Selumetinib

Absorption

Based on several studies investigating selumetinib at various doses in both pediatric and adult populations, the Tmax generally ranges between 1- 1.5 hours. In healthy adults, the mean absolute oral bioavailability was reported to be 62%. Selumetinib should be administered on an empty stomach since food significantly decreases serum concentrations of the drug.

Toxicity

Toxicity information regarding selumetinib is not readily available. Patients experiencing an overdose are at an increased risk of adverse effects such as cardiomyopathy, ocular toxicity, and diarrhea. It is generally thought that since selumetinib is extensively protein-bound, dialysis is unlikely to be helpful in situations of overdose.

Description

Selumetinib (AZD6244; ARRY-142886) is an oral MEK inhibitor. In a randomized trial, NSCLC patients with wild-type KRAS were randomized to erlotinib alone or combination therapy with selumetinib, while mutant KRAS patients were randomized to selumetinib alone or combination therapy. The primary end points were PFS for the KRAS wild-type cohort and objective response rate (ORR) for the KRAS mutant cohort. Results were not impressive, with no PFS difference in the KRAS wild-type arm (2.4 vs. 2.1?months) and no ORR difference in the KRASmutated subgroup (0% vs. 10%). A planned trial of selumetinib in combination with the anti-PD-L1 antibody durvalumab has since been suspended (NCT03004105).

The Uses of Selumetinib

It is a tight-binding, uncompetitive inhibitor of mitogen-activated protein kinase kinases (MEK) 1 and 2 currently in clinical development.

The Uses of Selumetinib

It is a tight-binding, uncompetitive inhibitor of mitogen-activated protein kinase kinases (MEK) 1 and 2 currently in clinical development. It is useful as biomarker in human lung cancer cell. Potent MEK inhibitor.

What are the applications of Application

Selumetinib is a MEK-1 non-ATP competitive inhibitor

Indications

Although selumetinib has been investigated for the treatment of several types of cancer, it is currently only indicated for the treatment of neurofibromatosis type 1 (NF1) in patients ≥2 years who have symptomatic, inoperable plexiform neurofibromas (PN).

Background

Activation of the Raf-MEK-ERK signaling pathway is known to be implemented in several types of malignancies, thus, mitogen-activated protein kinase kinase (MEK) inhibitors such as selumetinib are important tools that can target the problematic overactivity of this pathway. Results from clinical trials investigating earlier developed MEK inhibitors were underwhelming. However, selumetinib demonstrated impressive efficacy and tolerability in Phase I trials, leading to its continued investigation for the treatment of various types of tumors in Phase II trials.
Currently, the novel MEK 1 / 2 inhibitor, selumetinib, is approved solely for the treatment of Neurofibromatosis type 1 (NF-1) in a limited age group. NF-1 is considered rare with an estimated incidence of 1/3000 individuals. It is a genetic, autosomal dominant condition resulting from mutations of the NF1 gene, which can lead to various complications including the development of multiple tumors in the nervous system. Some patients with this disorder develop plexiform neurofibromas (PN); however, this is considered to be relatively uncommon compared to other variants of NF-1. Luckily, the use of selumetinib in patients with NF-1 has shown efficacy in shrinking associated tumors and is linked to other positive clinical outcomes.

Definition

ChEBI: A member of the class of benzimidazoles that is 1-methyl-1H-benzimidazole which is substituted at positions 4, 5, and 6 by fluorine, (4-bromo-2-chlorophenyl)amino, and N-(2-hydroxyethoxy)aminocarbonyl groups, respectiv ly. It is a MEK1 and MEK2 inhibitor.

brand name

Koselugo

General Description

Class: dual threonine/tyrosine kinase; Treatment: children with NF1; Other name: AZD-6244, ARRY-142886; Oral bioavailability = 62%; Elimination half-life = 6.2 h; Protein binding = 97.7%

Pharmacokinetics

Selumetinib is a non-ATP-competitive mitogen-activated protein kinase kinase 1 and 2 (MEK1 and MEK2) inhibitor. By selectively targeting MEK1 and MEK2, selumetinib is able to inhibit oncogenic downstream effects of the Raf-MEK-ERK signaling pathway, which is often overactive in certain types of cancer. Indeed, a study investigating the effects of selumetinib in children with NF-1 found that treatment with the anti-neoplastic resulted in reduced tumor size. Decreases in tumor-associated pain and improvements in overall function were also subjectively reported.
Selumetinib has minimal off-target activity, contributing to its impressive safety profile.

