In the annals of cancer medicine, radiation has a long and distinguished reputation as a potent weapon. But like all cancer treatments, radiation can cause side effects, because it attacks healthy cells, as well as diseased ones.
In 2000, New York physician David Sheinberg started a company, Actinium Pharmaceuticals, around an idea for making radiation a more potent and targeted therapy: He wanted to attach radioactive isotopes to specific antibodies—proteins that are programmed to target cancer cells—and turn them into drugs. But rather than using isotopes that produce gamma radiation, which is standard in cancer treatment, he chose ones that emit alpha particles instead.
Why alpha radiation? “These particles have tremendous killing power, but they travel short paths,” says Dragan Cicic, who joined Actinium as CEO in 2005. “If you bring them into the cell, they will just kill that cell. They won’t do anything to the surrounding tissue.”
Sounds simple enough, but it actually took Actinium nearly a dozen years to figure out how to make alpha-radiation-armed antibodies that are safe and effective, and most importantly, that have a long enough half-life to be able to be transported to treatment centers before they lose their cancer-killing power. Now Actinium is approaching mid-stage trials of its lead drug candidate, and its executives are so confident they’re on the right track they’re planning a public offering in the fourth quarter of this year.
The key to the company’s technology platform, says Cicic, is the method Sheinberg developed to attach radioactive isotopes to antibodies. What he came up with was a “chelator,” which is a linker that binds to the antibody on one side and the radioactive element on the other. “The antibody then brings the killing agent to the cancer cell,” Cicic explains. (The company is named after Actinium 225, one of the alpha-emitting isotopes used in the platform.)
Actinium’s lead product has been tried in about 60 patients with acute myeloid leukemia (AML) and has not produced significant side effects, Cicic says. Because of the drug’s targeting ability, “the amount of radiation that’s given is miniscule. We’re looking at
