Assessing Novel Antibody‐Based Therapies in Reconstructive 3D Cell Models of the Tumor Microenvironment

Targeted, combinatorial, and immunomodulatory therapies, such as antibody-drug conjugates (ADCs) and immunomodulatory antibodies (Abs), are powerful weapons against tumor cells and immune cells within the tumor microenvironment (TME). Therefore, the evaluation of such therapies should be conducted in pre-clinical models able to recapitulate the complex cellular and molecular crosstalk of the TME. To build-in critical hallmarks of the TME, a breast cancer heterotypic 3D cell model (3D-3) is devised using a microencapsulation strategy with an inert biomaterial (alginate) and agitation-based cultures. Both stromal and immune components are added to multicellular tumor spheroids, therefore fostering cancer-associated fibroblasts (CAFs) and tumor-associated macrophages (TAMs) immunomodulatory interactions. The potential of the methodology to assess Ab-based therapies is then addressed by employing a series of anti-HER2-based ADCs. ADCs induced tumor-cell specific cytotoxicity toward HER2+ breast cancer spheroids while sparing HER2-negative CAFs. In addition, an immunomodulatory blocking Ab against colony-stimulating factor 1 receptor (CSF1R) decreases the expression of immunosuppressive and anti-inflammatory markers in TAMs, like what is previously observed upon in vivo α-CSF1R administration. Collectively, the human TME-based 3D-3 cell model is a suitable tool to evaluate the anti-tumor and immunomodulatory potential of novel antibody-based therapies directed against TME targets, such as cancer cells and macrophages.