First-in-human study of SBRT and adenosine pathway blockade to potentiate the benefit of immunochemotherapy in early-stage luminal B breast cancer: results of the safety run-in phase of the Neo-CheckRay trial.

BACKGROUND: Luminal B breast cancer (BC) presents a worse prognosis when compared with luminal A BC and exhibits a lower sensitivity to chemotherapy and a lower immunogenicity in contrast to non-luminal BC subtypes. The Neo-CheckRay clinical trial investigates the use of stereotactic body radiation therapy (SBRT) directed to the primary tumor in combination with the adenosine pathway inhibitor oleclumab to improve the response to neo-adjuvant immuno-chemotherapy in luminal B BC. The trial consists of a safety run-in followed by a randomized phase II trial. Here, we present the results of the first-in-human safety run-in. METHODS: The safety run-in was an open-label, single-arm trial in which six patients with early-stage luminal B BC received the following neo-adjuvant regimen: paclitaxel q1w×12 → doxorubicin/cyclophosphamide q2w×4; durvalumab (anti-programmed cell death receptor ligand 1 (PD-L1)) q4w×5; oleclumab (anti-CD73) q2w×4 → q4w×3 and 3×8 Gy SBRT to the primary tumor at week 5. Surgery must be performed 2-6 weeks after primary systemic treatment and adjuvant therapy was given per local guidelines, RT boost to the tumor bed was not allowed. Key inclusion criteria were: luminal BC, Ki67≥15% or histological grade 3, MammaPrint high risk, tumor size≥1.5 cm. Primary tumor tissue samples were collected at three timepoints: baseline, 1 week after SBRT and at surgery. Tumor-infiltrating lymphocytes, PD-L1 and CD73 were evaluated at each timepoint, and residual cancer burden (RCB) was calculated at surgery. RESULTS: Six patients were included between November 2019 and March 2020. Median age was 53 years, range 37-69. All patients received SBRT and underwent surgery 2-4 weeks after the last treatment. After a median follow-up time of 2 years after surgery, one grade 3 adverse event (AE) was reported: pericarditis with rapid resolution under corticosteroids. No grade 4-5 AE were documented. Overall cosmetical breast evaluation after surgery was 'excellent' in four patients and 'good' in two patients. RCB results were 2/6 RCB 0; 2/6 RCB 1; 1/6 RCB 2 and 1/6 RCB 3. CONCLUSIONS: This novel treatment combination was considered safe and is worth further investigation in a randomized phase II trial. TRIAL REGISTRATION NUMBER: NCT03875573.

Paclitaxel plus carboplatin and durvalumab with or without oleclumab for women with previously untreated locally advanced or metastatic triple-negative breast cancer: the randomized SYNERGY phase I/II trial.

Chemo-immunotherapy is the first-line standard of care for patients with PD-L1 positive metastatic triple-negative breast cancer (mTNBC). SYNERGY (NCT03616886) is a dose-finding phase I and a randomized phase II, open-label trial evaluating if targeting the immunosuppressive adenosine pathway can enhance the antitumor activity of chemo-immunotherapy. The phase I part included 6 patients with untreated locally-advanced or mTNBC to determine the safety and recommended phase II dose of the anti-CD73 antibody oleclumab in combination with the anti-PD-L1 durvalumab and 12 cycles of weekly carboplatin and paclitaxel. In the phase II part, 127 women were randomized 1:1 to receive chemo-immunotherapy, with (arm A) or without (arm B) oleclumab. The primary endpoint was the clinical benefit rate at week 24, defined as stable disease, partial or complete response per RECIST v1.1. Secondary endpoints included objective response rate, duration of response, survival outcomes (progression-free survival and overall survival), and safety. The trial did not meet its primary endpoint, as the 24-week clinical benefit rate was not significantly improved by adding oleclumab (43% vs. 44%, p = 0.61). Exploratory median progression-free survival was 5.9 months in arm A as compared to 7.0 months in arm B (p = 0.90). The safety profile was manageable in both arms.

