Chk1 (Ki = 0.9 nM); Chk1 (IC50 <1 nM); Chk2 (IC50 = 8 nM)

Prexasertib (LY2606368) mesylate inhibits BRSK2 (IC50=48 nM), ARK5 (IC50=64 nM), SIK (IC50=42 nM), and MELK (IC50=38 nM). In order to damage DNA, prexasertib mesylate needs CDK2 and CDC25A[1].
Prexasertib mesylate (33, 100 nM; for 7 hours) for 7 hours causes damage to DNA during the S-phase in HeLa cells[1].
Prexasertib mesylate (8-250 nM; pre-treated for 15 minutes) inhibits the autophosphorylation of CHK1 (S296) and CHK2 (S516)[1].
Prexasertib mesylate (4 nM; 24 hours) induces H2AX phosphorylation and causes a significant shift in cell cycle populations from G1 and G2-M to S-phase in U-2 OS cells[1].
Prexasertib mesylate (33 nM; for 12 hours) chromosomal fragmentation in HeLa cells. Prexasertib mesylate (100 nM; 0.5 to 9 hours) reduces the amount of RPA2 that is available to bind to DNA and causes replication stress[1].

Prexasertib mesylate (1-10 mg/kg; SC; twice daily for 3 days, rest 4 days; for three cycles) inhibits the growth of tumor xenografts[1].
Prexasertib mesylate (15 mg/kg; SC) causes the phosphorylation of RPA2 (S4/S8) and H2AX (S139) in addition to inhibiting CHK1 in the blood[1].

Prexasertib (LY2606368) inhibits CHK1 and CHK2 with IC50 values less than 1 nM and 8 nM, respectively, with a strong and specific potency. For CHK1 activity via serine 296 autophosphorylation, LY2606368 has an EC50 of 1 nM, and for HT-29 CHK2 autophosphorylation, it is <31 nM (S516). With an EC50 of 9 nM, LY2606368 potently inhibits the G2-M checkpoint that doxorubicin has activated in p53-deficient HeLa cells. Still, 100 nM Instead of weakly inhibiting PMA-stimulated RSK, LY2606368 slightly increases the phosphorylation of S6 on serines 235/236. LY2606368 exhibits broad antiproliferative activity against U-2 OS, Calu-6, HT-29, HeLa, and NCI-H460 cell lines, exhibiting IC50 values of 3 nM, 3 nM, 10 nM, 37 nM, and 68 nM, respectively. Induction of H2AX phosphorylation and a significant shift in cell-cycle populations from G1 and G2-M to S-phase are both brought about by LY2606368 (4 nM) in U-2 OS cells. The anti-proliferative properties of AGS and MKN1 cells are demonstrated by LY2606368 (25 μM). HR repair capacity in DR-GFP cells is inhibited by LY2606368 (20 nM). When combined with the PARP inhibitor BMN673, LY2606368 (5 nM) exhibits synergistic anticancer effects in gastric cancer cells.

On T25 flasks, HeLa cells were plated, and they were given 24 hours to heal. The final concentrations of 33 or 100 nmol/L were then obtained by adding LY2606368. In certain studies, the drug treatment included 20μmol/L Z-VAD-FMK. After the 12-hour treatment, 1 μg/mL of colchicine was added during the final two hours of treatment. Using the methodology of Bayani and Squire, nuclei were fixed for metaphase spreads. Chromosome spreads were done. A 12-μL volume of cell suspension in a 3:1 methanol/acetic acid fixative was dropped onto coverslips or dry glass slides from a height of 3 cm. After that, the slides were heated for 45 seconds on a metal block set at 43°C. After that, they were taken out to finish drying at room temperature. Using DAPI, coverslips were adhered to slides using Vectashield Hard Set mounting medium. A Leica DMR fluorescent microscope was used to examine the slides, and a SPOT RT3 Slider camera was used to take pictures.

Female CD-1 nu-/nu- mice (26-28 g) with Calu-6 cells[1]
1, 3.3, or 10 mg/kg
SC; twice daily for 3 days, rest 4 days; for three cycles

