Tag: immunotherapy

Categories : CancerTags :

Oxford-AstraZeneca Vaccine Tech Tapped to Treat Cancer

On By ModernMedia
Source: National Cancer Institute on Unsplash

The Oxford-AstraZeneca vaccine’s success against SARS-CoV-2 has prompted scientists to develop a vaccine for cancer, using Oxford’s viral vector vaccine technology.

When tested in mouse tumour models, the two-dose therapeutic cancer vaccine increased the numbers of anti-tumour T cells infiltrating the tumours and improved the efficacy of cancer immunotherapy. Compared to immunotherapy alone, combination with the vaccine resulted in a greater reduction in tumour size and improved survival.

The study, which was done by Professor Benoit Van den Eynde’s group at the Ludwig Institute for Cancer Research, University of Oxford in collaboration with co-authors Professor Adrian Hill and Dr Irina Redchenko at the University’s Jenner Institute, has been published in the Journal for ImmunoTherapy of Cancer.

Cancer immunotherapy has improved outcomes for some cancer patients. Anti-PD-1 immunotherapy works by unleashing anti-tumour T cells to allow them to kill cancer cells. However, in the majority of cancer patients, anti-PD-1 therapy is still ineffective .

One reason for the poor efficacy of anti-PD-1 cancer therapy is that some patients have low levels of anti-tumour T cells. Oxford’s vaccine technology generates strong CD8+ T cell responses, which are necessary for strong anti-tumour effects.

The team developed a two-dose therapeutic cancer vaccine with different prime and boost viral vectors, one of which is the same as the vector in the Oxford-AstraZeneca COVID vaccine. In order to create a vaccine treatment that specifically targets cancer cells, the vaccine was designed to target two MAGE-type proteins found on the surface of many types of cancer cells.

Preclinical experiments in mouse tumour models demonstrated that the cancer vaccine increased the levels of tumour-infiltrating CD8+ T cells and enhanced the response to anti-PD-1 immunotherapy. The combined vaccine and anti-PD-1 treatment resulted in a greater reduction in tumour size and improved the survival of the mice compared to anti-PD-1 therapy alone.

Benoit Van den Eynde, Professor of Tumour Immunology at the University of Oxford, said: “We knew from our previous research that MAGE-type proteins act like red flags on the surface of cancer cells to attract immune cells that destroy tumours.

“MAGE proteins have an advantage over other cancer antigens as vaccine targets since they are present on a wide range of tumour types. This broadens the potential benefit of this approach to people with many different types of cancer.

“Importantly for target specificity, MAGE-type antigens are not present on the surface of normal tissues, which reduces the risk of side-effects caused by the immune system attacking healthy cells.”

Human trials in 80 patients with non-small cell lung cancer will be launched later this year.

Adrian Hill, Lakshmi Mittal and Family Professorship of Vaccinology and Director of the Jenner Institute, University of Oxford, said: “This new vaccine platform has the potential to revolutionise cancer treatment. The forthcoming trial in non-small cell lung cancer follows a Phase 2a trial of a similar cancer vaccine in prostate cancer undertaken by the University of Oxford that is showing promising results.

“Our cancer vaccines elicit strong CD8+ T cell responses that infiltrate tumours and show great potential in enhancing the efficacy of immune checkpoint blockade therapy and improving outcomes for patients with cancer.”

Source: Oxford University

Categories : Cancer Immune SystemTags :

Unleashing the Immune System to Attack Cancers

On By ModernMedia
Shown here is a pseudo-colored scanning electron micrograph of an oral squamous cancer cell (white) being attacked by two cytotoxic T cells (red), part of a natural immune response. Photo by National Cancer Institute on Unsplash

A potential treatment has been identified, that could boost the immune system’s ability to find and destroy cancer cells, by impeding certain cells which regulate the immune system, which in turn can unleash other immune cells to attack tumours in cancer patients.

“A patient’s immune system is more than able to detect and remove cancer cells and immunotherapy has recently emerged as a novel therapy for many different types of cancers,” explained study leader Nullin Divecha, Professor of Cell Signalling at the University of Southampton. “However, cancer cells can generate a microenvironment within the tumour that stops the immune system from working thereby limiting the general use and success of immunotherapy,” he continued.

One of a number of types of T cells, Teffector cells (Teffs) carry out the task of detection and removal of cancer cells . How well Teff cells work in detecting and removing cancer cells is partly governed by other T cells called T-regulatory cells, or Tregs for short. Tregs physically interact with the Teff cells, producing molecules which dampen the functioning of the Teff cells.

Prof Divecha added, “Tregs carry out an important function in the human body because without them, the immune system can run out of control and attack normal cells of the body. However, in cancer patients we need to give the Teff cells more freedom to carry out their job.”

Molecules released by tumour cells exacerbate the problem by attracting and gathering Tregs, reducing the activity and function of Teff cells even further. Though there are mechanisms to inhibit Treg cells, since Treg and Teff cells are very similar, Teff cells are also generally inhibited.

In this new study, published in PNAS, scientists from the University of Southampton and the National Institute of Molecular Genetics in Milan showed that inhibition of a family of enzymes in cells called PIP4K could be the answer to how to restrict Tregs without affecting Teffs.

The research team isolated Tregs from healthy donors and used genetic technology to suppress the production of the PIP4K proteins. They saw that loss of PIP4Ks from Treg cells stopped their growth and response to immune signals, in turn stopping them from impeding Teff cell growth and function.

