Effectiveness of Multiactive Inhibitors Insufficient to Support Utility of Selective Inhibitor for Fighting Cancer

In Rasmusson, et al. v. Smithkline Beecham Corporation (Fed Cir.; June 27, 2005), the claims related to a method of treating prostate cancer by using finasteride as a selective 5?R inhibitor. Both parties agreed that a person of ordinary skill in the art at the time of Rasmusson’s applications would have recognized that finasteride was a selective 5?R inhibitor. However, the parties disagreed as to whether a person of ordinary skill in the art would have believed, before June 27, 1990, that finasteride would be effective in treating prostate cancer

The court noted that there were various references demonstrating that multi-active 5?R inhibitors were effective in treating prostate cancer. However, it still required proof as of the filing date of the application regarding the utility of selective 5?R inhibitors in fighting cancer:

Rasmusson did not make any contrary showing that a person of ordinary skill in
the art as of the filing date of the third application would have recognized
that a selective 5?R inhibitor in general, or finasteride in particular, would
be effective in treating prostate cancer. In particular, the evidence cited by
Rasmusson on appeal does not contravene the Board’s finding, because that
evidence is either dated too late with respect to the respective filing dates of
the applications or pertains only to the use of multi-active inhibitors to treat
prostate cancer.

In order to obtain a priority date earlier than June 27, 1990, Rasmusson needed to provide experimental proof that his invention could be effective in treating cancer. Because Rasmusson failed to do so and obtained a priority date only as of the filing date of his ’296 application, the Board was correct to find that all applications prior to that application were not enabled, and that Rasmusson is not entitled to a priority date earlier than the priority date of SmithKline’s ’310 and ’553 patents and the corresponding reissue applications.

Rasmusson argues that the enablement requirement of section 112 does not mandate a showing of utility or, if it does, it mandates only a showing that it is "not implausible" that the invention will work for its intended purpose. As we have explained, we have required a greater measure of proof, and for good reason. If mere plausibility were the test for enablement under section 112, applicants could obtain patent rights to "inventions" consisting of little more than respectable guesses as to
the likelihood of their success. When one of the guesses later proved true, the
"inventor" would be rewarded the spoils instead of the party who demonstrated
that the method actually worked. That scenario is not consistent with the
statutory requirement that the inventor enable an invention rather than merely
proposing an unproved hypothesis. Because we have upheld the Board’s
determination of priority due to lack of enablement, it is unnecessary for us to
address the Board’s ruling regarding lack of adequate written description.