Silence May Support Negative Claim Limitation

| Nima Zargari, Ph.D.Jeremy Anapol


Before Moore, Linn, and O’Malley.  Appeal from the United States District Court for the District of Delaware.

Summary: A patent application that was silent about a “loading dose” of a drug provided written description support for a negative claim limitation requiring the absence of such a dose.

HEC Pharm Co., Ltd. and HEC Pharm USA Inc. (collectively, “HEC”) filed an Abbreviated New Drug Application (“ANDA”) for a generic drug to treat multiple sclerosis.  Novartis Pharmaceuticals Corp. (“Novartis”) sued HEC, alleging that HEC’s ANDA infringed U.S. Patent No. 9,187,405 (“the ’405 patent”).  The district court found that the ’405 patent was not invalid and that the ANDA infringed.  HEC appealed to the Federal Circuit, arguing that the ’405 patent is invalid because its claims fail the written description requirement of 35 U.S.C. § 112(a).

The Federal Circuit affirmed, finding sufficient written description support for excluding a “loading” (larger than normal) dose from the claimed treatment method.  The ’405 patent described dosing regimens for both an experiment on rats and a potential clinical trial on humans, without mentioning a loading dose for either regimen.  The Federal Circuit found no clear error in the district court’s finding, based on expert testimony, that these dosing regimens would have indicated to a person of ordinary skill that the claimed invention lacked a loading dose.

Chief Judge Moore dissented, arguing that the patent’s silence about loading doses could not support the negative limitation requiring their absence.

Editor: Paul Stewart