Differential Benefit of Metronomic Chemotherapy Among Triple-Negative Breast Cancer Subtypes Treated in the IBCSG Trial 22-00.

PURPOSE: To explore whether specific triple-negative breast cancer (TNBC) molecular subtypes are predictive for a benefit from maintenance low-dose cyclophosphamide and methotrexate (CM) in the adjuvant IBCSG 22-00 phase III clinical trial. EXPERIMENTAL DESIGN: RNA sequencing was performed on a selection of 347 TNBC formalin-fixed paraffin-embedded (FFPE) tumor samples following a case-cohort-like sampling. TNBC subtypes were computed on gene expression data. The association between TNBC subtypes and treatment outcome was assessed using a Cox proportional-hazards interaction test. RESULTS: Immunomodulatory (IM) and basal-like/immune activated (BLIA) molecular subtypes showed a significant survival benefit when treated with low-dose CM [disease-free survival (DFS): HR, 0.5; 95% confidence interval (CI), 0.28-0.89; Pinteraction = 0.018 and HR, 0.49; 95% CI, 0.27-0.9; Pinteraction = 0.021]. Moreover, a high expression of regulatory T-cell immune signature was associated with a better prognosis in the CM arm, in line with a potential immunomodulating role of cyclophosphamide. In contrast, a worse outcome was observed in tumors with a mesenchymal (M) subtype treated with low-dose CM (DFS: HR, 1.9; 95% CI, 1.2-3; Pinteraction = 0.0044). CONCLUSIONS: Our results show a differential benefit of low-dose CM therapy across different TNBC subtypes. Low-dose CM therapy could be considered as a potential strategy for TNBC tumors with IM subtype in the early-disease setting.

Adenosine A2A receptor is a tumor suppressor of NASH-associated hepatocellular carcinoma.

Inhibition of adenosine A2A receptor (A2AR) is a promising approach for cancer immunotherapy currently evaluated in several clinical trials. We here report that anti-obesogenic and anti-inflammatory functions of A2AR, however, significantly restrain hepatocellular carcinoma (HCC) development. Adora2a deletion in mice triggers obesity, non-alcoholic steatohepatitis (NASH), and systemic inflammation, leading to spontaneous HCC and promoting dimethylbenzyl-anthracene (DMBA)- or diethylnitrosamine (DEN)-induced HCC. Conditional Adora2a deletion reveals critical roles of myeloid and hepatocyte-derived A2AR signaling in restraining HCC by limiting hepatic inflammation and steatosis. Remarkably, the impact of A2AR pharmacological blockade on HCC development is dependent on pre-existing NASH. In support of our animal studies, low ADORA2A gene expression in human HCC is associated with cirrhosis, hepatic inflammation, and poor survival. Together, our study uncovers a previously unappreciated tumor-suppressive function for A2AR in the liver and suggests caution in the use of A2AR antagonists in patients with NASH and NASH-associated HCC.

PIK3CA copy-number gain and inhibitors of the PI3K/AKT/mTOR pathway in triple-negative breast cancer.

