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Updated: Jul 3, 2026
Three-Dimensional 3D Tumor Spheroid Invasion Assay
Published on: May 1, 2015
Targeted therapy combinations with ipatasertib in multi-cell type 3D tumor spheroid models
Beverly A Teicher1, Naoko Takebe1, Thomas S Dexheimer2
1Division of Cancer Treatment and Diagnosis, National Cancer Institute, Bethesda, MD 20892, USA.
Abstract:
We investigated the growth-inhibitory activity of the pan-AKT inhibitor ipatasertib in combination with other targeted therapies. Thirty-nine patient-derived cancer cell lines from the NCI Patient-Derived Models Repository and nine NCI-60 tumor cell lines were grown as mct-spheroids. The mct-spheroids, a mixture of tumor cells (60%), endothelial cells (25%), and mesenchymal stem cells (15%), were established for 3 days before compounds(s) were added. All agents were tested at concentrations up to the reported clinical Cmax values or a high concentration of 10 μM. Cell viability was assayed using CellTiter-Glo 3D after 7 days of exposure. Ipatasertib was selective for tumor cells harboring activating PI3K/AKT/mTOR pathway mutations. Dual inhibition of the PI3K/AKT/mTOR and RAS/MEK/ERK pathways was very effective. The combination of ipatasertib with the MEK inhibitor selumetinib or the ERK inhibitor ravoxertinib resulted in additive and/or greater-than-additive cytotoxicity in approximately half the cell lines screened. The V600E mutation-specific BRAF inhibitor vemurafenib and the KRAS G12C selective inhibitor sotorasib in combination with ipatasertib were active in the eight BRAF V600E and four KRAS G12C mutant-containing cell lines, respectively. Vertical inhibition of the PI3K/AKT/mTOR pathway with the mTORC1/2 kinase inhibitor sapanisertib demonstrated additive and/or greater-than-additive effects in multiple cell lines. In early experiments, there was a correlation between the response to ipatasertib and selumetinib in two patient-derived tumor lines grown as mct-spheroids and the corresponding patient-derived xenografts. All data are accessible via the PubChem BioAssay public database.
Insights
The pan-AKT inhibitor ipatasertib showed selective growth-inhibitory activity in cancer cells with PI3K/AKT/mTOR pathway mutations. Combining ipatasertib with MEK or ERK inhibitors demonstrated significant cytotoxicity, suggesting potential combination therapies.
Area of Science:
- Oncology
- Molecular Biology
- Pharmacology
Background:
- The PI3K/AKT/mTOR pathway is frequently dysregulated in cancer, making it a key target for therapy.
- Ipatasertib is a pan-AKT inhibitor investigated for its anti-cancer properties.
- Combination therapies are crucial for overcoming resistance and improving treatment efficacy in cancer.
Purpose of the Study:
- To evaluate the growth-inhibitory activity of ipatasertib in combination with other targeted therapies.
- To identify specific cancer cell mutations that sensitize tumors to ipatasertib.
- To explore the efficacy of dual pathway inhibition strategies.
Main Methods:
- Utilized 39 patient-derived and 9 NCI-60 cancer cell lines grown as multicellular spheroids (mct-spheroids).
- Assessed cell viability using CellTiter-Glo 3D assay after 7-day exposure to compounds up to clinical Cmax or 10 μM.
- Tested combinations of ipatasertib with inhibitors of RAS/MEK/ERK, BRAF, and mTOR pathways.
Main Results:
- Ipatasertib demonstrated selectivity for tumor cells with activating PI3K/AKT/mTOR pathway mutations.
- Combinations of ipatasertib with MEK (selumetinib) or ERK (ravoxertinib) inhibitors showed additive or greater-than-additive cytotoxicity in about half of the cell lines.
- Specific BRAF and KRAS mutant cell lines responded to ipatasertib combined with BRAF (vemurafenib) or KRAS (sotorasib) inhibitors, respectively.
- Vertical inhibition with sapanisertib (mTORC1/2 inhibitor) also yielded additive or greater-than-additive effects.
Conclusions:
- Dual inhibition of PI3K/AKT/mTOR and RAS/MEK/ERK pathways is a promising strategy.
- Ipatasertib in combination with other targeted agents shows potential for treating specific cancer subtypes.
- Early data suggest a correlation between spheroid and xenograft responses to ipatasertib and selumetinib combinations.
