Around 30% of cancers develop in the wake of chronic localised inflammation. This is particularly the case of certain colorectal cancers, or cancers of the small intestine, liver or pancreas. © Adobe Stock

Nearly one in three cancers develops following chronic inflammation, whose origin remains unclear. In a new study, researchers from Inserm, CNRS, Université Claude-Bernard Lyon 1 and the Léon Bérard Centre at the Cancer Research Center of Lyon[1]identified lymphocytes involved in the inflammatory processes and that are thought to be implicated in the generation of these cancers. This research opens up new avenues in terms of prevention and treatment, and its findings have been published in Nature Immunology.

Around 30% of cancers develop in the wake of chronic localised inflammation. This is particularly the case of certain colorectal cancers, or cancers of the small intestine, liver or pancreas. However, many questions remained unanswered regarding their development. Is one specific immune cell responsible for the inflammatory process that leads to cancers, or more than one? And if so, which?

Answering these questions is one of the objectives of Inserm Research Director Julien Marie[2] and his team at the Cancer Research Center of Lyon (Inserm/CNRS/Université Claude-Bernard Lyon 1/Léon Bérard Centre) in order to better understand how the disease is initiated.

The researchers were particularly interested in TH17 lymphocytes – a population of immune cells which are already known to be involved in many inflammatory diseases, such as multiple sclerosis and Crohn’s disease.

Cells that cause cancer

The hypothesis was that TH17 cells are not a homogeneous population, but can actually be divided into several subgroups. Using single-cell RNA sequencing approaches, the scientists demonstrated this heterogeneity of TH17 cells within the gut.

‘More specifically, this study shows for the first time that there are actually eight TH17 subtypes with distinct roles. One of them has a tumorigenic role, which means that when certain activation barriers are removed, it will contribute to the development of cancers. On contact with these TH17 cells, the previously healthy gut cells become cancerous’, explains Marie.

The scientists then showed this tumorigenic population to be increased in patients at high risk of cancer. Finally, they also identified that a protein – cytokine TGF–β – is capable of inhibiting the formation of tumorigenic TH17 cells.

‘This study may make clinicians stop and think about the long-term use of immunotherapies in cancer patients, whose aim is to stimulate lymphocytes’, emphasises Marie.

While these therapies have transformed cancer care, they are also known to cause chronic gut inflammation. Therefore it is important to consider, for a given patient, the risks of immunotherapy being accompanied by the emergence of tumorigenic TH17 lymphocytes, which could eventually lead to the development of another cancer. Furthermore, this study lays the foundations for the development of new cancer preventive therapies by blocking the appearance of the TH17 subtype implicated by the scientists in this research.

[1]Scientists from the Institute of Molecular Genetics of Montpellier (CNRS/Université de Montpellier) also participated in this research.

[2]Julien Marie is the winner of the Bettencourt Coups d’Élan Prize for French Research.
Created by the Bettencourt-Schueller Foundation in 2000, this prize had been awarded to 78 French laboratories and over 900 researchers until 2021.

Cancer cell made in 3d software © Fotalia

Acute myeloid leukaemia is one of the deadliest cancers. Leukaemic stem cells responsible for the disease are highly resistant to treatment. A team from the University of Geneva (UNIGE), University Hospital of Geneva (HUG), and Inserm has made a breakthrough by identifying some of the genetic and energetic characteristics of these stem cells. Notably, a specific iron utilisation process. This process could be blocked, leading to the death or weakening of these stem cells without affecting healthy cells. These results, published in Science Translational Medicine, pave the way for new therapeutic strategies.

Acute myeloid leukaemia (AML) is the most common blood and bone marrow cancer in adults. Caused by an increase in immature cells that rapidly destroy and replace healthy blood cells (red and white blood cells and platelets), it is lethal in half of those affected under the age of 60, and in 85% of those over that age.

This unfavorable prognosis may be due to the presence of so-called ”dormant” or ”quiescent” leukaemic stem cells (LSCs), which evade chemotherapy. Often invisible, these cells can ”wake up” and reactivate the disease after an apparently successful course of treatment. Developing therapies that target these cells directly is therefore a major research challenge. However, the mechanisms controlling them are poorly understood.

By identifying genetic and metabolic characteristics specific to LSCs, a team from the UNIGE, HUG, and Inserm is providing new insights, as well as ways of combating the disease. These results, published in Science Translational Medicine, pave the way for a new therapeutic target and its clinical application.