As wider insights are gained on the molecular landscape of triple-negative breast cancer (TNBC), novel targeted therapeutic strategies might become an option in this setting as well. Activating mutations of PIK3CA represent the second most common alteration in TNBC after the TP53 mutation, with a prevalence of ∼10%-15%. Considering the well-established predictive role of PIK3CA mutations for response to agents targeting the PI3K/AKT/mTOR pathway, several clinical trials are currently evaluating these drugs in patients with advanced TNBC. However, much less is known regarding the actionability of PIK3CA copy-number gains, which represent a thoroughly common molecular alteration in TNBC, with a prevalence estimated at 6%-20%, and are listed as "likely gain-of-function" alterations in the OncoKB database. In the present paper, we describe two clinical cases in which patients harboring PIK3CA-amplified TNBC received a targeted treatment with the mTOR-inhibitor everolimus and the PI3K-inhibitor alpelisib, respectively, with evidence of disease response on 18F-FDG positron-emission tomography (PET) imaging. Hence, we discuss the evidence presently available regarding a possible predictive value of PIK3CA amplification for response to targeted treatment strategies, suggesting that this molecular alteration might represent an intriguing biomarker in this sense. Considering that few of the currently active clinical trials assessing agents targeting the PI3K/AKT/mTOR pathway in TNBC select patients based on tumor molecular characterization, and none of these based on PIK3CA copy-number status, we urge for the introduction of PIK3CA amplification as a criterion for patient selection in future clinical trials in this setting.

Immunotherapy in breast cancer: an overview of current strategies and perspectives.

Recent progress in immunobiology has led the way to successful host immunity enhancement against breast cancer. In triple-negative breast cancer, the combination of cancer immunotherapy based on PD-1/PD-L1 immune checkpoint inhibitors with chemotherapy was effective both in advanced and early setting phase 3 clinical trials. These encouraging results lead to the first approvals of immune checkpoint inhibitors in triple-negative breast cancer and thus offer new therapeutic possibilities in aggressive tumors and hard-to-treat populations. Furthermore, several ongoing trials are investigating combining immunotherapies involving immune checkpoint inhibitors with conventional therapies and as well as with other immunotherapeutic strategies such as cancer vaccines, CAR-T cells, bispecific antibodies, and oncolytic viruses in all breast cancer subtypes. This review provides an overview of immunotherapies currently under clinical development and updated key results from clinical trials. Finally, we discuss the challenges to the successful implementation of immune treatment in managing breast cancer and their implications for the design of future clinical trials.

Predictive Biomarkers for Response to Immunotherapy in Triple Negative Breast Cancer: Promises and Challenges.

Triple negative breast cancer (TNBC) is a highly heterogeneous disease with a poor prognosis and a paucity of therapeutic options. In recent years, immunotherapy has emerged as a new treatment option for patients with TNBC. However, this therapeutic evolution is paralleled by a growing need for biomarkers which allow for a better selection of patients who are most likely to benefit from this immune checkpoint inhibitor (ICI)-based regimen. These biomarkers will not only facilitate a better optimization of treatment strategies, but they will also avoid unnecessary side effects in non-responders, and limit the increasing financial toxicity linked to the use of these agents. Huge efforts have been deployed to identify predictive biomarkers for the ICI, but until now, the fruits of this labor remained largely unsatisfactory. Among clinically validated biomarkers, only programmed death-ligand 1 protein (PD-L1) expression has been prospectively assessed in TNBC trials. In addition to this, microsatellite instability and a high tumor mutational burden are approved as tumor agnostic biomarkers, but only a small percentage of TNBC fits this category. Furthermore, TNBC should no longer be approached as a single biological entity, but rather as a complex disease with different molecular, clinicopathological, and tumor microenvironment subgroups. This review provides an overview of the validated and evolving predictive biomarkers for a response to ICI in TNBC.

Post-Neoadjuvant Treatment Strategies for Patients with Early Breast Cancer.

Pre-surgical treatments in patients with early breast cancer allows a direct estimation of treatment efficacy, by comparing the tumor and the treatment. Patients who achieve a pathological complete response at surgery have a better prognosis, with lower risk of disease recurrence and death. Hence, clinical research efforts have been focusing on high-risk patients with residual disease at surgery, who may be "salvaged" through additional treatments administered in the post-neoadjuvant setting. In the present review, we aim to illustrate the development and advantages of the post-neoadjuvant setting, and to discuss the available strategies for patients with early breast cancer, either approved or under investigation. This review was written after literature search on main scientific databases (e.g., PubMed) and conference proceedings from major oncology conferences up to 1 August 2022. T-DM1 and capecitabine are currently approved as post-neoadjuvant treatments for patients with HER2-positive and triple-negative breast cancer, respectively, with residual disease at surgery. More recently, other treatment strategies have been approved for patients with high-risk early breast cancer, including the immune checkpoint inhibitor pembrolizumab, the PARP inhibitor olaparib and the CDK 4/6 inhibitor abemaciclib. Novel agents and treatment combinations are currently under investigation as promising post-neoadjuvant treatment strategies.

