DUO delivers for duvelisib

Structural optimization towards promising β-methyl-4-acrylamido quinoline derivatives as PI3K/mTOR dual inhibitors for anti-cancer therapy: The in vitro and in vivo biological evaluation

Built upon the 4-acrylamido quinoline derivative 4, a previously discovered PI3K/mTOR dual inhibitor, structural modification was undertaken in this study with the attempt to improve its oral exposure via introducing steric hindrance to the 4-acrylamido functionality. Consequently, 14d, as the representative among the synthesized compounds, exhibited IC₅₀ values of 0.80, 0.67, 1.30, 1.30 and 5.0 nM against PI3Kα, PI3Kβ, PI3Kγ, PI3Kδ and mTOR, respectively. Besides, 14d displayed comparable anti-proliferative activity against both PC3 and U87MG cell lines to that of the positive reference GSK2126458 with respective GI₅₀ value of 0.36 and 0.14 μM. Kinase selectivity assay showed that 14d was selective to PI3K family. In U87MG cells, 14d can strongly down-regulate PI3K/Akt/mTOR pathway via blocking both PI3K and mTOR signaling at the concentration as low as 25 nM. Importantly, following a PO dose of 5 mg/kg in male SD rats, 14d displayed favorable oral exposure (AUC_0-t = 1336.16 h × ng/mL, AUC_0-∞ = 1447.63 h × ng/mL) and high maximum plasma concentration (C_max = 903.00 ng/mL). In a U87MG glioblastoma xenograft model, tumor growth inhibition of 93.5% and tumor regression were observed at PO dose of 30 and 60 mg/kg, respectively. Meanwhile, no overt loss of body weight was observed in the 14d-treated groups. Taken together, 14d, by virtue of its attractive performance, merits further development as a potential anti-tumor candidate.

Anti-tumor activity of dual inhibition of phosphatidylinositol 3-kinase and MDM2 against clear cell ovarian carcinoma

INTRODUCTION

PI3K pathway signaling has received attention as a molecular target in clear cell ovarian carcinoma (CCOC). MDM2 is one of the AKT effectors in the PI3K pathway, which binds to and degrades p53. In this study, we aimed to clarify the prognostic significance of PIK3CA and MDM2 expression, and potential therapeutic effect of a dual inhibition of the PI3K pathway and MDM2.

MATERIALS AND METHODS

cDNA expression was evaluated by using microarray data using 75 samples of CCOC. DS-7423 (dual inhibitor of pan-PI3K and mTOR) and RG7112 (MDM2 inhibitor) were used on CCOC cell lines to evaluate cell proliferation, expression level of MDM2 related proteins, and apoptosis by MTT assay, western blotting, and flow cytometry. DS-7423 (3 mg/kg) and/or RG7112 (50 mg/kg) were orally administrated every day for three weeks, and the anti-tumor effect was evaluated using tumor xenografts, along with immunohistochemistry.

RESULTS

Tumors with high expression of both PIK3CA and MDM2 showed significantly worse prognosis in expression array of 71 CCOCs (P = 0.013). Dual inhibition of the PI3K pathway by DS-7423 and MDM2 by RG7112 showed synergistic anti-proliferative effect in 4 CCOC cell lines without TP53 mutations. The combination therapy more robustly induced pro-apoptotic proteins (PUMA and cleaved PARP) with increase of sub G1 population and apoptotic cells, compared with either single agent alone. The combination therapy significantly reduced tumor volume in mice (P < 0.001 in OVISE, and P = 0.038 in RMG-I) without severe body weight loss. Immunohistochemistry from the xenograft tumors showed that the combination treatment significantly reduced vascularity and cell proliferation, with an increase of apoptotic cell death.

CONCLUSION

A combination therapy targeting the PI3K pathway and MDM2 might be a promising therapeutic strategy in CCOC.