A distinctive genetic signature

”Using advanced bioinformatics techniques, and in collaboration with the team of Dr Petros Tsantoulis from the Department of Oncology and Precision Oncology at the HUG, we first established that these quiescent cells contain a unique genetic signature consisting of 35 genes. When we used this signature in large clinical databases of patients with AML, we were able to show that this signature was strongly linked to the prognosis of the disease,” explains Jérôme Tamburini, associate professor in the Department of Medicine and the Centre for Translational Research in Onco-haematology (CRTOH) in the UNIGE Faculty of Medicine and at the Swiss Cancer Center Léman (SCCL), staff physician in the Division of Oncology at HUG, who led this research.

 

Locking a specific nutrient

The study also highlights a metabolic difference between dormant and active leukaemic stem cells. In general, to survive, cells trigger chemical reactions that enable them to break down nutrients and thus produce energy. This also involves ”autophagy”, a process that allows cells to recycle cellular components to generate new ones and to provide energy in case of a lack of external nutrients. Scientists have discovered that dormant leukaemic stem cells depend on ”ferritinophagy”, a specific form of autophagy targeting ferritin, the main iron storage molecule.

‘‘This process is mediated by a protein called NCOA4. It controls the availability of iron in cells. By inhibiting it, either genetically or chemically, we observed that leukaemia cells, especially dormant stem cells, are more likely to die, whereas healthy blood stem cells remain intact,” reveals Inserm researcher Clément Larrue, a former post-doctoral researcher in Jérôme Tamburini’s group, currently a post-doctoral researcher at the Toulouse Cancer Research Center, and first author of the study.

 

Towards clinical trials

Experiments conducted with mouse models have confirmed that blocking the NCOA4 protein reduces tumour growth, viability and self-renewal of leukaemic stem cells. Targeting ferritinophagy through this inhibition pathway could therefore be a promising therapeutic strategy. The compound used to block NCOA4 is in the early stages of development for future clinical trials, under the direction of one of the study’s co-authors, Jun Xu, a professor at Sun Yat-Sen University in China.

The next step for the UNIGE team will be to further explore further the mechanisms of ferritinophagy and its association with mitophagy, another key mechanism in the regulation of LSCs. This new stage of research is supported by the Swiss Cancer League.

A French-Swiss team has highlighted the long-term impact of socioeconomic inequalities on the quality of life of women who have had breast cancer. © Photo Angiola Harry / Unsplash

When it comes to health, inequalities can be seen at every level for women with breast cancer: prevention, screening, diagnosis, treatment, and survival. But what about their quality of life? A team from the University of Geneva (UNIGE), the University Hospitals of Geneva (HUG), Inserm, and Gustave Roussy has tracked nearly 6,000 women diagnosed with breast cancer over a 2-year period, showing that socioeconomic status has a major and lasting impact on their quality of life, despite identical medical treatment. These results from the UNICANCER-sponsored CANTO study, published in the Journal of Clinical Oncology, call for socioeconomic factors to be taken into greater account in support programmes for women with breast cancer.

Social and economic determinants (such as income and educational levels) impact how individuals cope with illness and are one of the main causes of inequalities in health. In cancer care, socioeconomic inequalities are present throughout the continuum of care, from prevention to diagnosis, treatment, and survival.

‘‘However, the extent of socioeconomic inequalities in the quality of life of women diagnosed with breast cancer and how these change during treatment was not known,’’ explains José Sandoval, an oncologist at the HUG Department of Oncology and a researcher in the Departments of Medicine and Community Health and Medicine at the UNIGE Faculty of Medicine, first author of this study. ‘‘We sought to quantify the inequalities in quality of life for these women, both at the time of diagnosis and in the following two years.’’

Nearly 6,000 women monitored over two years

The 5,900 women who took part in this study were treated in France for early breast cancer, a common form of cancer from which more than 80% of women recover.

‘‘Many of the women received heavy treatment in the first year following their diagnosis – including surgery followed by chemotherapy— followed by endocrine therapy in the second year. We followed them over two years to capture changes in quality of life over the medium term,’’ explains Gwenn Menvielle, research director at Inserm and at Gustave Roussy, who led this research.

