“Obvious to Try” Rationale Insufficient to Institute IPR Trial Directed to Venlafaxine

5541491_sThe rate at which the Board denies inter partes review petitions has been climbing in recent months, and will be helped along by the Board’s denial of review in Neptune Generics v. Auspex Pharm., IPR2015-01313.  Neptune Generics filed a challenge to Auspex Pharmaceuticals’ patent no. 7,456,317, which covers a “deuterated form of venlafaxine, an inhibitor of monoamine neurotransmitters.”  The Board found the prior art did not teach the patented substitution of deuterium for hydrogen, nor that such a substitution would have been obvious to try, and thus denied review of all challenged claims.

The patent taught that the deuterated form is more stable (and thus has better pharmacokinetics and toxicity profiles) than normal venlafaxine.  Petitioner asserted that it would have been obvious to substitute deuterium (an isotope of hydrogen) for the hydrogen in venlafaxine.  Petitioner relied on two pieces of prior art:  Fogelman, showing the transformation of venlafaxine into its two major metabolites; and Miwa, showing a carbon-deuterium bond is stronger than a carbon-hydrogen.  Petitioner argued, with a supporting expert declaration, that a person of ordinary skill would have used Miwa’s teaching (not directed to venlafaxine) to modify venlafaxine because cleavage of hydrogen (via a hydroxyl group) is part of venlafaxine’s metabolism.  The Board found the record did not establish that a person of ordinary skill in the art would have been motivated to modify venlafaxine to change its metabolism, and, further, that the effect of the substitution explained by Miwa is unpredictable and varies depending on what compound it is applied to, and there was no specific teaching to modify venlafaxine in that way (or a reasonable expectation of success).  Further, Petitioner failed to show that switching deuterium for hydrogen would have been obvious to try, because there are over 124 million possible deuterated forms of venlafaxine, and no prior art teaching as to which should be used.

In the pharma space, “obvious to try” challenges are common. It is interesting to see the Board’s treatment of the issue here, and another IPR bullet dodged by a pharma patent owner.