ABCB1 and Decreased total leukocyte count: With taxane-based chemotherapy, the 2677G>T/A polymorphism of ABCB1 is associated with leukopenia (Sissung et al, 2006; Tran et al, 2006), greater tumour response(Green et al, 2006), longer PFS (Johnatty et al, 2008) but higher drug clearance(Gréen et al, 2009).