and altering the tumor microenvironment. Novel NK cell-based therapies, such as CAR-NK cells and combination approaches with immune checkpoint inhibitors, enhance NK cell persistence and therapeutic efficacy against both hematologic and solid malignancies. Clinical trials suggest improved safety profiles compared to CAR-T therapies, with reduced cytokine release syndrome and graft-versus-host disease. Conclusions: While NK cell-based immunotherapies hold great promise, challenges remain, including limited persistence and tumor-induced immunosuppression. Addressing these hurdles will be critical for optimizing NK cell therapies and advancing next-generation, off-the-shelf immunotherapeutics for broader clinical applications.

Structural Characteristics and Immunomodulatory Effects of Melanoidins from Black Garlic

Melanoidins are considered to have several biological activities. In this study, black garlic melanoidins (MLDs) were collected using ethanol solution extraction; 0%, 20%, and 40% ethanol solutions were used for chromatography. Three kinds of melanoidins were produced by macroporous resin, named MLD-0, MLD-20, and MLD-40. The molecular weight was determined, and the infrared and microscopic structures were studied. In addition, Balb/c mice were induced with cyclophosphamide (CTX) to establish an immune deficiency model to evaluate the immune efficacy of black garlic melanoidins (MLDs). The results showed that MLDs restored the proliferation and phagocytosis ability of macrophages, and the proliferation activity of B lymphocytes in the MD group was 63.32% (♀) and 58.11% (♂) higher than that in the CTX group, respectively. In addition, MLDs alleviated the abnormal expression of serum factors such as IFN-γ, IL-10, and TNF-α. 16SrDNA sequencing of intestinal fecal samples of mice showed that MLDs changed the structure and quantity of intestinal flora, and especially that the relative abundance of Bacteroidaceae was significantly increased. The relative abundance of Staphylococcaceae was significantly reduced. These results showed that MLDs improved the diversity of intestinal flora in mice, and improved the adverse state of immune organs and immune cells. The experiments confirm that black garlic melanoidins have potential value in immune activity, which provides an important basis for the development and utilization of melioidosis.

The application of autologous cancer immunotherapies in the age of memory-NK cells

Cellular immunotherapy has revolutionized the oncology field, yielding improved results against hematological and solid malignancies. NK cells have become an attractive alternative due to their capacity to activate upon recognition of "stress" or "danger" signals independently of Major Histocompatibility Complex (MHC) engagement, thus making tumor cells a perfect target for NK cell-mediated cancer immunotherapy even as an allogeneic solution. While this allogeneic use is currently favored, the existence of a characterized memory function for NK cells ("memory-like" NK cells) advocates for an autologous approach, that would benefit from the allogeneic setting discoveries, but with added persistence and specificity. Still, both approaches struggle to exert a sustained and high anticancer effect in-vivo due to the immunosuppressive tumor micro-environment and the logistical challenges of cGMP production or clinical deployment. Novel approaches focused on the quality enhancement and the consistent large-scale production of highly activated therapeutic memory-like NK cells have yielded encouraging but still unconclusive results. This review provides an overview of NK biology as it relates to cancer immunotherapy and the challenge presented by solid tumors for therapeutic NKs. After contrasting the autologous and allogeneic NK approaches for solid cancer immunotherapy, this work will present the current scientific focus for the production of highly persistent and cytotoxic memory-like NK cells as well as the current issues with production methods as they apply to stress-sensitive immune cells. In conclusion, autologous NK cells for cancer immunotherapy appears to be a prime alternative for front line therapeutics but to be successful, it will be critical to establish comprehensives infrastructures allowing the production of extremely potent NK cells while constraining costs of production.

Are we there yet? cellular therapies for cutaneous T cell lymphoma

Cutaneous T cell lymphomas (CTCLs) are a heterogenous group of skin-involved T-cell non-Hodgkin lymphoma which Mycosis Fungoides and Sezary Syndrome are the most common variants. Despite considerable progress in distinguishing the pathophysiology, the treatment options are still limited for advanced-stage disease. Recent approval of novel agents such as vorinostat, brentuximab vedotin and mogamulizumab paved a way. Allogeneic hematopoietic stem cell transplantation has been shown to be a feasible option in selected advanced-stage CTCL patients. Chimeric antigen receptor (CAR) T cells have been promising for the treatment of B-cell tumors and have been approved for second-line treatment in non-Hodgkin's lymphoma. Although several obstacles still need to be addressed, CAR T cell treatment for CTCLs seems not far off. This review discusses new discoveries in pathophysiology, the state of cellular therapies in current practice, challenges for cellular treatment in advanced CTCL, and how to overcome these challenges.

Histone deacetylases (HDACs) as the promising immunotherapeutic targets for hematologic cancer treatment

Bone marrow transplantation is regarded as the most effective immunotherapy for hematologic cancer, but it generally faces difficulties in matching. Aberrant expression of histone deacetylases (HDACs) is closely related to the occurrence and development of hematological cancer. Recent studies suggested that HDACs might play a critical role in initiating anti-cancer immune response or enhancing anti-cancer immunotherapy. Besides, combining HDAC inhibition and immunotherapy could prevent immunotherapy resistance in some degree and reach an extended treatment window. This review summarized the relationship between HDACs and immune and described the current understanding of HDACs in immunotherapy for hematologic cancer.