The research team examined five areas of quality of life — general tiredness, psychological state, sexual health, and side effects — according to a number of socioeconomic indicators: level of education, household income, and perceived financial situation. Combining these elements produces a score where 0 indicates no inequalities.

Inequalities are increasing rapidly

At diagnosis, the inequalities in quality of life between the two socioeconomic extremes are notable, with a score of 6,7. The score increases to 11 during treatment, then remains at 10 two years after diagnosis, a higher score than at that time.

‘‘If we expected a certain degree of inequality at the start of the disease, the fact that these inequalities increase rapidly and persist for so long is a surprise,’’ mentions José Sandoval. ‘‘The impact on quality of life is much more pronounced for women with fewer resources, irrespective of the biological characteristics of their cancer, their age or the treatment they have received.’’

Why? The answers are to be found not in the treatment, which is similar for all women, but probably in all the elements of support around medical management.

‘‘Having the time, money, and access to information to take care of oneself, find support resources, and better manage the physical and psychological side-effects of the disease will probably be easier for women of high socioeconomic status than for, say, a single mother on a low income with no carer for her children,’’ points out José Sandoval. ‘‘These factors influence the disease and its consequences on patients’ physical and psychological health.’’

Taking better account of inequalities

Equal access to healthcare is not synonymous with the absence of inequality. The socioeconomic context can have a major impact on health status in the same way as biological characteristics.

‘‘When we talk about precision oncology, we need to consider the whole person, including their social dimension,’’ add the authors. ‘‘Our data concerns women treated in France, a country with equal healthcare access. In countries without a universal healthcare system, these inequalities are likely to be even more pronounced.’’

These results are part of the CANTO study: ‘‘étude des toxicités chroniques des traitements anticancéreux chez les malades porteurs de cancer localisé’’, supported by the French Government under the “Investment for the Future” program managed by the National Research Agency (ANR), grant n° ANR-10-COHO-0004.

Scanning electron microscopy. Here we see how platelets (in blue/purple) attach to two tumour cells (in red) in a pre-clinical mouse model. © Maria Jesus Garcia Leon (unit 1109 Inserm/Université de Strasbourg)

What if our blood platelets[1], which play a major role in maintaining the integrity of our circulatory system, were not always on our side? Research teams from Inserm, Université de Strasbourg and the French Blood Establishment have studied their role in the process of metastasis formation. Their findings suggest that platelets, by binding specifically to circulating cancer cells, promote their survival not just in the bloodstream, but also within metastases. This research, published in Nature Communications, also shows that using treatments to target this binding could fight the formation of metastases without the same bleeding risk[2] as with conventional antiplatelets.

A metastasis is a ‘secondary’ tumour which is usually formed from cancer cells that have broken off from a ‘primary’ tumour before migrating through the blood or lymphatic vessels to settle elsewhere in the body. During their migration, these cancer cells encounter the blood platelets – which prove to be unexpected allies. By binding to the cancer cells, the platelets help them to survive the immune cells in the blood environment and exit the bloodstream to reach their metastasis site.

However, not all cancer cells receive the same protection because some bind to the platelets more easily than others. This dictates their capacity to survive in the blood circulation, target certain vascular regions and, as such, their ability to metastasise. Furthermore, in-depth analyses of lung metastases have shown the presence of large numbers of platelets which may play a role that differs from or complements the role they play in blood vessels.

Two teams led by Inserm researchers Jacky Goetz, from the Molecular Immuno-Rheumatology Unit (Inserm/Université de Strasbourg) and Pierre Mangin, from the Biology and Pharmacology of Blood Platelets: Haemostasis, Thrombosis, Transfusion Unit (Inserm/French Blood Establishment/Université de Strasbourg), studied the moments at which the platelets intervened during the migration of cancer cells to promote their survival and spread. They also looked at how to counter this alliance without using conventional antiplatelet drugs which, by altering bleeding cessation, present the risk of haemorrhage.

In a mouse model, the researchers artificially induced controlled falls in the number of platelets at different stages in the formation of lung metastases. They saw that by removing platelets early (while they were still circulating in the blood), they limited the exit from the blood vessel of the cancer cells with a high affinity for the platelets, and thereby inhibited the formation of metastases. Those cancer cells with low levels of platelet binding were also affected, but only when the platelet level was decreased later, when the lung metastases were already formed.

