It is well established that objective evidence of nonobviousness (e.g., commercial success, long-felt but unresolved needs, unexpected results, etc.) must be taken into account when evaluating the obviousness of a claimed invention. This standard applies during patent prosecution, in proceedings before the PTAB, and in litigation. However, as demonstrated by a recent IPR decision involving Kyle Bass’s Coalition for Affordable Drugs[1], it can be can be challenging to provide sufficient evidence of unexpected results and long-felt need.

The patent at issue in this IPR, US 7,582,621, relates to treatment of infections, including nail fungus, using tavaborole. The patent owner asserted many theories of nonobviousness, including unexpected results and long-felt need. The patent owner’s theories did not convince the panel, which held the claims of the ’621 patent to be unpatentable over the petitioner’s cited art. With respect to the arguments related to unexpected results and long-felt need, the panel found that the patent owner failed to provide sufficient evidence of either factor.

The patent owner argued that a 1000-fold selective toxicity for fungi over humans was unexpected. However, the patent owner did not identify the closest prior art and thus gave the panel no meaningful frame of reference in which to evaluate whether the selective toxicity was indeed unexpected, resulting in the panel essentially dismissing the patent owner’s arguments.

The patent owner also argued (i) that there was a long-felt need for a safer and more effective topical treatment for nail fungal infection, (ii) that the only available treatment at the time, ciclopirox, was not very effective, and (iii) that attempts by other pharmaceutical companies to develop better treatments were unsuccessful. The patent owner further argued that tavaborole met the long-felt need. Interestingly, the panel did not challenge whether a long-felt need existed but instead questioned whether tavaborole actually satisfied the need. The panel stated that the patent owner did not provide “sufficient and credible evidence” to show that tavaborole was more effective than ciclopirox. As a result, the panel concluded that it remained unclear whether tavaborole met the long-felt need.


The panel’s inability to reach a conclusion regarding the credibility of the patent owner’s arguments related to unexpected results and long-felt need emphasizes a key point in presentation of evidence: Both of these secondary considerations require comparison of the claimed invention to a reference point in order to tie the alleged invention to the objective indicia of nonobviousness. In order to avoid being in the position of the patent owner in this IPR, it is important to identify the appropriate frame of reference needed—for example, the closest prior art for unexpected results—and to be prepared to compare the claimed invention to the frame of reference to show that it was actually the invention, and not some other aspect of the product or drug, that led to the improved results. Given how long it can take to generate comparative experimental evidence, it could be advantageous to try to identify potential frames of reference as early as possible, even as early as the patent application drafting stage.