Bulletin Autumn‧Winter 1999

Extending Half-Life to Extend Life: Method for Drug Improvement Transferred to Biotechnology Company What's Half-Life? P r o f. M i c h a e l Tam of t he D e p a r t m e nt of Physiology has developed a method for protein d r u g i mp r o v eme nt w h e r e in the d r u g 's t i me inside the h u m a n b o d y, or ' ha l f - l i f e' as i t is medically called, is lengthened wh i le the level of its desired effects is maintained. The method was developed i n a project, begun i n 1995, to extend the half-life of trichosanthin, a protein i n the tuber of Trichosanthes kirilowii, a c l i mb i ng p l a nt w h i c h g r ows w i l d i n eastern Ch i na. T r i chosan t h in has been f o u nd to i n h i b it the r e p r o d u c t i on of the h u m a n i mmu n o d e f i c i e n cy v i ms ( H I V) i n infected cells w i t h o ut affecting no rmal cells. However its curative effects are short-lived as it remains i n the body for only a very brief period. Benefits of Extending half-Life of Drugs The technology aroused the interest of LeaderGene, a H o n g Kong-based b i o t echno l ogy c ompany w h i c h has a related company i n Shanghai that produces interferon, an a n t i - v i r al p r o t e in d r u g for n o n - A and non -B hepatitis. I n t e r f e r o n, if a dm i n i s t e r ed i n t i me, can p r e v e nt complications such as sclerosis and cancer of the liver. However a dose of i n t e r f e r on costs tens of thousands of dollars. Ex t end i ng the half-life of interferon w o u l d lengthen the drug's activity i n the body, and hence lower the number of doses required, thereby reducing costs and also the drug's side-effects. From Trichosanthin to Interferon LeaderGene approached the University to discuss the use of the technology. This resulted i n the s i gn i ng of a licensing agreement between the t wo i n September 1998 under wh i ch Prof. Tam and his researchers w i l l wo r k w i t h the research and development department of LeaderGene to extend the half-life of interferon, using the technology w h i c h he has d e v e l o p ed to e x t e nd t he h a l f - l i fe of trichosanthin. 8