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Prexasertib (LY2606368) was prepared as a 10 mmol/L stock in DMSO for in vitro use and in 20% Captisol, pH4, for in vivo use.
In vivo biochemistry and tumor growth inhibition[1]
Female CD-1 nu-/nu- mice (26–28 g) from Charles River Labs were used for this study. Tumor growth was initiated by subcutaneous injection of 1 × 106 Calu-6 cells in a 1:1 mixture of serum-free growth medium and Matrigel in the rear flank of each subject animal. When tumor volumes reached approximately 150 mm3 in size, the animals were randomized by tumor size and body weight, and placed into their respective treatment groups. Vehicle consisting of 20% Captisol pH4 or Prexasertib (LY2606368) was administered by subcutaneous injection in a volume of 200 μL. Four, eight, 12, 24, and 48 hours after drug administration, blood for plasma drug exposure was extracted via cardiac puncture and assayed on a Sciex API 4000 LC/MS-MS system. The xenograft tissue was promptly removed and prepared as previously described. Lysates were analyzed by immunoblot analysis for protein phosphorylation levels. Group means, SEs and P values were calculated using Kronos.[1]
To measure xenograft tumor growth inhibition, tumors were implanted, established, and the animals randomized as above. Eight animals were used in each treatment group. Vehicle alone or Prexasertib (LY2606368) was administered BIDx3, followed by 4 days of rest and repeated for an additional two cycles. Tumor size and body weight were recorded biweekly and compared between vehicle- and drug-treated groups.

[1]. LY2606368 Causes Replication Catastrophe and Antitumor Effects through CHK1-Dependent Mechanisms. Mol Cancer Ther. 2015 Sep;14(9):2004-1.

[2]. Chk1 inhibition potentiates the therapeutic efficacy of PARP inhibitor BMN673 in gastric cancer. Am J Cancer Res. 2017 Mar 1;7(3):473-483.

Prexasertib has been used in trials studying the treatment and basic science of mCRPC, Leukemia, Neoplasm, breast cancer, and Ovarian Cancer, among others. Prexasertib is an inhibitor of checkpoint kinase 1 (chk1) with potential antineoplastic activity. Upon administration, prexasertib selectively binds to chk1, thereby preventing activity of chk1 and abrogating the repair of damaged DNA. This may lead to an accumulation of damaged DNA and may promote genomic instability and apoptosis. Prexasertib may potentiate the cytotoxicity of DNA-damaging agents and reverse tumor cell resistance to chemotherapeutic agents. Chk1, a serine/threonine kinase, mediates cell cycle checkpoint control and is essential for DNA repair and plays a key role in resistance to chemotherapeutic agents.

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CHK1 is a multifunctional protein kinase integral to both the cellular response to DNA damage and control of the number of active replication forks. CHK1 inhibitors are currently under investigation as chemopotentiating agents due to CHK1's role in establishing DNA damage checkpoints in the cell cycle. Here, we describe the characterization of a novel CHK1 inhibitor, LY2606368, which as a single agent causes double-stranded DNA breakage while simultaneously removing the protection of the DNA damage checkpoints. The action of LY2606368 is dependent upon inhibition of CHK1 and the corresponding increase in CDC25A activation of CDK2, which increases the number of replication forks while reducing their stability. Treatment of cells with LY2606368 results in the rapid appearance of TUNEL and pH2AX-positive double-stranded DNA breaks in the S-phase cell population. Loss of the CHK1-dependent DNA damage checkpoints permits cells with damaged DNA to proceed into early mitosis and die. The majority of treated mitotic nuclei consist of extensively fragmented chromosomes. Inhibition of apoptosis by the caspase inhibitor Z-VAD-FMK had no effect on chromosome fragmentation, indicating that LY2606368 causes replication catastrophe. Changes in the ratio of RPA2 to phosphorylated H2AX following LY2606368 treatment further support replication catastrophe as the mechanism of DNA damage. LY2606368 shows similar activity in xenograft tumor models, which results in significant tumor growth inhibition. LY2606368 is a potent representative of a novel class of drugs for the treatment of cancer that acts through replication catastrophe.[2]

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The primary objective was to determine safety, toxicity, and a recommended phase II dose regimen of LY2606368, an inhibitor of checkpoint kinase 1, as monotherapy. Patients and methods: This phase I, nonrandomized, open-label, dose-escalation trial used a 3 + 3 dose-escalation scheme and included patients with advanced solid tumors. Intravenous LY2606368 was dose escalated from 10 to 50 mg/m(2) on schedule 1 (days 1 to 3 every 14 days) or from 40 to 130 mg/m(2) on schedule 2 (day 1 every 14 days). Safety measures and pharmacokinetics were assessed, and pharmacodynamics were measured in blood, hair follicles, and circulating tumor cells. Conclusion: An LY2606368 dose of 105 mg/m(2) once every 14 days is being evaluated as the recommended phase II dose in dose-expansion cohorts for patients with SCC.[1]

C19H23N7O5S

461.50

461.148

C, 49.45; H, 5.02; N, 21.25; O, 17.33; S, 6.95

1234015-55-4

Prexasertib;1234015-52-1;Prexasertib dihydrochloride;1234015-54-3;Prexasertib dimesylate;1234015-58-7;Prexasertib Mesylate Hydrate;1234015-57-6