ROSALINE: a phase II, neoadjuvant study targeting ROS1 in combination with endocrine therapy in invasive lobular carcinoma of the breast.

Invasive lobular carcinoma (ILC) is the most common histologic subtype of breast cancer after invasive ductal carcinoma (i.e., no special type [NST]). ILC differs from NST in clinical presentation, site-specific metastases and response to conventional therapies. Loss of E-cadherin protein expression, due to alterations in its encoding gene CDH1, is the most frequent oncogenic event in ILC. Synthetic lethality approaches have shown promising antitumor effects of ROS1 inhibitors in models of E-cadherin-defective breast cancer in in vivo studies and provide the rationale for testing their clinical activity in patients with ILC. Entrectinib is a tyrosine kinase inhibitor targeting TRK, ROS1 and ALK tyrosine kinases. Here, the authors present ROSALINE (NCT04551495), a phase II study testing neoadjuvant entrectinib and endocrine therapy in women with estrogen receptor-positive, HER2-negative early ILC.

Breast cancer is the most common cancer among women worldwide. Breast cancer is not a unique disease, but rather a heterogeneous disease, with different subtypes. Lobular breast cancer is the second most common histologic subtype of breast cancer after ductal breast cancer. Lobular breast cancer has some peculiar characteristics that make it a distinct entity in the context of breast cancer. Nevertheless, few clinical studies so far have focused specifically on this subtype. ROSALINE is a clinical study aimed to test entrectinib, a new drug that showed promising activity in preliminary research studies, in combination with endocrine therapy in women with lobular breast cancer before surgery. Trial Registration Number: NCT04551495 (ClinicalTrials.gov).

Neo-CheckRay: radiation therapy and adenosine pathway blockade to increase benefit of immuno-chemotherapy in early stage luminal B breast cancer, a randomized phase II trial.

BACKGROUND: Residual breast cancer after neo-adjuvant chemotherapy (NACT) predicts disease outcome and is a surrogate for survival in aggressive breast cancer (BC) subtypes. Pathological complete response (pCR) rate, however, is lower for luminal B BC in comparison to the triple negative (TNBC) and HER2+ subtypes. The addition of immune checkpoint blockade (ICB) to NACT has the potential to increase pCR rate but is hampered by the lower immunogenicity of luminal B BC. Novel strategies are needed to stimulate the immune response and increase the response rate to ICB in luminal B BC. METHODS: The Neo-CheckRay trial is a randomized phase II trial investigating the impact of stereotactic body radiation therapy (SBRT) to the primary breast tumor in combination with an anti-CD73 (oleclumab) to increase response to anti PD-L1 (durvalumab) and NACT. The trial is designed as a three-arm study: NACT + SBRT +/- durvalumab +/- oleclumab. The result at surgery will be evaluated using the residual cancer burden (RCB) index as the primary endpoint. Six patients will be included in a safety run-in, followed by a randomized phase II trial that will include 136 evaluable patients in 3 arms. Inclusion is limited to luminal B breast cancers that are MammaPrint genomic high risk. DISCUSSION: combination of ICB with chemotherapy in luminal B BC might benefit from immune priming agents to increase the response rate. As none have been identified so far, this phase II trial will evaluate SBRT and oleclumab as potential immune priming candidates. TRIAL REGISTRATION: trial registered on ClinicalTrials.gov ( NCT03875573 ) on March 14th, 2019.

