Related Experiment Video
Updated: Jan 22, 2026
Isolation of Next-Generation Gene Therapy Vectors through Engineering, Barcoding, and Screening of Adeno-Associated Virus AAV Capsid Variants
Published on: October 18, 2022
Reducing off target viral delivery in ovarian cancer gene therapy using a protease-activated AAV2 vector platform
Abstract:
Gene therapy is a promising strategy for treating metastatic epithelial ovarian cancer (EOC). However, efficient vector targeting to tumors is difficult and off-target effects can be severely detrimental. Most vector targeting approaches rely on surface receptors overexpressed on some subpopulation of cancer cells. Unfortunately, there is no universally expressed cell surface biomarker for tumor cells. As an alternative, we developed an adeno-associated virus (AAV) based "Provector" whose cellular transduction can be activated by extracellular proteases, such as matrix metalloproteinases (MMP) that are overexpressed in the tumor microenvironments of the most aggressive forms of EOC. In a non-tumor bearing mouse model, the Provector demonstrates efficient de-targeting of healthy tissues, especially the liver, where viral delivery is <1% of AAV2. In an orthotopic HeyA8 tumor model of EOC, the Provector maintains decreased off-target delivery in the liver and other tissues but with no loss in tumor delivery. Notably, approximately 10% of the injected Provector is still detected in the blood at 24 h while >99% of injected AAV2 has been cleared from the blood by 1 h. Furthermore, mouse serum raised against the Provector is 16-fold less able to neutralize Provector transduction compared to AAV2 serum neutralizing AAV2 transduction (1:200 vs 1:3200 serum dilution, respectively). Thus, the Provector appears to generate less neutralizing antibodies than AAV2. Importantly, serum against AAV2 does not neutralize the Provector as well as AAV2, suggesting that pre-existing antibodies against AAV2 would not negate the clinical application of Provectors. Taken together, we present an EOC gene delivery vector platform based on AAV with decreased off-target delivery without loss of on-target specificity, and greater immunological stealth over the traditional AAV2 gene delivery vector.
Insights
A novel gene therapy vector, the Provector, shows reduced off-target effects and lower immune response for treating ovarian cancer. This protease-activated adeno-associated virus (AAV) platform improves tumor targeting while minimizing damage to healthy tissues.
Area of Science:
- Oncology
- Gene Therapy
- Virology
Background:
- Metastatic epithelial ovarian cancer (EOC) presents challenges for gene therapy due to difficulties in vector targeting and detrimental off-target effects.
- Current targeting strategies often rely on cell surface receptors, but a universal biomarker for EOC cells is lacking.
Purpose of the Study:
- To develop a novel adeno-associated virus (AAV) based gene delivery vector, termed Provector, for enhanced EOC treatment.
- To engineer the Provector for protease-activated transduction, specifically targeting matrix metalloproteinases (MMPs) prevalent in aggressive EOC tumor microenvironments.
Main Methods:
- Development of a protease-activated AAV vector (Provector) designed for MMP-mediated cellular entry.
- Evaluation of Provector's biodistribution and targeting efficiency in non-tumor bearing and orthotopic HeyA8 EOC mouse models.
- Assessment of Provector's immunogenicity and neutralization by pre-existing antibodies compared to standard AAV2.
Main Results:
- Provector demonstrated significantly reduced viral delivery to healthy tissues, particularly the liver (<1% of AAV2 levels), in non-tumor bearing mice.
- In an orthotopic EOC model, Provector maintained tumor delivery while exhibiting decreased off-target delivery in the liver and other organs.
- Provector showed prolonged presence in blood (10% at 24h vs. >99% AAV2 clearance by 1h) and generated 16-fold less neutralizing antibodies than AAV2, with reduced susceptibility to AAV2-neutralizing antibodies.
Conclusions:
- The Provector represents a promising gene delivery platform for EOC, offering decreased off-target effects without compromising tumor targeting.
- This novel vector exhibits enhanced immunological stealth compared to traditional AAV2, potentially overcoming pre-existing immunity challenges in clinical applications.
- The protease-activated mechanism provides a targeted approach for gene therapy in aggressive EOC, minimizing adverse events associated with non-specific viral transduction.
More Related Videos
Related Concept Videos
02:57Targeted Cancer Therapies
There are several types of targeted therapies against...
00:59Gene Therapy
02:49Cancer Therapies
However, cancer treatments can pose several challenges, as therapies used to kill cancer cells are generally also toxic to normal cells. Moreover, cancer cells mutate rapidly and can develop resistance to chemical agents or radiation therapy. Besides, all types of cancer cells may not respond to the same therapy. Some cancer cells respond to one...
01:05Cancer-Critical Genes II: Tumor Suppressor Genes
When the function of certain critical genes, especially those involved in cell cycle regulation and cell growth signaling cascades, gets disrupted, it upsets the cell cycle progression. Such cells with unchecked cell cycles start proliferating uncontrollably and eventually develop into tumors.
Such genes that act...
00:57Viral Recombination