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Senescence is a persistent state of cell cycle arrest. Induction of senescence has been explored as a barrier against tumor progression and is used as a therapeutic option. Despite the advantages of the introduction of senescence‐inducing compounds in the clinic, recent studies show that their side‐effects can be partially masking their antitumor potential. This is due to the deleterious effects that accumulation of senescent cells in tissues and organs causes on tissue microenvironment that confer tumor‐promoting properties. In this study, it is demonstrated that the presence of senescent endothelium favors cancer cell migration and show that palbociclib systemic treatment induces senescence in veins in an orthotopic triple‐negative breast cancer mouse model. Moreover, it is found that following palbociclib‐induced senogenesis, the elimination of senescent cells using the nanoencapsulated senolytic navitoclax (NP(nav)‐Gal) produces the selective elimination of endothelial senescent cells and induces a marked recovery of endothelial tissue functionality. Finally, the treatment with NP(nav)‐Gal produces a significant decrease of senescence in veins which is consistent with the decrease in metastasic burden observed. These results evidence the potential of reducing vascular senescence using senolytic therapies as a strategy to limit the metastatic dissemination of tumors cells in breast cancer patients subjected to chemotherapeutic treatments.

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Triple Negative Breast Cancer (TNBC), a subtype of breast cancer, has fewer successful therapeutic therapies than other types of breast cancer. Insulin-like growth factor receptor 1 (IGF1R) and the Insulin receptor (IR) are associated with poor outcomes in TNBC. Targeting IGF1R has failed clinically. We aimed to test if inhibiting both IR/IGF1R was a rationale therapeutic approach to treat TNBC. We showed that despite IGF1R and IR being expressed in TNBC, their expression is not associated with a negative survival outcome. Furthermore, targeting both IR/IGF1R with inhibitors in multiple TNBC cell lines did not inhibit cell growth. Linsitinib, a small molecule inhibitor of both IGF1R and IR, did not block tumour formation and had no effect on tumour growth in vivo. Cumulatively these data suggest that while IGF1R and IR are expressed in TNBC, they are not good therapeutic targets. A potential reason for the limited anti-cancer impact when IR/IGF1R was targeted may be because multiple signalling pathways are altered in TNBC. Therefore, targeting individual signalling pathways may not be sufficient to inhibit cancer growth.