Periodic Reporting for period 4 - REACT (REsponsive theranostic nanosystems for Advanced Cancer Treatment)
Berichtszeitraum: 2023-07-01 bis 2024-12-31
Cancer remains one of the leading causes of mortality worldwide, with tumors such as glioblastoma (GBM) presenting particularly aggressive and treatment-resistant profiles. While nanomedicine has emerged as a promising approach for improving drug solubility, tolerability, and circulation time, the clinical translation of nanoparticle-based systems has largely fallen short of expectations. Most approved nanotherapeutics operate through passive accumulation and offer only modest improvements over conventional chemotherapy, lacking mechanisms for site-specific action or responsiveness to tumor biology. This limitation is especially critical in treating brain tumors, where systemic toxicity and the blood-brain barrier (BBB) pose additional hurdles.
The REACT project was conceived to overcome these shortcomings by developing a multifunctional, stimuli-responsive therapeutic platform that integrates nanocarriers with injectable hydrogels for localized and sustained drug delivery, primarily focused on GBM, a highly lethal brain tumor. The aim was to create a delivery system capable of responding to specific biochemical signals in the tumor microenvironment -such as enzymatic activity, acidic pH, or elevated reducing agents- to trigger the release of chemotherapeutic and diagnostic agents only where and when they are needed.
The approach combined advanced nanoparticle engineering with polymer science to produce injectable hydrogels capable of forming in situ depots for drug release at the tumor site, either post-surgical or via minimally invasive administration routes. Importantly, the research extended beyond GBM, with certain technological developments adapted for other localized diseases, such as neuroblastoma and wet age-related macular degeneration (AMD).
By the end of the action, REACT have successfully designed, synthesized, and validated a novel nanocarrier-hydrogel system. The project demonstrated proof-of-concept for tumor-targeted, site-responsive drug release, with efficacy confirmed in both 3D tumor spheroid cultures and orthotopic GBM models in vivo. The platform showed significant promise in improving drug accumulation at the tumor site, reducing systemic toxicity, and enabling simultaneous imaging and therapy -offering a comprehensive strategy to advance precision oncology.
The REACT project was conceived to overcome these shortcomings by developing a multifunctional, stimuli-responsive therapeutic platform that integrates nanocarriers with injectable hydrogels for localized and sustained drug delivery, primarily focused on GBM, a highly lethal brain tumor. The aim was to create a delivery system capable of responding to specific biochemical signals in the tumor microenvironment -such as enzymatic activity, acidic pH, or elevated reducing agents- to trigger the release of chemotherapeutic and diagnostic agents only where and when they are needed.
The approach combined advanced nanoparticle engineering with polymer science to produce injectable hydrogels capable of forming in situ depots for drug release at the tumor site, either post-surgical or via minimally invasive administration routes. Importantly, the research extended beyond GBM, with certain technological developments adapted for other localized diseases, such as neuroblastoma and wet age-related macular degeneration (AMD).
By the end of the action, REACT have successfully designed, synthesized, and validated a novel nanocarrier-hydrogel system. The project demonstrated proof-of-concept for tumor-targeted, site-responsive drug release, with efficacy confirmed in both 3D tumor spheroid cultures and orthotopic GBM models in vivo. The platform showed significant promise in improving drug accumulation at the tumor site, reducing systemic toxicity, and enabling simultaneous imaging and therapy -offering a comprehensive strategy to advance precision oncology.
REACT produced a robust portfolio of scientific innovations with direct translational potential. At its core was the design of hybrid organic-inorganic nanoparticles capable of encapsulating a broad range of therapeutic and diagnostic agents, including standard chemotherapeutics (e.g. doxorubicin, temozolomide, paclitaxel) and a novel organoruthenium compound with selective cytotoxicity against GBM cells. The latter exhibited an eightfold increase in intracellular concentration when delivered via the nanocarrier system, compared to the free drug. In addition to small molecules, the porous nanostructure was adapted for the delivery of nucleic acids, most notably siRNA targeting VEGF in retinal cells, demonstrating the flexibility and modularity of the platform.
A pivotal innovation was the development of molecular gates -peptide, pH-, and redox-sensitive moieties- that allowed for stimulus-triggered drug release in response to tumor-specific conditions. These gates were engineered to degrade in the presence of matrix metalloproteinases, acidic environments, or elevated levels of glutathione, all commonly found in tumor tissue. This enabled highly selective release of payloads at the tumor site, minimizing off-target effects and improving therapeutic index. The integration of diagnostic imaging agents further allowed real-time tracking of drug release, moving the platform into the realm of theranostics.
To achieve localized administration, these nanoparticles were incorporated into injectable hydrogels based on hyaluronic acid and chitosan/beta-glycerophosphate. These hydrogels could form a solid depot upon injection, releasing their cargo over time as the matrix degraded. Chemical crosslinking strategies improved their flexibility and drug-loading capacity, and cytotoxicity assays in both 2D and 3D GBM models confirmed their efficacy.
The system was tested in preclinical animal models, including an orthotopic GBM model involving surgical resection followed by hydrogel implantation into the tumor cavity. This clinically relevant setup showed reduced tumor recurrence and improved therapeutic outcomes. Additionally, an intranasal administration route was explored as a non-invasive alternative for delivering the hydrogel-nanoparticle system directly to the central nervous system, bypassing the BBB.
REACT also played a key role in advancing in vitro tumor modeling by developing scaffold-free 3D GBM spheroids. These models more closely mimic the architecture and microenvironment of real tumors compared to conventional 2D cultures, and were instrumental in correlating in vitro drug response with in vivo outcomes.
