From:  Spheroids and organoids derived from colorectal cancer as tools for in vitro drug screening

 Advantages and disadvantages of in vitro methods for preclinical drug screening for CRC

MethodsAdvantagesDisadvantagesKey typesReferences
2D cell culture systemSimple and low consumption for maintenance; rapid screening; high reproducibilityRequire considerable large panel; marked discrepancy with in vivo and clinical studies; lacks in vivo characteristicsNCI60 panel[51, 52]
Bodmer group (> 120 CRC cell lines)[53]
Co-culture of CRC cell lines with CAFs[54, 55]
Microfluidic based-cell culture systemLow reagent consumption; allow high throughput screening; stable biochemical/concentration gradient; shear stress generation; microvasculatureLack of representative functional vascular network and heterogeneous phenotype of tumor; present transient effects of cell-drug behavior; not able to withstand long-term experiment; difficult to determine individual cell effectMicrofluidic CRC culture[56–59]
Microfluidic co-culture of CRC with fibroblasts[60, 61]
3D spheroid

  • Recapitulate tumor oxygen gradients and hypoxia with multiple layers of formation

  • Retain chemoresistance behaviour with multiple layers and decreased sphericity

  • Recapitulate the multifaceted and heterogeneous TME with multiple cells culture

  • Avascular characteristic and passive chemical diffusion disrupt cells processes or functions and affect drug readout

  • Lack of size uniformity leads to data variation

  • Complex and non-standardized drug readout assays

  • Difficult to determine individual cell effect to drug

Scaffold-free spheroid[23]
Co-culture CRC spheroids with fibroblasts[60, 62–64]
MCTS[65]
3D organoids

  • Withstand long-term culture; recapitulate tumor heterogeneity with heterogeneous drug responses; reproduce molecular and cellular composition of tumor

  • Recapitulate tumor ECM stiffness; support the organoids growth and sensitivity to drug

  • Retain genomic characteristic of tumor

  • Retain inter-tumor heterogeneity; support personalized therapy

  • Specific cancer subtype modelling for precision medicine

  • Time-consuming; laborious; inefficient data analysis; intra- and inter-batch heterogeneity; low batch-to-batch reproducibility

  • Lack of cells intrinsic processes such as cell adhesion and migration can lead to inefficient drug readout

  • Limited predictive ability to certain drug response (i.e., combination based involving oxaliplatin response)

Organoids in Matrigel[66]
Organoids in chemically defined synthetic hydrogels[67]
CTCDO[68]
PDO[69–72]
Serrated CRC organoids[73–77]
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NCI: National Cancer Institute; CTCDO: circulating tumor cells (CTCs)-derived organoids; MCTS: multicellular tumor spheroids; PDO: patient-derived organoid