TEAM LEADER : Eric Tartour
Mail : eric.tartour@egp.aphp.fr
PHONE :+33 1 53 98 80 26
Localisation :
DOCTORAL SCHOOL : Bio SPC
The team directed by Eric Tartour develops two main objectives : i) Following recent works showing that anti-angiogenic therapy reversed immunosuppression in cancer patients, we aim to better understand mechanisms explaining why the inhibition of angiogenesis impacts on immune cells and molecules in the tumor microenvironment.
We also address the value of these immune parameters modified by this therapy, as biomarker of clinical response. ii) The second project is dedicated to the development of therapeutic cancer vaccines against papillomavirus to treat HPV associated head and neck cancers and Her2 for tumors expressing this oncogene (breast cancer, lung cancer, gastric cancer, ovarian cancer…).
One originality of our approach is i) the use of a delivery vector, the B subunit of Shiga toxin which targets antigen into dendritic cells ii) to modulate the tumor angiogenesis to improve the homing of T cells in tumor and the efficacy of cancer vaccine.
During the last years, the team pursues the analysis of the off target effect of VEGF on immune cells and extends the role VEGF in the induction of an immunosuppressive tumor microenvironment, especially in the regulation of checkpoint inhibitors on CD8+T cells.
In 2013, we have shown that VEGF in combination with TCR stimulation increases the proliferation of regulatory T cells which express VEGF-R2 (Terme M et al Cancer Res 2013). This observation may explain why the administration of anti-angiogenic molecules in cancer patients decreases the number of regulatory T cells as already reported by the team (Adotevi et al J Immunother 2010).
The recent development of therapies targeting PD-1 and CTLA-4 have raised great interest since they induced long-lasting objective responses in patients suffering from advanced metastatic tumors. However, the regulation of PD-1 expression, and thereby the mechanism of T cell exhaustion, is unclear.
In a first experiment, we show that blocking VEGF-A/VEGFR axis in tumor bearing mice, decreases PD-1 expression on intratumoral CD8+ T cells, and restores IFNg production in these cells. To understand whether VEGF-A can act directly on CD8+ T cells, we first analyzed the expression of the two VEGF-A receptors, VEGF-R1 and -R2, on CD8+ T cells in vivo. We observed that these two receptors are expressed only at very low levels in spleens of tumor-free and tumor-bearing mice, but are strongly increased on tumor-infiltrating CD8+ T cells.
In addition, these receptors are induced on CD8+T cells after activation.Interestingly, anti-CD3 stimulation induced expression of PD-1, but addition of VEGF-A enhanced PD-1 expression on these cells in a dose-dependent manner. Thus, VEGF-A directly increases PD-1 expression on activated CD8+ T cells.
We also observed that VEGF-A not only enhances PD-1 expression but also increases the percentages of Tim-3- and CTLA-4-expressing CD8+ T cells in a dose-dependent manner (Figure 1). Anti-VEGF-R2 but not anti-VEGF-R1 antibody was able to block the VEGF-A-induced upregulation of these inhibitory receptors demonstrating the involvement of VEGF-R2 in this phenomenon. VEGF-A enhances the expression of inhibitory receptors involved in T cell exhaustion via activation of the VEGFR2/PLCg/calcineurin/NFAT pathway. In order to document if VEGF-A neutralization could revert expression of PD-1 and other inhibitory receptors in vivo, we tested anti-VEGF-A treatment on CT26 (colorectal cancer) -bearing mice.
Consistent with our in vitro results, VEGF-A inhibition decreased the proportion of tumor-infiltrating CD8+ T cells expressing PD-1/Tim-3, PD-1/CTLA-4 and PD-1/Lag-3. Altogether, these results showed that targeting VEGF-A can decrease the VEGF-induced expression of inhibitory receptors mediating CD8+ T cell exhaustion.
We next tried to combine anti-VEGFA antibody with anti-PD-1 antibody in our mouse model of colorectal cancer expressing high levels of VEGF-A. Noteworthy, anti-VEGF-A treatment reduced tumor growth, and anti-PD-1 antibody alone had no significant effect, but the anti-VEGF-A and anti-PD-1 combination induced a strong anti-tumor effect as compared to anti-VEGF-A alone or anti-PD-1 alone.
This result suggests that anti-angiogenic therapies targeting VEGF-A/VEGFR in tumors expressing high levels of VEGF-A could synergize with anti-PD-1 treatment strategies. In view of these results, association of anti-angiogenic molecules with immunomodulators of inhibitory checkpoints may be of particular interest in VEGF-A-producing tumors.
This work was performed by M Terme (firstly Post-doctoral fellow in the team and now associate professor at universite Paris Descartes) and T Voron (firstly M2 in the team and actually PhD), under the supervision of J Taieb (PU-PH). A manuscript about this work has been published in the Journal of Experimental Medicine and a related review
– Voron T, Colussi O, Marcheteau E, Pernot S, Nizard M, Pointet AL, Latreche S, Bergaya S, Benhamouda N, Tanchot C, Stockmann C, Combe P, Berger A, Zinzindohoue F, Yagita H, Tartour E, Taieb J, Terme M. VEGF-A modulates expression of inhibitory checkpoints on CD8+ T cells in tumors. J Exp Med 212 (2) : 139-48 (2015) (13.9)(scientists of the team underlined)
– Voron T, Tartour E, Taieb J, Terme M. Impact of VEGF-A in exhaustion of intratumoral T cells. Med Sci ;31(5):473-5 (2015)
In collaboration with the group of E Deutsch at Institut Gustave Roussy, we set up an orthotopic model of head and neck cancer expressing the oncogenic E6 and E7 protein of HPV16. HPV16 is the most frequent serotype of oncogenic HPV expressed in 4-5% of human tumors.