‘These observations suggest that as well as protecting the cancer cells in the bloodstream, the platelets could also protect them against the immune system later on – i.e. within the metastases themselves, helping them to proliferate there, explains Goetz. So the aim of our future research will be to understand how the platelets colonise growing metastases.’

But how can we circumvent the issue of bleeding risk associated with antiplatelet treatments?

One initial avenue could involve a specific protein found on the platelet surface: glycoprotein VI (GPVI). Previous research has suggested that it could modulate the pro-metastatic activity of platelets without causing bleeding. The expression of this protein could be inhibited by glenzocimab, a molecule currently being evaluated in patients for the treatment of stroke. When they used glenzocimab in their animal model, the scientists saw that it effectively reduced the development of already established lung metastases, without affecting the cessation of bleeding.

‘These observations reinforce the idea of the contribution of platelets to the formation of metastases after cancer cells leave the circulation, explains Mangin. In addition, our research highlights the possibilities of developing new therapeutic strategies which, unlike conventional antiplatelet treatments, would not disrupt bleeding cessation and could therefore be considered in oncology, particularly to reduce the progression of lung metastases. Our two teams are currently working to explore this potential,’ adds the researcher.

This study, carried out on experimental animal models, reconciles previous contradictory data on the role of platelets in the metastatic process.

‘Studies in humans, for example on cohorts of patients with long-term exposure to antiplatelet agents for cardiovascular indications, or to evaluate the efficacy of oncology treatments in patients on antiplatelet therapy, could be excellent indicators for verifying these findings,’ concludes Goetz.

[1]Platelets (thrombocytes) present in the blood are not cells per se, but fragments of large bone marrow cells: megakaryocytes. They play a major role in the rapid cessation of bleeding (haemostasis). As such, platelet counts that are too low can lead to clotting disorders and therefore a risk of bleeding (in the event of injury, for example).

[2] See footnote 1

Neural organoid with immune environment magnified twice on the left, 20 times on the right: green macrophages, red and blue neural progenitor cells (fluorescence microscopy). © Gustave Roussy

French, Singaporean and British researchers, led by Prof. Florent Ginhoux, head of a research team at Gustave Roussy/Inserm, have succeeded in demonstrating in a neuronal organoid the role of the brain’s immune environment in its formation and development. The development of these three-dimensional structures integrating neuronal cells and the immune environment is, to date, one of the most complete in vitro models of the human brain. This work is published in Nature.

At Gustave Roussy, these organoids are used to model the development of childhood brain cancers, to understand their mechanisms and discover new avenues of treatment.

“Although microglial cells, immune cells derived from the evolution (differentiation) of primitive macrophages present in the embryonic brain, are known to contribute to multiple aspects of brain development and function, their precise role remains poorly understood and little studied”, says Prof. Florent Ginhoux, director of a research team at Gustave Roussy/Inserm and Senior Principal Investigatorat A*STAR’s Singapore Immunology Network (SIgN).

The use of neuronal organoids to study their functions is one of the avenues currently favored by research.

An organoid is a 3D structure grown in the laboratory which reproduces certain morphological and functional characteristics of a human body organ or tissue. In research, these cell-cultured pseudo-organisms are a new biological model in full development in various fields, notably neurology; most studies of neuron formation (neurogenesis) are based on animal models.

With their 3D structure, the function and properties of these organoids are close to those of a real organ, but not quite as advanced. They measure just one millimeter and have no thoughts, consciousness or emotions. By generating neural organoids from human induced pluripotent stem cells (iPS cells), it is possible to model some of the key features of early human brain development. “However, current approaches do not include microglial cells,“ explains Prof. Florent Ginhoux.

The international team of researchers led by Prof. Florent Ginhoux has succeeded in producing a new type of model: neuronal organoids with microglia, by cultivating together organoids and primitive-type macrophages, all generated from the same culture of iPS induced stem cells.

Organoids and primitive macrophages are prepared separately. It takes around 25 days to obtain them. The macrophages are then placed in contact with the organoids for a further 15 to 20 days.

In the model developed by the researchers, macrophages colonized the organoids. In this 3D environment, in contact with immature neuronal cells, they differentiated into microglial cells expressing the genes and functions specific to this cell type. These microglial cells proved capable of controlling the differentiation of neuronal precursors (so-called neuronal progenitor cells), thus limiting their multiplication (proliferation), while promoting synapse creation (synaptogenesis) and axon growth (axonogenesis), two key elements in the transmission of the nerve message from neuron to neuron.

