MTOR and neoplasm: Interestingly, even in the refractory PDX models, the simultaneous PI3Kβ/δ and mTOR inhibition resulted in a significant synergistic effect compared to the single drugs alone which prevented the outgrowth of the tumor (P = .0006 for AZD8186 vs. AZD8186/AZD2014 on day 12 for WEHA, P = .002 for AZD8186 vs. AZD8186/AZD2014 on day 9 for KTC) (Fig. 6e).