Increased drug sensitivity towards sotorasib in spheroids of KRAS G12C mutant cell lines

Altered drug response in 3D spheroids compared to 2D monolayer cultures

  • In vitro 3D spheroids more closely mimic important features of solid tumors compared to 2D monolayer cultures.

  • These features include cell-cell interactions, morphology, degree of proliferation, diffusion of nutrients and oxygen, and gene expression profiles [1-3].

  • Spheroid cultures, therefore, provide an attractive model for anti-cancer drug screening in a complex cellular environment.

  • The small molecule inhibitor sotorasib (AMG-510), which selectively and irreversibly targets KRAS G12C, was evaluated in spheroids of KRAS wild-type and KRAS G12C mutant cell lines.

  • A visual decrease in spheroid diameter was observed for the KRAS wild-type cell line only at high sotorasib concentrations, whereas a concentration-dependent decrease in diameter was observed for the KRAS G12C mutant cell lines at considerably lower concentrations.

  • For quantitative evaluation of cell viability in these spheroids, an ATP-monitoring luminescence assay was used.

  • In cell viability assays, spheroids of KRAS G12C mutant cell lines were more sensitive to sotorasib than monolayer cultures of the same cell lines, whereas the sensitivity of the KRAS wild-type cell line remained unaffected.

3D spheroid morphology of KRAS wild-type U-87 MG cells and KRAS G12C mutant UM-UC-3 and MIA PaCa-2 cells, exposed to a 9-point dilution series of sotorasib.
Dose-response curves of sotorasib in viability assays with the KRAS wild-type cell line U-87 MG and KRAS G12C mutant cell lines UM-UC-3 and MIA PaCa-2 in 2D (blue) compared to 3D culture (red).


[1] Djordjevic et al. (2006) Cell-cell interactions in spheroids maintained in suspension, Acta Oncologica, 45(4), 412-420.

[2] Lama et al. (2013) Development, validation and pilot screening of an in vitro multi-cellular three-dimensional cancer spheroid assay for anti-cancer drug testing, Bioorganic & medicinal chemistry, 21(4), 922-931.

[3] Hamer et al. (2008) The genomic profile of human malignant glioma is altered early in primary cell culture and preserved in spheroids, Oncogene, 27(14), 2091-2096.