## 1 Introduction  
The phosphatidylinositol3-kinase (PI3K)/protein kinase B (also known as AKT)/ mammalian target of rapamycin (MTOR) pathway plays an important role in the growth and proliferation of tumour cells [1]. Clinical data indicate that this signalling pathway is abnormally activated in more than 30% of malignant tumours. Meanwhile, numerous data show that the inhibition of this signalling pathway can effectively inhibit tumour growth. Therefore, targeting the key protein molecules of the PI3K/AKT/MTOR signalling pathway has attracted increased attention in the research and development of new antitumor drugs.  
AKT is a general name for three subtypes of serine/threonine protein kinases, AKT1, AKT2, and AKT3 [2], which are closely related to and play a significant role in regulating the growth, proliferation, survival, and metabolism of cells. PI3K activation generates phosphatidylinositol (3,4,5)-trisphosphate (PIP3), which interacts with the pleckstrin homology (PH) domain of AKT, resulting in its translocation and conformational changes. After PIP3 binds to the PH domain of AKT, PDK1 and PDK2 phosphorylate; AKT is activated only after both are phosphorylated. The activated AKT is transferred from the cell membrane to the cytoplasm or nucleus, where it targets and regulates, via phosphorylation, downstream signalling molecules, such as MTOR, BAD, and cyclin D1, to promote cell growth and inhibit apoptosis. Therefore, AKT is the core protein in the PI3K/AKT/MTOR signalling pathway. It can inhibit tumour cell apoptosis and promote tumour cell survival [3; 4; 5]. It can also promote the tumour cell cycle, which results in tumour cell overproliferation [5; 6; 7].  
With increasing insights into the structure, function, and mechanism of action of AKT, the application of small-molecule AKT inhibitors in the field of antitumor therapy has received increasing attention, and numerous structural types of small-molecule AKT inhibitors have been reported [8; 9]. Since 2000, more than 10 AKT inhibitors, such as perifosine, triciribine, GSK690693, XL418, and UCN-01, have entered clinical trials. However, most of the developed AKT-specific antitumor therapy candidate compounds show problems such as a poor stability, poor cell permeability, and poor solubility.  
\(N\)-((3S,4S)\(4\)-(3,4-Difluorophenyl))piperidin-3-yl)-2-fluoro-4-(1-methyl-1\(H\)-pyrazol-5-yl)benzamide (Hu7691) is a new-generation selective AKT inhibitor, which was independently developed at Zhejiang University [10]. Hu7691 was systematically optimised via molecular docking and rational drug design, mainly to overcome the problems of poor kinase selectivity and hERG channel blockade by AKT inhibitors. Consequently, improved kinase selectivity and improved in vitro and in vivo efficacy and safety were achieved. Nevertheless, no studies have reported the detection methods used in biological samples from Hu7691. In this study, a novel UPLC-MS/MS method for bioanalysis of Hu7691 in dog plasma was established, validated, and applied to pharmacokinetic monitoring and bioavailability assessment in beagles. The data of this study may be used for future preclinical and clinical evaluation of this compound.