Molecular Pathways: Mechanism of Action for Talimogene Laherparepvec, a New Oncolytic Virus Immunotherapy

Oncolytic viruses are native or engineered viruses that preferentially replicate in and lyse cancer cells. Selective tumor cell replication is thought to depend on infection of neoplastic cells, which harbor low levels of protein kinase R (PKR) and dysfunctional type I IFN signaling elements. These...

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Bibliographic Details
Published in:Clinical cancer research 2016-03, Vol.22 (5), p.1048-1054
Main Authors: Kohlhapp, Frederick J, Kaufman, Howard L
Format: Article
Language:English
Subjects:
Antigens, Neoplasm - immunology
Granulocyte-Macrophage Colony-Stimulating Factor - genetics
Granulocyte-Macrophage Colony-Stimulating Factor - therapeutic use
Humans
Immunotherapy - methods
Melanoma - genetics
Melanoma - immunology
Melanoma - therapy
Melanoma - virology
Oncolytic Virotherapy - methods
Oncolytic Viruses - genetics
Signal Transduction
Simplexvirus - genetics
Virus Replication - genetics
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Summary:Oncolytic viruses are native or engineered viruses that preferentially replicate in and lyse cancer cells. Selective tumor cell replication is thought to depend on infection of neoplastic cells, which harbor low levels of protein kinase R (PKR) and dysfunctional type I IFN signaling elements. These changes allow more efficient viral replication, and with selected deletion of specific viral genes, replication in normal cells with activated PKR may not be possible. Direct tumor cell lysis, release of soluble tumor antigens, and danger-associated molecular factors are all thought to help prime and promote tumor-specific immunity. Talimogene laherparepvec (T-VEC) is a genetically modified herpes simplex virus, type I and is the first oncolytic virus to demonstrate a clinical benefit in patients with melanoma. T-VEC has also been evaluated for the treatment of head and neck cancer, pancreatic cancer, and likely other types of cancer will be targeted in the near future. T-VEC has been modified for improved safety, tumor-selective replication, and induction of host immunity by deletion of several viral genes and expression of human granulocyte-macrophage colony stimulating factor. Although the mechanism of action for T-VEC is incompletely understood, the safety profile of T-VEC and ability to promote immune responses suggest future combination studies with other immunotherapy approaches including checkpoint blockade through PD-1, PD-L1, and CTLA-4 to be a high priority for clinical development. Oncolytic viruses also represent unique regulatory and biosafety challenges but offer a potential new class of agents for the treatment of cancer.
ISSN:1078-0432
1557-3265
DOI:10.1158/1078-0432.ccr-15-2667