Natural Killer cells and anti-tumor immunity

In the ecosystem that is our body, NK cells are fearsome and highly selective hunters: in just a few hours they kill tumor or infected cells while sparing healthy cells.

In several laboratories around the world, scientists have joined forces to understand how these killers eliminate their targets, and only their targets, even though they lack the highly selective antigen receptors of their close relatives, the T lymphocytes.

Today, we not only know how NK cells are controlled, but also how they in turn control other agents of the immune system. But the NK story is far from over... we are trying to manipulate NK cells to cure cancer.

N for natural, K for killer, as their name suggests, NK cells are primarily killer cells. Together with other cells of the innate immune system (neutrophils, monocytes, macrophages, dendritic cells and Tγδ lymphocytes), they patrol the body and mark cancer or infected cells. Once identified, the diseased cells are destroyed within minutes by a mechanism known as cytotoxicity: the NK cells attack in packs by releasing substances that puncture the "skin" of their victims; this is death by cell lysis. In the meantime, the NK cells release cytokines (the "hormones" of the immune system) that stimulate and control the response of the other agents of innate immunity and the lymphocytes of the adaptive immune system

How do NK cells manage to distinguish a diseased cell from a healthy cell? The team played a key role in solving this puzzle in the mid-1990s.


"To distinguish the normal from the pathological, the NK cell has developed a sophisticated recognition system," says Eric Vivier. "It is based on a surface radar that is coupled with intracellular signaling pathways that transmit information to the cell nucleus so that it can make its decision: to kill or not to kill. These radars can be divided into activating and inhibitory receptors. The former recognizes the danger signals sent out by stressed cells and put the NK cell into 'destruction' mode." The latter recognize self-molecules (the so-called major histocompatibility complex class I or MHC I) on all healthy cells of the individual and deactivate the cytotoxic function of the NK cell: the target is spared and the predator can go back on patrol."

In most cases, however, the NK cell receives these antagonistic signals simultaneously. How does it make its decision in this context? "In the course of evolution, it has simply learnt to count!" says Eric Vivier. "The NK cell adds up the signals it receives: it spares healthy cells that send inhibitory signals and few or no activating signals, while it kills cancer cells or infected cells that not only send 'danger signals' but are also no longer able to send inhibitory protective signals. To summarize, the NK cell functions like an ideal drug: effective and non-toxic."

In reality, our NK cells are not always able to effectively fight the pathogens and cancers we face. Hence the idea of using these discoveries to stimulate their activity. Thanks to monoclonal antibodies, various strategies are possible. Some of these approaches are being developed by Innate Pharma, a company that emerged in 1999 from the work of Alessandro Moretta, professor at the University of Genoa, and Eric Vivier. These antibodies are currently undergoing clinical trials in cancer and inflammatory diseases.

In the last decade, new therapies have been developed to stimulate anti-tumor immunity. These therapies were essentially aimed at stimulating T lymphocytes, a type of white blood cell that plays an important role in the adaptive anti-tumor response. Although these therapies have achieved unprecedented success, they only work in a minority of cancer patients. This highlights the importance of finding new cells and molecules that can be used in the next generation of "immunotherapies", i.e. therapies that mobilize immunity. Harnessing so-called "innate" immunity appears to be a promising therapeutic approach to improve the efficacy of cancer therapies and overcome resistance to current T-cell immunotherapies. In particular, the use of NK cells in cancer patients offers the dual advantage of not only eliminating tumor cells but also participating in a multicellular immune response against tumor cells. Correlations have been observed between the clinical outcome of patients and the infiltration of NK cells in the tumor bed or the cytotoxicity of peripheral NK cells.

The aim of our team is to investigate the role of NK cells and their close relatives, the innate lymphoid cells type 1 (ILC1), in various cancers in order to propose innovative treatments for these diseases based on their manipulation by antibody-based drugs.

Axis 1: Treating liver metastasis.
Principal Investigator : Pr Eric VIVIER, PU-PH, AMU

Liver metastases frequently occur in almost 50% of patients with various types of cancer. Colorectal carcinoma (CRC) is the most common type of cancer that metastasizes to the liver. At least 25% of colorectal cancer patients develop colorectal liver metastases during the course of their disease.

Colorectal liver metastases represent the greatest clinical need for this type of cancer, as the 5-year survival rate for patients with unresectable disease is no more than 2%. Recently, new therapies have been developed to promote anti-tumor immunity, focusing primarily on enhancing the T-cell response. These therapies have led to unprecedented results but are only effective in a minority of patients, emphasizing the need to identify new cells and molecules that could be exploited in next-generation immunotherapies. We hypothesize that immunotherapy of liver metastases could be significantly improved by harnessing the biology of NK cells and ILC1 as well as myeloid cells such as macrophages and dendritic cells.

Our team brings together experts in myeloid cell biology (Prof Ginhoux), tissue-resident lymphoid cell biology (Prof Gasteiger), liver immunology (Dr Fumagalli) and the development of new immunotherapeutic strategies that modulate immune cells in the fight against cancer (Pr Vivier).

