UK scientists announced Monday that they developed a "smart bomb" cancer drug, derived from a British flower, that can target and destroy tumors without damaging healthy tissues.

Scientists from the University of Bradford, northern England, turned chemicals from crocuses into a drug that targets cancerous tumors, regardless of cancer type, without causing side effects.

Five different types of cancer so far were tested -- breast, colon, lung, sarcoma and prostate -- with no adverse effects observed. The drug, at an early stage of development, was tested only on mice. However, in one test, half of the tumors in a group of mice vanished completely after a single dose.

"What we've designed is, effectively, a 'smart bomb' that can be targeted directly at any solid tumor to kill it without appearing to harm healthy tissue," according to Professor Laurence Patterson, from the university's Institute for Cancer Therapeutics (ICT).

The drug's main ingredient is based on colchicine, a natural compound derived from the autumn crocus, a native British flower described in ancient herbal books as a treatment for inflammation.

"Although it's well known for having anti-cancer properties, colchicine is not used to treat cancer because it is too toxic against normal tissues within the body," researcher Kevin Adams said.

"We've found a way to harness colchicine's power so that it's harmless to healthy tissue but still toxic to tumor blood vessels."

Clinical trials are planned to start at St. James's University Hospital in Leeds, northern England, and could begin in as little as 18 months, following final pre-clinical assessments. If successful, the drug could be available in six to seven years.