3D microfluidic model of Small Cell Lung Carcinoma to validate targeted therapies against B7-H3 positive tumor cells and vasculature

Small cell lung carcinoma (SCLC) is a type of lung cancer that accounts for about 15% of all lung cancer cases. Although SCLC patients initially respond to chemotherapy and immune checkpoint blockade (ICB), however, resistance invariably emerges. Currently, there are no predictive biomarkers of response, and patients with SCLC continue to have a poor prognosis with limited treatment options. Recent multiparametric profiling of SCLC cell lines and patient samples has revealed significant inter-tumoral and intra-tumoral heterogeneity. Non-neuroendocrine (Non-NE) SCLC exhibits increased innate immune signaling and robust upregulation of antigen presentation on MHC-I, whereas neuroendocrine (NE) SCLC subpopulations downregulate MHC-I. Based on this, MHC-I low SCLC was predicted to be vulnerable to NK cell-mediated control. However, the MHC-I low SCLC tumor-immune microenvironment (TIME) is characterized by a scarcity of immune cells, possibly due to the vascular barrier in the absence of sufficient chemokine gradients. In the context of novel therapeutic approaches, Antibody-Drug Conjugate (ADC)-based therapies are focused on targeting cell-surface proteins selectively expressed by malignant cells. Recently, there has been increased interest in B7-H3/CD276, whose dual overexpression on tumor and tumor-associated vasculature provides an opportunity for the development of therapies that simultaneously target and destroy both the tumor cells and the tumor vasculature, preserving healthy tissues. In this thesis, we developed an advanced MicroPhysiological System (MPS) using a microfluidic technology, that is highly adaptable and precisely controlled, enabling it to replicate TIME biology. Through this platform, we modeled the interaction between solid tumor (in terms of SCLC spheroids) and immune cells in the presence of a vascular barrier and external stimuli, and we used it to explore various strategies to test cell therapies and explore the mechanisms of B7-H3 targeted ADC-based therapy, which drug is currently in phase 1/2 clinical trial. Firstly, the CD276/B7H3 protein is mainly upregulated in non-NE SCLC and vasculature, we tested the efficacy of an ADC designed to target CD276/B7H3 positive cells. The compound demonstrated cytotoxicity against non-NE SCLC spheroids in a 2D viability assay. Furthermore, B7H3-ADC cytotoxicity was tested on vascular elements in a self-assembled 3D microvascular network assay. The impact on disrupting vasculature was confirmed by 3D permeability assay on a macrovessel model. Then, using a 3D model of vascular extravasation, we have confirmed that vascular priming leads to enhanced vascular permeability and the promotion of NK cell extravasation. Similarly, since B7H3 causes vascular disruption, lead us to believe that it could stimulate immune cell infiltration. We then demonstrated that NE-SCLC appears to be vulnerable to natural killer (NK) cell-mediated cytotoxicity triggered by natural killer (NK) cells in a 2D and 3D viability co-culture assay, suggesting that once NK cells can cross the vascular barrier, they are able to eradicate the tumor. Our MPS platform has proven to be a promising tool for exploring and testing strategies testing novel targeted therapies, offering a bridge for translational medicine purposes toward better outcomes for cancer patients.