PDGFR; WT KIT (IC50 = 4 nM); D816H KIT (IC50 = 5 nM); V654A KIT (IC50 = 8 nM); D816V KIT (IC50 = 14 nM)

In the GIST T1 xenograft model, DCC-2618 administration at 50 mg/kg results in an ED90 for KIT phosphorylation inhibition, which corresponds to an EC90 concentration of roughly 470 ng/mL. This oral dose causes nearly total tumor stasis when taken twice a day. In a KIT exon 17 N822K AML xenograft model and a patient-derived xenograft (PDX) GIST expressing KIT exon 11 delW557K558/exon 17 Y823D, this dosage of DCC-2618 results in tumor regressions[1]. DCC-2618 inhibits PDGFRA- and KIT-driven tumor growth in xenograft studies, including KIT exon 17 mutants present in AML (N822K), GIST (Y823D), and mastocytosis (D816V) models[3].

In order to assess KIT and BTK signaling, ROSAKIT WT, ROSAKIT D816V, HMC-1.1, and HMC-1.2 cells were incubated for 4 hours at 37°C in either control medium or DCC-2618 (0.5–5 μM). Western blotting was done essentially according to other instructions. In order to assess the downstream signaling pathways of KIT, HMC-1.1, HMC-1.2, ROSAKIT WT, and ROSAKIT D816V cells were initially pre-cultured for an entire night in Iscove-modified Dulbecco medium that was devoid of stem cell factor and fetal calf serum. Then, for 90 minutes at 37°C, DCC-2618 (0.001–10 μM) was applied to 106 cells from each line. Following the course of treatment, ROSAKIT WT cells were stimulated for 10 minutes at room temperature using 10% of the supernatants of Chinese hamster ovary cells transfected with the murine scf (kl) gene (CHO-KL). Western blotting was then carried out essentially in the same manner as previously mentioned.

In order to assess KIT and BTK signaling, HMC-1.1, HMC-1.2, ROSA (KIT WT), and ROSA (KIT D816V) cells are incubated for 4 hours at 37°C in either control medium or DCC-2618 (0.5–5 μM). One method used is western blotting.

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Ripretinib (DCC-2618) was tested for inhibition of KIT isoforms using a standard PK/LDH coupled spectrophotometric assay. CHO cells were transiently transfected to express mutant KIT or PDGFRα constructs. Transfected cells were treated with a range of DCC-2618 and levels of phosphorylated KIT or PDGFRα in cell lysates were determined by ELISA or western blot. Cell proliferation of several cell lines was measured using the fluorescent dye resazurin. Experiments were performed in triplicate.[1]

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Western blotting[2]
For evaluation of KIT and BTK signaling, HMC-1.1, HMC-1.2, ROSAKIT WT and ROSAKIT D816V cells were incubated in control medium or in Ripretinib (DCC-2618) (0.5–5 μM) for 4 h at 37°C. Western blotting was performed essentially as described elsewhere. For evaluation of downstream signaling pathways of KIT, HMC-1.1, HMC-1.2, ROSAKIT WT and ROSAKIT D816V cells were first pre- incubated overnight in Iscove modified Dulbecco medium devoid of fetal calf serum and of stem cell factor. Cells (106) from each line were then treated with DCC-2618 (0.001–10 μM) for 90 min at 37°C. At the end of the treatment, ROSAKIT WT cells were stimulated with stem cell factor-containing supernatants (10%) of Chinese hamster ovary cells transfected with the murine scf (kl) gene (CHO-KL) at room temperature for 10 min. Thereafter, Western blotting was performed essentially as described previously.

xenograft models (mice)
100 mg/kg/day or 25 mg/kg/day or 50 mg/kg BID
oral

Absorption, Distribution and Excretion
Ripretinib is absorbed in the gastrointestinal tract and Tmax is achieved in 4 hours, with steady-state concentrations reached within 14 days.
Ripretinib is 34% excreted in the feces and 0.2% excreted in the urine.
The mean volume of distribution of ripretinib is 307 L.
The mean apparent clearance of ripretinib is 15.3 L/hour.

