MMAF Auristatin C-Terminal Modification for ADC Delivery
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Solution Overview
Problem
Current monoclonal antibody-drug conjugates (mAbs) face challenges with the cytotoxic agent MMAF's impaired intracellular access due to a charged C-terminal phenylalanine residue, leading to reduced potency and systemic toxicity, necessitating a structural modification to enhance delivery and efficacy.
Innovation Solution
Replacing the C-terminal phenylalanine residue of MMAF with carboxylic acid equivalents like phosphonophenylalanine to create more potent auristatin derivatives that can be effectively conjugated to internalizing antibodies via protease cleavable linkers, facilitating intracellular delivery and increasing drug concentration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the C-terminal phenylalanine residue of MMAF is kept intact, then the drug maintains its basic structure, but intracellular access is impaired and potency is reduced
Solution Approach 1:
The patent applies parameter changes by modifying the chemical structure of the C-terminal phenylalanine residue through various transformations including oxidation to carboxylic acid, conversion to amide, and replacement with bioisosteric groups. These structural parameter changes enable improved intracellular access while maintaining or enhancing cytotoxic potency, directly resolving the contradiction between reliable intracellular delivery and drug effectiveness
2Reliability
If MMAF is conjugated to monoclonal antibodies, then targeted delivery to tumor cells is achieved, but systemic toxicity increases due to premature linker cleavage
Solution Approach 1:
The patent applies local quality by designing linkers with specific protease sensitivity profiles that match the enzymatic environment of target cells. Different linker sequences are engineered to be cleaved preferentially by intracellular proteases rather than serum proteases, creating localized activation at the tumor site while minimizing premature cleavage in circulation, thus reducing systemic toxicity while maintaining targeted delivery
3Stability of the object's composition
If the charged phenylalanine residue is used, then the drug structure is stable, but intracellular uptake is reduced
Solution Approach 1:
The patent systematically changes the charge parameter of the C-terminal residue through chemical modification. The charged phenylalanine is converted to neutral or differently charged forms including carboxylic acid (negative charge), amide (neutral), and various bioisosteric replacements. These parameter changes in charge state and chemical functionality improve intracellular uptake mechanisms while maintaining structural stability of the auristatin core
Data Source
AI summary
Auristatin peptide analogs of MeVal-Val-Dil-Dap-Phe (MMAF) having a carboxylic acid equivalent at the C-terminal phenylalanine were prepared and attached to ligands through various linkers, including maleimidocaproyl-val-cit-PAB. The resulting ligand-drug conjugates were active in vitro and in vivo in inhibiting cell proliferation and are represented by the general structure ofLv-[(LU)0-1-(D)1-4]p wherein L- is Ligand unit; LU is a Linker unit (LU); v is 1; p is an number ranging from about 1 to about 20; and D is a drug moiety having the formula:wherein the moiety —N(R9)Z1 is a phenylalanine bioisostere, wherein Z1 is —CH(R10)Z2 so that the phenylalanine bioisostere has the structure of Formula A:and wherein the substituents R2-R10, X1 and Z2 are as defined.