46837045

Yellow solid powder

4

11

8

32

592

0

S(C)(=O)(=O)O.O(CCCN)C1C=CC=C(C=1C1=CC(NC2C=NC(C#N)=CN=2)=NN1)OC

WGCKOJKXQKKLQW-UHFFFAOYSA-N

InChI=1S/C18H19N7O2.CH4O3S/c1-26-14-4-2-5-15(27-7-3-6-19)18(14)13-8-16(25-24-13)23-17-11-21-12(9-20)10-22-17;1-5(2,3)4/h2,4-5,8,10-11H,3,6-7,19H2,1H3,(H2,22,23,24,25);1H3,(H,2,3,4)

5-[[5-[2-(3-aminopropoxy)-6-methoxyphenyl]-1H-pyrazol-3-yl]amino]pyrazine-2-carbonitrile;methanesulfonic acid

2934.99.9001

Powder      -20°C    3 years

                     4°C     2 years

In solvent   -80°C    6 months

                  -20°C    1 month

Room temperature (This product is stable at ambient temperature for a few days during ordinary shipping and time spent in Customs)

Note: Listed below are some common formulations that may be used to formulate products with low water solubility (e.g. < 1 mg/mL), you may test these formulations using a minute amount of products to avoid loss of samples.

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Injection Formulation 1: DMSO : Tween 80： Saline = 10 : 5 : 85 (i.e. 100 μL DMSO stock solution → 50 μL Tween 80 → 850 μL Saline)
*Preparation of saline: Dissolve 0.9 g of sodium chloride in 100 mL ddH ₂ O to obtain a clear solution.
Injection Formulation 2: DMSO : PEG300 ：Tween 80 : Saline = 10 : 40 : 5 : 45 (i.e. 100 μL DMSO → 400 μLPEG300 → 50 μL Tween 80 → 450 μL Saline)
Injection Formulation 3: DMSO : Corn oil = 10 : 90 (i.e. 100 μL DMSO → 900 μL Corn oil)
Example: Take the Injection Formulation 3 (DMSO : Corn oil = 10 : 90) as an example, if 1 mL of 2.5 mg/mL working solution is to be prepared, you can take 100 μL 25 mg/mL DMSO stock solution and add to 900 μL corn oil, mix well to obtain a clear or suspension solution (2.5 mg/mL, ready for use in animals).

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Injection Formulation 4: DMSO : 20% SBE-β-CD in saline = 10 : 90 [i.e. 100 μL DMSO → 900 μL (20% SBE-β-CD in saline)]
*Preparation of 20% SBE-β-CD in Saline (4°C，1 week): Dissolve 2 g SBE-β-CD in 10 mL saline to obtain a clear solution.
Injection Formulation 5: 2-Hydroxypropyl-β-cyclodextrin : Saline = 50 : 50 (i.e. 500 μL 2-Hydroxypropyl-β-cyclodextrin → 500 μL Saline)
Injection Formulation 6: DMSO : PEG300 : castor oil : Saline = 5 : 10 : 20 : 65 (i.e. 50 μL DMSO → 100 μLPEG300 → 200 μL castor oil → 650 μL Saline)
Injection Formulation 7: Ethanol : Cremophor : Saline = 10： 10 : 80 (i.e. 100 μL Ethanol → 100 μL Cremophor → 800 μL Saline)
Injection Formulation 8: Dissolve in Cremophor/Ethanol (50 : 50), then diluted by Saline
Injection Formulation 9: EtOH : Corn oil = 10 : 90 (i.e. 100 μL EtOH → 900 μL Corn oil)
Injection Formulation 10: EtOH : PEG300：Tween 80 : Saline = 10 : 40 : 5 : 45 (i.e. 100 μL EtOH → 400 μLPEG300 → 50 μL Tween 80 → 450 μL Saline)

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Oral Formulation 1: Suspend in 0.5% CMC Na (carboxymethylcellulose sodium)
Oral Formulation 2: Suspend in 0.5% Carboxymethyl cellulose
Example: Take the Oral Formulation 1 (Suspend in 0.5% CMC Na) as an example, if 100 mL of 2.5 mg/mL working solution is to be prepared, you can first prepare 0.5% CMC Na solution by measuring 0.5 g CMC Na and dissolve it in 100 mL ddH2O to obtain a clear solution; then add 250 mg of the product to 100 mL 0.5% CMC Na solution, to make the suspension solution (2.5 mg/mL, ready for use in animals).

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Oral Formulation 3: Dissolved in PEG400
Oral Formulation 4: Suspend in 0.2% Carboxymethyl cellulose
Oral Formulation 5: Dissolve in 0.25% Tween 80 and 0.5% Carboxymethyl cellulose
Oral Formulation 6: Mixing with food powders

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Note: Please be aware that the above formulations are for reference only. InvivoChem strongly recommends customers to read literature methods/protocols carefully before determining which formulation you should use for in vivo studies, as different compounds have different solubility properties and have to be formulated differently.

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 (Please use freshly prepared in vivo formulations for optimal results.)