A discovery within a discovery

Prof. Florent Ginhoux’s team also observed that the organoids’ microglial cells contain high levels of perilipin-2, a molecule belonging to a family of proteins that coat lipids – including cholesterol – in droplets, enabling them to be stored in and exported from the cells. Armed with these perilipin-2-laden droplets, microglial cells facilitate cholesterol transport to the organoids. The neural progenitor cells that absorb this cholesterol undergo metabolic reprogramming as they differentiate into nerve cells.

The approach developed by Prof. Florent Ginhoux and his colleagues has significantly advanced the complexification of organoid models by integrating microglial cells. This progress is illustrated by the discovery of a key lipid-mediated pathway between microglia and neural progenitor cells, essential for the synthesis of new neurons.

“With microglia cells incorporated, the neural organoids we have succeeded in generating are a new, more complete 3D model, closer to reality. We know that the immune system plays a fundamental role in the development of cancers, so at Gustave Roussy we’re going to use them to better understand and discover the mechanisms that regulate the development of pediatric brain tumors“, concludes Prof. Florent Ginhoux.

This work has been supported by the Gustave Roussy Foundation’s “Curing childhood cancer in the 21st century” campaign.

By studying immune cells in the lung, researchers from Institut Curie and Inserm have provided new knowledge on the topic.© Fotolia

Cancer and aging are closely linked processes, but the mechanisms underlying this relationship are still not well understood. By studying immune cells in the lung, researchers from Institut Curie and Inserm have provided new knowledge on the topic. They show that targeting ruptures of the nuclear envelope of these cells would represent a new opportunity for therapeutic intervention in age-related diseases, in particular cancer, thus improving the quality of life of the elderly in the long term. Funded by the Fondation ARC, this work has just been published in the journal Nature Aging.

Age is one of the main risk factors for the development of a number of diseases, such as viral or bacterial infections and neuro-degenerative diseases, but also cancers. The economic and societal issues related to the overall aging of the population constitute a major challenge. Furthermore, the notion of “healthy aging” increasingly suggests that targeting aging rather than its consequences is a far better strategy for reducing morbidity among the elderly.

More than two thirds of new cancers diagnosed in France occur in people over the age of 65[1]. The appearance of cancers with age can be explained by the accumulation of genetic alterations during a lifetime, less effective DNA repair mechanisms, and also by an aging immune system with diminished protective functions (immunosenescence). What are the mechanisms that govern this phenomenon? How can we develop strategies to counter immunosenescence?

The nucleus of immune cells sensitive to deformations

It is these questions that the Inserm and Institut Curie researchers attempted to answer. With time, DNA becomes fragile and one of the characteristic markers of cell aging is genome instability. When they patrol through the various tissues within the body, the immune system cells are sensitive to deformations which weaken their nucleus and promote DNA breakage. To maintain the structure of the nucleus and thus the genome’s integrity, the cell relies on a dense network of proteins, which include lamins. Among them lamin A/C is studied in particular since it undergoes alterations over the course of aging. In addition, mutations in the gene coding for this protein are known to cause early aging syndromes.

“Repeated ruptures of the nuclear envelope lead to DNA damage. It is vital to understand the processes at work in this regard since they promote not just aging of the body, but also the development of cancers. For example, ruptures of the nucleus make the DNA “visible” by damaging proteins, thus triggering a response from the cell that will promote the development of metastases“, explains Dr. Nicolas Manel, Inserm research director and team leader at Institut Curie.

 

“Two-photon” microscopy of the extreme deformation of an alveolar macrophage, when it passes between two alveoli. During these migrations the nucleus is also deformed, and it is at this point that the DNA can be damaged.

A protein identified in the lung: lamin A/C

At Institut Curie, the Innate Immunity team of Dr. Nicolas Manel, Inserm research director, studied a new experimental model in which the immune system’s cells are deficient in lamin A/C. Researchers looked closely at a population of lung macrophages – alveolar macrophages – which are highly dependent on lamin A/C for their survival. The role of these alveolar macrophages is to constantly monitor the lungs, and they are one of the main entry points for a number of pathogens.

