Technologies to Assess Drug Response and Heterogeneity in Patient-Derived Cancer Organoids

Abstract

Patient-derived cancer organoids (PDCOs) are organotypic 3D cultures grown from patient tumor samples. PDCOs provide an exciting opportunity to study drug response and heterogeneity within and between patients and this research can guide new drug development and inform clinical treatment planning. We review technologies to assess PDCO drug response and heterogeneity, discuss best practices for clinically relevant drug screens, and assert the importance of quantifying single-cell and organoid heterogeneity to characterize response. Autofluorescence imaging of PDCO growth and metabolic activity is highlighted as a compelling method to monitor single-cell and single-organoid response robustly and reproducibly. We also speculate on the future of PDCOs in clinical practice and drug discovery. Future development will require standardization of assessment methods for both morphology and function in PDCOs, increased throughput for new drug development, prospective validation with patient outcomes, and robust classification algorithms. Expected final online publication date for the Annual Review of Biomedical Engineering, Volume 24 is June 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

Replacement, Reduction, and Refinement of Animal Experiments in Anticancer Drug Development: The Contribution of 3D In Vitro Cancer Models in the Drug Efficacy Assessment

“…Many of these techniques are common to both spheroids and organoids. However, some assays are more frequently used and have to be preferred over others, depending on the final scope of the study, on the 3D culture system under consideration, and on the characteristics of the cells composing the system [ 125 , 126 , 127 ].…”

“…In addition to previously discussed issues, viability assays provide only a well-level quantification of organoid response to treatment and fail to capture the contributions of inter- and intra-heterogeneity of PDO cultures. Consequently, the presence of cell subpopulations with varying drug sensitivities cannot be detected through cell viability assessment [ 127 , 154 ]. Additional techniques, such as imaging-based assays, must be used to better understand the heterogeneity of cancer organoid response to drug treatment.…”

“…Single-object tracking is also crucial to account for the intra-organoid variability of size, shape, growth pattern and response to treatment and, thus, to overcome the limitation of a well-level quantification of treatment efficacy. To this regard, Skala et al showed that normalizing growth to the pretreatment size for each organoid structure decreased the measurement noise, highlighting the importance of monitoring each organoid individually [ 127 ]. Kim et al proposed a very complete quantification workflow, based on dynamic confocal live cell imaging, to monitor tumor growth and drug response in CRC PDOs at single-object level [ 170 ].…”

Establishment of organoid models based on a nested array chip for fast and reproducible drug testing in colorectal cancer therapy

“…Second, the model achieves high reproducibility of organoid size, cellular activity, and drug response. The 3D implanting hole on the chip provides uniform and controlled shaping of the matrigel that allows organoids to grow in a fixed location [38]. Additionally, consistency of organoid implantation is required between holes, which poses a challenge to matrigel-based organoid culture systems due to perturbation during replacement with fresh media [16].…”

In vitro models as tools for screening treatment options of head and neck cancer

“…This technology is time consuming, has high costs due to the supplements, and requires well-established protocols for standardization as maintenance is tumor type dependent. A huge advantage of this method is that tumor organoids can phenocopy the in vivo tumor characteristics thereby allowing their use for monitoring in vitro drug responses linked to genetic alterations present in the original tumor ( 55 , 74 , 75 ), which can be also correlated to the individual clinical outcome and to the response of the corresponding tumor organoids ( 74 , 76 ). However, it should be noted that next to the complexity of their establishment and manipulation, the size of organoids can largely vary thereby influencing the drug penetrance, efficiency, and reproducibility of results ( 66 , 77 ).…”