Naltrexone HCl & Bupropion HCl – USA

Naltrexone HCl & Bupropion HCl – USA

On Aug 15, 2019, Federal Circuit affirmed-in-part & reversed-in-part district court’s decision regarding Contrav® patents related to extended release composition & method of use patents.
This appeal is related to Nalpropion’s patents, US 7,375,111; US 7,462,626 and US 8,916,195. The ’626 patent is drawn to a method for treating over-weight or obesity comprising administering this combination. The ’195 patent is also directed to methods of treating overweight or obesity, but the claims are drawn to specific dosages of sustained-release naltrexone and bupropion that achieve a specific dissolution profile. The ’111 patent is directed to a composition of sustained-release bupropion and naltrexone for affecting weight loss.
Appellee Nalpropion Pharmaceuticals, Inc. holds NDA for & market Contrave® for weight management in overweight or obese adults. Actavis filed ANDA with USFDA to market generic version of Contrave®. In response to the infringement suit in district court, Actavis brought invalidity counter-claims, challenging claim 11 of the ’195 patent as invalid for lack of adequate written description and challenging claim 1 of the ’111 patent and claims 26 and 31 of the ’626 patents as invalid as obvious. The district court held a bench trial on all of these issues and held each claim not invalid and infringed. Actavis appealed.
a. Appeal regarding written description –

Claim 11 of the ’195 patent recites a method of treating overweight or obesity comprising orally administering about 16 mg of naltrexone and about 180 mg of bupropion, both in sustained-release formulations administered twice daily. This method claim also requires that the claimed naltrexone formulation have an in vitro dissolution profile. Actavis argued that claim 11 of the ’195 patent lacked adequate written description support because its claimed dissolution profile was achieved using the USP Apparatus 2 Paddle Method (“USP 2”), but the specification discloses data obtained using the different USP Apparatus 1 Basket Method (“USP 1”). According to Actavis, both inventor and expert testimony demonstrated that the two dissolution methods would produce different results.
Federal Circuit said that it is important to take note of the peculiarity of claim 11, which begins clearly enough by reciting a method of treating overweight or obesity by carrying out the specific, positive steps of administering a formulation of specific amounts of sustained-release naltrexone and bupropion in twice a day. Dissolution profile as measured by USP 2 relates only to the measurement of resultant in vitro parameters, not to the operative steps to treat over-weight or obesity. Federal Circuit sided with district court & said that, irrespective of the method of measurement used, the specification shows that the inventors possessed the invention of treating overweight or obesity with naltrexone and bupropion in particular amounts and adequately described it. District court correctly concluded, on the facts, that USP 1 and USP 2 would be “substantially equivalent.” Having found USP 1 and USP 2 substantially equiva-lent, the district court found Table 5 and Table 10 ade-quately supported the dissolution data ranges in claim 11.
Federal Circuit, however, said that…”While as a general matter written description may not be satisfied by so-called equivalent disclosure, in this case, buttressed by the district court’s fact-finding, and where the so-called equivalence relates only to resultant dissolution parameters rather than operative claim steps, we affirm the district court’s conclusion. Rigidity should yield to flexible, sensible interpretation”.
b. Appeal regarding obviousness –

Actavis challenged claim 1 of the ’111 patent and claims 26 and 31 of the ’626 patent as obvious in view of O’Malley and Jain. O’Malley (US 6,541,478) in general relates to Smoking Cessation Treatments Using Naltrexone and Related compounds. Claim 1 of O’Malley is drawn to a method of treating a person for nicotine dependency and minimizing weight gain during smoking cessation therapy comprising “administering . . . an effective amount of naltrexone and another compound selected from the group consisting of . . . bupropion. . . .” Jain is a research paper entitled “Bupropion SR vs. Placebo for Weight Loss in Obese Patients with Depressive Symptoms.” Jain discloses that “preliminary studies suggest that bupropion SR is also an effective adjunct to diet for weight loss during acute and long-term therapy in nondepressed patients” and “is associated with weight loss in overweight or obese depressed patients.
District court rejected Actavis’s obviousness argument & said that the weight loss effects of bupropion were known to be relatively modest at best, and prior art references reported potential risks, including a potential for seizures. Because a person of skill would not understand bupropion’s mechanism of action and because of its modest effectiveness, a person of skill would not have found bupropion to be an obvious starting point for further study. The district court was also convinced that a person of skill would not have understood naltrexone to be effective for weight loss. As for the combination of the two drugs, the district court concluded that prior arts did not teach a person of ordinary skill that the combination was effective for weight loss. According to the court, neither reference teaches anything about weight loss or that naltrexone enhances bupropion’s weight loss effects.
On appeal, the parties primarily dispute whether a person of skill would have been motivated to combine bupropion and naltrexone with reasonable expectation of success. Federal Circuit held that, given that both drugs had shown weight loss effects, a person of ordinary skill would have been motivated to combine them. A person of skill would have understood that a combination for reducing weight gain and decreasing carbohydrate cravings may affect weight loss as well. Nalpropion argued that bupropion does not possess sufficient weight loss efficacy to obtain FDA approval by itself. Therefore, a person of skill would not have been motivated to develop bupropion for weight loss. Federal Circuit, however disagreed & said that “[t]here is no requirement in patent law that the person of ordinary skill be motivated to develop the claimed invention based on a rationale that forms the basis for FDA approval.” Allergan, Inc. v. Sandoz Inc., 726 F.3d 1286, 1292 (Fed. Cir. 2013). “Motivation to combine may be found in many different places and forms; it cannot be limited to those reasons the FDA sees fit to consider in approving drug applications.” Also, every limitation in the claims at issue was met by O’Malley and Jain. Federal Circuit finally rejected objective indicia of nonobviousness & reversed the district court’s holding that these claims are not invalid.
Thus, Federal Circuit affirmed written description decision & reversed non-obviousness decision of district court.

Chief Judge, Prost in dissent criticized the “substantially equivalent” test for written description requirement. She said that based on her understanding of this court’s precedent, she would find claim 11 of the ’195 patent invalid for lack of adequate written description. She essentially differed in 3 aspects: First, the USP 2 clause is limiting. Second, the majority’s “substantially equivalent” rule is inconsistent with this court’s precedent. Third, the district court clearly erred in finding that the ’195 patent’s written description includes a disclosure “substantially equivalent” to USP 2.
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