OMO-1 reduces progression and enhances cisplatin efficacy in a 4T1-based non-c-MET addicted intraductal mouse model for triple-negative breast cancer

Abstract

Abstractc-MET is considered a driver of cancer progression, impacting tumor growth and tumor-supporting stroma. Here, we investigated the therapeutic efficacy of OMO-1, a potent and selective c-MET inhibitor, in an immunocompetent intraductal mouse model for triple-negative breast cancer (TNBC). OMO-1 reduced non-c-MET addicted 4T1 tumor progression dose dependently as monotherapeutic and provided additional disease reduction in combination with cisplatin. At the stromal level, OMO-1 significantly reduced neutrophil infiltration in 4T1 tumors, promoted immune activation, and enhanced cisplatin-mediated reduction of tumor-associated macrophages. OMO-1 treatment also reduced 4T1 tumor hypoxia and increased expression of pericyte markers, indicative for vascular maturation. Corroborating this finding, cisplatin delivery to the 4T1 primary tumor was enhanced upon OMO-1 treatment, increasing cisplatin DNA-adduct levels and tumor cell death. Although verification in additional cell lines is warranted, our findings provide initial evidence that TNBC patients may benefit from OMO-1 treatment, even in cases of non-c-MET addicted tumors.

One cisplatin dose provides durable stimulation of anti-tumor immunity and alleviates anti-PD-1 resistance in an intraductal model for triple-negative breast cancer

“… 16–18 This model is based on the inoculation of 4T1 mammary tumor cells in the mammary ducts of lactating syngeneic BALB/c mice and ensures that tumor cells initially grow in the mammary ducts, being representative for the ductal carcinoma in situ (DCIS) stage of TNBC in patients. In line with a previous report from our group, 19 cisplatin significantly decreased disease progression upon transition from the DCIS to the invasive carcinoma (IC) stage. This decrease was confirmed in an alternative, non-metastatic but highly proliferative Py230-based intraductal model as also characterized by our group.…”

“…reported that cisplatin treatment prevents breast cancer metastasis by inducing expression of activating transcription factor 3 (ATF3) and antagonizing transforming growth factor (TGF)-β-mediated early EMT. 42 Both our current and previous preclinical data 19 describe that frequent cisplatin treatment also reduces the hypoxic conditions in the 4T1 primary tumor, which may reduce its aggressive progression given the growth-stimulating properties of tumor hypoxia. Stromal components of the TME, including the CD31 + vascular endothelial cells are likely an additional target for cisplatin, which may also explain the increased risk for hypertension and thromboembolic complications in patients treated with cisplatin.…”

“…administered every 5 d as also performed in a previous study from our group. 19 A recombinant mouse monoclonal antibody against PD-1 (Anti-mPD-1-mIgG1e3 InvivoFit™ from Invivogen and derived from clone RMP1-14), specifically designed for in vivo mouse studies, was i.p. administered every w at 200 µg/mouse.…”

“…Immunohistochemistry required pressurized antigen retrieval of 2–3 µm sections at 95°C for 30 min using either 10 mM tri-sodium citrate buffer (Santa Cruz Biotechnology, Heidelberg, Germany) at pH 6 or 10 mM Tris-1 mM EDTA buffer (Thermo Fisher Scientific) at pH 9, both containing 0.05% Tween-20 (Sigma-Aldrich) as previously described. 18 , 19 Following a 10 min blocking step for endogenous peroxidase (using 3% H 2 O 2 ) and aspecific binding (using serum-free protein block from Dako, Heverlee, Belgium), stainings with primary antibodies diluted in Antibody diluent (Dako) were performed for 1 h. Primary antibodies, clones and dilutions used in the study are described in Table 3 . Secondary antibodies were incubated for 30 min and included either Rat-on-Mouse HRP-Polymer (Biocare Medical, CA, USA) or Dako EnVision+ Rabbit (Dako).…”

“…ImageJ was applied to quantify positive staining (color deconvolution and automatic counting of % area), ImageJS was applied to determine Ki67 proliferation indices as previously described. 18 , 19 , 26 …”