Search

More than half of non‐muscle‐invasive bladder cancer (NMIBC) patients eventually relapse even if treated with surgery and BCG without optional bladder‐preserving therapy. This study aims to investigate the antitumor activity and safety of a HER2‐targeted antibody‐drug conjugate, RC48‐ADC, intravesical instillation for NMIBC treatment. In this preclinical study, it is revealed that human epidermal growth factor receptor 2 (HER2) expression scores of 1+, 2+, and 3+ are recorded for 16.7%, 56.2%, and 14.6% of NMIBC cases. The antitumor effect of RC48‐ADC is positively correlated with HER2 expression in bladder cancer (BCa) cell lines and organoid models. Furthermore, RC48‐ADC is revealed to exert its antitumor effect by inducing G2/M arrest and caspase‐dependent apoptosis. In an orthotopic BCa model, tumor growth is significantly inhibited by intravesical instillation of RC48‐ADC versus disitamab, monomethyl auristatin E, epirubicin, or phosphate‐buffered saline control. The potential toxicity of intravesical RC48‐ADC is also assessed by dose escalation in normal nude mice and revealed that administration of RC48‐ADC by intravesical instillation is safe within the range of effective therapeutic doses. Taken together, RC48‐ADC demonstrates promising antitumor effects and safety with intravesical administration in multiple preclinical models. These findings provide a rational for clinical trials of intravesical RC48‐ADC in NMIBC patients. [ABSTRACT FROM AUTHOR]

As a key step of tumor lymphatic metastasis, lymphangiogenesis is regulated by VEGFC‐VEGFR3 signaling pathway mediated by immune cells, mainly macrophages, in the tumor microenvironment. However, little is known whether tumor associated neutrophils are involved in lymphangiogenesis. Here, it is found that TANs infiltration is increased in LN‐metastatic BCa and is associated with poor prognosis. Neutrophil depletion results in significant reduction in popliteal LN metastasis and lymphangiogenesis. Mechanistically, transcription factor ETV4 enhances BCa cells‐derived CXCL1/8 to recruit TANs, leading to the increase of VEGFA and MMP9 from TANs, and then facilitating lymphangiogenesis and LN metastasis of BCa. Moreover, phosphorylation of ETV4 at tyrosine 392 by tyrosine kinase PTK6 increases nuclear translocation of ETV4 and is essential for its function in BCa. Overall, the findings reveal a novel mechanism of how tumor cells regulate TANs‐induced lymphangiogenesis and LN metastasis and identify ETV4 as a therapeutic target of LN metastasis in BCa. [ABSTRACT FROM AUTHOR]