LongeCityNews Last Updated: 07 March 2025 - 03:31 AM

A chimeric antigen receptor (CAR) T cell has been genetically engineered to express a receptor that both binds to a desired target, such as a distinctive surface feature on a cancer cell, and activates the T cell once bound, provoking it into destroying the target. Making this technology into a therapy involves sampling a patient's T cells, incorporating the new CAR gene, then expanding the cells in culture, and introducing them back into the patient. This is an expensive proposition, but has performed well in blood cancers.

Unfortunately, blood cancers are very different in character from the many other forms of cancer that form solid tumors. The cells making up a solid tumor deploy many different strategies to hide from, subvert, suppress, and co-opt the immune system, even inducing immune cells to aid in its growth in some cases, and can rapidly evolve new strategies. Throwing more immune cells at the tumor, even immune cells specifically equipped to recognize tumor cells as a target, often fails.

Nonetheless, CAR-T therapies have worked so very well in their initial uses that a great deal of effort is going into trying to make them work for solid tumors - or if this fails, to understand why it failed, and how to work around the problem. As today's open access paper notes, some of these efforts are aimed at equipping different types of immune cell with chimeric antigen receptors. How well this will work given the nature of the relationship between tumors and the immune system remains to be seen, but hope springs eternal.

Chimeric Antigen Receptor Cell Therapy: Empowering Treatment Strategies for Solid Tumors

CAR-T cell therapy has revolutionized blood cancer treatment, but its application in solid tumors faces challenges, resulting in limited effectiveness and inconsistent outcomes in real-world situations. The disparity between clinical trial results and real-world outcomes underscores the complexity of CAR-T cell therapy for treating solid tumors. Second and third generations of CAR-T cell therapy mark advancements in solid tumor treatment. Second-generation cells incorporate co-stimulatory domains, enhancing T cell activation and persistence in the fight against cancer cells. Third-generation cells combine multiple domains, which may enhance the anti-tumor response. These advancements aim to overcome limitations in solid tumors.

The design of CARs is modular, comprising an antigen-binding domain, a hinge, and a transmembrane domain, along with an intracellular signaling domain. CAR-T cell therapy is a promising cancer treatment that targets specific antigens on tumor cells, enabling the identification of cell surface proteins without depending on the major histocompatibility complex (MHC). However, the effectiveness of CAR-T therapy depends on the presence of specific human leukocyte antigen (HLA) types, limiting its application to a restricted patient population. CAR-T cells exhibit sensitivity to reduced HLA expression and flaws in the antigen processing pathway, tactics employed by tumor cells to escape immune responses. Initial iterations of CARs featured solely a T cell activation domain; however, subsequent designs have incorporated signaling domains from co-stimulatory molecules. CARs are classified as either second- or third-generation based on the quantity of co-stimulatory molecules present.

Despite these challenges, understanding real-world experiences is crucial in optimizing CAR-T cell therapy for solid tumors. Tumor heterogeneity and immune evasion are crucial concepts in cancer biology and treatment resistance. Tumor heterogeneity refers to the diverse characteristics of cancer cells within a single tumor, influencing their interactions with the immune system. Cellular plasticity, particularly dedifferentiation, helps tumors to evade detection. Further exploration and innovation are needed to enhance its effectiveness in this area.

When CAR-T therapy fails, the exploration of alternative options like CAR-NK, CAR-iNKT, or CAR-M therapies becomes increasingly relevant in the landscape of cancer treatment. CAR-NK cells retain natural cytotoxicity, allowing them to target tumors even when cancer cells downregulate antigen expression. CAR-iNKT cells combine natural killer T cells with CAR technology, enhancing effectiveness against various tumors while minimizing toxicity. CAR-M cells, derived from macrophages, penetrate tumors more effectively and exhibit enhanced antitumor efficacy with reduced toxicity. These therapies offer distinct advantages for personalized cancer immunotherapy.

CAR-NK cells present numerous benefits when contrasted with CAR-T cells. Production can occur using established cell lines or allogeneic NK cells that lack matched MHC. Furthermore, they possess the ability to eradicate cancer cells through both CAR-dependent and CAR-independent pathways, while demonstrating diminished toxicity, especially regarding cytokine release syndrome and neurotoxicity. Macrophages infiltrate tumors adeptly, act as crucial immune regulators, and are plentiful within the tumor microenvironment. There is significant enthusiasm surrounding the advancement of CAR macrophages for cancer immunotherapy, aimed at tackling critical challenges associated with CAR T/NK therapy, especially in the context of solid tumors.

