Silence May Be Sufficient Written Description Disclosure for Negative Limitation

By on January 13, 2022
Posted In Patents

Addressing the issue of written description in a Hatch-Waxman litigation, the US Court of Appeals for the Federal Circuit affirmed the district court’s finding that the patent adequately described the claimed daily dose and no-loading dose negative limitation. Novartis Pharms. v. Accord Healthcare Inc., Case No. 21-1070 (Fed. Cir. Jan. 3, 2022) (Linn, O’Malley, JJ.) (Moore, CJ, dissenting).

Novartis’s Gilenya is a 0.5 mg daily dose of fingolimod hydrochloride medication used to treat relapsing remitting multiple sclerosis (RRMS). HEC filed an abbreviated new drug application (ANDA) seeking approval to market a generic version of Gilenya. Novartis sued, alleging that HEC’s ANDA infringed a patent directed to methods of treating RRMS with fingolimod or a fingolimod salt at a daily dosage of 0.5 mg without an immediately preceding loading dose.

The specification described the results of an Experimental Autoimmune Encephalomyelitis (EAE) experiment induced in Lewis rats showing that fingolimod hydrochloride inhibited disease relapse when administered daily at a dose of 0.3 mg/kg or administered orally at 0.3 mg/kg every second or third day or once a week, and a prophetic human clinical trial in which RRMS patients would receive 0.5, 1.25 or 2.5 mg of fingolimod hydrochloride per day for two to six months. The specification did not mention a loading dose associated with either the EAE experiment or the prophetic trial. It was undisputed that loading doses were well known in the prior art and used in some medications for the treatment of multiple sclerosis.

The district court found that HEC had not shown that the patent was invalid for insufficient written description for the claimed 0.5 mg daily dose or the no-loading dose negative limitation. The district court also found sufficient written description in the EAE experiment and/or prophetic trial and credited the testimony of two of Novartis’s expert witnesses. HEC appealed.

The Federal Circuit affirmed the district court’s decision. Turning first to the daily dose limitation, the majority held that the prophetic trial described daily dosages of 0.5, 1.25 or 2.5 mg and found no clear error by the district court in crediting expert testimony converting the lowest daily rat dose described in the EAE experiment to arrive at the claimed 0.5 mg daily human dose. Reciting Ariad, the Court explained that a “disclosure need not recite the claimed invention in haec verba” and further, that “[b]laze marks” are not necessary where the claimed species is expressly described in the specification, as the 0.5 mg daily dose was here.

Turning to the no-loading dose negative limitation, the majority disagreed with HEC’s arguments that there was no written description because the specification contained zero recitation of a loading dose or its potential benefits or disadvantages, and because the district court inconsistently found that a prior art abstract (Kappos 2006) did not anticipate the claims because it was silent as to loading doses. The Court explained that there is no “new and heightened standard for negative claim limitations.” The majority acknowledged that silence alone is insufficient disclosure but emphasized that written description can take any form so long as a skilled artisan would read the disclosure as describing the claimed invention. The majority again found no clear error by the district court in crediting expert testimony stating that the EAE experiment and prophetic trial did not include administration of a loading dose. Similarly, the Court found it was not clear error for the district court to find that a skilled artisan would read the specification as not including a loading dose while reading the Kappos 2006 abstract as silent on the presence or absence of a loading dose.

Chief Judge Kimberly A. Moore dissented, arguing that silence was not sufficient disclosure for the no-loading dose negative limitation. As Judge Moore observed, “There is no disclosure in the specification of preventing a loading dose. Loading doses—whether to be used or not—are never discussed. As the majority concedes, we have long held that silence cannot support a negative limitation; for if the specification is silent there is no evidence that the inventor actually possessed the invention.” In Judge Moore’s view, the majority decision contradicted well-established precedent and the US Patent and Trademark Office’s guidance in the Manual of Patent Examining Procedure, which provides that negative claim limitations are adequately supported only when the specification conveys to a skilled artisan that the inventor intended the exclusion, i.e., describes a reason to exclude the relevant limitation. She argued that if silence alone were sufficient, then every later-added negative limitation would be supported as long as the patent makes no mention of it, which is a fundamental error of law.

Practice Note: Issues related to written description in the context of biotech cases have been the subject of several recent Federal Circuit decisions (listed below) and, given the chief judge’s dissent, may be ripe for en banc review.

Mandy H. Kim
Mandy H. Kim focuses her practice on intellectual property litigation. Mandy has significant experience managing complex litigations across a wide range of technologies, including in the life sciences, biotechnology, medical devices, computer hardware and software, and consumer electronics industries. Mandy routinely handles motion practice, fact and expert discovery matters, and has litigated a number of cases from pleadings through trial and/or settlement. She has represented clients in federal and state courts, and before the International Trade Commission. Read Mandy H. Kim's full bio.