Preclinical formulation for the pharmacokinetics and efficacy of GBO-006, a selective polo like kinase 2 (PLK2) inhibitor for the treatment of triple negative breast cancer

Srinivas Maddi,Duraiswamy A Jeyaraj,Ravi Akkireddy,Jang B Gupta,Srinivas Lenkalapelly,Joshodeep Boruwa,Chandra Deb,Manoj Maniar,Sachin Bansal,Pratima Srivastava,Arnab Roy Chowdhury,Premkumar Reddy ,Ramana Reddy

doi:10.5599/admet.4.4.341

Srinivas Maddi, Duraiswamy A Jeyaraj + Show 11 more

Open Access

https://doi.org/10.5599/admet.4.4.341

Copy DOI

Abstract

GBO-006 was shown to be a highly specific and selective PLK2 inhibitor that promoted mitotic arrest in various cancer cell lines, subsequently resulting in their apoptotic death. Intraperitoneal alternate day dosing of GBO-006 using 100 % DMSO as formulation showed significant tumor regression in xenograft models, demonstrating proof of concept of PLK2 inhibition in vivo. These studies necessitated the development of a suitable and GRAS (generally considered as safe) preformulation for pharmacokinetic and efficacy studies. GBO-006 possesses challenging physicochemical and biopharmaceutical properties like poor solubility in aqueous media, low permeability and a crystalline nature. Different methods like cosolvency, complexation and micellar solubilization were employed to improve the solubility of GBO-006. A strategy of co-solvency is used to solubilize the GBO-006 up to 10 mg/mL. A formulation with 20 % DMSO, 40 % PEG 400, 30 % of 100 mM citrate buffer (pH 3.0) and 10 % solutol displayed clear solution without any visual precipitation of the drug even after 2 weeks of storage. GBO-006 showed moderate clearance in rat and high systemic clearance in mouse and dog. It showed poor oral bioavailability across all species. Intraperitoneal dosing of GBO-006 demonstrated the linear exposure. GBO-006 showed significant inhibition of tumor progression.

Highlights

The up regulation of Polo like kinase PLK1 plays a key role in mitosis but little is known about the oncogenic significance of PLK2 [1,2]
In our attempt to develop ATP-mimetic compounds that are cytotoxic against a panel of cancer cell lines, we identified several sulfonyl pyridopyrimidines that exhibit cyto-toxicity at nanomolar concentrations [6,7,8]
Intraperitoneal alternate day dosing of GBO-006 using 100 % DMSO as formulation lead to significant tumor regression in Xenograft models, demonstrating proof of concept of PLK2 inhibition in vivo

Summary

Introduction

The up regulation of Polo like kinase PLK1 plays a key role in mitosis but little is known about the oncogenic significance of PLK2 [1,2]. In our attempt to develop ATP-mimetic compounds that are cytotoxic against a panel of cancer cell lines, we identified several sulfonyl pyridopyrimidines that exhibit cyto-toxicity at nanomolar concentrations [6,7,8]. The most potent of these compounds, GBO-006 (2-(1H-indol-5-ylamino)-6-(2,4difluorophenylsulfonyl)-8-methylpyrido[2,3-d]pyrimidin-7(8H)-one) was found to be a specific PLK2 inhibitor when profiled against a panel of 288 wild-type, 55 mutant and 12 special kinases. The cytotoxic effect of the drug is mediated by apoptosis as evidenced by the induction of caspase 3/7 activity and by the cleavage of PARP in a dose dependent manner [9]. It affects cell cycle progression by blocking tumor cells in the G2/M phase. The developed formulation was subsequently used to perform pharmacokinetic studies (mice, rats and dogs) and efficacy studies, with GBO-006 as a single agent in SCID Beige mouse xenograft models

Methods

Results

Conclusion