PIK3CA and prostate cancer: Controversially, however, previous work by us indicates that TGX-221 treatment alone in a Pten-deficient prostate cancer transgenic mouse model is not sufficient to significantly reduce tumor burden, although tumor regression was observed when TGX-221 was combined with the p110α isoform-specific PI3K inhibitor A66 [21], indicating that p110β inhibition may shift dependency to p110α in this setting [21,168].