Broad claim language may render patent invalid under obviousness

Originally published by Haynes and Boone Benefits Group.

Eric Li
Counsel
Haynes and Boone, LLP

In BTG Int’l Ltd. v. Amneal Pharms. LLC (Fed. Cir. May 14, 2019), the Federal Circuit affirmed the decisions of the Patent Trial and Appeal Board (PTAB) and the District Court in a consolidated appeal addressing whether generic versions of an anti-cancer drug infringed the claims of U.S. Patent No. 8,822,438 (the ’438 patent) held by BTG International Ltd (BTG).  The PTAB and the District Court found that the asserted claims of the ’438 patent were obvious and therefore invalid. The Federal Circuit focused on one of the final written decisions of the PTAB, which it affirmed, rendering the remaining appeals moot.

Background

BTG produces Zytiga (abiraterone acetate), a CYP17 inhibitor used in conjunction with prednisone to treat refractory prostate cancer.  The ’438 patent discloses a method to treat cancer by administering a therapeutically effective amount of a CYP17 inhibitor and a therapeutically effective amount of an additional therapeutic anti-cancer agent or a steroid.  With more specificity, independent claim 1 of the patent claims a treatment method combining a therapeutically effective amount of abiraterone acetate and a therapeutically effective amount of prednisone.

Appeal

The central issue for the Federal Circuit was whether a person having ordinary skill in the relevant art would have known that prednisone could be used as a cancer treatment.  Prednisone had been part of the standard of care for treating refractory prostate cancer prior to issuance of the ’438 patent, but BTG asserted that its patent required that prednisone have a direct anti-cancer effect on its own, as opposed to its well-known use of reducing side effects of co-administered cancer treatment.  However, the Federal Circuit determined that the “treatment” described in the ’438 patent could mean either a direct anti-cancer effect, or a palliative effect reducing toxicity of abiraterone.

The Federal Circuit’s analysis began with the claim language and specification.  Independent claim 1 claims a method for the treatment of prostate cancer comprising administering a therapeutically effective amount of prednisone along with abiraterone.  The specification defines a “therapeutically effective amount” of a “therapeutic agent” as an amount for treating a disease or disorder such as cancer, and states that a “therapeutic agent” may be either “an anti-cancer agent or a steroid.”  The Federal Circuit concluded that the use of “or” in the specification suggested that a steroid is not necessarily the same thing as an anti-cancer agent.

The Federal Circuit discussed how, if BTG intended to limit “treating” and “therapeutic agents” to “anti-cancer agents,” the patent would not have identified steroids separately as agents for reducing adverse side effects of CYP17 inhibitors, nor described prednisone in the specification as a steroid without mentioning any anti-cancer effect.  Thus, the Federal Circuit concluded that treatment with prednisone must logically include more than just anti-cancer effects, and should include the long-familiar use of steroids for palliation and reduction of side effects.

The Federal Circuit determined that the prosecution history also supported this conclusion.  During prosecution, the examiner initially rejected claims based on a combination of prior art discussing abiraterone’s anti-cancer effects and the treatment of refractory prostate cancer by co-administering prednisone to relieve the toxicity of anti-cancer drugs.  The examiner subsequently allowed the claims after determining that the unexpected commercial success of abiraterone in combination with prednisone overcame the obviousness rejection.  The examiner also noted that the cited art did not suggest that there would be a difference in survival rates between one cancer agent alone versus the same agent combined with prednisone.

Thus, the Federal Circuit concluded that the prosecution history was consistent with the understanding that the claimed treatment requires the combination of abiraterone with prednisone,   and the claims would not have been allowable otherwise.  However, the Federal Circuit agreed with the PTAB that a person having ordinary skill in the art would have had a reasonable expectation of success in combining abiraterone and prednisone because they were both considered, together and individually, promising prostate cancer treatments at the time.  In particular, a combination of prior art taught that (1) patients with hormone refractory metastatic prostate cancer responded favorably to a combination of ketoconazole (a CYP17 inhibitor) and prednisone; (2) abiraterone treats prostate cancer by suppressing testosterone, and it is common to administer a supplemental glucocorticoid; (3) prednisone alone significantly reduces PSA levels, an indicator of disease activity, in patients with hormone-refractory prostate cancer.

Although administration of glucocorticoids such as prednisone had not demonstrated a survival advantage at the time the ’438 patent was filed, the law only requires a reasonable expectation of success.  In addition, while BTG’s product did have considerable commercial success, BTG also owned a blocking patent that would have deterred others from exploring the commercial potential of abiraterone.  Accordingly, the Federal Circuit rejected BTG’s appeal, and held that its patent was invalid based on obviousness.

Conclusion

Although the ’438 patent focused on prednisone’s anti-cancer effects, the patent also contained broad language about prednisone’s use as a steroid, and because prednisone was already being used in treating refractory prostate cancer for the traditional palliative effects associated with steroids, the asserted claims were rejected as obvious.  As the Federal Circuit stated, if BTG intended to limit “treating” and “therapeutic agents” to anti-cancer agents, the claim would not have also identified prednisone as a steroid and an agent for reducing adverse effects of abiraterone.  Thus, patent drafters would be wise to craft specific claims and be wary of using overly broad language in their specification.

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