Discovery of AZD4573, a Potent and Selective Inhibitor of CDK9 That Enables Short Duration of Target Engagement for the Treatment of Hematological Malignancies.

A CDK9 inhibitor having short target engagement would enable a reduction of Mcl-1 activity, resulting in apoptosis in cancer cells dependent on Mcl-1 for survival. We report the optimization of a series of amidopyridines (from compound 2), focusing on properties suitable for achieving short target engagement after intravenous administration. By increasing potency and human metabolic clearance, we identified compound 24, a potent and selective CDK9 inhibitor with suitable predicted human pharmacokinetic properties to deliver transient inhibition of CDK9. Furthermore, the solubility of 24 was considered adequate to allow i.v. formulation at the anticipated effective dose. Short-term treatment with compound 24 led to a rapid dose- and time-dependent decrease of pSer2-RNAP2 and Mcl-1, resulting in cell apoptosis in multiple hematological cancer cell lines. Intermittent dosing of compound 24 demonstrated efficacy in xenograft models derived from multiple hematological tumors. Compound 24 is currently in clinical trials for the treatment of hematological malignancies.

Using quantitative structure activity relationship models to predict an appropriate solvent system from a common solvent system family for countercurrent chromatography separation.

Countercurrent chromatography (CCC) is a form of liquid-liquid chromatography. It works by running one immiscible solvent (mobile phase) over another solvent (stationary phase) being held in a CCC column using centrifugal force. The concentration of compound in each phase is characterised by the partition coefficient (Kd), which is the concentration in the stationary phase divided by the concentration in the mobile phase. When Kd is between approximately 0.2 and 2, it is most likely that optimal separation will be achieved. Having the Kd in this range allows the compound enough time in the column to be separated without resulting in a broad peak and long run time. In this paper we report the development of quantitative structure activity relationship (QSAR) models to predict logKd. The QSAR models use only the molecule's 2D structure to predict the molecular property logKd.

Developing counter current chromatography to meet the needs of pharmaceutical discovery.

Experiments have been carried out to evaluate Counter Current Chromatography (CCC) as an alternative purification technique to preparative Reverse Phase High Performance Liquid Chromatography (RP-HPLC) for small molecule pharmaceuticals. The major drawback of CCC is the extensive time required in selecting the solvents to perform the separation. This is equivalent to choosing both the stationary phase and the mobile phase at the same time. In RP-HPLC it is a simple matter of deciding on the gradient, most samples can be purified on a C18 column with a water:acetonitrile gradient. The majority of the initial work was based on a standard test set of commercially available compounds, developed within our group to evaluate the performance of the HPLC apparatus and the column prior to the start of work each day. The work carried out on CCC has shown that the technique offers similar capabilities and can be carried out using similar protocols to RP-HPLC. CCC also has some advantages over RP-HPLC and can be regarded as a valuable addition to the chromatography toolbox.

Gradient elution in counter-current chromatography: a new layout for an old path.

Gradient elution in CCC is a powerful tool, which needs further systematic development to become robust and easy to use. The first attempt to build a correlation between gradient elution profile and distribution ratio (K(D)) values for model mixtures containing typical representatives of pharmaceutical compounds is presented in this paper. The three step estimation of the solvent system composition of a heptane-ethyl acetate-methanol-water (HEMWat) series is described. The estimation is based on simple measurements of initial and final stationary phase retention for gradient elution run, calculating gradient distribution ratio and correlating it with static K(D) against HEMWat number.