The Toxic Tale of Hong Kong's First Patented Drug

One man's poison is another man's cure. At least that's the case for arsenic. Best known as a favourite substance for killing off royalty and victims in murder mystery stories, arsenic has enjoyed a comeback in recent years as a medical treatment, in particular for leukaemia.

Professor Yok-lam Kwong, Chui Fook Chuen Chair in Molecular Medicine of the Department of Medicine, has been a close follower of its revival and was inspired to produce Hong Kong's first patented drug - an oral form of arsenic.

''Arsenic is a very strange thing,'' he says. ''It used to be considered a type of traditional Chinese medicine and it also has a long history in Western medicine, but it is also a poison and has this bad reputation.'' One interesting example is that the use of arsenic was mentioned in the clinical case notes of Sir Arthur Conan Doyle, Scottish physician and author of the Sherlock Holmes stories.

The advent of chemotherapy after the Second World War pushed arsenic out of the medical picture. Its role in medicine did not re-emerge until the 1980s and 1990s when scientists in Mainland China applied modern scientific tests to show arsenic was indeed effective against leukaemia.

With the help of medical records of the 1950s in the Department of Medicine, Queen Mary Hospital, Professor Kwong found out that arsenic originally was used in an oral formulation, unlike the intravenous drug developed by the Mainland doctors. He decided to see if he could develop a new oral formulation that met modern standards. And he did all the basic research without any research grants.

The result is oral arsenic trioxide treatment which has been tested on patients with acute promyelocyctic leukaemia (APL) and found to be almost 100 per cent effective in inducing a remission.

The patient outcome is similar to the intravenous drug, but importantly, the treatment is much easier on them. Patients take the oral drug at home, while intravenous patients typically stay in hospital for a month. The psychological stress caused to patients is much lower as a result.  Besides, the side effects are much reduced and the cost is much cheaper - intravenous treatment typically costs about US$50,000 for a full course. ''I'm sure it will become the standard treatment for APL,'' Professor Kwong says.

Professor Kwong works with Versitech to turn his research result into a product for clinical application. The drug is the first prescription medication to be developed in Hong Kong and it has been patented in the U.S. and Japan. It is now ready to go to market and he hopes it will be made affordable to less developed countries, where intravenous treatment is too expensive.

Moreover, oral arsenic trioxide, when it comes to market, should be affordable for testing in other ailments. Already, HKU has filed patents for its use in treating lymphoma and certain types of arthritis. Hopefully, there will be more to come.

It's been more than 10 years since Professor Kwong started his research in arsenic, and his technology transfer journey continues. It's all about perseverance, for the sake of patients.