Albumin-Binding PSMA Ligands for Tumor Uptake
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Solution Overview
Problem
Current radiolabeled prostate-specific membrane antigen (PSMA)-targeting agents for prostate cancer treatment, such as 177Lu-PSMA-617, have limited efficacy due to low complete response rates and high costs, primarily due to the limited availability of 225Ac and the indirect damage caused by 177Lu emissions, which are less effective than the high linear energy transfer of α-particles from 225Ac.
Innovation Solution
Development of novel compounds, including 177Lu-labeled HTK01169, which incorporate an albumin-binding domain and a Lys-ureido-Glu PSMA-binding moiety, modulating albumin and PSMA binding to enhance tumor uptake and retention, thereby increasing the radiation dose deposited in tumors and potentially reducing costs by using more readily available 177Lu.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If 177Lu-labeled PSMA-targeting agents are used for endoradiotherapy, then treatment can be provided with commercially available radioisotopes, but the radiation dose deposited in tumors per unit administered radioactivity is insufficient
Solution Approach 1:
The patent modifies the chemical structure of PSMA-targeting ligands by incorporating albumin-binding domains (such as human serum albumin or fatty acid moieties) to alter the pharmacokinetic parameters of the radiopharmaceutical. This structural modification extends blood circulation half-life and enhances tumor uptake, thereby increasing the radiation dose deposited in tumors per unit administered radioactivity while maintaining use of commercially available 177Lu isotopes
2Reliability
If 225Ac-PSMA-617 is used instead of 177Lu-PSMA-617, then therapeutic efficacy is improved due to high linear energy transfer of α-particles, but the supply of 225Ac is globally limited
Solution Approach 1:
The patent employs 177Lu, a commercially abundant and cost-effective radioisotope with sufficient half-life for therapeutic application, as a substitute for the scarce and expensive 225Ac. By optimizing the delivery mechanism through albumin-binding modifications, the patent achieves improved tumor uptake with 177Lu, making it a practical alternative that balances efficacy with availability and cost considerations
3Ease of operation
If conventional PSMA-targeting agents are used, then treatment can be administered, but complete response rates are low and costs are high
Solution Approach 1:
The patent creates composite radiopharmaceutical structures by combining PSMA-targeting ligands (such as Lys-urea-Glu sequences) with albumin-binding domains. This composite structure enables dual functionality: specific targeting of PSMA-expressing prostate cancer cells and extended circulation through albumin binding, resulting in enhanced tumor accumulation and improved complete response rates while maintaining ease of administration
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The novel compounds demonstrate improved tumor uptake and sustained retention, delivering higher radiation doses to tumors, potentially achieving similar therapeutic efficacy with lower administered activity compared to existing agents, and are more cost-effective due to the widespread availability of 177Lu.
Implementation Method 1
R4 is a radiometal chelator optionally bound by radiometal X
Data Source
AI summary
This application relates to compounds of Formula (I-a) or Formula (I-b), or is salts or solvates thereof. R1 is —(CH2)5CH3 or comprises 2-4 fused benzene rings. R2 is I, Br, F, Cl, H, OH, OCH3, NH2, NO2 or CH3. R3 is a peptide-bonded glycine, aspartate or glutamate or is glutamate peptide bonded through Cdelta. L is —CH2NH—, —(CH2)2NH—, —(CH2)3NH—, or —(CH2)4NH—. R4 is a radiometal chelator optionally bound by a radiometal. Variable ‘n’ is 1-3. The compounds may be useful for imaging prostate specific membrane antigen (PSMA)-expressing tissues or for treating PSMA-expressing diseases (e.g. cancer).