Sofosbuvir – USA

Sofosbuvir – USA

On Jun 21, 2017 a Federal Circuit panel affirmed a Patent Trial and Appeal Board (PTAB) ruling in Interference proceedings that Gilead Pharmasset LLC invented a hepatitis C treatment before Idenix Pharmaceuticals LLC and will be granted a patent.
The patent interference contest involved methods of treating hepatitis C by administering compounds having a specific chemical and stereochemical structure. The interference was declared between an issued patent (US 7,608,600, Storer; assigned to Idenix Pharmaceuticals) and a pending application (US11/854,218, Clark; assigned to Gilead), both of which were filed before the effective date of the America Invents Act. PTAB held that Storer’s provisional application was not enabling for the count of the interference, and on that ground the PTAB entered judgment granting priority to Clark. Storer appeals that judgment.
The only question focuses on whether the Storer’s provisional application together with the prior art enabled compounds having a 2´F(down) substituent. “When a party to an interference seeks the benefit of an earlier-filed United States patent application, the earlier application must meet the requirements of 35 U.S.C. § 120 and 35 U.S.C. § 112 ¶ 1 for the subject matter of the count.” Hyatt v. Boone, 146 F.3d 1348, 1352 (Fed. Cir. 1998). To establish enablement of a claim whereby new chemical compounds are provided for use to treat disease, the application must enable production or synthesis of the new compounds. In re Brebner, 455 F.2d 1402, 1404 (C.C.P.A. 1972).
The Board determined that the claimed compounds having a 2´F(down) substituent were not enabled in Storer’s S1 provisional application, in that undue experimentation would be required to produce this structure. The Board analyzed the disclosure in terms of the evidentiary factors set forth in Wands & concluded that:
(1) synthesis of a 2ˊ-fluoro-2ˊ-methyl nucleoside with the fluoro moiety in the “down” position required at least two years of a high-priority experimentation by persons skilled in the art, including multiple consultations with experts at the top of their fields and additional formal training;
(2) the S1 application provides little in the way of direction or guidance as to how to synthesize such a compound;
(3) the S1 application provides no explicit example of a 2ˊ-fluoro-2ˊ-methyl nucleoside, nor was an example provided by the relevant art as of the S1 application’s filing date;
(4) the invention is characterized as the administration of a genus of nucleosides used in the treatment of viruses, particularly those of the family Flaviviridae (which includes HBV and HCV) and an embodiment of the count requires a 2ˊ-fluoro(“down”) 2ˊ-methyl nucleoside;
(5) although organic fluoridation techniques were well-known in the art at the time the S1 application was filed, fluoridation of tertiary alcohols to produce a 2ˊ “down” tertiary fluorine was not taught or suggested by the prior art;
(6) the level of skill in the art was highly sophisticated: a person possessing the ordinary level of skill in this art, as of the time of invention, would hold a doctoral degree in the field of organic, synthetic, or medicinal chemistry with at least a year’s experience in the field of nucleoside synthesis or relevant drug discovery; and
(7) the art, at least with respect to fluoridation of tertiary alcohols to produce a tertiary fluorine in the 2ˊ “down” position, was highly unpredictable.
We therefore find that Wands factors 1, 2, 3, 5, and 7 strongly indicate that a person skilled in the art would not arrive at the claimed invention without undue experimentation.
On appeal Storer argues that the Matsuda reference, together with the information in the S1 provisional, enable synthesis of 2´F(down) compounds. On review, Federal circuit concluded that substantial evidence supports the Board’s findings that the synthetic schemes in Storer’s provisional application do not teach or suggest conversion of any precursor into the 2´F(down) structure, and that the Matsuda synthesis of a corresponding 2´- methyl (down), 2´-hydroxyl (up) structure does not enable a person of ordinary skill to produce the target compounds without undue experimentation.
The first Wands factor is concerned with “undue” experimentation, and recognizes that what is “undue” of itself depends on the subject matter and skill. The Board discussed the amount of experimentation needed to produce the claimed compounds, and correctly found that: a high amount of experimentation is necessary to synthesize a 2´-fluoro-2´-methyl nucleoside with the fluoro moiety in the “down” position, requiring at least two years of a high priority experimentation by persons skilled in the art, including multiple consultations with experts at the top of the fields and additional formal training.

Federal circuit finally concluded that substantial evidence supports the Board’s finding & we affirm the PTAB decision.
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