In Molecular Therapy, a team of researchers has described how increasing the expression of a form of Klotho, a protein that has been frequently found to have rejuvenative effects, leads to longer lifespans in male mice.

Klotho has various forms

In their introduction, the researchers distinguish between the various forms of Klotho. The full mRNA sequence that generates Klotho creates two homologous effective sections (KL1 and KL2) and a membrane that is meant for transportation between cells: this full version is m-KL [1]. Once enzymes take away this membrane, however, it becomes p-KL, with each section being p-KL1 and p-KL2.

However, this full version interferes with the function of FGF23, a protein that manages the metabolism of minerals [2]. Artificially upregulating this protein, therefore, is not safe [3].

Another form of Klotho, secreted Klotho (s-KL), does not have this problem. s-KL has been found to have multiple anti-aging effects according to a review of 65 studies [4]. Of course, without the transmembrane protein, it is not fit for intercellular transportation. Therefore, the researchers used an adeno-associated virus (AAV) to deliver a gene therapy that upregulates Klotho in the mice in this experiment.

Improvements in lifespan

The researchers used a total of 96 mice of the Black 6 strain: a group that received the AAV at 6 months, a group that received the AAV at 12 months, and a control group that received an ineffective AAV at 6 months. Both male and female mice were included in this experiment.

The treatment had far different effects in males and females. In female mice, the treatment had similar effects at 6 months and 12 months, but the increase in s-KL was accompanied by serious health problems during the course of the experiment, including skin ulcers and bleeding from the anus. In male mice, the AAV upregulated s-KL much more than in female mice, and it was much more effective at 12 months than at 6 months. Despite having far more s-KL, the males did not experience any of the health problems that the females did; instead, they received significant improvements to their lifespan.

Improvements to tissues and performance

Interestingly, at the age of 24 months, females showed improvements on the rotarod balance test that males did not. Both sexes given the s-KL AAV at 12 months were able to hold onto a horizontal bar longer than their control groups. In a three-trial grip strength test, the AAV-treated males performed far better, while the females performed better during only the first trial. The males also had significant reductions in fibrosis.

Regeneration capability was tested by transplanting muscles from old mice into younger mice. The muscle fibers in the AAV-treated animals became much larger than those from the control group. Muscles derived from the animals treated at 6 months old grew a wider variety of fiber sizes than those derived from animals treated at 12 months. Proliferation markers, and markers relating to a muscle-related fate of stem cells, were increased in the muscles derived from the mice that had received the s-KL AAV.

The researchers also tested bone tissue, seeing significant improvements to bone structure in females treated at 6 months and non-significant improvements in males treated at 12 months. Curiously, while FGF23 was upregulated along with many other bone-related factors in male mice, it was downregulated in female mice. This may be beneficial for females, as age-related increases in FGF23 have been linked to osteoporosis [5].

While no behavior testing was done in this study, the researchers did examine the mice’s brains. They found that, in the treated animals, there were more functional neurons and a thicker cellular layer, and markers of cellular proliferation were increased in the hippocampus. An examination of differently expressed genes revealed that the treated animals had fewer age-related changes than the control group.

The researchers note that this is the first time an AAV for s-KL has demonstrated lifespan increases in wild-type mice; previous experiments used transgenic mice. They believe that further experiments should test mice with different genetic backgrounds, because the side effects they saw in this experiment may or may not be limited to the AAV’s effects on Black 6 mice. Further work may elucidate exactly why klotho treatment has such different effects on males and females.

Literature

[1] Chen, C. D., Tung, T. Y., Liang, J., Zeldich, E., Tucker Zhou, T. B., Turk, B. E., & Abraham, C. R. (2014). Identification of cleavage sites leading to the shed form of the anti-aging protein klotho. Biochemistry, 53(34), 5579-5587.

[2] Kurosu, H., Ogawa, Y., Miyoshi, M., Yamamoto, M., Nandi, A., Rosenblatt, K. P., … & Kuro-o, M. (2006). Regulation of fibroblast growth factor-23 signaling by klotho. Journal of Biological Chemistry, 281(10), 6120-6123.

[3] Roig-Soriano, J., Sánchez-de-Diego, C., Esandi-Jauregui, J., Verdés, S., Abraham, C. R., Bosch, A., … & Chillón, M. (2023). Differential toxicity profile of secreted and processed α-Klotho expression over mineral metabolism and bone microstructure. Scientific reports, 13(1), 4211.

