SLFN11 and neoplasm: There was a weak but significant correlation between evofosfamide efficacy and MKI67 expression (r = −0.682, P = 0.04; Figure 5D), but not between evofosfamide efficacy and POR (r = −0.558, P = 0.12) or SLFN11 (r = −0.481, P = 0.19), with the highest expression for each gene observed in ACS-HN11, the tumour model that was most sensitive to evofosfamide.