Comparing and Combining Viroimmunotherapies for Intrahepatic Cholangiocarcinoma
This project uses cancer-killing (oncolytic) viruses to treat a rare and aggressive liver cancer called intrahepatic cholangiocarcinoma (iCCA). Oncolytic viruses can recruit and activate tumor-killing immune cells but remain an understudied yet promising treatment for iCCA.
The project uses an immunocompetent iCCA model to quantify and characterize immune and inflammatory responses to different viruses, either alone or as a cooperative combination treatment. Direct comparisons and combinations of viruses in an elegantly characterized model of iCCA is astonishingly novel. Any positive findings could rapidly alter clinical trial design and personalized treatment regimens for people with this aggressive disease.
Intrahepatic cholangiocarcinoma (iCCA) is an aggressive malignancy with few effective treatment options. Characterized by immunosuppressive tumor stroma with few activated immune cells, iCCA is largely unresponsive to immunotherapy.
Although understudied in iCCA, oncolytic viroimmunotherapy (OV) can transform cold immune-suppressed tumor microenvironments into hot ones by recruiting and activating effector immune cells.
Highly immunogenic vaccinia vectors (VACVs) with large double-stranded (ds)-DNA genomes are the most widely clinically explored viruses for liver tumors. While effective at infiltrating and destroying small tumor sections, VACVs are clinically insufficient to eradicate tumor.
Emerging concepts suggest that VACV cooperates well with other viruses, like small, agile, single-stranded (ss)-RNA vesicular stomatitis virus (VSV) that is capable of rapid dissemination through tumor microenvironments.
Because VACV strongly inhibits anti-viral IFNα/β, while VSV is highly sensitive to IFNα/β, we hypothesize that infecting iCCA with VACV followed by VSV will dampen IFNα/β expression, allow increased oncolysis, and enhance antigen-specific anti-tumor immunity.
To test this hypothesis, we will first examine interplay of anti-viral IFNα/β and VACV infection with and without VSV in vitro. We will further ascertain the relevance of VACV-induced IFNα/β suppression to VSV oncolysis by employing:
- Replication-incompetent VACV infection that will not suppress IFNα/β.
- Pharmacologic inhibition of IFN activation using JAK-STAT inhibitor Ruxolitinib (Aim 1a).
We will confirm these in vitro findings in patient-derived xenograft (PDX) models of iCCA with clinically relevant genotypes (Aim 1b).
In the next aim, we will examine impacts of oncolysis and IFNα/β expression on immunogenicity by treating a well-established syngeneic orthotopic model of iCCA with VACV and VSV alone or in combination.
In this syngeneic setting, we also will reexamine the relevance of oncolysis to anti-viral IFNα/β expression using replication incompetent VACV as a control (Aim 2a).
Because durable clinical responses to OVs in other solid tumors have demonstrated CD8+-dependent antigen-specific anti-tumor immunity, we will examine the impact of IFNγ-induced recruitment on effector CD8+ T cells by coculturing T cells from treated mice with cancer cells alone or with viral treatment, and then measuring activation markers and IFNγ production.
To assess relevance of CD8+ T cell activation in vivo, we will repeat OV combinations using antibodies to block CD8 and IFNγ (Aim 2b).
We anticipate that VACV and VSV infection work cooperatively to optimally disseminate OV throughout a tumor microenvironment and induce a durable anti-tumor immune response.
We believe this cooperativity will occur by first evading innate immunity (IFNα/β) and then exploiting adaptive (antigen-specific effector CD8+ T cell) immune responses to viral infection.
These experiments will be the first to study combination OV therapy in a syngeneic murine iCCA model.
The preliminary data generated from this work will serve as a foundation for expanded mechanistic preclinical studies and potential clinical trials of combination viroimmunotherapy.