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Research Area
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Description
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Solid tumours |
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Biological Activity
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Description
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MK-1775 is a potent and selective Wee1 inhibitor with IC50 of 5.2 nM. |
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Targets
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Wee1 |
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IC50 |
5.2 nM [1] |
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In Vitro
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MK-1775 inhibits Wee1 kinase in an ATP-competitive manner. Compared to Wee1, MK-1775 displays 2- to 3-fold less potency against Yes with IC50 of 14 nM, 10-fold less potency against seven other kinases with >80% inhibition at 1 μM, and >100-fold selectivity over human Myt 1, another kinase that inhibits cyclin-dependent kinase 1 (CDC2) by phosphorylation at an alternative site (Thr14). By abrogating the DNA damage checkpoint via blockade of Wee1 activity in WiDr cells bearing mutated p53, MK-1775 treatment inhibits the basal phosphorylation of CDC2 at Tyr15 (CDC2Y15) with EC50 of 49 nM, and suppresses gemcitabine-, carboplatin- or cisplatin-induced phosphorylation of CDC2 and cell cycle arrest in a dose-dependent manner, with EC50 of 82 nM and 81 nM, 180 nM and 163 nM, as well as 159 nM and 160 nM, respectively. MK-1775 treatment alone at 30-100 nM has no significant antiproliferative effect in WiDr and H1299 cells, whereas MK-1775 at 300 nM, sufficient to inhibit Wee1 by >80%, displays moderate but significant antiproliferative effects by 34.1% in WiDr cells and 28.4% in H1299 cells. [1] |
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In Vivo
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MK-1775 treatment alone at ~20 mg/kg displays minimal antitumor effects against WiDr xenografts in rats with T/C of 69% at day 3. Antitumor efficacy by MK-1775 alone in the nude rat HeLa-luc and TOV21G-shp53 xenograft models models is also moderate. [1] |
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Clinical Trials
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A Phase I dose escalation study evaluating MK-1775 in both monotherapy and in combination with Gemcitabine, Cisplatin, or Carboplatin in adult subjects with advanced solid tumors is currently ongoing. |
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Features
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First reported Wee1 inhibitor |
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Combination Therapy
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Description
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In WiDr cells, MK-1775 treatment at 30 nM or 100 nM in combination with gemcitabine remarkably enhances the antigrowth effect of gemcitabine, reducing the IC50 of gemcitabine (>100 nM) to 21.5 nM and 7.1 nM, respectively. MK-1775 (300 nM) or gemcitabine (100 nM) treatment alone induces only a minimal sub-G1 population by 2.9% and 5.2%, respectively, whereas the combination treatment drastically induces sub-G1 population in a MK-1775 dose-dependent manner by 55% at 100 nM and 59% at 300 nM. MK-1775 cotreatment dramatically sensitizes TOV21G-shp53 cells but not the TOV21G-vec cells to gemcitabine, carboplatin, or cisplatin, suggesting that MK-1775 abrogates G2 DNA damage checkpoint by Wee1 inhibition, sensitizing cells to apoptosis selectively in p53-deficient cells. Gemcitabine alone only moderately inhibits tumor growth of WiDr xenografts in rats with T/C of 35%, whereas cotreatment with MK-1775 significantly enhances the antitumor effects in a dose-dependent manner with T/C of 1% and -25% at doses of 10 mg/kg and 20 mg/kg, respectively, and reduces the dose of chemotherapy required to achieve a similar or better antitumor efficacy. MK-1775 also significantly enhances the antitumor effects of carboplatin and cisplatin in the nude rat HeLa-luc and TOV21G-shp53 xenograft models models. The cotreatment does not significantly increase toxicity, which is correlated with inhibition of CDC2Y15 phosphorylation in tumor tissue and skin hair follicles. [1] MK-1775 in combination with Chk1 inhibitor AR458323 synergistically inhibits proliferation in multiple cancer cell types, resulting in dramatic decreases in inhibitory phosphorylation of cyclin-dependent kinases, an increase in DNA damage, alterations in cell-cycle profile, and collapse of DNA synthesis, which is correlated with a synergistic induction of apoptosis. [2] A Phase II study of MK-1775 in combination with Paclitaxel and Carboplatin versus Paclitaxel and Carboplatin alone in adult patients with platinum sensitive p53 mutant ovarian cancer is currently ongoing. |
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Protocol
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Kinase Assay
[1]
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| In vitro kinase assays |
Recombinant human Wee1 is used. Kinase reaction is conducted with 10 μM ATP, 1.0 μCi of [γ-33P]ATP, and 2.5 μg of poly(Lys, Tyr) as a substrate in the presence of increasing concentrations of MK-1775 at 30°C for 30 minutes. Radioactivity incorporated into the substrate is trapped on MultiScreen-PH plates and is counted on a liquid scintillation counter. |
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Cell Assay
[1]
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| Cell Lines |
WiDr, NCI-H1299, TOV21G, and HeLa |
| Concentrations |
Dissolved in DMSO, final concentrations ~10 μM |
| Incubation Time |
24 hours |
| Methods |
Cells are treated with or without gemcitabine for 24 hours, then with MK-1775 for an additional 24 hours. Cell viability is determined with a WST-8 kit using SpectraMax. Cellular caspase-3/7 activities are determined with a Caspase-3/7 Glo kit. |
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Animal Study
[1]
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| Animal Models |
Immunodeficient nude rats (F344/NJcl-rnu) bearing WiDr, HeLa-luc, or TOV21G-shp53 tumors |
| Formulation |
Prepared in a vehicle of 0.5% methylcellulose solution |
| Doses |
~20 mg/kg/day |
| Administration |
Orally |
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