Mukd-546 !!better!! May 2026

A. Patel (email: a.patel@cam.ac.uk) Abstract Background: The MAPK/ERK signaling cascade is frequently hyper‑activated in a wide spectrum of solid tumours, driving uncontrolled proliferation and resistance to conventional chemotherapy. Mukd‑546, a newly synthesized heterocyclic small‑molecule, was designed to selectively inhibit MEK1/2, the central kinases of this pathway.

¹ Department of Pharmacology, University of Cambridge, UK ² Institute of Molecular Medicine, Shanghai Jiao Tong University, China ³ Center for Cancer Research, Universidad Nacional Autónoma de México, Mexico ⁴ Department of Chemistry, University of California, San Diego, USA ⁵ Division of Oncology, Seoul National University Hospital, South Korea mukd-546

Mukd‑546; MEK inhibitor; MAPK/ERK pathway; pre‑clinical oncology; targeted therapy; KRAS; BRAF 1. Introduction The MAPK/ERK cascade (RAS‑RAF‑MEK‑ERK) orchestrates critical cellular processes such as proliferation, differentiation, and survival. Aberrant activation—most commonly via KRAS, NRAS, or BRAF mutations—underpins the pathogenesis of >30 % of human cancers, including pancreatic ductal adenocarcinoma (PDAC), colorectal carcinoma, and melanoma. While several MEK inhibitors (e.g., trametinib, binimetinib) have entered clinical practice, therapeutic efficacy is limited by dose‑dependent toxicities and rapid emergence of resistance (e.g., MAPK re‑activation, feedback loops). Consequently, there remains a pressing need for next‑generation MEK inhibitors with improved potency, selectivity, and pharmacologic properties. ¹ Department of Pharmacology, University of Cambridge, UK

A. Patel¹, J. Liu², M. García³, S. K. Singh¹, L. R. Thompson⁴, H. Kim⁵ While several MEK inhibitors (e

Mukd‑546 (chemical name: ) is a novel heterocyclic scaffold derived from a structure‑based design campaign targeting the allosteric pocket of MEK1. Preliminary SAR (structure‑activity relationship) studies indicated that the sulfonyl‑pyrimidine core confers high affinity while the 4‑fluorophenyl substituent enhances metabolic stability.

Mukd‑546: Pre‑clinical Evaluation of a Novel Small‑Molecule Inhibitor of the MAPK/ERK Pathway for Targeted Cancer Therapy

Docking studies revealed a nanomolar‑range binding energy (ΔG = –11.2 kcal·mol⁻¹) within the ATP‑binding pocket of MEK1. In vitro kinase assays confirmed a mean IC₅₀ of 8 nM against MEK1/2, with >200‑fold selectivity over a panel of 30 off‑target kinases. Mukd‑546 reduced viability of KRAS‑mutant PDAC (MIA‑PaCa‑2, IC₅₀ = 45 nM) and BRAF‑mutant melanoma (A375, IC₅₀ = 28 nM) cells, induced G₁ arrest, and triggered caspase‑3/7‑mediated apoptosis. In rats, oral administration (10 mg·kg⁻¹) yielded a bioavailability of 62 % and a half‑life of 6.3 h. In xenograft models, daily oral dosing (30 mg·kg⁻¹) for 21 days produced tumor growth inhibition (TGI) of 84 % in PDAC and 78 % in melanoma, with no significant weight loss or histopathological toxicity.