The researchers showed that without lamin A/C, the alveolar macrophages show serious signs of fractures in their nucleus and damage to the DNA, leading to a dramatic drop in their number in the lungs. Furthermore, the surviving alveolar macrophages have many characteristics similar to those of aged alveolar macrophages, and accumulate markers characteristic of aging.

The team also revealed that without lamin A/C in the macrophages, the implantation and growth of lung tumors is a lot faster, encouraged by the malfunction of the aged macrophages.

The loss of lamin A/C would therefore constitute a mechanism for alveolar macrophage aging and a prime study model for understanding how lung cancers develop in the elderly.

“Our results open up many new opportunities for studying aging of the immune system, caused by rupture of the nuclear envelope and the decrease in its effectiveness against infections and tumors, in the lungs but also in other organs“, concludes Dr. Nicolas Manel.

These studies are funded in the amount of 2.5 million euros as part of the call for projects “Cancer and Aging” of Fondation ARC for cancer research.

[1] Source INCa : https://www.e-cancer.fr/Professionnels-de-sante/L-organisation-de-l-offre-de-soins/Oncogeriatrie/Epidemiologie

3D cancer cell © Fotalia

Almost half of breast and ovarian cancers are connected to deficiencies in the biological systems that repair DNA breaks. Researchers from Institut Curie, Inserm and CEA reveal a hitherto unknown DNA repair mechanism involving a protein: PolꝊ, which is able to act during cell division. Published in Nature on 6 September, 2023, their results pave the way for the development of new therapeutic targets for treating cancers, particularly breast and ovarian cancer.

Ultraviolet rays, alcohol, tobacco, genetic predisposition, spontaneous mutations… so many factors constantly damage our genome. Among these lesions, breaks that affect both DNA strands simultaneously are the most harmful. Our body is constantly repairing this damage through several repair systems, including homologous recombination. However, when these mechanisms fail (due to a genetic mutation, for example), they may cause cancer to occur. Also, the proven correlation between these homologous recombination deficiencies and the aggressiveness of cancers or their resistance to current chemotherapies underlines the pressing need for targeted cancer-fighting therapies.

A new major player in DNA repair: PolꝊ

A few years ago, a new player in DNA repair (polymerase theta or PolꝊ) was identified as a therapeutic hope for treating these cancers[1]. The “Alternative DNA Repair Mechanisms in Human Cancers”[2] team headed by Dr. Raphaël Ceccaldi, Inserm researcher at Institut Curie, has just clarified the mechanism for the action of this polymerase and the reason why this enzyme is vital to the development of breast and ovarian cancers.

For the first time scientists have shown that PolꝊ works where other DNA repair pathways do not. While it was believed that DNA repair was impossible during cell division (when DNA is extremely compacted), the team from Institut Curie showed that PolꝊ is active specifically during mitosis when the other contributors to repair were proven ineffective.

“Along with my team at Institut Curie, we looked closely at the mechanisms that the cell puts in place to repair its DNA, enabling cancer cells to survive. It is by understanding such mechanisms that we can build new options to thwart cancer“, explains Dr. Raphaël Ceccaldi, Inserm researcher and team leader at Institut Curie. “Our discoveries on the role and functioning of polymerase theta in maintaining integrity of the genome gives us hope for new therapeutic strategies against cancer, particularly breast and ovarian cancer.“

Genome integrity highly preserved by PolꝊ

Through a collaboration with the team of Dr. Sophie Zinn-Justin, researcher at the CEA (Laboratoire de Biologie Structurale et Radiobiologie), researchers went even further, showing that, in order to repair DNA, PolꝊ had to be activated by an enzyme specifically present during cell division. In addition, the mechanisms that enable this activation of PolꝊ seem to have been extremely well-preserved throughout evolution. This suggests that they play an important role in maintaining the stability of the genome needed for development of eukaryotic organisms.

A therapeutic hope for breast and ovarian cancer

The team of Dr. Raphaël Ceccaldi also discovered that inhibiting PolꝊ during cell division by mitosis prevents the proper repair of DNA and as a result leads to the death of cancer cells. With almost half of breast and ovarian cancers showing DNA repair deficiencies by homologous recombination, this step therefore represents a milestone in the fight against these cancers. Clarifying the molecular mechanisms governing the use and regulation of PolꝊ could ultimately lead to the development of new therapeutic targets for treating these cancers.