[4] Abraham, C. R., & Li, A. (2022). Aging-suppressor Klotho: Prospects in diagnostics and therapeutics. Ageing Research Reviews, 82, 101766.

[5] Sirikul, W., Siri-Angkul, N., Chattipakorn, N., & Chattipakorn, S. C. (2022). Fibroblast growth factor 23 and osteoporosis: evidence from bench to bedside. International Journal of Molecular Sciences, 23(5), 2500.

The blood-brain barrier surrounds blood vessels passing through the brain and tightly controls which molecules are allowed to pass. It separates the metabolism of the brain from that of the rest of the body. With age, the blood-brain barrier becomes dysfunctional, allowing unwanted cells and molecules to leak into the brain, where they contribute to the chronic inflammation of brain tissue. Researchers here focus on the structure of one specific thin layer of the blood-brain barrier, note that it becomes dysregulated with age, and find a way to improve its function via gene therapy.

The blood-brain barrier (BBB) is highly specialized to protect the brain from harmful circulating factors in the blood and maintain brain homeostasis. The brain endothelial glycocalyx layer, a carbohydrate-rich meshwork composed primarily of proteoglycans, glycoproteins and glycolipids that coats the BBB lumen, is a key structural component of the BBB. This layer forms the first interface between the blood and brain vasculature, yet little is known about its composition and roles in supporting BBB function in homeostatic and diseased states.

Here we find that the brain endothelial glycocalyx is highly dysregulated during ageing and neurodegenerative disease. We identify significant perturbation in an underexplored class of densely O-glycosylated proteins known as mucin-domain glycoproteins. We demonstrate that ageing- and disease-associated aberrations in brain endothelial mucin-domain glycoproteins lead to dysregulated BBB function and, in severe cases, brain haemorrhaging in mice. Finally, we demonstrate that we can improve BBB function and reduce neuroinflammation and cognitive deficits in aged mice by restoring core 1 mucin-type O-glycans to the brain endothelium using adeno-associated viruses overexpressing two age-downregulated mucin-type O-glycan biosynthetic enzymes, C1GALT1 and B3GNT3.

Cumulatively, our findings provide a detailed compositional and structural mapping of the ageing brain endothelial glycocalyx layer and reveal important consequences of ageing- and disease-associated glycocalyx dysregulation on BBB integrity and brain health.

Link: https://doi.org/10.1038/s41586-025-08589-9

In the wet form of age-related macular degeneration, damage and dysfunction gives rise to a maladaptive growth of leaky blood vessels into the retina, destroying its cells, structure, and function. Researchers here report on an early stage clinical trial of a twofold approach to the problem, combining surgery to remove blood vessels with delivery of retinal cells derived from stem cells in order to replace damaged tissue. Efficacy has yet to be determined rigorously, but initial results are encouraging, at least for those patients in which the surgery was successful in achieving the goal of clearing out the unwanted blood vessels.

Wet age-related macular degeneration (AMD) in its early stages can be treated with drugs to reduce the formation of new blood vessels, but this treatment is inefficient in cases where blood vessel formation is already in its advanced stages. A new, alternative treatment for those patients may be surgical removal of the abnormal blood vessels followed by the transplantation of stem cell-derived retinal cells.

In their clinical study, involving 10 patients with wet AMD, researchers first developed a method for safely removing the newly formed blood vessels followed by the transplantation of stem cell-derived retinal cells to replace the patients' damaged or lost retinal cells. The retinal structure improved in those patients where blood vessel patches were completely removed during surgery, suggesting that the transplanted cells survived and repaired the damaged retina. Further, visual acuity remained stable or improved in those patients during the 12-months follow-up, with limited side effects. In contrast, patients where the blood vessel patches could only partially be removed experienced persistent bleeding and inflammation in the eye and an incomplete regeneration of the retina, and vision did not improve in those patients.

Researchers concluded that complete and safe removal of the blood vessel patches prevents inflammation and generates a milieu favorable for transplant survival and integration. Follow up studies with larger groups of patients are required to confirm the clinical efficacy and favorable safety profile of this type of treatment.

Link: https://www.isscr.org/isscr-news/stem-cell-transplant-clears-clinical-safety-hurdle-for-the-treatment-of-wet-age-related-macular-degeneration