(T1330-01-06) A Novel Liposome Delivering Adavosertib for Ovarian Cancer Treatment

Purpose: Ovarian cancer is the most lethal gynecological cancer. It is the second leading cause of death among gynecological malignancies, with a 5-year survival rate of only 50.8%. Ovarian cancer is a heterogeneous collection of malignancies, among which the most common type is high-grade serous ovarian cancer, which comprises 75% of the total cases. Adavosertib (ADA), a WEE 1 inhibitor, has been shown to have potential efficacy against ovarian cancer. However, systemic administration of the ADA solution often fails to control tumor growth due to poor tumor distribution. Multiple nanocarriers were formulated to improve tumor-specific delivery of the chemotherapeutics through enhanced permeability and retention effect. Liposomes are one of the first therapeutic nanocarriers to be approved clinically for their proven biocompatibility, biodegradability, and low toxicity. In our study, we prepared liposomal formulations for the delivery of ADA and investigated its in vitro antitumoral efficacy against the SKOV-3 ovarian cancer cell line.

Methods: The lipids used are soy lecithin, cholesterol, and DSPE-PEG2000 in 0.75:0.24:0.01 molar ratios, respectively. ADA-loaded liposomes were prepared using a thin film hydration method. Liposomes were then dialyzed against deionized water for 8 hours to remove unencapsulated drugs. The size and surface charge of the liposomes were measured using the Zetasizer Nano ZS instrument. The liposome morphology was determined using transmission electron microscopy (TEM). The encapsulation efficiency of the liposomal formulation was determined by HPLC. The storage stability of the liposomal formulation was done at 4°C for 5 weeks. The in vitro drug release study was performed using a Float-A-Lyzer dialysis device (MWCO – 3.5-5 kD), and 0.5% (v/v) tween 80 in phosphate-buffered saline was used as release media. The entire set was kept in a shaker at 37°C at rpm 100. The amount of drug released was determined using the HPLC method. An in vitro cytotoxicity assay was performed using MTS on the SKOV-3 cells.

Results: The size and charge of ADA-loaded liposome were 110.4 ± < 0.9 nm and -17.8 ± 1.4 mV, respectively. The encapsulation efficiency of the liposome was 67.63%. The in vitro drug release study confirmed the almost complete release of ADA within 24 hours. Liposomes appeared as homogenous spherical vesicles, as shown by TEM images. The liposome encapsulated ADA showed superior in vitro cytotoxicity against SKOV-3 cells (IC50 of 1.8 nM) compared to the free drug (IC50 of 8.0 nM).

Conclusion: We have successfully formulated ADA-encapsulated liposomes with a high encapsulation efficiency. The liposomes were stable at 4 ͦ C throughout the study period. It has been shown that 80% of ovarian cancer cells overexpress folate receptors. In the future, we will formulate folate-conjugated liposomes, and in vitro and in vivo efficacy of the folate-conjugated ADA liposomes will be compared with folate-free as well as unencapsulated ADA formulation using suitable tumor models.

Acknowledgements: This work was supported by the National Institute of General Medical Sciences (NIGMS) Center of Biomedical Research Excellence (COBRE) award 2P20 GM109024.


Representative image of liposome morphology as determined using transmission electron microscopy (TEM)


The hydrodynamic size (A) and charge (B) of ADA-loaded liposome as measured by DLS method (n=6).


The in vitro drug release study of ADA-loaded liposome