TY - JOUR
T1 - Concomitant inhibition of PI3Kb and BRAF or MEK in PTEN-Deficient/BRAF-Mutant melanoma treatment
T2 - Preclinical assessment of SAR260301 oral PI3Kβ-Selective inhibitor
AU - Bonnevaux, Helene
AU - Lemaitre, Olivier
AU - Vincent, Loic
AU - Levit, Mikhail N.
AU - Windenberger, Fanny
AU - Halley, Frank
AU - Delorme, Ćecile
AU - Lengauer, Christoph
AU - Garcia-Echeverria, Carlos
AU - Virone-Oddos, Angela
PY - 2016/7/1
Y1 - 2016/7/1
N2 - Class IA PI3K pathway activation resulting from PTEN deficiency has been associated with lack of sensitivity of melanoma to BRAF kinase inhibitors. Although previous studies have shown synergistic activity when pan-PI3K inhibitors were combined with MAPK inhibitors in the treatment of melanoma exhibiting concurrent genetic abnormalities, overlapping adverse events in patients limit optimal dosing and clinical application. With the aim of specifically targeting PTEN-deficient cancers and minimizing the potential for on-target toxicity when inhibiting multiple PI3K isoforms, we developed a program to discover PI3Kbselective kinase inhibitors and identified SAR260301 as a potent PI3Kb-selective, orally available compound, which is now in clinical development. Herein, we provide a detailed biological characterization of SAR260301, and show that this compound has outstanding biochemical and cellular selectivity for the PI3Kb isoform versus the a, d, and g isoforms and a large panel of protein and lipid kinases. We demonstrate that SAR260301 blocks PI3K pathway signaling preferentially in PTEN-deficient human tumor models, and has synergistic antitumor activity when combined with vemurafenib (BRAF inhibitor) or selumetinib (MEK inhibitor) in PTEN-deficient/BRAF-mutated human melanoma tumor models. Combination treatments were very well tolerated, suggesting the potential for a superior safety profile at optimal dosing using selective compounds to inhibit multiple signaling pathways. Together, these experiments provide a preclinical proof-of-concept for safely combining inhibitors of PI3Kb and BRAF or MEK kinase modulators to improve antitumor activity in PTEN-deficient/BRAF-mutant melanoma, and support the evaluation of SAR260301-based combinations in clinical studies.
AB - Class IA PI3K pathway activation resulting from PTEN deficiency has been associated with lack of sensitivity of melanoma to BRAF kinase inhibitors. Although previous studies have shown synergistic activity when pan-PI3K inhibitors were combined with MAPK inhibitors in the treatment of melanoma exhibiting concurrent genetic abnormalities, overlapping adverse events in patients limit optimal dosing and clinical application. With the aim of specifically targeting PTEN-deficient cancers and minimizing the potential for on-target toxicity when inhibiting multiple PI3K isoforms, we developed a program to discover PI3Kbselective kinase inhibitors and identified SAR260301 as a potent PI3Kb-selective, orally available compound, which is now in clinical development. Herein, we provide a detailed biological characterization of SAR260301, and show that this compound has outstanding biochemical and cellular selectivity for the PI3Kb isoform versus the a, d, and g isoforms and a large panel of protein and lipid kinases. We demonstrate that SAR260301 blocks PI3K pathway signaling preferentially in PTEN-deficient human tumor models, and has synergistic antitumor activity when combined with vemurafenib (BRAF inhibitor) or selumetinib (MEK inhibitor) in PTEN-deficient/BRAF-mutated human melanoma tumor models. Combination treatments were very well tolerated, suggesting the potential for a superior safety profile at optimal dosing using selective compounds to inhibit multiple signaling pathways. Together, these experiments provide a preclinical proof-of-concept for safely combining inhibitors of PI3Kb and BRAF or MEK kinase modulators to improve antitumor activity in PTEN-deficient/BRAF-mutant melanoma, and support the evaluation of SAR260301-based combinations in clinical studies.
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U2 - 10.1158/1535-7163.MCT-15-0496
DO - 10.1158/1535-7163.MCT-15-0496
M3 - Article
C2 - 27196754
AN - SCOPUS:84979248260
SN - 1535-7163
VL - 15
SP - 1460
EP - 1471
JO - Molecular Cancer Therapeutics
JF - Molecular Cancer Therapeutics
IS - 7
ER -