BCG priming followed by a novel interleukin combination activates Natural Killer cells to selectively proliferate and become anti-tumour long-lived effectors.

The short-lived nature and heterogeneity of Natural Killer (NK) cells limit the development of NK cell-based therapies, despite their proven safety and efficacy against cancer. Here, we describe the biological basis, detailed phenotype and function of long-lived anti-tumour human NK cells (CD56highCD16+), obtained without cell sorting or feeder cells, after priming of peripheral blood cells with Bacillus Calmette-Guérin (BCG). Further, we demonstrate that survival doses of a cytokine combination, excluding IL18, administered just weekly to BCG-primed NK cells avoids innate lymphocyte exhaustion and leads to specific long-term proliferation of innate cells that exert potent cytotoxic function against a broad range of solid tumours, mainly through NKG2D. Strikingly, a NKG2C+CD57-FcεRIγ+ NK cell population expands after BCG and cytokine stimulation, independently of HCMV serology. This strategy was exploited to rescue anti-tumour NK cells even from the suppressor environment of cancer patients' bone marrow, demonstrating that BCG confers durable anti-tumour features to NK cells.

Intravenous administration of BCG in mice promotes natural killer and T cell-mediated antitumor immunity in the lung.

Intravesical administration of Bacillus Calmette-Guérin (BCG) was one of the first FDA-approved immunotherapies and remains a standard treatment for bladder cancer. Previous studies have demonstrated that intravenous (IV) administration of BCG is well-tolerated and effective in preventing tuberculosis infection in animals. Here, we examine IV BCG in several preclinical lung tumor models. Our findings demonstrate that BCG inoculation reduced tumor growth and prolonged mouse survival in models of lung melanoma metastasis and orthotopic lung adenocarcinoma. Moreover, IV BCG treatment was well-tolerated with no apparent signs of acute toxicity. Mechanistically, IV BCG induced tumor-specific CD8+ T cell responses, which were dependent on type 1 conventional dendritic cells, as well as NK cell-mediated immunity. Lastly, we also show that IV BCG has an additive effect on anti-PD-L1 checkpoint inhibitor treatment in mouse lung tumors that are otherwise resistant to anti-PD-L1 as monotherapy. Overall, our study demonstrates the potential of systemic IV BCG administration in the treatment of lung tumors, highlighting its ability to enhance immune responses and augment immune checkpoint blockade efficacy.

BCG-activation of leukocytes is sufficient for the generation of donor-independent innate anti-tumor NK and γδ T-cells that can be further expanded in vitro.

Bacillus Calmette-Guérin (BCG), the nonpathogenic Mycobacterium bovis strain used as tuberculosis vaccine, has been successfully used as treatment for non-muscle invasive bladder cancer for decades, and suggested to potentiate cellular and humoral immune responses. However, the exact mechanism of action is not fully understood. We previously described that BCG mainly activated anti-tumor cytotoxic NK cells with upregulation of CD56 and a CD16+ phenotype. Now, we show that stimulation of human peripheral blood mononuclear cells with iBCG, a preparation based on BCG-Moreau, expands oligoclonal γδ T-cells, with a cytotoxic phenotype, together with anti-tumor CD56high CD16+ NK cells. We have used scRNA-seq, flow cytometry, and functional assays to characterize these BCG-activated γδ T-cells in detail. They had a high IFNγ secretion signature with expression of CD27+ and formed conjugates with bladder cancer cells. BCG-activated γδ T-cells proliferated strongly in response to minimal doses of cytokines and had anti-tumor functions, although not fully based on degranulation. BCG was sufficient to stimulate proliferation of γδ T-cells when cultured with other PBMC; however, BCG alone did not stimulate expansion of purified γδ T-cells. The characterization of these non-donor restricted lymphocyte populations, which can be expanded in vitro, could provide a new approach to prepare cell-based immunotherapy tools.

NKG2D Ligands in Liquid Biopsy: The Importance of Soluble and Vesicle-Bound Proteins for Immune Modulation.

The identification of biomarkers allowing diagnostics, prognostics and patient classification is still a challenge in oncological research for patient management. Improvements in patient survival achieved with immunotherapies substantiate that biomarker studies rely not only on cellular pathways contributing to the pathology, but also on the immune competence of the patient. If these immune molecules can be studied in a non-invasive manner, the benefit for patients and clinicians is obvious. The immune receptor Natural Killer Group 2 Member D (NKG2D) represents one of the main systems involved in direct recognition of tumor cells by effector lymphocytes (T and Natural Killer cells), and in immune evasion. The biology of NKG2D and its ligands comprises a complex network of cellular pathways leading to the expression of these tumor-associated ligands on the cell surface or to their release either as soluble proteins, or in extracellular vesicles that potently inhibit NKG2D-mediated responses. Increased levels of NKG2D-ligands in patient serum correlate with tumor progression and poor prognosis; however, most studies did not test the biochemical form of these molecules. Here we review the biology of the NKG2D receptor and ligands, their role in cancer and in patient response to immunotherapies, as well as the changes provoked in this system by non-immune cancer therapies. Further, we discuss the use of NKG2D-L in liquid biopsy, including methods to analyse vesicle-associated proteins. We propose that the evaluation in cancer patients of the whole NKG2D system can provide crucial information about patient immune competence and risk of tumor progression.

[Bladder cancer immunological background and biomarkers.] / Bases inmunológicas del cáncer vesical y biomarcadores.

Bladder cancer was one of the first to have a successful treatment based on immune system stimulation, recognized by patient survival and tumor recurrence data. In addition, bladder tumors are now known to have high antigenic load and are therefore considered to be susceptible to respond well to new immunotherapies. For these reasons, studying the mechanism of action of bladder cancer immunological-based treatments can provide valuable information both to improve their current use and to under stand why they work in some patients while others do not tolerate this therapy or have tumor progression. In this article, we will focus on the immune response generated by treatment of non-muscle invasive bladder tumors with BCG, as well as the relationship between this knowledge and new immunotherapies. We will first describe the main activities of the immune system, to continue with the treatment of bladder cancer with BCG, its mechanism of action and biomarkers. Finally, we will summarize the observations that led to the useof monoclonal antibody immunotherapy in cancer and will describe some of the new immunotherapies in use to treat bladder cancer patients.

El cáncer vesical fue uno de los primeros en tener un tratamiento de éxito basado en la estimulación del sistema inmunitario, apoyado por los datos de supervivencia de los pacientes y recurrencia de los tumores. Además, hoy día se sabe que los tumores de vejiga presentan alta carga antigénica y, por ello, se considera que son susceptibles de responder favorablemente a las nuevas inmunoterapias. Por estos motivos, estudiar el mecanismo de acción de los tratamientos inmunológicos de cáncer de vejiga nos puede aportar información muy valiosa tanto para mejorar su uso actual como para comprender por qué funcionan en unos pacientes mientras que otros no toleran la terapia o tienen progresión tumoral. En este artículo vamos a centrarnos en la respuesta inmunitaria generada por el tratamiento de los tumores devejiga no-músculo invasivos con BCG, así como la relación entre estos conocimientos y las nuevas inmunoterapias. Para ello, en primer lugar describiremos las principales actividades del sistema inmunitario para continuar con los fundamentos del tratamiento del cáncer devejiga con BCG, su mecanismo de acción y biomarcadores. Por último, recordaremos las observaciones que llevaron al uso de la inmunoterapia con anticuerpos monoclonales en cáncer y describiremos algunas de las nuevas inmunoterapias que se están introduciendo para tratar cánceres vesicales.