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Published on: November 24, 2014
A novel assay to assess primary human cancer infectibility by replication-selective oncolytic adenoviruses
Yaohe Wang1, Stephen Thorne, Joseph Hannock
1Cancer Research UK Molecular Oncology Unit, Imperial School of Medicine, London, United Kingdom.
Purpose:
Replication-selective oncolytic adenoviruses hold promise for cancer treatment, but the predictive use of cell lines, dissociated tumor tissue, and animal models for efficacy against primary cancers are unclear. To further evaluate cytotoxicity and the potential for efficacy of replication-competent adenoviruses we therefore developed a novel methodology using primary human cancer specimens ex vivo; ovarian, colon, rectal, and breast carcinomas were included.
Experimental Design:
Tissue culture conditions were developed to maintain viability of adenocarcinomas ex vivo for 48 hours postsurgery. Explants were infected by replication-competent (wild type 5 and E1A mutant dl922-947) and replication-defective (dl312) adenoviruses; early (E1A) and late (hexon) viral gene expression, alphav integrins, coxsackievirus and adenovirus receptor (CAR) and tissue viability were assessed by immunohistochemistry and histopathology. Viral replication was verified by replication assays on selected samples.
Results:
Viral gene expression varied dramatically among cancer specimens (n = 41). With Ad5, hexon expression was high in 8 of 11 tested specimens, whereas E1A levels were detectable in 16 of 27 tumor explants. Viral gene expression, distribution, and cytopathic effects were greater postinfection with dl922-947. Specimens that supported early gene expression (E1A) also supported viral replication in 13 of 14 tested cases, determined by recovery of infectious units. As predicted, the replication-defective adenovirus dl312 was not associated with viral gene expression.
Conclusions:
Primary human tumor tissue remained viable when cultured ex vivo enabling evaluation of viral mutants in tissue with intact morphology. This assay may have great use in determining treatment-sensitive cancers and assess specific oncolytic mutants in individual cases.
Insights
This study developed an ex vivo method to test oncolytic adenoviruses on primary human tumors. The novel assay shows promise for predicting cancer treatment sensitivity and selecting effective viral mutants.
Area of Science:
- Oncolytic virotherapy
- Cancer research
- Adenovirus biology
Background:
- Replication-selective oncolytic adenoviruses are promising cancer therapeutics.
- Predicting efficacy using traditional models (cell lines, animal models) for primary cancers remains challenging.
Purpose of the Study:
- To develop and evaluate a novel ex vivo methodology using primary human cancer specimens to assess oncolytic adenovirus efficacy.
- To investigate the cytotoxicity and potential efficacy of replication-competent adenoviruses against ovarian, colon, rectal, and breast carcinomas.
Main Methods:
- Developed tissue culture conditions to maintain ex vivo viability of human adenocarcinomas for 48 hours.
- Infected tumor explants with replication-competent (wild type 5, dl922-947) and replication-defective (dl312) adenoviruses.
- Assessed viral gene expression (E1A, hexon), integrin/receptor expression, and tissue viability using immunohistochemistry and histopathology; verified viral replication.
Main Results:
- Significant variation in viral gene expression was observed across 41 cancer specimens.
- Replication-competent adenovirus dl922-947 showed greater viral gene expression, distribution, and cytopathic effects compared to Ad5.
- Early gene expression (E1A) correlated strongly with viral replication, with 13 of 14 cases supporting replication.
Conclusions:
- Primary human tumor tissue can be maintained ex vivo with intact morphology, enabling evaluation of viral mutants.
- This ex vivo assay is a valuable tool for identifying treatment-sensitive cancers.
- The methodology allows for the assessment of specific oncolytic adenovirus mutants in individual patient tumor samples.
