The novel PI3K inhibitor WX-037 and the novel MEK inhibitor WX-554 have demonstrated in vitro activity in a range of cancer cell lines including breast, fibrosarcoma, thyroid, melanoma, colorectal, ovarian and pancreas lines with a broad range of GI50 values, where generally the cell lines most sensitive to WX-037 had PIK3CA mutations or PTEN loss, and to WX-554 had BRAF or RAS mutations [5]. Here, PTEN is linked to fibrosarcoma.