Medical researchers now know that many forms of cancer are caused by viruses, among them liver cancer (hepatitis B and C viruses), cervical cancer (human papillomaviruses, or HPV), and lymphoma (Epstein- Barr virus). Researchers are pursuing treatments that will kill the viruses before they trigger the uncontrolled growth of cells or tumors.
Radioimmunotherapy (RIT) uses antibodies outfitted with radioisotopes to create “warheads” that seek and destroy the antigens. But viral antigens associated with cancer typically lurk inside the infected cells, so researchers assumed they were out of reach.
We had a hunch that rapidly growing tumors can ‘outgrow’ their blood supply, resulting in dead tumor cells that might spill their viral antigens amongst the living cancer cells,” says Arturo Casadevall, chair of microbiology and immunology at Yeshiva University’s Albert Einstein College of Medicine. “We hoped that, by injecting the antibodies hitched to isotopes into the blood, they’d be carried deep into the tumor mass and would latch onto these nowexposed antigens. Then the blast of radiation emitted by the radioisotope would destroy the live tumor cells nearby.”
When the group tested their theory in two sets of mice infected with tumors, the cancerous regions they treated with RIT grew far slower and, in the case of cervical cancer cells, actually shrank.
Radioimmunotherapy allows doctors to use higher, more toxic levels of radiation to kill the cancerous cells with less worry of damage to nearby cell tissue. According to Ekaterina Dadachova, co-author of the Einstein report, the treatment “not only worked against these cancers, but was confined entirely to the tumor masses, leaving healthy tissues undamaged.”
The success of the study suggests that, in the future, doctors might use RIT to treat a wide variety of viral infections, including those that could lead to cancer.
“Virus-associated cancers account for some 1.3 million cancer cases each year,” Dadachova says, “so the need for new strategies in treating them is obvious and urgent. The approach also holds promise for cancer prevention. In people chronically infected with hepatitis B or C, human papillomaviruses, or other viruses known to cause cancer, radioimmunotherapy could potentially eliminate virus-infected cells before they’re able to transform into cancer cells.”
-Cynthia G. Wagner and Patrick Tucker
Originally published in THE FUTURIST, March-April 2008.