Dimeric Smac Mimetics Inhibit IAP Binding to Sensitize Cancer Cells
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Solution Overview
Problem
Current therapies for cancer, particularly solid tumors, face challenges in effectively targeting cancer cells due to their resistance to apoptosis, which is often mediated by Inhibitor of Apoptosis Proteins (IAPs) that inhibit caspase activation, making it difficult to induce programmed cell death.
Innovation Solution
Development of dimeric compounds that inhibit SMAC protein binding to IAPs or activated caspase protein binding to IAPs, combined with bispecific antibodies targeting Death Receptor 5 (DR5) and Fibroblast Activation Protein (FAP), to activate the caspase cascade and induce apoptosis in cancer cells.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If IAP proteins are present in cancer cells, then caspase activity is inhibited and apoptosis is blocked, but this leads to resistance against standard cancer treatments
Solution Approach 1:
The patent uses Smac mimetics as intermediary molecules that bind to IAP proteins, displacing caspases from IAP binding sites. The Smac mimetic acts as a mediator that competes with caspases for IAP binding, thereby releasing caspase inhibition and enabling apoptosis without directly activating caspases themselves.
Solution Approach 2:
The patent modifies the natural Smac protein by replacing its N-terminal BIR-binding domain with a small molecule pharmacophore that specifically targets BIR domains. This parameter change transforms a large protein into a drugable small molecule while maintaining the ability to bind and neutralize IAP proteins.
2Reliability
If small molecules are designed to bind BIR3 domain of IAPs, then caspase inhibition can be overcome, but the molecules may not effectively engage BIR2 domain or achieve optimal potency
Solution Approach 1:
The patent divides the IAP protein family into distinct functional domains (BIR2 and BIR3) and designs dimeric compounds where each monomer targets a specific BIR domain. This segmentation allows independent optimization of binding to different IAP family members, achieving broad-spectrum inhibition through modular design.
Solution Approach 2:
The patent combines two Smac mimetic monomers into a dimeric structure that can simultaneously engage multiple BIR domains on IAP proteins. The dimeric architecture merges the binding capabilities of individual monomers, creating a synergistic effect that overcomes IAP inhibition more effectively than monomeric compounds.
3Ease of manufacture
If monomeric Smac mimetics are used, then the molecules are simpler to design, but they may have limited ability to simultaneously target multiple IAP family members
Solution Approach 1:
The patent transitions from monomeric to dimeric compounds, adding a dimensional aspect to the molecular architecture. This dimeric structure provides an additional binding interface that can simultaneously engage multiple IAP family members, expanding the scope of target coverage while maintaining synthetic feasibility through modular assembly.
Data Source
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AI summary
The present invention provides a compound of formula I which act as inhibitors of SMAC protein binding to Inhibitor of Apoptosis Proteins (IAPs), and/or inhibitors of activated caspase protein binding to IAPs (I) their manufacture, pharmaceutical compositions containing them and their use as therapeutically active substances, alone or in combination with DR5/FAP agonist antibodies. The active compound of the present invention is useful in the amelioration, treatment or control of cancer, especially solid tumors.