PolꝊ (green) marks DNA breaks (gH2AX, red) in the mitotic chromosomes (DAPI, blue) – Scale 5μM

[1] Ceccaldi R, Liu JC, Amunugama R, Hajdu I, Primack B, Petalcorin M, O’Connor KW, Konstantinopoulos PA, Elledge SJ, Boulton SJ, Yusufzai T, D’Andrea AD. Homologous recombination (HR)-deficient tumors are hyper-dependent on POLQ-mediated repair. Nature. 2015 Feb 12;518(7538):258-62.

[2]Cancer, Heterogeneity, Instability and Plasticity unit – CHIP (U830, Institut Curie/Inserm)

CAR T cells attacking a tumor, visualized using intravital imaging. Live tumor cells are shown in white, apoptotic tumor cells in blue and CAR T cells in green. © Morgane Boulch, Philippe Bousso / Institut Pasteur

The aim of immunotherapy strategies is to use cells in the patient’s own immune system to destroy tumor cells. CAR T cell therapy is an immunotherapy that is effective in treating blood cancer. Around 35,000 people are affected by blood cancer each year in France, with 1.24 million cases worldwide. By closely investigating some of the immune cells generated during this therapy, known as CD4 T cells, scientists from the Institut Pasteur and Inserm, in collaboration with clinicians from the Paris Public Hospital Network (AP-HP), discovered that these cells are capable of remotely neutralizing tumor cells by producing interferon gamma (IFN-γ). This study raises new hopes for blood cancer patients with an incomplete response to CAR T cell therapy and for cancers sensitive to IFN-γ. The results were published on May 29, 2023 in the journal Nature Cancer.

CAR T cell therapy is an immunotherapy that has produced remarkable results in treating certain types of leukemia or lymphoma. But some patients who receive this treatment relapse because their tumor cells evade the therapy. A multidisciplinary team of scientists from the Institut Pasteur and Inserm and clinicians from the Paris Public Hospital Network (AP-HP) sought to shed light on how the therapy works with the aim of obtaining even more effective responses.

The principle of CAR T cell therapy is to isolate the patient’s T cells, genetically modify them so that they specifically target tumor cells, and multiply them before injecting them back into the patient in large numbers. This army of killer CAR T cells is composed of CD4 T cells and CD8 T cells in varying proportions from one patient to the next. While we know that CD8 killer T cells need to come into direct contact with tumor cells to destroy them, the mechanism of action of CD4 T cells had not previously been fully explored.

The research team studied these CD4 CAR T cells more closely and revealed a very interesting property: their ability to kill tumor cells remotely by secreting a molecule involved in the immune response, interferon gamma (IFN-γ).

“For some types of cancer that are sensitive to IFN-γ, this destruction mechanism is highly efficient. We also observed that, among patients with a high quantity of CD4 T cells, those that produce a large amount of IFN-γ respond better to treatment,” explains Philippe Bousso, Head of the Institut Pasteur’s Dynamics of Immune Responses Unit (Inserm 1223) and last author of the study.

To reveal the novel mechanism of action of these remote killer cells, the scientists began by exploring preclinical models to analyze the mechanism in detail, in particular using in vivo imaging techniques, then they checked the relevance of the results on samples from patients.

CAR T cells attacking a tumor, visualized using intravital imaging. Live tumor cells are shown in white, apoptotic tumor cells in blue and CAR T cells in green. The white circles indicate the destruction of tumor cells when they come into direct contact with CAR T cells, and the red circles show the remote destruction of tumor cells. © Morgane Boulch, Philippe Bousso / Institut Pasteur

“This discovery opens new avenues for adjusting treatments to prevent tumor cells evading CAR T therapy. It also raises new therapeutic hopes for patients, offering the possibility of a more personalized treatment approach whereby a larger quantity of CD4 CAR T cells can be used to activate IFN-γ depending on tumor cell sensitivity,” comments Philippe Bousso.

By developing a better understanding of how CD4 T killer cells work, it may also be possible to extend the scope of this therapy to other solid tumor cancers that are sensitive to IFN-γ. The clinical data will be confirmed on other cohorts.

This research was funded by the institutes cited above, and also by the French National Cancer Institute (INCa) and the European Research Council.