Metabolism

Selumetinib is heavily metabolized in the liver and the proposed metabolic pathway is as follows :
Hydrolysis of selumetinib’s amide functional group produces M15 (AZ13326637), which contains a carboxylic acid.
Elimination of the ethanediol moiety from the parent compound results in the formation of the primary amide M14 (AZ12791138) metabolite. Amide hydrolysis transforms M14 into M15, glucuronidation and further oxidation of M14 leads to M2, M6 and M1, and N-demethylation of M14 produces M12.
The amide glucuronide (M2) is thought to be the major circulating metabolite.
Demethylation of selumetinib produces the pharmacologically active M8 (AZ12442942), and further oxidation of M8 leads to M11. Glucuronidation of M8 produces M3 or M5, and elimination of the ethanediol moiety from M8 results in a primary amide, producing M12.
Although the N-demethylated metabolite (M8) accounts for <10% of the circulating metabolites, it is responsible for approximately 21-35% of any observed pharmacological activity.
Ribose conjugation transforms M12 into M9, while oxidation of M12 leads to M10 and M13 metabolites. Glucuronidation of M10 produces M1.
Direct glucuronidation of selumetinib produces M4 or M7, which can both eventually transform into M3 and M5 metabolites.

Metabolism

Following oral administration of radiolabeled selumetinib, the most prominent drug-related component in the plasma was selumetinib, accounting for 40% of the plasma radioactivity. The major circulating metabolite was an amide glucuronide 2, which accounted for 22% of the plasma radioactivity. This metabolite resulted from loss of the ethanediol moiety to give the primary amide 1, which underwent glucuronidation and an additional loss of 2 mass units, most likely due to further oxidation of the N-methylbenzimidazole moiety (Fig. 5).

storage

Store at -20°C

Dosage

Selumetinib is characterized by a moderate oral bioavailability (62%) and a relatively short half-life (6.2 h), and these properties contribute to twice-daily dosing regimen (25 mg dosage).

References

1) Davies?et al. (2007),?AZD6244(ARRY-142886), a potent inhibitor of mitogen-activated protein kinase/extracellular signal-regulated kinase kinase 1/2 kinases: mechanism of action in vivo, pharmacokinetic/pharmacodynamics relationship, and potential for combination in preclinical models; Mol. Cancer Ther.,?6?2209 2) Yeh?et al. (2007),?Biological characterization of ARRY-142886 (AZD6244), a potent, highly selective mitogen-activated protein kinase kinase 1/2 inhibitor; Clin. Cancer Res.,?13?1576 3) Catalanotti?et al. (2013),?Phase II trial of MEK inhibitor selumetinib(AZD6244) in patients with BRAFV600E/K-mutated melanoma; Clin. Cancer Res.,?19?2257 4) O’Neil?et al. (2011),?Phase II study of the mitogen-activated protein kinase 1/2 inhibitor selumetinib in patients with advanced hepatocellular carcinoma; J. Clin. Oncol.,?29?2350 5) Khurum?et al. (2012),?A phase I dose escalation study of oral MK-2206 (allosteric Akt inhibitor) with oral selumetinib (AZD6244)(MEK 1/2 inhibitor) in patients with advanced or metastatic solid tumors; J. Clin. Oncol.,?30?e13599 6) Hainsworth?et al. (2010),?A phase II, open label, randomized study to assess the efficacy and safety of AZD6244 versus pemetrexed in patients with non-small cell lung cancer who have failed one or two prior chemotherapeutic regimens; J. Thorac. Oncol.,?5?1630 7) Bodoky?et al. (2012),?A phase II open-label randomized study to assess the efficacy and safety of selumetinib (AZD6244) versus capecitabine in patients with advanced or metastatic pancreatic cancer who have failed first-line gemcitabine therapy; Invest. New Drugs,?30?1216