The role of natural killer cells in cutaneous T celllymphoma: pathophysiological mechanisms and clinical implications

Christoph Iselin was awarded this “MD-PhD scholarship” in May 2023 for 3 years. He is performing his research in Prof. Emmanuella Guenova’s lab at the University of Lausanne.

Cutaneous T cell lymphoma (CTCL) is a group of rare but potentially lethal non-Hodgkin’s lymphomas, originating from malignant CD4+ T cells. The patient’s immune system is deemed an important determining factor of disease progression, and immunomodulatory therapies reliably improve outcomes. Therefore, understanding the effect of CTCL on the immune system and its cells is imperative for improving therapeutic options.

CTCL immunomodulatory effects lead to immune cell exhaustion, explaining the so far disappointing results of T- and dendritic cell-dependent therapies when compared to other types of cancer. However, there is recent evidence that natural killer (NK) cells account for the response of immunomodulatory treatment in CTCL.

Given the immunomodulatory nature of CTCL, its profoundly immunosuppressive tumor microenvironment and the reduced anti-tumor activity of NK cells in CTCL patients, I formulate the following hypothesis: the tumor microenvironment-driven suppression of NK cell function is a crucial factor for tumor progression in CTCL, and the rescue of NK cell activity can be used as an effective treatment strategy in CTCL and cancer in general.

The overarching goal of this project is to reverse the CTCL-impaired NK cell activity by targeting the factors which negatively regulate NK cell function. The first step will be to phenotype the NK cells in the tissue microenvironment (TME) of CTCL through computational, single-cell sequencing analysis. I will examine this comprehensive dataset for factors and pathways that specifically alter NK cells in CTCL by comparing it with that of the NK cells in healthy skin, inflammatory skin diseases and solid skin tumors.

All discovered candidate molecules will then be individually validated by reverse transcription PCR (RT-PCR), fluorescence-activated cell sorting (FACS) and protein immunoblotting in NK cells from CTCL patients and individuals suffering from the aforementioned other diseases as controls. The number and state of activity of NK cells will be compared to the existing patient-specific clinical data to evaluate the impact of disease stage and progression. I will then test the reversibility of the suppressive effect of promising candidate molecules on NK cell activity in vitro and develop a combinatorial therapy plan to treat CTCL in a syngeneic T cell lymphoma model. In this way, I will test in vivo whether the target molecules discovered in steps 1 and 2 can be used to rescue the anti-tumor potential of NK cells and improve the outcome of CTCL.

If successful, this project will advance our understanding of the role of NK cells in CTCL pathology and treatment, as well as in inflammatory skin diseases and solid skin tumors. The factors and pathways initially identified through computational analysis, experimentally validated in vitro as reversible and found to be effective in vivo can be the basis for further studies to test their clinical applicability. 

The role of the brain-derived neurotrophic factor in the neuro-immune control of acute myeloid leukemia

Benedetta Fiordi was awarded this “PhD scholarship” in March 2023 for 3 years. She is performing her research in Prof. Camilla Jandus’ lab at the University of Geneva.

The immune system and the peripheral nervous system are present throughout the body and cooperate to ensure vital organs maintain tissue homeostasis and the overall health of the host. However, it is still poorly understood how this cooperation is modified or lost in cancer, in particular in leukemia, and more thorough investigation is needed to ideally identify targetable determinants able to restore the correct crosstalk. Leukemia is a group of blood cancers originating in the bone marrow (BM), a highly innervated tissue.

In this project, I will focus on acute myeloid leukemia (AML), a disease that urgently requires a more complete understanding, the overall survival rate being below 20% due to drug resistance and disease relapse. The main cause of treatment failure in AML are leukemic stem cells (LSC) that are resistant to chemotherapy, that survive and give rise to other leukemic clones that proliferate and engraft in the patients. LSCs reside in the BM and are sustained by cells and soluble factors, including neural-derived factors, that constitute the BM microenvironment, also called the BM niche. Previously published findings from the host laboratory show that innate lymphoid cells (ILC), a recently described family of immune cells involved in tissue homeostasis, inflammatory diseases and cancer, are present but functionally dysregulated in the BM of AML patients at disease onset and only partially restored after chemotherapy.

However, how ILCs interact with malignant cells including LSCs and whether this interaction is modulated by neurotrophic factors is yet to be discovered. Among the nerve-derived factors, I will focus on the role of the brain-derived neurotrophic factor (BDNF) in this project, since it has been associated with a favorable outcome in chronic lymphocytic leukemia (CLL) and was found to be dramatically reduced in the peripheral blood (PB) and BM of AML patients in my preliminary experiments. The aim of this project will be to understand whether its loss affects ILC anti-tumoral functions, promotes LSC survival and/or modulates their interactions.

Therefore, I plan to dissect the role of BDNF in the neuro-immune control of AML by: 1) identifying cellular and molecular players involved in BDNF-tropomyosin receptor kinase B (TrkB) signaling (Aim 1); 2) dissecting the tumor/stroma-immune cell crosstalk involving BDNF (Aim 2); and 3) assessing the impact of BDNF on leukemia clearance in vivo (Aim 3). Overall, I expect to shed light on a new layer of tumor immunity, i.e., the neuro-immune circuit in leukemia, a potential key contributor to disease progression and response to therapy.

