Ph. D. Project
Title:
Evaluation of the phototheranostic effects of indocyanine green nanoformulations on preclinical models of head and neck
tumors
Dates:
2025/10/01 - 2028/09/30
Supervisor(s):
Description:
PROJECT BACKGROUND, POSITIONING AND OBJECTIVES
Head and neck cancers, the 7th most common type of cancer, are highly heterogeneous in terms of clinical and histopathological expression, making them a major public health issue. Even today, most cases are identified at an advanced stage, which implies high recurrence and mortality rates. The development of new molecules for diagnosis and treatment at the earliest possible stage is essential.
In this context, the use of techniques employing irradiation seems to open up new prospects for the imaging and therapeutic modalities of these lesions. Contrast-enhanced photothermal therapy (CE-PTT) (i.e. using photothermal agents) is a rapidly developing field. PTT is also closely linked to photoacoustic imaging (PAI), an emerging non-invasive imaging modality that combines the advantages of deep ultrasound penetration and high optical contrast.
Indocyanine green (ICG) can be used as a photothermal agent. It has the immense advantage of already being used clinically and approved by the FDA as a fluorescent contrast agent. Unfortunately, its very short half-life, limited photothermal conversion rate and tendency to photobleaching severely limit its applicability in this therapeutic modality. Various studies have focused on the encapsulation of ICG in nano-vectors, in order to improve its performance (hal-02328843).
In this context, we have developed with photochemist colleagues (A. Pasc and Y. Bernhard; L2CM UMR 7053) an innovative nanoscale photothermal agent based on ICG J-aggregates for use in PTT and PAI (hal-04184000). These nanoparticles feature high photothermal conversion efficiency and significantly improved photostability compared with ICG. In vitro cellular uptake and cytotoxicity studies have also demonstrated that nanoparticles improve uptake and photothermal efficiency compared with non-vectorized ICG.
Although very promising, these results were obtained on a 2D cell model. We now need to test this compound on more advanced cell models, to come closer to the conditions observed in the clinic.
The use of 3D cell models is now an essential part of pre-clinical experimentation. The heterogeneity of the tumor microenvironment is one of the main sources of therapeutic failure in oncology. To reproduce this cellular organization, we have developed various spheroid models in co-culture, mixing head and neck cancer tumor cells with fibroblasts (hal-03955684; hal-02418797) or macrophages (hal-04291290).
The objectives of this project will be articulated around 3 main axes:
- Axis 1: Optimization of a head and neck cancer spheroid model formed from a co-culture of cancer cells and
healthy fibroblasts.
- Axis 2: Characterization of the phototheranostic effects of ICG-J/CX nanoparticles in vitro.
- Axis 3: Extension of the concept to PAI-guided in vivo PTT.
METHODOLOGY
Axis 1: Complex in vitro models of head and neck tumors
Building on our team's previous work (hal-03955684; hal-02418797; hal-04291290), we will optimize and characterize a spheroid model formed by co-culture of pharyngeal squamous cell carcinoma (FaDu) tumor cells with healthy human oral fibroblasts. The aim here is to work with healthy fibroblasts and evaluate their transformation into CAF when associated with cancer cells, in order to assess the consequences in terms of PTT and PAI.
Axis 2: Phototheranostic properties of ICG-J/CX nanoparticles
The aim of this 2nd axis is to optimize the conditions of use of ICG-J/CX nanoparticles in vitro. The results obtained with ICG-J/CX and ICG-J nanoparticles in 2D models will need to be confirmed in 3D models: to do this, we will verify the absence of dark toxicity of the compounds. We will then evaluate their incorporation and distribution in co-cultured spheroids over time.
We will then explore their efficacy as PTT agents and the possibility of visualizing them in PAI. After selecting the optimal treatment parameters, we will evaluate the phototoxicity of the treatment. The photoacoustic signature of spheroids loaded with our nanoparticles will be exploited using a bimodal fluorescence/photoacoustic imager recently acquired by our photochemistry colleagues (Tritom, Photosound®, USA).
Axisa 3: In vivo photothermal therapy guided by photoacoustic imaging.
The aim of Axis 3 is to extend the concept by refining the ICG/CX formulation and evaluating it in vivo on animal models of mice xenografted with FaDu cells. In vivo biodistribution, pharmacokinetics, photothermal agent integrity and PTT efficacy will be assessed using bimodal fluorescence and photoacoustic imaging.
Overall, an image-guidance strategy will be established in the following sequence: 1) monitoring of particle distribution and integrity via PAI and whole-body fluorescence imaging, to determine the DLI (Drug-Light Interval) for optimal treatment; 2) PTT treatment via NIR irradiation; 3) evaluation of response to PTT treatment by monitoring tumor regrowth and estimating particle integrity via fluorescence and photoacoustic response.
IMPACT OF THE PROJECT:
This thesis project will enable us to understand the mechanisms involved in phototherapeutic approaches linked to the use of photothermal agents, and will further validate the oncological potential of photothermal therapy assisted by photoacoustic imaging. It fits in perfectly with the laboratory's 2024-2028 project to develop the use of light as a mode of diagnosis and therapy.
