Quantitative Virus-Associated RNA Detection to Monitor Oncolytic Adenovirus Replication
Tereza Brachtlova1,2,3,4, Jing Li1,3, Ida H van der Meulen-Muileman1,3
1Medical Oncology, Amsterdam UMC Location Vrije Universiteit Amsterdam, 1081 HV Amsterdam, The Netherlands.
Abstract:
Oncolytic adenoviruses are in development as immunotherapeutic agents for solid tumors. Their efficacy is in part dependent on their ability to replicate in tumors. It is, however, difficult to obtain evidence for intratumoral oncolytic adenovirus replication if direct access to the tumor is not possible. Detection of systemic adenovirus DNA, which is sometimes used as a proxy, has limited value because it does not distinguish between the product of intratumoral replication and injected virus that did not replicate. Therefore, we investigated if detection of virus-associated RNA (VA RNA) by RT-qPCR on liquid biopsies could be used as an alternative. We found that VA RNA is expressed in adenovirus-infected cells in a replication-dependent manner and is secreted by these cells in association with extracellular vesicles. This allowed VA RNA detection in the peripheral blood of a preclinical in vivo model carrying adenovirus-injected human tumors and on liquid biopsies from a human clinical trial. Our results confirm that VA RNA detection in liquid biopsies can be used for minimally invasive assessment of oncolytic adenovirus replication in solid tumors in vivo.
Insights
Detecting virus-associated RNA (VA RNA) in liquid biopsies offers a minimally invasive method to confirm oncolytic adenovirus replication within solid tumors, aiding immunotherapy development.
Area of Science:
- Oncology
- Virology
- Molecular Biology
Background:
- Oncolytic adenoviruses show promise as cancer immunotherapies.
- Assessing intratumoral virus replication is crucial for efficacy but challenging non-invasively.
- Current methods like detecting systemic adenovirus DNA lack specificity for replication.
Purpose of the Study:
- To evaluate virus-associated RNA (VA RNA) detection in liquid biopsies as a marker for oncolytic adenovirus replication.
- To establish a minimally invasive method for monitoring treatment response in solid tumors.
Main Methods:
- Developed and validated RT-qPCR assays for VA RNA detection.
- Investigated VA RNA expression in adenovirus-infected cells.
- Analyzed VA RNA in extracellular vesicles from preclinical models and human clinical trial liquid biopsies.
Main Results:
- VA RNA expression is replication-dependent in infected cells.
- VA RNA is secreted via extracellular vesicles.
- Successfully detected VA RNA in peripheral blood from preclinical models and human trials.
Conclusions:
- VA RNA detection in liquid biopsies is a viable, minimally invasive method.
- This technique allows for assessment of oncolytic adenovirus replication in solid tumors.
- Facilitates monitoring of immunotherapy efficacy in clinical settings.
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