We demonstrated a synergy between local irradiation of tumor bearing mice with a cancer vaccine based on the targeting of dendritic cells by the B subunit of Shiga toxin coupled to the E7 protein (STxB-E7)(Collab L Johannes. Institut Curie).
The combined treatment led to a complete tumor clearance in the majority of mice not observed with each treatment alone. STxB-E7 and irradiation increased the levels of tumor-infiltrating, antigen-specific CD8+ T cells compared to each treatment alone.
These CD8+T cells were required for the clinical response and protected against local recurrence and tumor metastases suggesting the acquisition of a memory tumor immunity.
We also report for the first time that a combination therapy based on local irradiation and vaccination induces an increased pericyte coverage (as shown by NG2 and αSMA staining), an hallmark of vascular normalization, and ICAM-1 expression on vessels (See Highlights).
This was accompanied by an augmented tumor perfusion that correlated with the antitumor response. The combination strategy proposed here offers a promising approach that could potentially be transferred into early phase clinical trials. A manuscript has been accepted for publication in Mol Cancer Therapy and a patent also submitted
– Mondini M, Nizard M, Tran T, Mauge L, Loi M, Clémenson C, Dugue D, Maroun P, Louvet E, Adam J, Badoual C, Helley D, Dransart E, Johannes L, Vozenin MC, Perfettini JL, Tartour E, Deutsch E. Synergy of radiotherapy and a cancer vaccine for the treatment of HPV-associated head and neck cancer. Mol Cancer Ther. 14(6):1336-45. (2015) (IF 5.7)
– Combined vaccination/radiotherapy for cancer treatment. Application n°15000507.2. Patent N° 1453 (17.4.2015) (Inventor : Tartour, Deutsch, Johannes, Mondini, Perfetini, Tran, Nizard)
3.1 Mechanism regarding STxB-mediated antigen cross-presentation
In collaboration with L Johannes (Institut Curie), the receptor-binding B-subunit of Shiga toxin (STxB) has been developed as an antigen delivery tool.
We have demonstrated that this vector allow the targeting of antigen to dendritic cells which specifically express its Gb3 glycolipid receptor. STxB has also the remarkable capacity to transfer exogenous antigens to the cytosol for processing by proteasomes and subsequent presentation of major histocompatibility complex class-I (MHC-I) molecules, a process termed cross-presentation. The Shiga toxin composed of the A and B subunit followed a retrograde transport and are shuttled by vesicular transport from endosomes to the Golgi complex and continue to the endoplasmic reticulum to enter the cytosol where it inhibits protein synthesis by ribosomes.
Unexpectedely, we have found that retrograde trafficking to the Golgi complex was not required for STxB– saporin translocation to the cytosol or for STxB-dependent antigen cross-presentation.
Interestingly, experiments with reducible and non reducible linker-arm–STxB conjugates led to the conclusion that after translocation, STxB remains associated with the cytosolic membrane leaflet.
In summary, we report new facets of the endosomal escape process bearing relevance to antigen cross-presentation.
A manuscript has been published on this work in J Cell Sci
– Garcia-Castillo MD, Tran T, Bobard A, Renard HF, Rathjen SJ, Dransart E, Stechmann B, Lamaze C, Lord M, Cintrat JC, Enninga J, Tartour E*, Johannes L*. Retrograde transport is not required for cytosolic translocation of the B-subunit of Shiga toxin. J Cell Sci. 128(13):2373-87 (2015) *co-senior authorship (IF : 5.4)
3.2 STxB-E75 : A therapeutic cancer vaccine for low Her2/neu expressing tumor
The E75 peptide derived from the Her2/neu protein has been developed as vaccine and generated suboptimal results in clinical trials. Using a delivery vector targeting the E75 peptide to dendritic cells, we improved its potency both in terms of induction of CD8+T cells, and tumor protection in relevant preclinical models.
We also demonstrated in a series of human breast cancer cell lines, that high Her2/neu-expressing tumor cells are not efficiently recognized by anti-E75 CD8+T cells compared to low Her2/neu tumors.
These results were also translated and confirmed in in vivo models (Figure 2). Thus, although, Her2/neu is a validated target for various mAb in breast cancer and gastric cancer expressing high levels of this antigen, this study demonstrates that a Her2/neu cancer vaccine may be preferentially indicated in low Her2/neu-expressing tumors.
A synergistic effect was also observed when cancer vaccine was combined with anti-Her2/neu mAb treatment.
This work has just been accepted in Clin Cancer Res
– Tran T, Diniz MO, Dransart E, Gey A, Merillon N, Lone YC, Godefroy S, Sibley C, Ferreira LCS, Medioni J, Oudard S, Johannes L, Tartour E. A therapeutic Her2/neu vaccine targeting dendritic cells preferentially inhibits the growth of low Her2/neu-expressing tumor in HLA-A2 transgenic mice. Clin Cancer Res (2016) (IF: 8.7)
