Cell experiment:

WM793, Lu1205, WM1346 and WM1366 melanoma cells are seeded at 1500 cells in 50 μL per well in 384-well plates. Cells are allowed to attach overnight. SBI-0640756 (SBI-756) or derivatives analogs are serially diluted 2-fold with media from stock solutions and added to cells. Tests are performed in triplicate, and each microplate included media and DMSO control wells. Cell viability is assessed using ATPlite after 48 or 72 h. Cell growth inhibition is calculated as a percentage of DMSO-treated controls and plotted against the log drug concentration. IC50 values are interpolated from the resulting linear regression curve fit[1].

Animal experiment:

Mice[1]Six-week-old female nu/nu mice are allowed to acclimatize for 1 week. A375 cells (1 × 106, suspended in 200 μL sterile PBS) are injected into subcutaneous flank tissue. When the xenograft size reach ~250 mm3, mice are sorted into different groups. For PLX4720 and SBI-0640756 (SBI-756) combination experiments, mice are either fed PLX4720-containing chow alone (AIN76A Roden Diet with 417 mg PLX4720/kg) for the control group or PLX4720-containing chow plus an IP injection of 1 mg/kg SBI-0640756 twice a week. For MEKi plus SBI-0640756 (SBI-756) experiments, PD0325901 at 20 mg/kg (formulated in 0.5% hydroxypropyl methylcellulose plus 0.2% Tween-80) is administered by oral gavage twice a week (Monday and Thursday) for the control group, or PD035901 plus IP injection of 1 mg/kg SBI-0640756 (SBI-756) is administered twice a week (Tuesday and Friday)[1].

SBI-0640756 is a water soluble inhibitor of eIF4G1 and disrupts the eIF4F complex.

SBI-0640756 is a water soluble inhibitor of eIF4G1. SBI-0640756 (0-1 μM) disrupts eIF4F complex in parent and BRAFi-resistant melanoma. SBI-0640756 shows inhibitory effect on human melanoma lines, and also suppresses AKT, NF-κB and AKT/mTORC1 activity[1].

SBI-0640756 (0.5 mg/kg, i.p.) delays tumor onset and reduces tumor incidence by 50% in NrasQ61K/Ink4a-/- genetic model. SBI-0640756 (1 mg/kg, 2 times per week, i.p.) in combination with BRAF inhibitor potently suppresses growth of established tumors and does not resume tumor growth in immunodeficient mice bearing A375 tumors[1].

[1]. Feng Y et al. SBI-0640756 Attenuates the Growth of Clinically Unresponsive Melanomas by Disrupting the eIF4F Translation Initiation Complex. Cancer Res, 2015 Dec 15, 75(24):5211-8.