The pharmacokinetic interaction between higher doses of WX-037 and WX-554 is in contrast to the results obtained with the combination of PD 0325901 and pictilisib in HCT116 tumour xenograft-bearing mice [25], where there was no significant pharmacokinetic interaction, and to pre-clinical and clinical reports that there was no pharmacokinetic interaction between the PI3K and MEK inhibitors, pictilisib and cobimetinib [52, 53]. The gene discussed is PIK3CA; the disease is neoplasm.