High-dimensional analysis of the adenosine pathway in high-grade serous ovarian cancer.

BACKGROUND: Hydrolysis of extracellular ATP to adenosine (eADO) is an important immune checkpoint in cancer immunology. We here investigated the impact of the eADO pathway in high-grade serous ovarian cancer (HGSC) using multiparametric platforms. METHODS: We performed a transcriptomic meta-analysis of eADO-producing CD39 and CD73, an eADO signaling gene signature, immune gene signatures and clinical outcomes in approximately 1200 patients with HGSC. Protein expression, localization and prognostic impact of CD39, CD73 and CD8 were then performed on approximately 1000 cases on tissue microarray, and tumor-infiltrating lymphocytes (TILs) were analyzed by flow cytometry and single-cell RNA sequencing on a subset of patients. RESULTS: Concomitant CD39 and CD73 gene expression, as well as high levels of an eADO gene signature, were associated with worse prognosis in patients with HGSC, notably in the immunoregulatory molecular subtype, characterized by an immune-active microenvironment. CD39 was further associated with primary chemorefractory and chemoresistant human HGSC and platinum-based chemotherapy of murine HGSC was significantly more effective in CD39-deficient mice. At protein level, CD39 and CD73 were predominantly expressed by cancer-associated fibroblasts, and CD39 was expressed on severely exhausted, clonally expanded and putative tissue-resident memory TILs. CONCLUSIONS: Our study revealed the clinical, immunological, subtype-specific impacts of eADO signaling in HGSC, unveiled the chemoprotective effect of CD39 and supports the evaluation of eADO-targeting agents in patients with ovarian cancer.

Impact of HIV infection on baseline characteristics and survival of women with breast cancer.

BACKGROUND: As women living with HIV (WLWH) become older, their risk of developing breast cancer increases. Nonetheless, literature is conflicting regarding tumor stage, distribution of subtypes and overall survival among WLWH vs. HIV-negative women with breast cancer. We assessed differences in clinicopathological characteristics and overall survival between these two groups. METHODS: Systematic review and meta-analysis using MEDLINE, Scopus, ISI Web of Knowledge, LILACS, SciELO and conference abstracts up to 1 January 2020. Cross-sectional/cohort studies comparing baseline characteristics (stage and/or subtypes) and/or overall survival of WLWH vs. HIV-negative women with breast cancer were included. We performed random-effects meta-analyses to estimate summary statistics and subgroup analyses according to region of the world. RESULTS: Eighteen studies [4 from North America, 14 from sub-Saharan Africa (SSA)] were included, with 3174 WLWH and 2 394 598 HIV-negative women. WLWH from North America and SSA were more likely to present with stage III/IV disease compared with HIV-negative women - pooled odds ratio (pOR) 1.76 [95% confidence interval (CI):1.58-1.95] and pOR 1.23 (95% CI: 1.06-1.42), respectively. WLWH from SSA were also less likely to have estrogen receptor-positive/HER2-negative tumors (pOR 0.81; 95% CI: 0.66-0.99). After adjustment, WLWH had worse overall survival compared with HIV-negative women, both in North America [pooled adjusted hazard ratio (aHR) 2.45; 95% CI: 1.11-5.41] and SSA (aHR 1.43; 95% CI: 1.06-1.92). CONCLUSION: Compared with HIV-negative women, WLWH are diagnosed with breast cancer at a more advanced stage and have a worse overall survival. These results should raise awareness regarding the detection and survival gap among WLWH with breast cancer and further studies are needed to decipher the reasons behind these disparities.

Management of early breast cancer in patients bearing germline BRCA mutations.