Lepista flaccida, an edible mushroom found in the northern hemisphere, was the focus of research by French teams into ways of correcting certain genetic mutations known as nonsense mutations. © MNHN/CNRS – Christine Bailly

A molecule obtained from an edible mushroom could open up therapeutic avenues for patients with cystic fibrosis, the most frequent rare genetic disease. A team led by Fabrice Lejeune, Inserm researcher at the Cancer Heterogeneity, Plasticity and Resistance to Therapies laboratory[1] (Inserm/ CNRS/ Université de Lille/Institut Pasteur de Lille/University Hospital Lille) tested the effects of 2,6-diaminopurine (DAP), one of the active principles contained in the Lepista flaccida mushroom, in different experimental models of the disease.  The scientists have shown that this molecule could be of therapeutic value in patients with cystic fibrosis linked to a particular type of mutation known as a nonsense mutation. Their findings have been published in Molecular Therapy.

Around 6,000 people in France have cystic fibrosis, a genetic disease that primarily affects digestive and respiratory function, and has a 40 to 50-year life expectancy. Nevertheless, therapeutic innovations have improved patient prognosis in recent years. Treatments are now available for the vast majority of patients – those whose disease is caused by the delta F508 mutation of the CFTR gene. In these patients, the CFTR protein (coded by the CFTR gene) is present in small amounts but is dysfunctional. The molecules currently available are able to correct this dysfunction and significantly improve their clinical symptoms.

However, they are not effective in the 10% of patients for whom the protein is completely absent, as is the case when the disease is linked to a nonsense mutation (see box).

Identifying ways to correct nonsense mutations is therefore an important challenge for researchers studying genetic diseases and who hope to develop new therapeutic options against cystic fibrosis.

In this context, Inserm researcher Fabrice Lejeune and his team[2] made an innovative finding in 2017 by showing that extracts of a commonplace edible mushroom known as Lepista flaccida could repair nonsense mutations in three cell lines isolated from cystic fibrosis patients. A few years later in 2020, Lejeune and his team published a study identifying the active principle in the mushroom that is capable of correcting the nonsense mutations associated with the UGA stop codon – the most common of the three stop codons of the human genetic code. The active principle concerned was 2,6 diaminopurine (DAP).

In their latest research, the scientists tested the effects of this molecule in four experimental models of cystic fibrosis: animal models of the disease, developed in the laboratory; cell lines; patient cells and organoids. This diversity of models makes it possible to be as close as possible to what is happening in the patient’s body, in order to assess the potential therapeutic benefits they may obtain.

The results obtained by the team suggest that DAP corrects the nonsense mutation in the different models studied, by re-establishing protein production and effectively restoring the function of the mutated gene.

In clinical terms, this results in an improvement in symptoms in animals. The treatment with DAP makes it possible to restore CFTR expression in the lungs and intestines as well as the function of this protein, significantly reducing the premature mortality observed prior to administration of this molecule.

In addition, the research team has also shown that DAP can be given orally and that it is distributed effectively throughout the body for around two hours. These characteristics are also a positive point when it comes to considering DAP as a serious therapeutic avenue, as this means that we could reach all the tissues in the body while limiting the duration of exposure to the molecule, thereby reducing possible side effects.

“DAP could represent the first molecule capable of providing therapeutic benefit to patients with cystic fibrosis linked to a nonsense mutation and, more broadly, to patients with a genetic disease linked to a nonsense mutation,” explains Lejeune.

These results pave the way for a potential clinical trial in the coming years to test the efficacy of the molecule in patients. Before this, the goal is to develop the best possible formulation for the drug and to carry out toxicity tests to ensure its safety in humans. In the shorter term, the teams also want to test DAP in models of other rare genetic diseases, particularly Duchenne muscular dystrophy and Rett’s syndrome, for which over 60% of patients are affected by nonsense mutations.

[1] Cancer Heterogeneity, Plasticity and Resistance to Therapies laboratory at the ONCOLille institute

[2]The following research units also contributed to these findings: Communication Molecules and Adaptation of Micro-organisms (CNRS/MNHN), Biometrics and Evolutional Biology Laboratory (CNRS/Université Claude Bernard Lyon 1/VetAgro Sup), Lille Platforms in Biology and Health (PLBS) (CNRS/University Hospital Lille/Inserm/Institut Pasteur Lille/Université Lille), Strasbourg Platform for Integrative Biological Chemistry (CNRS/Université de Strasbourg).