Structure-Based Development of Novel Spiro-Piperidine ASH1L Inhibitors.

Area of Science:

• Biochemistry
• Molecular Biology
• Cancer Research

Background:

• The absent, small, or homeotic-like 1 (ASH1L) protein is a key histone lysine methyltransferase implicated in various cancers, notably leukemia.
• ASH1L is an attractive therapeutic target, yet only one class of inhibitors has been identified to date.

Purpose of the Study:

• To design and develop novel, potent, and selective ASH1L inhibitors targeting its catalytic SET domain.
• To identify advanced inhibitors with improved activity and cellular efficacy compared to existing compounds.

Main Methods:

• Structure-based drug design and extensive medicinal chemistry efforts were employed.
• Inhibitory activity was assessed using biochemical assays (IC50 = 94 nM for 66s/AS-254s).
• Cellular efficacy was evaluated in leukemia cells harboring MLL1 translocations, assessing proliferation, apoptosis, and differentiation.

Main Results:

• Identification of 66s (AS-254s), a highly potent and selective ASH1L inhibitor with significantly enhanced activity.
• AS-254s demonstrated effective blockade of leukemia cell proliferation.
• AS-254s successfully induced apoptosis and differentiation in leukemia cells with MLL1 translocations.

Conclusions:

• This study provides a high-quality chemical probe, AS-254s, targeting the ASH1L catalytic SET domain.
• The developed inhibitor exhibits increased potency and cellular efficacy, valuable for studying ASH1L functions.
• These findings pave the way for developing novel anticancer therapeutics targeting ASH1L.