Federal Circuit affirms ruling to reject flu patent

The US Court of Appeals for the Federal Circuit has affirmed the Patent Trial and Appeal Board’s (PTAB) decision to reject a patent application centring on an influenza drug.

Relenza (zanamivir) is a treatment for infection by an influenza virus, and was invented by Constantin Efthymiopoulos, who had applied for a patent relating to methods of administering the drug through inhalation.

One of the rejected claims states that zanamivir should be administered by inhalation through the mouth alone.

Before the case reached the PTAB, the US Patent and Trademark Office (USPTO) noted that with respect to the method of using the drug, there would only be two possible inhalation methods, either oral or nasal.

In its ruling, the Federal Circuit explained: “In view of the other prior art references that taught the well-known availability of inhalers, that oral inhalation delivers more drug to the lungs than nasal inhalation, and the fact that influenza infects the lungs, the examiner concluded that treating influenza by oral inhalation of zanamivir would have been obvious.”

The PTAB had agreed with the USPTO ruling and affirmed all of the claim rejections.

Efthymiopoulos sought a rehearing with the PTAB, which again rejected the case, and he appealed further to the Federal Circuit, which also affirmed the USPTO’s initial decision.

The inventor argued that the PTAB erred in rejecting the pending claims as obvious, and further argued that a person of ordinary skill would not have expected that the administration of zanamivir only through inhalation by the mouth would be effective.

He added that at the time the drug was invented, it was thought that the delivery of anti-influenza drugs to the upper respiratory tract was required to be more effective.

The court said: “Efthymiopoulos’s argument that a skilled artisan would not reasonably expect zanamivir to be effective if administered through oral inhalation is also unpersuasive.”

It added: “We thus conclude that the board [PTAB] correctly affirmed the examiner’s [USPTO] rejection of all pending claims as obvious.”