Applicant Claims PTE Eligibility Based on PhotoCure Dicta; A Set-up to a Court Challenge?

By Kurt R. Karst –      

In our post last week on letters issued by the U.S. Patent and Trademark Office (“PTO”) clarifying when patents covering certain drug products are eligible for a Patent Term Extension (“PTE”) in light of the U.S. Court of Appeals for the Federal Circuit’s May 10, 2010 decisions in PhotoCure v. Kappos, 603 F.3d 1372 (Fed. Cir. 2010) and Ortho-McNeil Pharm., Inc. v. Lupin Pharms., Inc., 603 F.3d 1377 (Fed. Cir. 2010), we made reference to some dicta in the PhotoCure decision and a pending PTE request and promised to blog on that issue soon.  That time is now.

As we noted last week, the Federal Circuit’s PhotoCure decision, which interpreted the term “product” in the PTE statute at 35 U.S.C. § 156(a)(5)(A) to mean “active ingredient” instead of “active moiety,” contains dicta to the effect that a patent – in that case, U.S. Patent No. 6,034,267 covering the drug product METVIXIA (methyl aminoevulinate HCl) – is eligible for a PTE not only because methyl aminoevulinate HCL is a different chemical compound from previously approved aminolevulinic acid, but because “it is not disputed that they differ in their biological properties, warranting separate patenting and separate regulatory approval, although their chemical structure is similar.” 

Latching on to the above-quoted language, a PTE application was recently submitted to the PTO for U.S. Patent No. RE 41,571 (“the ‘571 patent”), a method-of-use patent listed in the Orange Book covering BUTRANS (buprenorphine) Transdermal System.  FDA approved BUTRANS under NDA No. 21-306 on June 30, 2010 “for the management of moderate to severe chronic pain in patients requiring a continuous, around-the-clock opioid analgesic for an extended period of time.” 

Buprenorphine is, of course, not new.  FDA has approved several applications for drug products containing buprenorphine, including BUPRENEX (NDA No. 18-401), SUBUTEX (NDA No. 20-732), and SUBOXONE (NDA No. 20-733).  Nevertheless, the PTE applicant for the ‘571 patent claims eligibility for a PTE because:

In contrast to these three products, the active ingredient for Butrans™ is buprenorphine base, which has never before been approved by the FDA. Moreover, buprenorphine base was required to undergo full FDA review, and has pharmacological properties that set it apart from buprenorphine hydrochloride.  Accordingly, the ‘571 patent that covers Butrans™ remains eligible for a patent term extension under 35 U.S.C. § 156.  See Photocure ASA v. Kappos, 603 F.3d 1372 (Fed. Cir. 2010) (allowing a § 156 extension even where similar active ingredient was previously approved by the FDA, since later approved active ingredient covered by extension application had different biological properties and underwent separate regulatory approval); Ortho-McNeil Pharm. v. Lupin Pharm. 603 F.3d 1377 (Fed. Cir. 2010) (allowing § 156 extension for enantiomer even though the racemate had already been approved by the FDA).

In other words, notwithstanding FDA’s previous buprenorphine NDA approvals, the PTE applicant believes that the ‘571 patent covering BUTRANS is eligible for a PTE because the drug product contains a different active ingredient (i.e., buprenorphine base) and has different properties that warranted separate patenting and separate FDA NDA approval (i.e., a different regulatory review period). 

The PTE statute does not contain the additional requirements of products having different properties that warrant separate patenting and separate FDA approval for PTE eligibility, and the PTO has historically hewed closely to the PTE statutory language in the Office’s decisions.  Moreover, as we noted last week, the PTO framed the eligibility inquiry in three parts: (1) Has the active ingredient been previously approved? (2) Has a salt of the active ingredient been approved? (3) Has an ester of the active ingredient been approved?  A "yes" to any of these questions means that permission does not meet the first permitted commercial marketing prong of 35 U.S.C. § 156(a)(5)(A).  Given the PTO’s interpretation of the PTE statute, it is possible that the BUTRANS PTE application was submitted to elicit a denial that can be challenged in court.