By Siew Chong
On remand from the Federal Circuit, the Patent Trial and Appeal Board (PTAB) has granted a motion to amend in a patent directed to methods of treatment using cabazitaxel, a taxane compound. Mylan Labs. Ltd. v. Aventis Pharma S.A., IPR 2016-00712, Paper 112 (Oct. 22, 2019).

Mylan filed a petition requesting inter partes review of claims 1-5 and 7-30 of U.S. Patent No. 8,927,592 (the ‘592 patent) on Mar. 14, 2016. After the PTAB instituted review of all challenged claims on obviousness grounds, Sanofi (the parent of Aventis Pharma) filed a contingent motion to amend in conjunction with the Patent Owner’s Response. In a final written decision, the PTAB held that the challenged claims were unpatentable and denied Sanofi’s motion to amend the claims after finding that Sanofi had not met its burden of proving that the proposed amended claims were patentable. Mylan, Paper 99 (Sep. 21, 2017).

The Board’s decision was based on its construction of Sanofi’s proposed amended claim, which recites, “[a] method of increasing survival comprising administering to a patient in need thereof . . . .”   Sanofi argued that the preamble “increasing survival” is a limitation that confers patentability to the claim as the prior art did not suggest that the recited method of treatment would increase patient survival. The Board instead held that the preamble merely provides an additional description to the claim and does not give an “intentional purpose” for performing the method of treatment.

Shortly after, the Federal Circuit issued an en banc decision holding that the petitioner in an IPR, not the patent owner, bears the burden of persuasion on the patentability of challenged claims, original or amended. Aqua Products, Inc. v. Matal, 872 F.3d 1290, 1325 (Fed. Cir. 2017). Sanofi then appealed the Board’s claim construction and denial of the motion to amend to the Federal Circuit.

On review, the Federal Circuit vacated the Board’s denial of Sanofi’s motion and remanded for further proceedings. Writing for the panel, Judge O’Malley held that the Board improperly placed the burden on Sanofi to prove patentability of the proposed amended claims. Sanofi Mature IP v. Mylan Labs. Ltd., 757 Fed. Appx. 988, 991 (Fed. Cir. 2019).

Judge O’Malley also held that the Board incorrectly construed the preamble of the claim as non-limiting. The Fed. Cir. held that the claim at issue “closely mirrors” claims in prior Fed. Cir. cases, Rapoport v. Dement, 254 F.3d 1053 (Fed. Cir. 2001); Jansen v Rexall Sundown, Inc., 342 F.3d 1329 (Fed. Cir. 2003). In both cases, the Fed. Cir. found that a preamble identifying a method of treatment gives proper antecedent basis to the phrase “to a patient in need thereof.”

The Fed. Cir. panel also held that the preamble was limiting because it “articulated the purpose for which the method must be performed.” Sanofi at *993. Because the claims at issue have “nearly parallel” language to the claims in Jansen and Rapoport, the Fed. Cir. held that the preamble for the proposed amended claim is also limiting. Id. (The claim at issue in Jansen recited, “[a] method of treating or preventing macrocytic-megaloblastic anemia in humans . . . to a human in need thereof . . . .” The claim at issue in Rapoport recited, “[a] method for treatment of sleep apneas . . . to a patient in need of such treatment . . . .”)

The opinion also noted that the conclusion that Sanofi’s preamble was limiting was consistent with the specification of the challenged patent, which emphasizes improved survival rates of patients.

On remand, the Board analyzed whether Mylan had met its burden of proving the proposed amended claims were anticipated or obvious. By the effective filing date of the ’592 patent, a phase III clinical trial (TROPIC study) for testing cabazitaxel was already underway. The Board found that the TROPIC study did not anticipate the proposed amended claims because there was insufficient evidence that the treatment would work for its intended purpose. The Board also found that the study was only testing the hypothesis that cabazitaxel would increase survival, and was not a showing that there was a reasonable expectation of increased survival. Hence, Mylan had failed to prove obviousness, as well.

The Board also considered the testimony of expert witnesses for both Mylan and Sanofi and concluded that although the experts had expressed “hope” that the recited method would increase survival, that hope did not equate to a reasonable expectation of increased patient survival. Mylan, Paper 122, p. 16. The Board further found that the TROPIC study did not describe the premedication steps recited in the proposed claims.

In opposing the motion to amend, Mylan also asserted that the amended claims were not patent eligible because they were directed to a mental process intended to increase survival. The Board analyzed the proposed claims under the two-step Mayo/Alice subject matter eligibility test, as laid out in the 2019 Revised Patent Subject Matter Eligibility Guidance, 84 Fed. Reg. 50 (USPTO Jan. 7, 2019) (Guidance). Under Step 1 of the test, which queries whether the claims recite patentable subject matter, the Board found that the claims recite a process. Mylan, Paper 122, p. 28. In Step 2A, prong one, the Board found that the “intentional purpose” of the claim is a mental process, an abstract idea which falls into a judicial exception to patent eligibility.

However, under Step 2A, prong 2, the Board found that the intended purpose of increasing survival, albeit a mental process, has been integrated into a method of treatment. The Board concludes that when a mental process is directed to a method of treatment, it is not an abstract idea. Id. at p. 29. (citing Vanda Pharms. Inc. v. West-Ward Pharms, 887 F.3d 1117, 1134 (Fed. Cir. 2018)).

The Board’s decision illustrates how the shift in the burden of persuasion enabled Sanofi to obtain a seldom granted motion to amend in an IPR. The favorable outcome from the Board’s evaluation of the proposed amended claims according to the Subject Matter Eligibility Guidance in conjunction with the Vanda decision affirming patent eligibility of treatment method claims are also encouraging developments for patent owners defending treatment method patents in IPRs.

A practice note for drafting treatment methods claim, especially when relying on a phrase in the preamble for patentability, would be to repeat the phrase in the body of the claim, e.g., “and wherein the survival of the patient is improved.”