Axe 2: Treating Breast cancer.
Principal Investigator: Dr Emilie NARNI-MANCINELLI, CR1, INSERM

Breast cancer is the most frequently diagnosed cancer in women worldwide, and metastatic breast cancer is the second leading cause of cancer-related death in women in the United States. Breast cancer is classified into four distinct molecular subtypes based on the expression profile of the estrogen receptor (ER), the progesterone receptor (PR) and the human epidermal growth factor receptor (HER2). In particular, triple-negative breast cancer (TNBC), which is characterized by the absence of overexpression of ER, PR and HER2, is the most aggressive breast cancer subtype. Similarly, HER2-positive tumors represent a subgroup of breast tumors with aggressive behavior. Improved early detection, high-resolution imaging techniques and the development of effective chemotherapy, radiotherapy, targeted and immunological therapies have significantly prolonged patients' lives. Nevertheless, the prognosis for patients with locally advanced or metastatic disease is still poor.

Our aim is to investigate the role of NK cells and ILC1 in breast cancer in order to propose innovative treatments for these diseases based on their manipulation by antibody-based drugs.
Our team brings together experts in NK cells (Dr Narni
-Mancinelli), breast cancer (Prof André) and the development of new immunotherapeutic strategies that modulate immune cells in the fight against cancer (Prof Vivier).

Axis 3: The RHU PIONeeR project: Precision Immuno-Oncology for patients with advanced non-small cell lung cancer and resistance to PD-(L)1 ICI.
Principal Investigator: Dr Frédéric VELY, MCU-PH, AMU
Grant:  RHU

The RHU PIONeeR project: Precision immuno-oncology for advanced patients with non-small cell lung cancer and PD-(L)1 ICI resistance.

Lung cancer is the leading cause of cancer-related deaths in France and in Western countries. in 2012, there were more than 1.8 million new cases and 1.5 million deaths worldwide. Recent advances in the treatment of patients with NSCLC include the use of therapies targeting oncogenes (EGFR, BRAF or HER2 mutations, ALK or ROS1 rearrangements), but a molecular alteration is currently found in only half of non-squamous non-small cell lung cancers NSCLC. Immune checkpoint inhibitors (ICI) have recently become available, initially targeting PD-(L)1 and showing an overall survival benefit over standard second-line chemotherapy in both squamous and non-squamous lung cancer. Unfortunately, this global survival benefit only affects about 20 % of patients, while the vast majority of patients already show progression in the first weeks of treatment. Several hypotheses have been proposed to explain this lack of benefit, but to date there is no predictive factor for the efficacy (or resistance) of PD-1 ICI.
To date, there is limited data on biomarkers in blood or tissue at the time of PD-1 progression in NSCLC patients. Three major findings were noted in patients treated with PD-L1 ICI: (1) little or no tumor-infiltrating immune cell infiltration - "immunological ignorance"; (2) presence of intra-tumoral immune infiltrate with minimal to no expression of PD-L1 - "non-functional immune response"; or (3) presence of immune infiltrate located only at the outer edge of the tumor cell mass. In addition, immune biomarkers in the blood were also analyzed. Several changes were observed, but these did not significantly correspond to disease response or progression after PD-L1-ICI administration.
Therefore, more knowledge about the mechanisms of resistance is needed to better address the precise treatment of advanced NSCLC patients responding to previously available PD-1 ICIs.
The PIONeeR bioprofiling study aimed to collect blood, tissue and stool samples from advanced NSCLC patients treated with PD1 ICI to better understand the mechanisms of resistance. Our primary goal is to validate the presence and distribution of the hypothetical immune profile (in blood and tumor tissue) that explains primary or adaptive resistance to standard PD-(L)1 inhibitors administered alone or in combination in advanced NSCLC patients. Our contribution to this project is the implementation of biobanking (cryopreservation of PBMC) and data generation from blood samples (immunophenotyping and quantification of soluble proteins).

Axis 4: Generation of therapeutic antibodies targeting type 2 Innate Lymphoid cells in asthma.
Principal Investigator: Dr Carole BERRUYER, associate Professor
Grant:  ERC Proof Of Concept POC Minfla-Tilc (Prof VIVIER, Dr BERRUYER)

There is no cure for asthma, which affects 300 million people worldwide and is expected to rise to 400 million by 2025. Available treatments such as inhaled corticosteroids are often ineffective due to adverse effects and incomplete targeting of the underlying immunopathology. Targeting innate lymphoid cells 2 (ILC2), which play a central role in allergic asthma, is promising. Studies show that ILC2 play a crucial role in the development of asthma, suggesting that they may be potential therapeutic targets. Our MInfla-Tilc project focuses on the development of a novel antibody treatment targeting ILC2. We have developed a trispecific NK cell engager (NKCE) that specifically targets ILC2 via the expression of CRTH2 on the cell surface and triggers NK cell cytotoxicity. We're also developing a mouse model that expresses the human CRTH2 gene to test the therapeutic effect of our NKCE. We're currently in the phase of validation testing of our tools in an inflammatory context.