A novel assay to assess primary human cancer infectibility by replication-selective oncolytic adenoviruses.
OBJECTIVE
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.


METHODS
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.
Wang
Yaohe
Y
Cancer Research UK Molecular Oncology Unit, Imperial School of Medicine, London, United Kingdom.
Thorne
Stephen
S
Hannock
Joseph
J
Francis
Jennelle
J
Au
Tina
T
Reid
Tony
T
Lemoine
Nick
N
Kirn
David
D
Halldén
Gunnel
G
D000230:Adenocarcinoma / Q000378:metabolism / Q000473:pathology*; D000256:Adenoviridae / Q000235:genetics*; D017500:Adenovirus E1A Proteins / Q000096:biosynthesis; D045744:Cell Line, Tumor; D062727:Coxsackie and Adenovirus Receptor-Like Membrane Protein; D003588:Cytopathogenic Effect, Viral; D005260:Female; D015967:Gene Expression Regulation, Viral; D005821:Genetic Techniques; D006801:Humans; D007150:Immunohistochemistry; D039564:Integrin alphaV / Q000378:metabolism; D008297:Male; D009154:Mutation; D009369:Neoplasms / Q000378:metabolism*; D018809:Proliferating Cell Nuclear Antigen / Q000378:metabolism; D011991:Receptors, Virus / Q000378:metabolism; D013997:Time Factors; D014407:Tumor Cells, Cultured; D014779:Virus Replication
D017500:Adenovirus E1A Proteins; C568771:CLMP protein, human; D062727:Coxsackie and Adenovirus Receptor-Like Membrane Protein; D039564:Integrin alphaV; D018809:Proliferating Cell Nuclear Antigen; D011991:Receptors, Virus