The phosphoinositide 3-kinase α selective inhibitor BYL719 enhances the effect of the protein kinase C inhibitor AEB071 in GNAQ/GNA11-mutant uveal melanoma cells

G-protein mutations are one of the most common mutations occurring in uveal melanoma activating the protein kinase C (PKC)/mitogen-activated protein kinase and phosphoinositide 3-kinase (PI3K)/AKT pathways. In this study, we described the effect of dual pathway inhibition in uveal melanoma harboring GNAQ and GNA11 mutations via PKC inhibition with AEB071 (sotrastaurin) and PI3K/AKT inhibition with BYL719, a selective PI3Kα inhibitor. Growth inhibition was observed in GNAQ/GNA11-mutant cells with AEB071 versus no activity in wild-type cells. In the GNAQ-mutant cells, AEB071 decreased phosphorylation of myristoylated alanine-rich C-kinase substrate, a substrate of PKC, along with ERK1/2 and ribosomal S6, but persistent AKT activation was present. BYL719 had minimal antiproliferative activity in all uveal melanoma cell lines, and inhibited phosphorylation of AKT in most cell lines. In the GNA11-mutant cell line, similar effects were observed with ERK1/2 inhibition, mostly inhibited by BYL719. With the combination treatment, both GNAQ- and GNA11-mutant cell lines showed synergistic inhibition of cell proliferation and apoptotic cell death. In vivo studies correlated with in vitro findings showing reduced xenograft tumor growth with the combination therapy in a GNAQ-mutant model. These findings suggest a new therapy treatment option for G-protein-mutant uveal melanoma with a focus on specific targeting of multiple downstream pathways as part of combination therapy.

BRAF and beyond: Tailoring strategies for the individual melanoma patient

Until recently, options for therapy in metastatic melanoma were limited. The understanding of immune check-point blockade and the discovery of molecular pathways involving driver mutations like BRAF has transformed the therapeutic landscape in this disease. Ipilimumab was the first drug shown to improve survival while vemurafenib demonstrated rapid responses never seen before in melanoma. Drugs from these classes and others are now in advanced stages of development and primed to positively impact patient survival in an incremental fashion. In this review, we highlight some of the developments during this renaissance in melanoma therapy and discuss agents of promise. Clinical challenges we face include individualizing therapy for patients, overcoming resistance to molecularly targeted therapy and developing rationale combinations or sequences of drugs. A concerted bench and bedside effort in this direction will undoubtedly keep melanoma in the forefront in an era of personalized medicine.