The most common drug-related adverse events of any grade in the 2 mg/kg and 10 mg/kg groups were fatigue ( 29 [ 33 % ] vs 31 [ 37 % ] ) , pruritus ( 23 [ 26 % ] vs 16 [ 19 % ] ) , and rash ( 16 [ 18 % ] vs 15 [ 18 % ] ) .