Preclinical Testing Techniques: Paving the Way for New Oncology Screening Approaches

Abstract

Prior to clinical trials, preclinical testing of oncology drug candidates is performed by evaluating drug candidates with in vitro and in vivo platforms. For in vivo testing, animal models are used to evaluate the toxicity and efficacy of drug candidates. However, animal models often display poor translational results as many drugs that pass preclinical testing fail when tested with humans, with oncology drugs exhibiting especially poor acceptance rates. The FDA Modernization Act 2.0 promotes alternative preclinical testing techniques, presenting the opportunity to use higher complexity in vitro models as an alternative to in vivo testing, including three-dimensional (3D) cell culture models. Three-dimensional tissue cultures address many of the shortcomings of 2D cultures by more closely replicating the tumour microenvironment through a combination of physiologically relevant drug diffusion, paracrine signalling, cellular phenotype, and vascularization that can better mimic native human tissue. This review will discuss the common forms of 3D cell culture, including cell spheroids, organoids, organs-on-a-chip, and 3D bioprinted tissues. Their advantages and limitations will be presented, aiming to discuss the use of these 3D models to accurately represent human tissue and as an alternative to animal testing. The use of 3D culture platforms for preclinical drug development is expected to accelerate as these platforms continue to improve in complexity, reliability, and translational predictivity.

Keywords: 3D bioprinting; 3D culture; drug screening; oncology; organ-on-a-chip; organoid; preclinical; spheroid.

Figure 1

Common methods for producing spheroids for preclinical drug development such as (A) hanging drop, (B) liquid overlay, (C) rotary culture, (D) nanofiber suspension, and (E) magnetic levitation. Created using BioRender.com.

Figure 2

Schematic of common methods of 3D bioprinting including (A) extrusion, (B) digital light processing (DLP), and (C) two-photon polymerization (2PP). Created using BioRender.com.

Figure 3

Recent 3D bioprinted cancer models for preclinical testing using (A–C) breast cancer and osteoblast co-culture [162] and (D–F) prostate cancer and fibroblast co-culture [163]. (A) Schematic diagram of light-activated 3D bioprinting process using cell-laden osteoblast scaffolding seeded with breast cancer cells to model breast cancer metastasis. (B) Confocal images of osteoblasts and breast cancer cells in co-culture after 1, 3, and 5 days. (C) Proliferation of breast cancer cells when cultured in mono-culture versus metastatic co-culture model with osteoblasts. (D) Schematic diagram of 3D bioprinting extrusion process for prostate and fibroblast co-culture model. (E) Extrusion printing of complex structures for prostate–fibroblast model. (F) DTX drug resistance of PC-3 (prostate cancer) cells in co-culture model. * indicates p < 0.05 and ** indicates p < 0.01. (A–C) Reprinted (adapted) with permission from [162]. Copyright 2016 American Chemical Society. (D,E) Reprinted under terms of the Creative Commons Attribution 4.0 License accessed on 24 August 2023 from https://creativecommons.org/licenses/by/4.0/ [163].