Schematic representation of the proposed project

Modeling and Investigating the Tumor Microenvironment of Non-Small Cell Lung Cancer Brain Metastasis

This « ISREC grant for translational oncology » was awarded to Benoît Duc in November 2021 for 3 years. Benoît Duc works in the group of Prof. Johanna Joyce at the Ludwig Institute for Cancer Research, University of Lausanne.

Lung cancer, including the most common type, non-small cell lung cancer, is the leading cause of cancer-related deaths worldwide. Metastasis represents the final stage of lung cancer progression, when cancer cells have successfully spread to a new organ and colonized it. Critically, 20-40% of lung cancer patients develop brain metastasis over the course of the disease progression. We urgently need to devise novel therapies for lung cancer brain metastasis because, first, more than 50% of the patients die in the year following diagnosis, and second, these metastases cause deaths in patients in which the disease in the lung and other sites of metastasis is under control.

However, the lack of animal models that faithfully represent human lung cancer brain metastasis impedes our current understanding of the underlying molecular mechanisms. Yet this information is urgently required for the identification of the unique vulnerabilities of these mechanisms for future therapeutic targeting.

In this project, we will take advantage of our collaborations with pathologists, surgeons and scientists within the Swiss Cancer Center Léman and overseas, to reveal novel therapeutic combinations that target the non-cancerous cells in the tumors (the tumor microenvironment), including the immune cells. We will generate a first of its kind mouse model of lung cancer that recapitulates all the steps of lung cancer brain metastasis. Since these mice will have an intact immune system (which is not the case in many current models), we will be able to determine how the body’s defenses react to lung cancer metastasis in the brain, and identify therapies that can boost this response.

In parallel, we will leverage novel technologies that describe the cellular interactions that determine how the non-cancerous cells react to the cancer cells and where these interactions occur in the tumor. By performing these analyses in patient samples and in our animal model, we aim to identify yet unappreciated vulnerabilities in the non-cancerous cells of lung cancer brain metastasis, which we will target in our novel mouse model. We hope that this will ultimately lead to a personalized management of non-small cell lung cancer brain metastasis, whereby rationally designed treatments will target distinct molecular subtypes.

Mechanisms and therapeutic targeting of the neuronal NMDAR signaling pathway promoting breast cancerpathogenesis

This “ISREC grant” was awarded to Simge Yücel in November 2020 for four years. Simge Yücel is working in the laboratories of Professors Douglas Hanahan and Michele De Palma, EPFL/SV/ISREC.

The research will focus on elucidating pathogenic mechanisms and exploring innovative therapeutic targeting strategies for breast cancer. The focus will be on a neuronal signaling pathway – centered upon the NMDA receptor (NMDAR) – that the Hanahan lab discovered to be hijacked by cancer cells to enhance invasion and metastasis, the hallmarks of malignancy that cause cancer mortality. The NMDAR’s role in cancer pathogenesis was initially discovered and described in 2013 (Li & Hanahan, Cell), and further characterized in 2018 (Li, Zeng et al., Cancer Cell), principally in pancreas cancer. Then in 2019, the role of NMDAR signaling in the metastasis of breast cancer to the brain was established in a major article in Nature (Zeng et al.). Unpublished data from the Hanahan lab suggest that the NMDAR may also be hijacked in certain primary breast tumors and in metastasis to other sites. Simge Yücel will use mouse models of breast cancer in conjunction with analysis of human breast cancer biopsies to pursue the following lines of investigation:

Line of investigation 1

What are the effects of conditional, cancer cell-specific genetic ablation of the key signaling subunit of NMDAR (GluN2B) on the development and lethal progression of invasive primary and lung-metastatic tumors in the MMTV-PymT mouse model of breast cancer? (The 2013 Cell publication showed that the NMDAR is activated in this model.) Other models, e.g. the C3Tag transgenic model of triple negative breast cancer, may also be employed. The plan is to assess not only invasion and metastasis but also effects on the tumor microenvironment, using a portfolio of sophisticated histopathological, cellular and molecular ‘-omic’ technologies, including single cell RNA

Line of investigation 2

Similarly, Simge Yücel will assess the effects of conditional cancer-specific deletion of candidate downstream effectors of NMDAR described in the 2018 Cancer Cell publication, in particular the transcription factor HSF1 and the translational regulator FMRP. She will use engineered breast cancer cell lines in culture and as transplant tumors to further investigate these effectors and to identify key genes amongst the myriad of genes regulated by each one.

Line of investigation 3

She will work with collaborators in Lund, Sweden, and Bern to assess tissue microarrays of human breast cancer for expression of components of the NMDAR signaling pathway, and in particular diagnostic pathway activity, as revealed by immunostaining for phosphorylated GluN2B. She will look for correlations with histological and molecular subtypes of human breast cancer, and associations with poor survival. She will study both primary breast tumors and metastases to other organs, such as lung, liver, and bone. She will develop hypotheses which she will then test in appropriate mouse models of breast

Line of investigation 4

Simge Yücel will explore mechanism-guided therapeutic targeting strategies aimed to pharmacologically inhibit either NMDAR signaling or genetically validated downstream effectors of its malignancy-enhancing program, in particular to impair invasion and metastasis. She will test rational combinations with drugs that disrupt other key tumor progression pathways, or that modulate the immune system so as to promote the efficacy of

These lines of investigation are likely to reveal new opportunities, which will be incorporated in the research.