An invention must be useful to be patentable. The utility requirement, as explained by the Supreme Court in Brenner v. Manson, stems from the U.S. Constitution and the congressional intent that to receive a patent monopoly the invention must have a substantial utility and a specific current benefit.
An area where the utility requirement has had a significant impact is the patenting of genes and gene products such as biomarkers and their uses. In In re Fisher, the Federal Circuit held that expressed sequence tags are not patentable unless the functions of the corresponding gene are known or identified. It is increasingly clear that such uses as research intermediates or tools for monitoring gene expression (or other for-further-research types of utility) are not enough where the underlying gene lacks substantial and specific utility.
It is often the case that a patent application on a therapeutic or a diagnostic invention is filed before any clinical trial result is available. In fact, in many cases no human trials have even begun before patent filing. In general, one does not have to show a definitive correlation between a particular activity and an asserted therapeutic use of a compound, nor is evidence needed of actual success in treating humans. What is required is a reasonable correlation between the biological activity and the use asserted in the claims.
If appropriate, one way to satisfy the utility requirement is to include evidence of structural similarity between claimed compounds and a compound known to have a particular therapeutic, diagnostic, or pharmacological utility. Also worth noting is that data from in vitro assays or animal models, if reasonably correlated to the particular therapeutic, pharmacological, or diagnostic utility, may be sufficient to satisfy the utility requirement.
It should be noted that the nature and amount of evidence needed depends on the claim sought by the patent applicant. If one claims that a compound is useful in “treating a symptom” of an incurable disease it is likely to need less evidence or support than where one claims that the compound is useful in “curing” the disease.
Similarly, claims directed to the use of broad classes of agents, or treatment for multiple conditions, will generally require more written support than claims that are directed to a particular class or condition. Patent counsel should be apprised of the desired claim scope and the available evidence that could support the asserted utility.