BMN 673 (Synonyms: Talazoparib)

PARP enzyme assays

For PARP inhibitor Ki determination, enzyme assays were conducted in 96-well FlashPlate with 0.5 U PARP1 enzyme , 0.25x activated DNA, 0.2 mCi [3H] NAD, and 5 mmol/L cold NAD(Sigma) in a final volume of 50 mL reaction buffer containing 10% glycerol (v/v), 25 mmol/L HEPES, 12.5 mmol/L MgCl2, 50 mmol/L KCl, 1 mmol/L dithiothreitol (DTT), and 0.01% NP-40 (v/v), pH 7.6. Reactions were initiated by adding NAD to the PARP reaction mixture with or without inhibitors and incubated for 1 minute at room temperature. Fifty microliter of ice-cold 20% trichloroacetic acid (TCA) was then added to each well to stop the reaction. The plate was sealed and shaken for a further 120 minutes at room temperature, followed by centrifugation. Radioactive signal bound to the FlashPlate was determined using Top-Count. PARP1 Km was determined using Michaelis–Menten equation from various substrate concentrations (1–100 mmol/L NAD). Compound Ki was calculated from enzyme inhibition curve according to the formula: Ki ¼ IC50/[1þ (substrate)/Km]. Km for PARP2 enzyme and compound Ki were determined with the same assay protocol except 30 ng PARP2, 0.25x activated DNA, 0.2 mCi [3H] NAD, and 20 mmol/L cold NAD were used in the reaction for 30 minutes at room temperature.

Cell lines

SCLC cell lines

Preparation method

Limited solubility. General tips for obtaining a higher concentration: Please warm the tube at 37 ℃ for 10 minutes and/or shake it in the ultrasonic bath for a while. Stock solution can be stored below -20℃ for several months.

Reaction Conditions

24 h-96 h

Applications

BMN 673 exhibits a potent inhibitory effect on a panel of 11 SCLC cell lines (IC50=1.7 to 15 nmol/L), which are all within clinically achievable ranges. In addition, sensitivity to BMN673 correlates to DNA repair protein expression and PI3K pathway activity.

Animal models

Nude mice bearing established subcutaneous MX-1 tumor xenografts.

Dosage form

Oral gavage and twice daily for 28 consecutive days.

Applications

BMN 673 inhibits the growth of MX-1 xenografts in mice, with 4 of 6 mice achieving a complete response. 0.33 and 0.1 mg/kg BMN 673 is well tolerated, with no animal lethality.

Other notes

Please test the solubility of all compounds indoor, and the actual solubility may slightly differ with the theoretical value. This is caused by an experimental system error and it is normal.

References:

1. Shen Y, Rehman FL, Feng Y et al. BMN 673, a novel and highly potent PARP1/2 inhibitor for the treatment of human cancers with DNA repair deficiency. Clin Cancer Res. 2013 Sep 15;19(18):5003-15.

2. Cardnell RJ, Feng Y, Diao L et al. Proteomic markers of DNA repair and PI3K pathway activation predict response to the PARP inhibitor BMN 673 in small cell lung cancer. Clin Cancer Res. 2013 Nov 15;19(22):6322-8.