Yann Kieffer, Fatima Mechta-Grigoriou, Jean Marc Guinebretière, Roman Rouzier, Delphine Hequet, Floriane Pelon, Sylvain Ladoire, Christophe Blanchet, Anne Vincent-Salomon, Antoine Elies, Claire Bonneau, Brigitte Bourachot, Unité de génétique et biologie des cancers (U830), Institut Curie [Paris]-Institut National de la Santé et de la Recherche Médicale (INSERM), Centre Régional de Lutte contre le cancer Georges-François Leclerc [Dijon] (UNICANCER/CRLCC-CGFL), UNICANCER, Institut Curie [Paris], Risques cliniques et sécurité en santé des femmes et en santé périnatale (RISCQ), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Institut National de la Santé et de la Recherche Médicale, Inserm ANR-10-EQPX-03, INCa-DGOS-Inserm-12554, STROMAE INCa-DGOS-9963 Institut National Du Cancer, INCa: INCa-11692, INCa-DGOS-4654, INCa-DGOS-9963 Fondation pour la Recherche Médicale, FRM Institut Curie: PIC3i CAFi Ligue Contre le Cancer: PC201317 Fondation Simone et Cino Del Duca, C.B. was supported by the Institut National de la Santé et de la Recherche Médicale (Inserm, Plan Cancer - Formation à la recherche translationnelle), A.E. by the association d’aide en Cancérologie de Saint-Cloud (ARCS), and Y.K. by the Institut National du Cancer, INCa (INCa-DGOS-9963, INCa-11692), SIRIC (INCa-DGOS-4654), and the Fondation pour la Recherche Medicale (FRM). The experimental work was supported by grants from the Ligue Nationale Contre le Cancer (Labelisation), Inserm (PC201317), Institut Curie (Incentive and Cooperative Program Tumor Micro-environment PIC TME/T-MEGA, PIC3i CAFi), ICGex (ANR-10-EQPX-03), SIRIC (INCa-DGOS-4654), and INCa (STROMAE INCa-DGOS-9963, CaLYS INCa-11692, INCa-DGOS-Inserm-12554). F.M-G acknowledges both the Association 'Le cancer du sein, Parlons-en' and the Simone and Cino del Duca Foundation for attribution of their 'Grand Prix'. F.M-G is very grateful to all her funders for providing support throughout the years., and F.M-G. received research support from Innate-Pharma, Roche and Bristol-Myers-Squibb (BMS). R. R received financial support for research (travel reimbursement) and speaker honoraria from Nanostring Technologies. Other authors declare no potential conflict of interest.
BackgroundEarly luminal breast cancer (BC) represents 70% of newly diagnosed BC cases. Among them, small (under 2 cm) BC without lymph node metastasis (classified as T1N0) have been rarely studied, as their prognosis is generally favorable. Nevertheless, up to 5% of luminal T1N0 BC patients relapse with distant metastases that ultimately prove fatal. The aim of our work was to identify the mechanisms involved in metastatic recurrence in these patients.MethodsOur study addresses the role that autonomous and non-autonomous tumor cell features play with regard to distant recurrence in early luminal BC patients. We created a cohort of T1N0 luminal BC patients (tumors between 0.5–2 cm without lymph node metastasis) with metastatic recurrence (“cases”) and corresponding “controls” (without relapse) matched 1:1 on main prognostic factors: age, grade, and proliferation. We deciphered different characteristics of cancer cells and their tumor micro-environment (TME) by deep analyses using immunohistochemistry. We performed in vitro functional assays and highlighted a new mechanism of cooperation between cancer cells and one particular subset of cancer-associated fibroblasts (CAF).ResultsWe found that specific TME features are indicative of relapse in early luminal BC. Indeed, quantitative histological analyses reveal that “cases” are characterized by significant accumulation of a particular CAF subset (CAF-S1) and decrease in CD4+T lymphocytes, without any other association with immune cells. In multivariate analysis, TME features, in particular CAF-S1 enrichment, remain significantly associated with recurrence, thereby demonstrating their clinical relevance. Finally, by performing functional analyses, we demonstrated that CAF-S1 pro-metastatic activity is mediated by the CDH11/osteoblast cadherin, consistent with bones being a major site of metastases in luminal BC patients.ConclusionsThis study shows that distant recurrence in T1N0 BC is strongly associated with the presence of CAF-S1 fibroblasts. Moreover, we identify CDH11 as a key player in CAF-S1-mediated pro-metastatic activity. This is independent of tumor cells and represents a new prognostic factor. These results could assist clinicians in identifying luminal BC patients with high risk of relapse. Targeted therapies against CAF-S1 using anti-FAP antibody or CDH11-targeting compounds might help in preventing relapse for such patients with activated stroma.