List of current researches being done on breast cancer organoids as study models.

Table 1: List of current researches being done on breast cancer organoids as study models.

Type of study	Source of organoid	Significance	References
Primary tumour drug response prediction
Optical metabolic imaging (OMI)	Xenograft • BT-474, HR6 Primary tumour • ER+, HER2+, triple negative	• ER+ organoids treated with combination of trastuzumab, paclitaxel, tamoxifen, and XL147 showed significant reduction in OMI indices as quickly as 24 h. • HER2+ organoids treated with trastuzumab and A4 showed significant reduction in OMI indices as quickly as 24 h. • Triple negative organoids treated with trastuzumab and tamoxifen showed no significant reduction in OMI indices at 24 h.	Walsh, et al. [14]
Optical metabolic imaging (OMI)	DMSO frozen and flash frozen xenograft • BT-474, HR6 DMSO frozen and flash frozen primary tumour	• All organoids were treated with trastuzumab, paclitaxel, and XL147, with drug responses validated by OMI at different timepoints. • Drug response of BT474 and HR6 organoids derived from frozen-thawed tumourgrafts matched that of fresh tumourgraft organoids. • Drug response of primary tumour organoids derived from frozen-thawed samples matched that of fresh tumour organoids, despite DMSO frozen tissue derived organoids provide less inconsistencies.	Walsh, et al. [71]
Quantitative immunofluorescence imaging	Primary tumour • ER+, PR+, HER2+, triple negative	• ER+, PR+, HER2+, and triple negative subtypes were distinguished in primary tumour organoids from different patients. • Results suggest patients’ responses differ depending on individual tumour drug vulnerabilities.	Sowder, et al. [83]
High content imaging	Primary tumour	• Ongoing study plans to compare responses of poly ADP ribose polymerase (PARP) inhibitor between PDX and primary tumour organoids of patients.	Broutier, et al. [85]
Development of tumour-on-a-chip	2D cell line • MCF-7	• MCF-7 derived organoids embedded on collagen-gel matrix in silicon-based chip offers valuable insight to growing breast tumour-on-a-chip for multiplex drug testing.	Torisawa, et al. [90]
Development of tumour-on-a-chip	2D cell line • MCF-7	• MCF-7 derived organoids were grown in polydimethylsiloxane attached with air plasma treatment successfully utilized to examine cytotoxicity of MMC, 5-FU, and doxorubicin.	Kim, et al. [89]
Molecular biomarker discovery
RNA interference and CRISPR/Cas9 genome editing	Mammary stem cell	• Inactivation of 2 key genes normally mutated in human breast cancer, Ptpn22 and Mll3, can accelerate tumour progression via P13K pathway.	Zhang, et al. [73]
Gene ontology analysis	2D cell line (25 in total) • BT-474, MDA-MB, MCF-7, etc.	• Culture microenvironment deduced to pose significance in gene expression profile by differences in some genomic profiles between 2D and 3D cultures of breast cancer.	Kenny, et al. [91]