Another Win for BMS and Pfizer’s APIXABAN Patents

Another Win for BMS and Pfizer’s APIXABAN Patents

Pankhuri Malik is an IPilogue Writer, IP Innovation Clinic Fellow, and an LLM Candidate at Osgoode Hall Law School.

On August 04, 2022, the Federal Court of Appeal (“FCA”) reaffirmed the Federal Court’s decision, upholding the validity of two of Bristol-Myers Squibb (“BMS”) and Pfizer’s patents. The relevant patents concerned the active pharmaceutical ingredient Apixaban, used in thrombosis treatment. Apixaban is a selective inhibitor of the enzyme Factor Xa (“FXa”) which works by blocking certain blood-clotting proteins.

Through its lawsuit, and subsequent appeal, Pharmascience Inc. (“PMS”) challenged the validity of two of BMS’s patents, Canadian Patent Nos. 2,461,202 (“202”) and 2,791,171 (“171”) on different grounds.

The 202 patent describes the action of many FXa inhibitors, including Apixaban, in thrombosis treatment. This patent was challenged by citing BMS’s expired patent, Canadian Patent Number 2,349,330 (“330”) on the following grounds:

  1. Lack of Status as a Selection Patent: Essentially, PMS alleged that the Federal Court did not identify the 202 patent as a selection patent and failed to appreciate that it does not disclose a special advantage over the 330 patent, which is essential for it to be recognized as a selection patent. The FCA, however, reaffirmed the lower court’s finding that a special advantage was disclosed by inference. FCA confirmed that Apixaban, under the 202 patent, was identified from the genus of compounds protected by the 330 patent because it was useful.
  2. Anticipation and obviousness, falling within the broad ambit of double patenting: PMS also claimed that the 202 patent did not identify the inventive concept of the claims in issue. PMS claimed that since 202 does not disclose a special advantage, the patent is fatally flawed due to anticipation and obviousness. The FCA disagreed and reaffirmed Federal Court’s finding that apixaban’s inventive concept is that it is an effective FXa inhibitor useful in treatment of Thromboembolic disorders, as opposed to the 303 patent which only had the potential to be useful.
  3. Insufficiency: Lastly, PMS challenged the 202 patent as Apixaban was not identified by the patentee at the date of publication of patent; PMS argued that this error constitutes insufficient of identification of the invention. The Court, however, disagreed PMS and held that the relevant specification for determination of sufficiency is the issued patent, and not the publicized patent.

The 171 patent relates directly Apixaban tablets’ formulation, particularly the particle size and dissolution rate of the medicine. The 171 patent describes the method of formulation such that it displays solution-like properties in the body, which optimize absorption.

The primary challenge was obviousness (as discussed here). The contention in this case pertained to a fifth additional component of the test, the “obvious to try” test. This component questions the validity of a patent on grounds that some inventions might be obvious to try due to their chemical structural similarity. PMS claimed that the Federal Court should have concluded that the claims in 171 are invalid because the invention was obvious to try.

However, FCA disagreed. The Court agreed with the lower court in that the formulations of the 171 patent are indeed inventive because a skilled person in the art would not have thought to reduce the particle size to improve absorption, or to target a lower dissolution rate. The FCA held that the lower court considered the correct and relevant factors in determining what would have been obvious to try to a person skilled in the art. The FCA confirmed that the lower court correctly held the patent valid.

Other jurisdictions

It is noteworthy that BMS and Pfizer’s patents for Apixaban have faced similar challenges outside of Canada as well. The companies have, so far, successfully enforced their patents in the USA. This Canadian decision adds another point to the companies’ win column.