Women diagnosed with breast cancers (BCs) that harbor BRCA1/2 mutations have an increased lifetime risk of a second BC and ovarian cancer. They may benefit from risk-reducing surgical strategies such as mastectomy and salpingo-oophorectomy. In cases of triple negative BC with BRCA mutation, there is some evidence that adding platinum-agents in the neoadjuvant setting improves the pathologic complete response. Lastly, ongoing clinical trials testing the efficacy of PARP inhibitor therapy in tumors with BRCA1/2 mutations will be determinant for future guideline recommendations in selecting best adjuvant treatment options for this specific population. For pre-menopausal patients whose tumors have BRCA mutations and hormone-receptor positive BC, the option of combined bilateral annexectomy and hormonal therapy with aromatase inhibitor can be discussed with high-risk patients. This review summarizes the latest results from clinical trials evaluating treatment and prevention strategies for breast cancers harboring BRCA1/2 mutations and discusses the current management of this patient population.

Publisher Correction: The adenosine pathway in immuno-oncology.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

The adenosine pathway in immuno-oncology.

Cancer immunotherapy based on immune-checkpoint inhibition or adoptive cell therapy has revolutionized cancer care. Nevertheless, a large proportion of patients do not benefit from such treatments. Over the past decade, remarkable progress has been made in the development of 'next-generation' therapeutics in immuno-oncology, with inhibitors of extracellular adenosine (eADO) signalling constituting an expanding class of agents. Induced by tissue hypoxia, inflammation, tissue repair and specific oncogenic pathways, the adenosinergic axis is a broadly immunosuppressive pathway that regulates both innate and adaptive immune responses. Inhibition of eADO-generating enzymes and/or eADO receptors can promote antitumour immunity through multiple mechanisms, including enhancement of T cell and natural killer cell function, suppression of the pro-tumourigenic effects of myeloid cells and other immunoregulatory cells, and promotion of antigen presentation. With several clinical trials currently evaluating inhibitors of the eADO pathway in patients with cancer, we herein review the pathophysiological function of eADO with a focus on effects on antitumour immunity. We also discuss the treatment opportunities, potential limitations and biomarker-based strategies related to adenosine-targeted therapy in oncology.

Unraveling Triple-Negative Breast Cancer Tumor Microenvironment Heterogeneity: Towards an Optimized Treatment Approach.

BACKGROUND: Recent efforts of gene expression profiling analyses recognized at least four different triple-negative breast cancer (TNBC) molecular subtypes. However, little is known regarding their tumor microenvironment (TME) heterogeneity. METHODS: Here, we investigated TME heterogeneity within each TNBC molecular subtype, including immune infiltrate localization and composition together with expression of targetable immune pathways, using publicly available transcriptomic and genomic datasets from a large TNBC series totaling 1512 samples. Associations between molecular subtypes and specific features were assessed using logistic regression models. All statistical tests were two-sided. RESULTS: We demonstrated that each TNBC molecular subtype exhibits distinct TME profiles associated with specific immune, vascularization, stroma, and metabolism biological processes together with specific immune composition and localization. The immunomodulatory subtype was associated with the highest expression of adaptive immune-related gene signatures and a fully inflamed spatial pattern appearing to be the optimal candidate for immune check point inhibitors. In contrast, most mesenchymal stem-like and luminal androgen receptor tumors showed an immunosuppressive phenotype as witnessed by high expression levels of stromal signatures. Basal-like, luminal androgen receptor, and mesenchymal subtypes exhibited an immune cold phenotype associated with stromal and metabolism TME signatures and enriched in margin-restricted spatial pattern. Tumors with high chromosomal instability and copy number loss in the chromosome 5q and 15q regions, including genomic loss of major histocompatibility complex related genes, showed reduced cytotoxic activity as a plausible immune escape mechanism. CONCLUSIONS: Our results demonstrate that each TNBC subtype is associated with specific TME profiles, setting the ground for a rationale tailoring of immunotherapy in TNBC patients.

Comprehensive evaluation of methods to assess overall and cell-specific immune infiltrates in breast cancer.

