Unlocking the Therapeutic Potential of Integrin‐Linked Kinase Inhibitors in Bioengineered <scp>3D</scp> Breast Tumor Stroma Models

The tumor microenvironment (TME) plays a pivotal role in breast cancer progression and metastasis, and the efficacy of targeted therapies is influenced by the heterogeneous nature of the TME. Interactions between breast cancer cells and their surrounding stromal cells modulate proliferation, invasion, and survival pathways, often via integrin-mediated mechanotransduction and growth factor signaling. Integrin-linked kinase (ILK) is a serine/threonine protein kinase that has been widely established as a critical driver of breast cancer progression, metastasis, and therapeutic resistance. Its expression is frequently upregulated in breast cancer tumors and correlates with poor prognosis. Given that ILK activity is highly dependent on cell-matrix interactions that are only recapitulated in 3D culture, we investigated the effect of an ILK inhibitor in 3D bioengineered compartmentalized breast tumoroid models to better mimic in vivo conditions. Two tumor cell masses (MDA-MB-231 or MCF-7) were cultured within a primary breast tissue stromal compartment representative of breast tissue or a metastatic representative of lung tissue. In highly invasive and highly hypoxic MDA-MB-231 3D tumoroid models, ILKI treatment was 2.2 fold more effective in 3D models representative of breast tissue (p-value < 0.0001) compared to those with the metastatic lung compartment (p-value = 0.03). However, ILKI treatment was slightly more effective (1.4 fold) in the less invasive and less hypoxic MCF-7 3D tumoroid models with the metastatic lung compartment compared to those with the primary breast compartment. Non-invasive imaging of oxygen gradients in the 3D models shows alleviation of hypoxia following treatment and correlation with enhanced treatment efficacy. These results emphasize the necessity of modeling both the tumor and the stroma since this interaction can directly influence drug efficacy. Moreover, ILK inhibitor treatment holds promise for breast cancer therapy particularly in chemotherapeutic resistant cases.