Results were disseminated through nine high-impact publications, including:
- Sci Rep 2023, 13, 5094: Demonstrated the efficacy of nanocomposite hydrogels for GBM treatment.
- Pharmaceutics 2023, 15(4), 1071: Detailed hydrogel formulation and injectable system design.
- Heliyon 2025, 11(1), e41151: Showcased pH-responsive chlorotoxin-functionalized nanoparticles.
- Int J Mol Sci 2023, 24(3), 2753: Presented siRNA-loaded nanoparticle delivery in retinal models.
- J Sol-Gel Sci Technol 2024, 111, 95–105: Described MRI-visible, pH-triggered drug release.
In addition, a patent application (ES2816632A1) has been filed to protect the hydrogel-based delivery technology, and further development toward clinical translation is ongoing.
A pivotal innovation was the development of molecular gates -peptide, pH-, and redox-sensitive moieties- that allowed for stimulus-triggered drug release in response to tumor-specific conditions. These gates were engineered to degrade in the presence of matrix metalloproteinases, acidic environments, or elevated levels of glutathione, all commonly found in tumor tissue. This enabled highly selective release of payloads at the tumor site, minimizing off-target effects and improving therapeutic index. The integration of diagnostic imaging agents further allowed real-time tracking of drug release, moving the platform into the realm of theranostics.
To achieve localized administration, these nanoparticles were incorporated into injectable hydrogels based on hyaluronic acid and chitosan/beta-glycerophosphate. These hydrogels could form a solid depot upon injection, releasing their cargo over time as the matrix degraded. Chemical crosslinking strategies improved their flexibility and drug-loading capacity, and cytotoxicity assays in both 2D and 3D GBM models confirmed their efficacy.
The system was tested in preclinical animal models, including an orthotopic GBM model involving surgical resection followed by hydrogel implantation into the tumor cavity. This clinically relevant setup showed reduced tumor recurrence and improved therapeutic outcomes. Additionally, an intranasal administration route was explored as a non-invasive alternative for delivering the hydrogel-nanoparticle system directly to the central nervous system, bypassing the BBB.
REACT also played a key role in advancing in vitro tumor modeling by developing scaffold-free 3D GBM spheroids. These models more closely mimic the architecture and microenvironment of real tumors compared to conventional 2D cultures, and were instrumental in correlating in vitro drug response with in vivo outcomes.
Results were disseminated through nine high-impact publications, including:
- Sci Rep 2023, 13, 5094: Demonstrated the efficacy of nanocomposite hydrogels for GBM treatment.
- Pharmaceutics 2023, 15(4), 1071: Detailed hydrogel formulation and injectable system design.
- Heliyon 2025, 11(1), e41151: Showcased pH-responsive chlorotoxin-functionalized nanoparticles.
- Int J Mol Sci 2023, 24(3), 2753: Presented siRNA-loaded nanoparticle delivery in retinal models.
- J Sol-Gel Sci Technol 2024, 111, 95–105: Described MRI-visible, pH-triggered drug release.
In addition, a patent application (ES2816632A1) has been filed to protect the hydrogel-based delivery technology, and further development toward clinical translation is ongoing.
REACT’s major scientific contribution lies in its transition from passive nanomedicine concepts to an active, stimuli-responsive, and localized delivery strategy tailored to the biology of solid tumors. Unlike current nanotherapeutics that rely on passive accumulation, REACT's platform actively responds to tumor-specific conditions, ensuring controlled, spatiotemporal drug release.
The integration of imaging and therapeutic functions within the same platform, achieved through nanoparticle engineering, marks a substantial advancement in theranostic systems. By enabling visualization of drug release in real time, this approach supports the development of personalized and adaptive treatment regimens.
Another breakthrough was the application of injectable hydrogels as post-surgical therapeutic depots, particularly relevant for GBM. This not only enhanced local drug concentration but also reduced systemic exposure and toxicity. The innovation holds promise for clinical integration, especially in neurosurgical settings where local therapy can be administered directly into the resection cavity.
Unexpectedly, the platform’s versatility was demonstrated by its adaptation for siRNA delivery, opening new opportunities in gene therapy -including applications in ophthalmology, such as AMD. This unanticipated outcome broadens the scope of REACT’s technology far beyond its original oncology-focused goals.
Finally, the development of 3D tumor models and clinically relevant animal models was instrumental in bridging the translational gap, aligning basic research outcomes with real-world therapeutic applications. This comprehensive pipeline, from design to preclinical validation, positions REACT at the forefront of translational nanomedicine.
The integration of imaging and therapeutic functions within the same platform, achieved through nanoparticle engineering, marks a substantial advancement in theranostic systems. By enabling visualization of drug release in real time, this approach supports the development of personalized and adaptive treatment regimens.
Another breakthrough was the application of injectable hydrogels as post-surgical therapeutic depots, particularly relevant for GBM. This not only enhanced local drug concentration but also reduced systemic exposure and toxicity. The innovation holds promise for clinical integration, especially in neurosurgical settings where local therapy can be administered directly into the resection cavity.
Unexpectedly, the platform’s versatility was demonstrated by its adaptation for siRNA delivery, opening new opportunities in gene therapy -including applications in ophthalmology, such as AMD. This unanticipated outcome broadens the scope of REACT’s technology far beyond its original oncology-focused goals.
Finally, the development of 3D tumor models and clinically relevant animal models was instrumental in bridging the translational gap, aligning basic research outcomes with real-world therapeutic applications. This comprehensive pipeline, from design to preclinical validation, positions REACT at the forefront of translational nanomedicine.