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Metabolism / Metabolites
Ripretinib is metabolized by the CYP3A subfamily of enzymes with contributions from CYP2D6 and CYP2E1 to its active metabolite, DP-5439.

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Biological Half-Life
The average half-life of ripretinib is 14.8 hours.

Hepatotoxicity
In the prelicensure placebo-controlled clinical trial in patients with refractory and extensively treated GIST, ALT elevations arose in 13% of ripretinib- vs 5% of placebo-treated subjects. ALT elevations were generally transient and mild, and were above 5 times the ULN in only 1% of treated patients and did not require dose modification or discontinuation. Bilirubin elevations were reported in 22% of ripretinib treated patients but only 7.5% of placebo controls. The bilirubin elevations were transient and mild, but were not characterized as to their timing, severity and whether conjugated or unconjugated (direct or indirect). In the open label and controlled trials supporting the approval of ripretinib, there were no instances of clinically apparent liver injury, hepatic failure, or deaths from liver injury. Since its approval in the United States and Europe, there have been no reported cases of clinically apparent liver injury associated with ripretinib therapy.
Likelihood score: E (unlikely cause of clinically apparent liver injury).

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Effects During Pregnancy and Lactation
◉ Summary of Use during Lactation
No information is available on the use of ripretinib during breastfeeding. Because ripretinib and its metabolite are more than 99% bound to plasma proteins, the amounts in milk are likely to be low. However, their half-lives are long. The manufacturer recommends that mothers should not breastfeed during treatment with ripretinib and for 1 week after the final dose.
◉ Effects in Breastfed Infants
Relevant published information was not found as of the revision date.
◉ Effects on Lactation and Breastmilk
Relevant published information was not found as of the revision date.

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Protein Binding
Ripretinib is over 99% bound to albumin and alpha-1 acid glycoprotein.

[1]. Cancer Res (2015) 75 (15_Supplement): 2690.

[2]. Haematologica . 2018 May;103(5):799-809.

[3]. AACR Annual Meeting. 2018: Abstract 3925; Poster Section 39, Board 5.

Ripretinib is a kinase inhibitor used for the treatment of advanced gastrointestinal stromal tumor (GIST) that has not adequately responded to other kinase inhibitors such as [sunitinib] and [imatinib]. Ripretinib, also known as Qinlock, is manufactured by Deciphera Pharmaceuticals and was initially approved by the FDA on May 15, 2020. It is the first drug approved as a fourth-line therapy in the specific setting of prior treatment with a minimum of 3 other kinase inhibitors.
Ripretinib is a Kinase Inhibitor. The mechanism of action of ripretinib is as a Stem Cell Factor (KIT) Receptor Inhibitor, and Platelet-derived Growth Factor alpha Receptor Inhibitor, and Cytochrome P450 2C8 Inhibitor, and P-Glycoprotein Inhibitor, and Breast Cancer Resistance Protein Inhibitor.
Ripretinib is a multikinase inhibitor that is used to treat refractory forms of advanced gastrointestinal stromal tumors. Serum aminotransferase elevations occur in a small proportion of patients treated with ripretinib, but episodes of clinically apparent liver injury with jaundice have not been reported with its use.
Ripretinib is an orally bioavailable switch pocket control inhibitor of wild-type and mutated forms of the tumor-associated antigens (TAA) mast/stem cell factor receptor (SCFR) KIT and platelet-derived growth factor receptor alpha (PDGFR-alpha; PDGFRa), with potential antineoplastic activity. Upon oral administration, ripretinib targets and binds to both wild-type and mutant forms of KIT and PDGFRa specifically at their switch pocket binding sites, thereby preventing the switch from inactive to active conformations of these kinases and inactivating their wild-type and mutant forms. This abrogates KIT/PDGFRa-mediated tumor cell signaling and prevents proliferation in KIT/PDGFRa-driven cancers. DCC-2618 also inhibits several other kinases, including vascular endothelial growth factor receptor type 2 (VEGFR2; KDR), angiopoietin-1 receptor (TIE2; TEK), PDGFR-beta and macrophage colony-stimulating factor 1 receptor (FMS; CSF1R), thereby further inhibiting tumor cell growth. KIT and PDGFRa are tyrosine kinase receptors that are upregulated or mutated in a variety of cancer cell types; mutated forms play a key role in the regulation of tumor cell proliferation and resistance to chemotherapy.

