Antiviral Treatment Blocks Brain Tumor Growth

Several types of cancers have been linked to infection by Cytomegalovirus (CMV), and a recent study showed that anti-inflammatory and antiviral drugs that prevent replication of the virus also block tumor growth.

Investigators at Karolinska Institutet (Stockholm, Sweden) worked with both cancer cells growing in tissue culture and with an animal model in which human medulloblastoma cells were implanted in immunocompromised mice. They reported in the September 26, 2011, online edition of the Journal of Clinical Investigation that 92% of tumors from medullablastoma patients were infected with CMV and that cells from these tumors expressed high levels of the enzyme cyclooxygenase-2 (COX-2) and produced prostaglandin-E2 (PGE2), which stimulates tumor cell proliferation.

The antiviral drug valganciclovir and the specific COX-2 inhibitor celecoxib were used to treat CMV-infected cell cultures and mice that had received human tumor cell implants. This treatment prevented CMV replication in vitro, and inhibited PGE2 production and reduced medulloblastoma tumor-cell growth both in vitro and in vivo. Tumors that had not been infected by CMV were not affected by the drug combination.

“We show in this study that CMV is found in 92% of tumors from medullablastoma patients,” said senior author Dr. Cecilia Söderberg-Nauclér, professor of medicine at the Karolinska Institutet. “We also show in experimental systems that we can inhibit the growth of these tumors with antiviral drugs, which opens up a new potential therapeutic approach to certain tumors in the future. Our experiments on mice show that tumor growth declines by around 40% when antiviral drugs or COX-2 inhibitors are used separately, and by no less than 72% when used in combination.”

“These are very promising and exciting results,” said Dr. Söderberg-Nauclér. “The virus infection is not cured by the treatment, nor is the tumor, but the virus in the tumor decreases, which affects its growth. This therefore presents a new approach to treating tumors and could henceforth be used as a possible complementary therapy.”

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