Patent Law

• Author: International Law Group

In 1983, the Institut Pasteur had isolated the Human Immunodeficiency Virus (HIV), the retrovirus shown to cause Acquired Immune Deficiency Syndrome (AIDS). Later that year, the British pharmaceutical giant, Glaxo/Wellcome (Glaxo or defendant), drew on its considerable expertise involving retroviruses and put together a group of scientists to begin looking for an anti-AIDS drug.

Scientists knew in 1984 that HIV attacks T-cells, which are crucial to the human immune system. HIV uses the enzyme "reverse transcriptase" to convert its own RNA to DNA and to insert this DNA into the DNA of the host cell.

The Glaxo researchers thought that the reverse transcription stage, unique to retroviruses, could be vulnerable and thus a potential drug target. AZT (Azidothymidine) is a compound synthesized and tested in 1964 as a potential cancer treatment for humans. Glaxo itself had been researching AZT as a possible anti-bacterial treatment.

In November 1984, Glaxo began testing various known compounds. Its researchers first introduced a retrovirus found in mice into mouse T-cells. They next decided how good each compound was in stopping the retrovirus from killing the T-cells. During these tests, AZT came out on top at ridding the T-cells of the virus.

Lacking the resources to perform testing on human cells, Glaxo turned, inter alia, to the U.S. National Institutes of Health (NIH). Without having the AZT identified to them, Drs. Samuel Broder and Hiroaki Mitsuya, did the critical NIH research. They used a human cell line that could propagate in vitro, and be infected in vitro with HIV. The tests showed AZT's probable effectiveness against HIV in the T-cells of living patients.

By February 6, 1985, Glaxo had drafted a patent application. On February 21, 1985, Drs. Broder and Mitsuya told Glaxo that their research showed that AZT did curb the replication of HIV in their in vitro HIV assay systems.

Based upon these results, the company predicted that physicians could prescribe AZT to treat HIV in humans. On March 16, 1985, while tests of AZT on human patients with HIV was still going on, Glaxo filed in the U. K. the patent application from which the Canadian patent claims priority.

Apotex, Inc. and Novopharm Ltd, two "generic" drug manufacturers (plaintiffs), sued Glaxo and others (collectively defendant) in a Canadian federal court to challenge the validity of defendant's patent based on three premises. First, plaintiffs alleged that defendant had not shown...