Synergistic effects of a combined treatment of PI3K/mTOR dual inhibitor LY3023414 and carboplatin on human endometrial carcinoma

Objectives: Our study aims to investigate whether PI3K/mTOR dual inhibitor LY3023414 has synergistic effects with carboplatin in suppressing endometrial Cancer (EC), and explore the mechanisms and toxicity of combined therapy.

Methods: The effects of combined therapy of LY3023414 and carboplatin on cell viability, long-term survival and cell Apoptosis were studied in vitro, and on subcutaneous xenograft model of HEC-1A cells and patient derived xenograft (PDX) models with different PI3K pathway mutational patterns in vivo. The synergistic mechanisms were explored on ATM/Chk2 and PI3K signaling pathway. The toxicity of combined therapy was also observed.

Results: Combined treatment of LY3023414 and carboplatin synergistically inhibited proliferation, colony formation, promoted Apoptosis of EC cells, and significantly activated ATM/Chk2 signaling pathway. LY3023414 had synergistic anti-tumor effects with carboplatin in HEC-1A subcutaneous xenograft which harbors PIK3CA mutation. The sensitivity to LY3023414 and carboplatin differed in PDX of EC cases with different mutational patterns of PI3K pathway, and combined therapy exhibited distinct synergistic anti-tumor effects in those harboring different PI3K pathway mutations. No increased drug toxicity in nude mice was seen in combined groups.

Conclusions: Combined therapy of PI3K/mTOR dual inhibitor LY3023414 and carboplatin had synergistic anti-tumor effects in EC cell line and some of the PDX EC models, without increasing the toxicity of single drug. Enhanced carboplatin-induced DNA damage response (DDR) and cell Apoptosis may be the mechanisms of synergistic effects. The anti-tumor effects may correlate with the mutational pattern of PI3K pathway, which provides experimental basis of individual treatments of ECs in the future.