Tumor-associated high endothelial venules mediate lymphocyte entry into tumors and predict response to PD-1 plus CTLA-4 combination immunotherapy

Recruitment of lymphocytes into tumors is critical for anti-tumor immunity and efficacious immunotherapy. We show in murine models that tumor-associated high endothelial venules (TA-HEVs) are major sites of lymphocyte entry into tumors at baseline and upon treatment with anti-PD-1/anti-CTLA-4 immune checkpoint blockade (ICB). TA-HEV endothelial cells (TA-HECs) derive from post-capillary venules, co-express MECA-79⁺ HEV sialomucins and E/P-selectins, and are associated with homing and infiltration into tumors of various T cell subsets. Intravital microscopy further shows that TA-HEVs are the main sites of lymphocyte arrest and extravasation into ICB-treated tumors. Increasing TA-HEC frequency and maturation increases the proportion of tumor-infiltrating stem-like CD8⁺ T cells, and ameliorates ICB efficacy. Analysis of tumor biopsies from 93 patients with metastatic melanoma reveals that TA-HEVs are predictive of better response and survival upon treatment with anti-PD-1/anti-CTLA-4 combination. These studies provide critical insights into the mechanisms governing lymphocyte trafficking in cancer immunity and immunotherapy.

Abstract P6-09-05: Prognostic and predictive values of high endothelial venules (HEV) and tumor infiltrating CD8+ lymphocytes (CD8) in tumors of patients included in the adjuvant PACS04 trial: HEV is predictive of outcome for HER2+ tumors exposed to trastuzumab

Background: HEV are specialized blood vessels that function as portals of entry for lymphocytes into lymphoid organs and tumor tissues (Moussion and Girard, Nature 2011, 479:542-546; Girard et al, Nature Rev Immunol 2012, 12:762-773). We retrospectively considered HEV and CD8 as potential prognostic and/or predictive factors in a large randomized adjuvant trial of node positive breast cancer patients (PACS04). This trial included 3010 node positive patients randomized between anthracyclins alone or anthracyclins and docetaxel chemotherapy. Patients with HER2+ expressing tumors had a second randomization with or without trastuzumab given sequentially for one year. With 59.5 median follow-up, metastatic free interval (MFI), the first end-point, was 84.5% at 5 years for the whole population.

Methods: 1660 tumor samples (9.7% triple negative, 67.5% HR+/HER2- and 22.8% HER2+) were collected and analyzed by immunostaining on full sections for HEV (MECA-79 mAb, BD Biosciences) and CD8 (C8/144B mAb, Dako). HEV densities were determined as previously described (Martinet et al., Cancer Res 2011, 71:5678-5687). CD8+ cells and tumor-infiltrating lymphocytes (TIL) were scored according to recently published guidelines. Univariate analyses were performed using cox proportional hazard model for continuous variable. Independent analyses for the predictive evaluation of trastuzumab outcome were performed in the HER2+ subgroup.

Results: MFI and overall survival at 5 years for this series are respectively of 84.9% (TN: 77.4%, HR+/HER2-: 89%, HER2+:75.8%) and 91% not different with the total group. The table shows expression of the different markers according to the subgroup of tumors.

Marker values according to sub molecular classification TNRH+/HER2-HER2+/RH-Number1601119378Metastatic events3411990HEV/mm2(median,range)0.51 (0, 7.73)0.13 (0, 10.23)0.38 (0, 13.63)CD8score (median, range)2 (0, 3)1 (0, 3)2 (0, 3)Table 1

No difference in univariate analysis was observed in TN and HR+/HER2- subgroups in terms of relationship between marker expression and outcomes. For the HER2+ group, HEV and CD8 were correlated to better outcome (HEV: HR=0.73, p =0.011; CD8: HR=0.64; p=0.006). For HER2+ patients not receiving trastuzumab (222 pts, 55 events), CD8 was predictive of metastasis risk (HR: 0.65, p=0.032), but not HEV (HR:0.82, p=0.09). Conversely, in the trastuzumab treated group (156 pts, 35 events), HEV was significantly correlated with a lower risk of relapse (HR: 0.45, p=0.02), but CD8 was not (HR:0.63, p=0.07). TIL counts are still ongoing and will be reported at time of presentation.

Conclusions: HEV and CD8 are associated with better prognosis in the HER2+ tumor group. Interestingly, HEV presence in the tumor seems to be a significant predictive factor of trastuzumab efficacy.

Citation Format: Roché HH, Lafouresse FF, Filleron T, Laffont R, Maisongrosse V, Pichery M, Le Guellec S, Penault-Llorca F, Lemonnier J, Lacroix-Triki M, Girard J-P. Prognostic and predictive values of high endothelial venules (HEV) and tumor infiltrating CD8+ lymphocytes (CD8) in tumors of patients included in the adjuvant PACS04 trial: HEV is predictive of outcome for HER2+ tumors exposed to trastuzumab [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P6-09-05.

Abstract B156: Tumor high endothelial venules (HEVs), specialized blood vessels which recruit lymphocytes to limit tumor progression

We discovered that some blood vessels present within the tumor microenvironment can be associated with favorable prognosis by contributing to tumor suppression rather than tumor growth (Martinet and Girard, Cancer Res 2011). These specialized blood vessels, designated high endothelial venules (HEVs), are normally found in lymph nodes where they mediate lymphocyte entry (Girard et al., Nat Rev Immunol 2012). A high density of tumor HEVs in human tumors was associated with high levels of cytotoxic lymphocyte infiltration, indicating that HEVs may contribute to the eradication of tumors by facilitating access of ‘killer’ lymphocytes into tumor tissues. It is thus important to better define the mechanisms regulating HEV formation. Our previous data have revealed a critical role for dendritic cells (Moussion and Girard, Nature 2011). Here, we will present our most recent results indicating that tumor HEVs may be central to the control of tumor growth in mouse tumor models.

Citation Format: Robin Laffont, Fanny Lafouresse, Jean-Philippe Girard. Tumor high endothelial venules (HEVs), specialized blood vessels which recruit lymphocytes to limit tumor progression. [abstract]. In: Proceedings of the CRI-CIMT-EATI-AACR Inaugural International Cancer Immunotherapy Conference: Translating Science into Survival; September 16-19, 2015; New York, NY. Philadelphia (PA): AACR; Cancer Immunol Res 2016;4(1 Suppl):Abstract nr B156.