Head and neck cancers, the 7th most common type of cancer, are highly heterogeneous in terms of clinical and histopathological expression, making them a major public health issue. Even today, most cases are identified at an advanced stage, which implies high recurrence and mortality rates. The development of new molecules for diagnosis and treatment at the earliest possible stage is essential.
In this context, the use of techniques employing irradiation seems to open up new prospects for the imaging and therapeutic modalities of these lesions. Contrast-enhanced photothermal therapy (CE-PTT) (i.e. using photothermal agents) is a rapidly developing field. PTT is also closely linked to photoacoustic imaging (PAI), an emerging non-invasive imaging modality that combines the advantages of deep ultrasound penetration and high optical contrast.
Indocyanine green (ICG) can be used as a photothermal agent. It has the immense advantage of already being used clinically and approved by the FDA as a fluorescent contrast agent. Unfortunately, its very short half-life, limited photothermal conversion rate and tendency to photobleaching severely limit its applicability in this therapeutic modality. Various studies have focused on the encapsulation of ICG in nano-vectors, in order to improve its performance (hal-02328843).
In this context, we have developed with photochemist colleagues (A. Pasc and Y. Bernhard; L2CM UMR 7053) an innovative nanoscale photothermal agent based on ICG J-aggregates for use in PTT and PAI (hal-04184000). These nanoparticles feature high photothermal conversion efficiency and significantly improved photostability compared with ICG. In vitro cellular uptake and cytotoxicity studies have also demonstrated that nanoparticles improve uptake and photothermal efficiency compared with non-vectorized ICG.
Although very promising, these results were obtained on a 2D cell model. We now need to test this compound on more advanced cell models, to come closer to the conditions observed in the clinic.
The use of 3D cell models is now an essential part of pre-clinical experimentation. The heterogeneity of the tumor microenvironment is one of the main sources of therapeutic failure in oncology. To reproduce this cellular organization, we have developed various spheroid models in co-culture, mixing head and neck cancer tumor cells with fibroblasts (hal-03955684; hal-02418797) or macrophages (hal-04291290).
The objectives of this project will be articulated around 3 main axes:
- Axis 1: Optimization of a head and neck cancer spheroid model formed from a co-culture of cancer cells and
healthy fibroblasts.
- Axis 2: Characterization of the phototheranostic effects of ICG-J/CX nanoparticles in vitro.
- Axis 3: Extension of the concept to PAI-guided in vivo PTT.
METHODOLOGY
Axis 1: Complex in vitro models of head and neck tumors
Building on our team's previous work (hal-03955684; hal-02418797; hal-04291290), we will optimize and characterize a spheroid model formed by co-culture of pharyngeal squamous cell carcinoma (FaDu) tumor cells with healthy human oral fibroblasts. The aim here is to work with healthy fibroblasts and evaluate their transformation into CAF when associated with cancer cells, in order to assess the consequences in terms of PTT and PAI.
Axis 2: Phototheranostic properties of ICG-J/CX nanoparticles
The aim of this 2nd axis is to optimize the conditions of use of ICG-J/CX nanoparticles in vitro. The results obtained with ICG-J/CX and ICG-J nanoparticles in 2D models will need to be confirmed in 3D models: to do this, we will verify the absence of dark toxicity of the compounds. We will then evaluate their incorporation and distribution in co-cultured spheroids over time.
We will then explore their efficacy as PTT agents and the possibility of visualizing them in PAI. After selecting the optimal treatment parameters, we will evaluate the phototoxicity of the treatment. The photoacoustic signature of spheroids loaded with our nanoparticles will be exploited using a bimodal fluorescence/photoacoustic imager recently acquired by our photochemistry colleagues (Tritom, Photosound®, USA).
Axisa 3: In vivo photothermal therapy guided by photoacoustic imaging.
The aim of Axis 3 is to extend the concept by refining the ICG/CX formulation and evaluating it in vivo on animal models of mice xenografted with FaDu cells. In vivo biodistribution, pharmacokinetics, photothermal agent integrity and PTT efficacy will be assessed using bimodal fluorescence and photoacoustic imaging.
Overall, an image-guidance strategy will be established in the following sequence: 1) monitoring of particle distribution and integrity via PAI and whole-body fluorescence imaging, to determine the DLI (Drug-Light Interval) for optimal treatment; 2) PTT treatment via NIR irradiation; 3) evaluation of response to PTT treatment by monitoring tumor regrowth and estimating particle integrity via fluorescence and photoacoustic response.
IMPACT OF THE PROJECT:
This thesis project will enable us to understand the mechanisms involved in phototherapeutic approaches linked to the use of photothermal agents, and will further validate the oncological potential of photothermal therapy assisted by photoacoustic imaging. It fits in perfectly with the laboratory's 2024-2028 project to develop the use of light as a mode of diagnosis and therapy.
Keywords:
Spheroids in coculture; Photothermal therapy; Photoacoustic imaging; Nanoparticles
Department(s):
| Biology, Signals and Systems in Cancer and Neuroscience |
Funds:
Doctoral contract from the University of Lorraine