Another phase 1 study of GDC-0425, a new selective small-molecule inhibitor of CHEK1, with gemcitabine demonstrated that 2 of 5 TNBC patients reached PR, and tumor biopsies showed that GDC-0425 administration decreased the pCDK1/2 expression induced by gemcitabine, in accordance with the checkpoint override caused by CHEK1 inhibitors [192]. The gene discussed is CHEK1; the disease is neoplasm.