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Drug Indication
Ripretinib is indicated to treat adults diagnosed with advanced gastrointestinal stromal tumor (GIST) who have had prior therapy with at least 3 kinase inhibitors, including with [imatinib].
FDA Label
Qinlock is indicated for the treatment of adult patients with advanced gastrointestinal stromal tumour (GIST) who have received prior treatment with three or more kinase inhibitors, including imatinib.

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Mechanism of Action
Protein kinases play important roles in cellular function, and their dysregulation can lead to carcinogenesis. Ripretinib inhibits protein kinases including wild type and mutant platelet-derived growth factor receptor A (PDGFRA) and KIT that cause the majority of gastrointestinal stromal tumor (GIST). In vitro, ripretinib has been shown to inhibit PDGFRB, BRAF, VEGF, and TIE2 genes. Ripretinib binds to KIT and PDGFRA receptors with mutations on the exons 9, 11, 13, 14, 17 and 18 (for KIT mutations), and exons 12, 14 and 18 (for PDGFRA mutations). The “switch pocket” of a protein kinase is normally bound to the activation loop, acting as an “on-off switch” of a kinase. Ripretinib boasts a unique dual mechanism of action of binding to the kinase switch pocket as well as the activation loop, thereby turning off the kinase and its ability to cause dysregulated cell growth.

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Pharmacodynamics
As a broad-spectrum kinase inhibitor, ripretinib inhibits various gene mutations, increasing progression-free survival in patients with advanced gastrointestinal stromal tumors (GIST). It is effective in treating mutations that are resistant to chemotherapy with other kinase inhibitors, such as imatinib. Ripretinib has the propensity to cause cardiac dysfunction and new primary cutaneous malignancy. It is important to measure cardiac ejection fraction before and during treatment as well as to perform regular dermatological assessments.

C24H21BRFN5O2

510.37

509.09

C, 56.48; H, 4.15; Br, 15.66; F, 3.72; N, 13.72; O, 6.27

1442472-39-0

1442472-39-0; 1225278-16-9 (wrong structure for DCC-2618);

71584930

White to off-white solid powder

4.1

3

5

5

33

746

0

CEFJVGZHQAGLHS-UHFFFAOYSA-N

InChI=1S/C24H21BrFN5O2/c1-3-31-21-12-22(27-2)28-13-14(21)9-17(23(31)32)16-10-20(19(26)11-18(16)25)30-24(33)29-15-7-5-4-6-8-15/h4-13H,3H2,1-2H3,(H,27,28)(H2,29,30,33)

1-[4-bromo-5-[1-ethyl-7-(methylamino)-2-oxo-1,6-naphthyridin-3-yl]-2-fluorophenyl]-3-phenylurea

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)

Solubility in Formulation 1: 2.08 mg/mL (4.08 mM) in 10% DMSO + 40% PEG300 + 5% Tween80 + 45% Saline (add these co-solvents sequentially from left to right, and one by one), suspension solution; with sonication.
For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 20.8 mg/mL clear DMSO stock solution to 400 μL PEG300 and mix evenly; then add 50 μL Tween-80 to the above solution and mix evenly; then add 450 μL normal saline to adjust the volume to 1 mL.
Preparation of saline: Dissolve 0.9 g of sodium chloride in 100 mL ddH₂ O to obtain a clear solution.

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Solubility in Formulation 2: 2.08 mg/mL (4.08 mM) in 10% DMSO + 90% (20% SBE-β-CD in Saline) (add these co-solvents sequentially from left to right, and one by one), suspension solution; with ultrasonication.
For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 20.8 mg/mL clear DMSO stock solution to 900 μL of 20% SBE-β-CD physiological saline solution and mix evenly.
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.

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Solubility in Formulation 3: ≥ 2.08 mg/mL (4.08 mM) (saturation unknown) in 10% DMSO + 90% Corn Oil (add these co-solvents sequentially from left to right, and one by one), clear solution.
For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 20.8 mg/mL clear DMSO stock solution to 900 μL of corn oil and mix evenly.

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