3D bioprinting as an emerging standard for cancer modeling and drug testing.

Neoplastic diseases are a leading cause of death worldwide accounting for 10 million mortalities in 2020. Despite constantly revised and improved therapeutic regimens, the number of fatal cases increases annually. Therefore, better preclinical models are needed to study tumorigenesis and assess new drugs. Although 2D cell cultures significantly contributed to the understanding of tumor biology, they present high clinical trial failure rates. This is because 2D cannot reproduce the intricate tumor architecture and multiple cell interactions.Nevertheless, novel 3D biofabrication technologies and 3D bioprinted tumor models successfully mirror the complexity of human tumors and are currently revolutionizing preclinical cancer research by using live cells encapsulated in a variety of biomaterials. Since bioinks possess excellent chemical and biophysical ECM-like characteristics, this allows for recreation of the intricate tumor-specific architecture with an unmatched level of control, accuracy, and reproducibility. The resulting cellular constructs approximate actual pathological microenvironment of the tumor and some key in vivo processes such as proliferation, differentiation, and metastasis. 3D bioprinted models of glioblastoma, cervical, ovarian, and breast cancer are already being successfully used to study tumorigenesis and cellular response to antitumor drugs. This success showcases the potential of these novel experimental platforms.