Importantly, the loss of the same enzymes in Teff cells did not limit their activity.

“This was surprising because PIP4Ks are in both types of T cells in similar concentrations but our study shows that they seem to have a more important function for Tregs than Teffectors,” said Dr. Alessandro Poli who carried out the experimental research.

Scientists must next develop molecules in order to inhibition of PIP4K as a potential therapy for patients. “Towards this end we show that treatment with a drug like inhibitor of PIP4K could enable the immune system to function more strongly and be better equipped to destroy tumour cells.”

Source: EurekAlert!

Categories : Cancer Immune SystemTags :

Study Reveals Natural Killer Cells’ Fuel Source

On By ModernMedia
Pictured is a false-colour scanning electron micrograph of an oral squamous cancer cell (white) being attacked by two cytotoxic T cells (red), part of a natural immune response. Photo by National Cancer Institute on Unsplash

Scientists have discovered how natural killer (NK) cells fuel their activities when fighting infections, which will in turn help inform the development of immune therapies.

When it comes to dealing with infections and cancer, if T cells are like a team of specialist doctors in an emergency room, then NK cells are the paramedics: They arrive first on the scene and perform damage control until reinforcements arrive. Their existence was revealed in the 1970s when scientists were trying to characterise T cell cytotoxicity.

NK cells belong to our innate immune system, which dispatches these first responders, and they come with a built-in ability to recognise and respond to danger. Learning what powers NK cells is an ongoing area of immunology research, with important clinical implications.

“There’s a lot of interest right now in NK cells as a potential target of immunotherapy,” said Joseph Sun, an immunologist in the Sloan Kettering Institute. “The more we can understand what drives these cells, the better we can program them to fight disease.”

First responders

Previous studies have shown that aerobic glycolysis provides the energy for T cells to carry out their protective activities. But it was not known whether NK cells use this form of metabolism in performing their functions.

Dr Sun and his colleagues studied NK cells in animal models instead of in vitro, in order to find out, in a natural setting, what type of metabolism NK cells use and compare it to T cells. They discovered that NK cells increase aerobic glycolysis about five days before T cells respond with their own glycolytic surge.

“This fits with the idea that NK cells are innate immune cells that are really critical for mounting a rapid response,” said Research Fellow Sam Sheppard.

The findings are relevant to ongoing efforts to use NK cells as immunotherapy in people with cancer and other conditions. These are particularly relevant for procedures that make use of NK cells as a form of cell therapy—when cells are grown outside the body and then introduced back into the patient.

Finding a delicate balance

“If you’re growing these cells in a dish and you push them to divide too rapidly, they may not have as much potential to undergo aerobic glycolysis when you put them into a patient,” Dr Sheppard explained.

For researchers designing clinical trials, the goal is to find a balance between encouraging NK cells to multiply and preserving their stamina. These NK cells are the paramedics of our immune system, so it’s important to keep them speedy and responsive.

The findings were reported June 1, 2021, in the journal Cell Reports.

Source: Eureka Alert

Categories : CancerTags :

Study Discovers How Melanoma Cells Hide From Immune System

On By ModernMedia

Melanomas in some patients do not respond well to immunotherapy treatments, and now researchers have discovered that a defect in STING gene expression in melanoma cells helps them escape immune cell surveillance.

Cancer cells use a variety of recently discovered mechanisms to avoid detection and destruction by immune cells, including defective detection and destruction of T cells, losses in expression of critical proteins on tumour cells and defective cell signaling in both immune and tumor cells.

The interferon signaling pathway is an important signaling pathway in interactions between tumour and immune cells. This pathway increases expression of molecules allowing tumour cells to be targeted by immune cells. One of the interferon signaling pathway’s key molecules is STING, which is activated by the protein cGAS.

Previously Moffitt researchers showed that STING activity is suppressed and altered in a subset of melanomas, rendering tumour cells invisible to the immune system.

Using a process called epigenetic modification to turn genes on or off with methylation groups, the researchers sought to improve the understanding of alterations in STING signaling in melanoma and find out how STING expression is suppressed. 

The researchers performed a series of laboratory experiments and discovered that the DNA regulatory region of the STING gene is highly modified by methylation groups resulting in loss of STING gene expression in certain melanoma cell lines. Importantly, they confirmed these findings in patient clinical samples of early and late-stage melanomas and showed similar methylation events and loss of expression of the upstream STING regulator cGAS.

The researchers demonstrated the possibility of reactivating STING and/or cGAS expression with a demethylating drug or genetic approaches. These successfully reactivated STING activity, resulting in increased interferon levels when triggered by STING agonist drugs that enabled the melanoma cells to now be recognised and targeted by immune cells.

“These studies show the critical importance of an intact STING pathway in melanomas for optimal T cell immunotherapy success, and how to overcome a notable STING defect in melanoma cases of gene hypermethylation by a combination therapy,” said senior author James J. Mulé, PhD, and Associate Center Director, Translational Science, H. Lee Moffitt Cancer Center & Research Institute.”Unless patients’ melanomas are pre-screened for intact versus defective STING, it is not at all surprising that clinical trials of STING agonists have, to date, uniformly failed.”

Source: News-Medical.Net

Journal information: Falahat, R., et al. (2021) Epigenetic reprogramming of tumor cell–intrinsic STING function sculpts antigenicity and T cell recognition of melanoma. Proceedings of the National Academy of Sciences. doi.org/10.1073/pnas.2013598118.