Two New Zealand scientists have discovered a new class of anti-cancer medicines that kill tumors without the side effects of traditional therapies, local media reported on Saturday.
Medicinal chemist Jeffrey Smaill and cancer biologist Adam Patterson, from Auckland University, said their "prodrugs" -- inactive compounds triggered by the body's own metabolic processes -- have already shown dramatic results in the lab.
Their discovery, announced at an international cancer drug conference in Boston this week, is being heralded as a major breakthrough in fighting hard-to-treat cancers, like those of the lungs, brain, pancreas and stomach, according to The Dominion Post newspaper.
Smaill, who has spent 10 years synthesizing the compounds, said they worked by targeting the proteins in tumors that tell cells to multiply.
"The main problem with previous drugs developed to target these proteins was they also affected normal, healthy tissue in the skin and gut, causing serious side effects such as severe diarrhea, rashes, nausea and vomiting, which limited the dose a patient could tolerate," he said.
The surface of a healthy gut is renewed every 48 hours - about the same rate as a tumor.
For half a century scientists have known that two-thirds of tumors have patches containing low levels of oxygen, called hypoxic tumor cells, which are harder to treat with radiation and more likely to spread. Dr Patterson said the prodrugs actually use this feature against the tumor, by zeroing in
on hypoxic cells before they activate.
"If we can target and kill these cells we should be able to dramatically improve the outcome for cancer patients," he said.
Unlike other drugs that only stay in the tumor for a few hours, the prodrug sticks to the tumor for over 72 hours.
"It's very common for tumors to start regrowing after you stop administering this type of cancer drug. But after we stopped doses of this prodrug, the tumors still hadn't regrown 30 days later," he said.