In a Post-Grant Review (“PGR”) at the U.S Patent and Trademark Office (“USPTO”), a petitioner can challenge the validity of a patent on several grounds including prior art, on-sale or public-use activity, and lack of compliance with 35 USC 112 (for example, lack of enablement, written description, or definiteness).

Last month, in a decision in an early pharma PGR, the USPTO upheld the validity of Paragon Bioteck’s U.S. 8,859,623 (“the ‘623 patent”). Altaire Pharmaceuticals had challenged the ‘623 patent, asserting that its claims were invalid as obvious over Altaire’s previously-sold product.

The ‘623 patent claims a method for dilating pupils by administering a composition containing an aqueous buffer and stable R-phenylephrine hydrochloride having a chiral purity of at least 95% at the time of administration. According to the ‘623 patent, R-phenylephrine hydrochloride is unstable, and “often turns brown over time and cannot be used.” The ‘623 patent stated that it had overcome such stability problems. Altaire argued that its prior art product was stable and rendered the ‘623 claims obvious.

There was no dispute that Altaire’s products contained all elements of the ‘623 claims except for the required chiral stability of R-phenylephrine hydrochloride.

The USPTO found that Altaire’s products did not render the ‘623 claims obvious because Altaire had not proven, by a preponderance of the evidence (“more likely than not”), that its product contained the required chiral stability because the standard HPLC method used by Altaire to determine stability was unreliable.

This finding leads to more questions than answers:

1. Can Paragon prove infringement in a future litigation?

The USPTO interpreted the ‘623 claims as requiring 95% chiral purity at the time of administration. Assuming the same interpretation during litigation, can Paragon show the required purity exists at the required time given that an accused infringer likely would not have control over and/or involvement in the time of administration?

2. What happened to 35 USC 112?

As noted above, invalidity under 35 USC 112 can be asserted in a PGR. So, issues such as enablement and indefiniteness are in play. Why weren’t they pursued here? In particular, two red flags exist indicating that the ‘623 claims could have difficulty satisfying section 112.

First, Altaire’s previous product contained all elements of the ‘623 claims except the required chiral stability of R-phenylephrine hydrochloride. So, apparently, all compositions having all required claim elements do not necessarily result in the required chiral stability. In view of this, does the ‘623 patent enable one of ordinary skill in the art to obtain the required stability (and avoid unstable compositions)?

Second, the standard HPLC method used by Altaire is apparently inadequate to determine chiral stability. If accurately determining such stability depends upon the testing methodology used, can one of ordinary skill in the art readily determine whether compositions satisfy the stability requirements in the ‘623 claims or not? If results vary based on testing methodology used, are the claims clear regarding which compositions fall inside or outside the claims?

3. Why was obviousness the contested issue, not anticipation?

The only prior art discussed in the USPTO opinion was Altaire’s previous product. No combination of references was discussed. Given that the only prior art was Altaire’s previous product and that the only issue was whether the R-phenylephrine hydrochloride in this product was inherently stable, wasn’t the issue really one of inherent anticipation, not obviousness?

So, a lot of questions, but not many answers.

Perhaps the only take-away lesson from this PGR is to make sure you consider all bases of invalidity – including section 112 – when filing a PGR.