BACKGROUND: Breast cancer (BC) immune infiltrates play a critical role in tumor progression and response to treatment. Besides stromal tumor infiltrating lymphocytes (sTILs) which have recently reached level 1B evidence as a prognostic marker in triple negative BC, a plethora of methods to assess immune infiltration exists, and it is unclear how these compare to each other and if they can be used interchangeably. METHODS: Two experienced pathologists scored sTIL, intra-tumoral TIL (itTIL), and 6 immune cell types (CD3+, CD4+, CD8+, CD20+, CD68+, FOXP3+) in the International Cancer Genomics Consortium breast cancer cohort using hematoxylin and eosin-stained (n = 243) and immunohistochemistry-stained tissue microarrays (n = 254) and whole slides (n = 82). The same traits were evaluated using transcriptomic- and methylomic-based deconvolution methods or signatures. RESULTS: The concordance correlation coefficient (CCC) between pathologists for sTIL was very good (0.84) and for cell-specific immune infiltrates slightly lower (0.63-0.66). Comparison between tissue microarray and whole slide pathology scores revealed systematically higher values in whole slides (ratio 2.60-5.98). The Spearman correlations between microscopic sTIL and transcriptomic- or methylomic-based assessment of immune infiltrates were highly variable (r = 0.01-0.56). Similar observations were made for cell type-specific quantifications (r = 0.001-0.54). We observed a strong inter-method variability between the omics-derived estimations, which is further cell type dependent. Finally, we demonstrated that most methods more accurately identify highly infiltrated (sTIL ≥ 60%; area under the curve, AUC, 0.64-0.99) as compared to lowly infiltrated tumors (sTIL ≤ 10%; AUC 0.52-0.82). CONCLUSIONS: There is a lower inter-pathologist concordance for cell-specific quantification as compared to overall infiltration quantification. Microscopic assessments are underestimated when considering small cores (tissue microarray) instead of whole slides. Results further highlight considerable differences between the microscopic-, transcriptomic-, and methylomic-based methods in the assessment of overall and cell-specific immune infiltration in BC. We therefore call for extreme caution when assessing immune infiltrates using current methods and emphasize the need for standardized immune characterization beyond TIL.

Adenosine A2a receptor promotes lymphangiogenesis and lymph node metastasis.

The formation of new lymphatic vessels, or lymphangiogenesis, is a critical step of the tissue repair program. In pathological conditions involving chronic inflammation or tumorigenesis, this process is often dysregulated and can contribute to disease progression. Yet, lymphangiogenesis is still incompletely understood. In this study, we identified A2a adenosinergic signaling as an important regulator of inflammatory and tumor-associated lymphangiogenesis. Using Adora2a (A2a)-deficient mice, we demonstrated that A2a signaling was involved in the formation of new lymphatic vessels in the context of peritoneal inflammation. We also demonstrated that tumor-associated and sentinel lymph node lymphangiogenesis were impaired in A2a-deficient mice, protecting them from lymph node metastasis. Notably, A2a signaling in both hematopoietic and non-hematopoietic cells contributed to sentinel lymph node metastasis. In A2a-deficient tumor-draining lymph nodes, impaired lymphangiogenesis was associated with a reduced accumulation of B cells and decreased VEGF-C levels. Supporting a role for non-hematopoietic A2a signaling, we observed that primary murine lymphatic endothelial cells (LEC) predominantly expressed A2a receptor and that A2a signaling blockade altered LEC capillary tube formation in vitro. Finally, we observed that Adora2a, Nt5e and Entpd1 gene expression positively correlated with Lyve1, Pdpn and Vegfc in several human cancers, thereby supporting the notion that adenosine production and A2a receptor activation might promote lymphangiogenesis in human tumors. In conclusion, our study highlights a novel pathway regulating lymphangiogenesis and further supports the use of A2a or adenosine blocking agents to inhibit pathological lymphangiogenesis in cancers and block the dissemination of tumor cells through the lymphatic system.