Vectorized Iridium(III) Complexes for Selective Photodynamic Therapy

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Solution Overview

Problem

Current photodynamic therapy (PDT) agents for cancer treatment face challenges such as lack of selectivity, high toxicity, and complex implementation, particularly in treating prostate and bladder cancers, due to issues with photostability, absorption, and cytotoxicity.

Innovation Solution

Development of modulable cyclometalated iridium(III) complexes with N-heterocyclic carbene-pyridine ligands that can target cancer cells specifically, offering improved photophysical and biological properties, including high selectivity, photostability, and adjustable excitation wavelengths for enhanced therapeutic and diagnostic efficacy.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional photosensitizers are used for photodynamic therapy, then cancer treatment can be performed, but they exhibit low solubility, low absorption, and poor reactive oxygen species production

Engineering Contradiction:
Improvetherapeutic efficacyVSAvoidsolubility and absorption
Core Design Contradiction:
ReliabilityVSEase of manufacture

Solution Approach 1:

The patent employs cyclometalated iridium(III) complexes as composite photodynamic agents that combine the metal center with organic ligands (C^N ligands) to achieve both high therapeutic efficacy and improved solubility. The complex structure integrates multiple functional components into a single molecule, resolving the contradiction between efficacy and manufacturability.

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The patent modifies physical and chemical parameters of the photosensitizer by using iridium(III) coordination complexes with specific ligand configurations. This changes the solubility, absorption coefficient, and reactive oxygen species generation efficiency simultaneously, improving multiple properties at once rather than addressing them separately.

Inventive Principle:
Principle #35Parameter changes

2Object-affected harmful factors

If non-selective photosensitizers are used to treat cancer, then broad coverage is achieved, but cytotoxicity increases and selectivity for cancer cells decreases

Engineering Contradiction:
Improvecancer cell coverageVSAvoidcytotoxicity
Core Design Contradiction:
Object-affected harmful factorsVSObject-generated harmful factors

Solution Approach 1:

The patent introduces a targeting vector as an intermediary component that mediates between the photosensitizer and cancer cells. This vector enables selective accumulation of the iridium complex at the tumor site through specific molecular recognition, thereby achieving cancer cell coverage while minimizing cytotoxicity to healthy tissues.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent applies the principle of local quality by making the photosensitizer selectively active only at the tumor location. The targeting vector confers localized binding affinity to cancer cells, so the harmful phototoxic effect is concentrated locally at the tumor site while healthy tissues remain unaffected.

Inventive Principle:
Principle #3Local quality

3Ease of operation

If fixed excitation wavelength photosensitizers are used, then the treatment protocol is simple, but adaptability to different cancer types and depths is limited

Engineering Contradiction:
Improvetreatment protocol simplicityVSAvoidwavelength adjustability
Core Design Contradiction:
Ease of operationVSAdaptability or versatility

Solution Approach 1:

The patent makes the excitation wavelength dynamic and adjustable by designing iridium complexes with ligands that can be tuned to absorb at different wavelengths. This allows the treatment protocol to be adapted to different cancer types, depths, and locations while maintaining operational simplicity through a systematic approach to wavelength selection.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The patent creates a universal photodynamic therapy platform using iridium(III) complexes that can function across multiple wavelengths and target different cancer types. The modular ligand design allows a single class of compounds to serve multiple therapeutic purposes, achieving versatility without sacrificing protocol simplicity.

Inventive Principle:
Principle #6Universality (Multi-functionality)

4Reliability

If existing PDT agents like Hexvix and Tookad are used, then FDA/EMA approval is obtained, but market acceptance is low due to high costs and complex implementation

Engineering Contradiction:
Improveregulatory approvalVSAvoidimplementation complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent segments the photodynamic therapy approach into a modular system with distinct components: the iridium photosensitizer, the targeting vector, and the ligand system. This segmentation allows for optimized synthesis, purification, and characterization of each component, reducing overall implementation complexity while maintaining regulatory approval standards.

Inventive Principle:
Principle #1Segmentation

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 cyclometalated iridium(III) complexes demonstrate increased selectivity for cancer cells, reduced cytotoxicity, and improved photodynamic performance, enabling effective treatment and diagnosis of prostate and bladder cancers with minimal side effects and improved treatment precision.

Implementation Method 1

PDT is a modern and rapidly developing method for the treatment of a wide range of diseases. The method is based on selective accumulation of photodynamic compound (PDC) (or photosensitizer (PS)) in the tumor tissue, which is capable of generating cytotoxic agents that cause the death of tumor cells under local exposure to light.

Methodology Applied
Scientific EffectPhotodynamic therapy:

Implementation Method 2

Absorption of light excites the photosensitizer from the ground electronic state to an excited singlet state, which is converted to a long-lived triplet excited state by intersystem crossing (ISC).

Methodology Applied
Scientific EffectIntersystem crossing:

Implementation Method 3

the iridium(III) complexes of the invention comprises (i) a targeting vector directly or indirectly linked to the N-heterocyclic carbene-pyridine (NHC-pyridine) thanks to which the selectivity towards cancer cells and, in particular, prostate cancer cells and bladder cancer cells is increased

Methodology Applied
Scientific EffectMolecular targeting:

Data Source

PatentEP4385995A1Vectorized NHC iridium(III) complexes and use thereof in photodynamic therapy and/or diagnostic
Publication Date: 2024.06.19 CENT NAT DE LA RECH SCI (C N R S)
  • EP4385995A1 patent drawingFigure 1a~1b
  • EP4385995A1 patent drawingFigure 1c~1d
  • EP4385995A1 patent drawingFigure 2A~2B

AI summary

The present invention concerns vectorized iridium(III) complex with N-heterocyclic carbene-pyridine and a pharmaceutical composition comprising such a complex. The present invention also concerns their use for photodynamic therapy implemented to treat and/or prevent cancers and their use for photodynamic diagnosis.