(in 3D preclinical model so far, but done with LOTS of cell lines--has a great chart of characteristics of lots of those cell lines, ie, which ones ER+, which ER- etc)
http://clincancerres.aacrjournals.or...5/12/4147.long
Clin Cancer Res. 2009 Jun 15;15(12):4147-56. Epub 2009 Jun 9.
Suppression of HER2/HER3-mediated growth of breast cancer cells with combinations of GDC-0941 PI3K inhibitor, trastuzumab, and pertuzumab.
Yao E, Zhou W, Lee-Hoeflich ST, Truong T, Haverty PM, Eastham-Anderson J, Lewin-Koh N, Gunter B, Belvin M, Murray LJ, Friedman LS, Sliwkowski MX, Hoeflich KP.
Department of Cancer Signaling, Genentech, Inc, South San Francisco, California, USA.
Abstract
PURPOSE: Oncogenic activation of the phosphatidylinositol 3-kinase (PI3K) signaling pathway is prevalent in breast cancer and has been associated with resistance to HER2 inhibitors in the clinic. We therefore investigated the combinatorial activity of GDC-0941, a novel class I PI3K inhibitor, with standard-of-care therapies for HER2-amplified breast cancer.
EXPERIMENTAL DESIGN: Three-dimensional laminin-rich extracellular matrix cultures of human breast cancer cells were utilized to provide a physiologically relevant approach to analyze the efficacy and molecular mechanism of combination therapies ex vivo. Combination studies were done using GDC-0941 with trastuzumab (Herceptin), pertuzumab, lapatinib (Tykerb), and docetaxel, the principal therapeutic agents that are either approved or being evaluated for treatment of early HER2-positive breast cancer.
RESULTS: Significant GDC-0941 activity (EC(50) <1 micromol/L) was observed for >70% of breast cancer cell lines that were examined in three-dimensional laminin-rich extracellular matrix culture. Differential responsiveness to GDC-0941 as a single agent was observed for luminal breast cancer cells upon stimulation with the HER3 ligand, heregulin. Combined treatment of GDC-0941, trastuzumab, and pertuzumab resulted in growth inhibition, altered acinar morphology, and suppression of AKT mitogen-activated protein kinase (MAPK) / extracellular signed-regulated kinase (ERK) kinase and MEK effector signaling pathways for HER2-amplified cells in both normal and heregulin-supplemented media. The GDC-0941 and lapatinib combination further showed that inhibition of HER2 activity was essential for maximum combinatorial efficacy. PI3K inhibition also rendered HER2-amplified BT-474M1 cells and tumor xenografts more sensitive to docetaxel.
CONCLUSIONS: GDC-0941 is efficacious in preclinical models of breast cancer. The addition of GDC-0941 to HER2-directed treatment could augment clinical benefit in breast cancer patients.
PMID: 19509167
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