ABT-263

ABT-263 is structurally related to ABT-737; it is a disruptor of Bcl-2/Bcl-xL interactions with pro-apoptotic proteins. Overexpression of the prosurvival Bcl-2 family members is commonly associated with tumor maintenance, progression, andchemoresistance.ABT-263 displays the protection afforded by overexpression of Bcl-2 or Bcl-xL with EC50 values of 60 and 20 nM, respectively. A wide range of cellular activity is observed with ABT-263 having a 50% growth inhibition (EC50) of 110 nM against the most sensitive line (H146), whereas its activity in the least sensitive line (H82) results in an EC50 at 22 μM. All four cell lines with EC50 values of <400 nM (H146, H889, H1963, and H1417) are also highly sensitive to ABT-737, and the two most resistant lines (H1048 and H82) are similarly resistant to ABT-263.