Cancer Immune Surveillance and Therapeutic Targeting
While immune evasion mechanisms in established tumors start to be well characterized, the very early events that permit pre-neoplasic cell detection remain poorly understood. Although diverse innate immune cells likely contribute to tumor sensing, it’s mainly cellular stress detection by NK cell through NKG2D/NKG2DL interaction that is so far established to mediate tumor recognition. Our project will focus on Breast Cancer (BC) and Colon carcinoma and use unbiased system biology and biologically-driven approaches, both in human and mice, to identify important mechanisms of immune sensing of the very early stages of cell transformation. The team project is guided by 2 major complementary concepts: i- existence of tumor cell intrinsic mechanisms of innate detection of cell transformation, ii- cooperation of dendritic cells (DC) with other innate cells to sense cell transformation and initiate adaptive immunity. It is expected that understanding mechanisms of early immune detection of cell transformation will yield to the discovery of important novel escape mechanisms that could be targeted in established tumors.
Thus, our team analyze Innate immune surveillance mechanisms with groups of Drs Marie-Cécile Michallet, Nathalie Bendriss-Vermare, Jenny Valladeau-Guilemond, and Isabelle Puisieux and adaptive immune surveillance and resistance mechanisms with groups of Drs Bertrand Dubois, Christine Ménétrier-Caux, and Stephane Depil.
We have hypothesized that innate immune surveillance is initiated early during transformation through oncogenic stress. This is supported in mouse model showing that expression of an oncogenic signal (HrasV12) induces innate immune cell recruitment required for tumor clearance (Xue, 2007, Kang, Nature 2011). To decipher the underlying mechanisms in vitro in human and in vivo in mice, we have developed approaches based on mammary epithelial cell lines expressing an inducible oncogene (Her2, Rasv12). In a mouse mammary tumor model where oncogenic stress leads to tumor rejection in immunocompetent (wt) mice but not in immunodeficient mice, an unbiased genome editing in vivo screen will be performed to select tumor clones developing in wt mice and to discover molecular pathways operating in the tumor cell leading to immune detection
Many innate immune cells such as dendritic cells (DC) and neutrophils contribute to the tumor immune surveillance. Our previous work and preliminary results have shown that :
i) pDC contribute to this surveillance process by sensing TLR-dependent signals in cooperation with neutrophils. This immune surveillance is counteracted in established tumors through several resistance mechanisms.
ii) another particular subset of DC named BDCA3+/XCR1+ DC infiltrate human tumors, produce IFN-III (IFNl), and, in cooperation with NK cells, have the unique capacity to cross-present cell-associated Ag from living cells to CD8+ T cells
iii) IL-33 detected in the tumor environment is a potent IFNg inducer by NK cells.
Thus, based on these data and on the concept that the innate immune system needs to be alerted through different pathways or cells, we hypothesize that pDC/neutrophils and IL-33/XCR1+ DC/NK cells cooperate to sense early stages of cell transformation and to induce adaptive immunity through cross-presentation to CD8+ T cells.
We thus analyze human early tumor lesions where we perform a comprehensive analysis of the functional/activation status of DC subsets, neutrophils, and NK cells in early (Hyperplasia and In Situ breast cancer and Colon polyps) compared to invasive tumors by multiparametric flow cytometry, deep scRNAseq and multi-immunofluorescence. Second, we performed same analysis of immune infiltrating cells in a mouse early mammary tumor model and using many transgenic mice.
Concerning adaptive immune surveillance, the team made several original observations suggesting the importance of the underexplored humoral response in tumor immune surveillance and the existence of novel classes of neo-antigens. The differential impact of B cell populations, TLS and Ig isotypes on tumor immune surveillance and efficiency of immunotherapy, and their antigenic targets will be deciphered using prospective and retrospective cohorts of patients using cytometry, multi-IF staining, RNAseq and peptide arrays. We recently showed for example that tumors associated to paraneoplastic neurologic diseases (rare autoimmune disorders satellite to a cancer), present genomic alterations in onconeural Ags (collab J. Honnorat, INMG, Lyon), resulting in tolerance breakdown and to efficient anti-tumor immune response against the created neo-epitopes and massive infiltration by plasma cells and CD8+ cytotoxic T cells.
Finally, concerning immune resistance mechanisms, we will mainly i) pursue biological investigations on adenosine pathway and ii) take advantage of ongoing immunotherapy clinical trials to identify novel immune resistance pathways. Indeed, we have identified CD4+ CD73+ potent polyfunctional anti-tumor effector T cells (Teffs) whose function is selectively blocked in the tumor environment by CD39+ Treg through CD39/CD73 produced immunosuppressive adenosine. We will thus analyze: i) the accumulation of CD73+ Teffs upon neo-adjuvant chemotherapy in patients, ii) their frequency and functional status in anti-PD-1/L1 treated patients, iii) the impact of combined anti-PD1 and anti-CD73 neutralizing mAbs or allosteric inhibitors in preclinical humanized mouse models.
In the objective to identify targetable resistance mechanisms in TNBC and ovarian tumors in particular, we will perform a comprehensive comparison of tumors from responding versus non-responding IT-treated patients (trials NeoPembrOV, Breast-Immun-3, and Chemo-Immune) through i) total RNAseq, ii) single cell RNAseq of both tumor and immune cell subsets, iii) nanostring DSP (Digital Spatial Profiling microscopy) single cell in situ analysis to generate spatial data. Through multiscale data integration (collab Synergie Lyon Cancer, Bio-informatic Platform ‘Gilles Thomas’), we expect to identify novel pathways of immune resistance. As for past programs, identified targets will be pursued for drug development and immune intervention (C3D & biotech partnership).