Challenges and innovations in CAR-T cell therapy: a comprehensive analysis.

Recent years have seen a marked increase in research on chimeric antigen receptor T (CAR-T) cells, with specific relevance to the treatment of hematological malignancies. Here, the structural principles, iterative processes, and target selection of CAR-T cells for therapeutic applications are described in detail, as well as the challenges faced in the treatment of solid tumors and hematological malignancies. These challenges include insufficient infiltration of cells, off-target effects, cytokine release syndrome, and tumor lysis syndrome. In addition, directions in the iterative development of CAR-T cell therapy are discussed, including modifications of CAR-T cell structures, improvements in specificity using multi-targets and novel targets, the use of Boolean logic gates to minimize off-target effects and control toxicity, and the adoption of additional protection mechanisms to improve the durability of CAR-T cell treatment. This review provides ideas and strategies for the development of CAR-T cell therapy through an in-depth exploration of the underlying mechanisms of action of CAR-T cells and their potential for innovative modification.

Tumor microenvironment: barrier or opportunity towards effective cancer therapy.

Tumor microenvironment (TME) is a specialized ecosystem of host components, designed by tumor cells for successful development and metastasis of tumor. With the advent of 3D culture and advanced bioinformatic methodologies, it is now possible to study TME's individual components and their interplay at higher resolution. Deeper understanding of the immune cell's diversity, stromal constituents, repertoire profiling, neoantigen prediction of TMEs has provided the opportunity to explore the spatial and temporal regulation of immune therapeutic interventions. The variation of TME composition among patients plays an important role in determining responders and non-responders towards cancer immunotherapy. Therefore, there could be a possibility of reprogramming of TME components to overcome the widely prevailing issue of immunotherapeutic resistance. The focus of the present review is to understand the complexity of TME and comprehending future perspective of its components as potential therapeutic targets. The later part of the review describes the sophisticated 3D models emerging as valuable means to study TME components and an extensive account of advanced bioinformatic tools to profile TME components and predict neoantigens. Overall, this review provides a comprehensive account of the current knowledge available to target TME.

COVID-19 immunotherapy: Treatment based on the immune cell-mediated approaches.

Multiple efforts are currently underway to control and treat severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), causing coronavirus disease 2019 (COVID-19) worldwide. Despite all efforts, the virus that emerged in Wuhan city has rapidly spread globally and led to a public health emergency of international concern (PHEIC) due to the lack of approved antiviral therapy. Nevertheless, SARS-CoV-2 has had a significant influence on the evolution of cellular therapeutic approaches. Adoptive immune cell therapy is innovative and offers either promising prophylactic or therapy for patients with moderate-to-severe COVID-19. This approach is aimed at developing safety and providing secure and effective therapy in combination with standard therapy for all COVID-19 infected individuals. Based on the effective results of previous studies on both inflammatory and autoimmune diseases, various immune cell therapies against COVID-19 have been reviewed and discussed. It must be considered that the application of cell therapy for treatment and to eliminate infected respiratory cells could result in excessive inflammation, so this treatment must be used in combination with other treatments, despite its many beneficial efforts.

Optimization of Large-Scale Expansion and Cryopreservation of Human Natural Killer Cells for Anti-Tumor Therapy.

Allogeneic natural killer (NK) cell therapy is a potential therapeutic approach for a variety of solid tumors. We established an expansion method for large-scale production of highly purified and functionally active NK cells, as well as a freezing medium for the expanded NK cells. In the present study, we assessed the effect of cryopreservation on the expanded NK cells in regards to viability, phenotype, and anti-tumor activity. NK cells were enormously expanded (about 15,000-fold expansion) with high viability and purity by stimulating CD3+ T cell-depleted peripheral blood mononuclear cells (PBMCs) with irradiated autologous PBMCs in the presence of IL-2 and OKT3 for 3 weeks. Cell viability was slightly reduced after freezing and thawing, but cytotoxicity and cytokine secretion were not significantly different. In a xenograft mouse model of hepatocellular carcinoma cells, cryopreserved NK cells had slightly lower anti-tumor efficacy than freshly expanded NK cells, but this was overcome by a 2-fold increased dose of cryopreserved NK cells. In vivo antibody-dependent cell cytotoxicity (ADCC) activity of cryopreserved NK cells was also demonstrated in a SCID mouse model injected with Raji cells with rituximab co-administration. Therefore, we demonstrated that expanded/frozen NK cells maintain viability, phenotype, and anti-tumor activity immediately after thawing, indicating that expanded/frozen NK cells can provide 'ready-to-use' cell therapy for cancer patients.

Phase I clinical trial of adoptive transfer of expanded natural killer cells in combination with IgG1 antibody in patients with gastric or colorectal cancer.

Natural killer (NK) cells exhibit strong cytotoxic activity against tumor cells without prior sensitization, and have the potential to exert antibody-dependent cellular cytotoxicity (ADCC). In this clinical trial, we examined the safety and efficacy of the use of NK cells, generated using a novel expansion system, in combination with IgG1 antibodies for the treatment of advanced gastric or colorectal cancers. Treatment consisted of trastuzumab- or cetuximab-based chemotherapy, plus adoptive NK cell therapy. For administration of expanded NK cells, dose escalation with a sequential 3 + 3 design was performed in three steps, at doses of 0.5 × 109 , 1.0 × 109 , and 2.0 × 109 cells/injection (N = 9). After 3 days of IgG1 antibody administration, patients were infused with expanded NK cells three times at triweekly intervals. NK cell populations expanded with our system were confirmed as being enriched in NK cells (median 92.9%) with high expression of NKG2D (97.6%) and CD16 (69.6%). The combination therapy was very well tolerated with no severe adverse events. Among six evaluable patients, four presented stable disease (SD) and two presented progressive disease. Of the four SD patients, three showed an overall decrease in tumor size after combination therapy. Immune monitoring suggested that combination therapy enhanced whole blood IFN-γ production and reduced peripheral regulatory T cells (Tregs). In conclusion, this phase I trial provides evidence of good tolerability, induction of Th1 immune responses, and preliminary anti-tumor activity for this combination therapy, in patients with advanced gastric and colorectal cancer that have received previous therapy.

Optimization of Large-Scale Expansion and Cryopreservation of Human Natural Killer Cells for Anti-Tumor Therapy

Allogeneic natural killer (NK) cell therapy is a potential therapeutic approach for a variety of solid tumors. We established an expansion method for large-scale production of highly purified and functionally active NK cells, as well as a freezing medium for the expanded NK cells. In the present study, we assessed the effect of cryopreservation on the expanded NK cells in regards to viability, phenotype, and anti-tumor activity. NK cells were enormously expanded (about 15,000-fold expansion) with high viability and purity by stimulating CD³⁺ T cell-depleted peripheral blood mononuclear cells (PBMCs) with irradiated autologous PBMCs in the presence of IL-2 and OKT3 for 3 weeks. Cell viability was slightly reduced after freezing and thawing, but cytotoxicity and cytokine secretion were not significantly different. In a xenograft mouse model of hepatocellular carcinoma cells, cryopreserved NK cells had slightly lower anti-tumor efficacy than freshly expanded NK cells, but this was overcome by a 2-fold increased dose of cryopreserved NK cells. In vivo antibody-dependent cell cytotoxicity (ADCC) activity of cryopreserved NK cells was also demonstrated in a SCID mouse model injected with Raji cells with rituximab co-administration. Therefore, we demonstrated that expanded/frozen NK cells maintain viability, phenotype, and anti-tumor activity immediately after thawing, indicating that expanded/frozen NK cells can provide ‘ready-to-use’ cell therapy for cancer patients.