Room Temp Prior Art Has Chilling Effect on Broadening Claim Language

By on January 22, 2020
Posted In Patents

In a case involving a patented method for purifying antibodies, the US Court of Appeals for the Federal Circuit determined that the process of chilling a composition to below room temperature could be found both obvious and anticipated by a process that purified that composition at room temperature. Genentech, Inc. v. Hospira, Inc., Case No. 18-1933 (Fed. Cir. Jan. 10, 2020) (Chen, J) (Newman, J, dissenting).

Genentech owns a patent related to a method of purifying antibodies. It was known in the art that this could be accomplished by running an antibody solution across a chromatography column coated with protein A. The antibodies bind to protein A while impurities and the rest of the composition pass through the column. The antibodies are then released from protein A by washing the column with a low pH solution. However, this process was known to release small amounts of the protein A from the column, contaminating the otherwise-purified antibody solution. The claimed invention solved this problem by significantly lowering the temperature of the composition to a “range from about 10°C to about 18°C.”

Hospira sought inter partes review (IPR) of the patent on multiple grounds of unpatentability, all of which relied on either WO’389 or van Sommeren as the primary reference. After institution, the Patent Trial and Appeal Board (PTAB) determined that all of the challenged claims were both anticipated and obvious by these two references. Genentech appealed the PTAB’s final written decision, challenging both its validity and the constitutionality of IPR proceedings as applied to patents issued before the enactment of the America Invents Act (AIA).

WO’389 taught a method for purifying certain antibodies using protein A chromatography, wherein “[a]ll steps are carried out at room temperature (18–25°C).” The Court found that this range overlapped with the claimed range of “about 10°C to about 18°C.” The Court explained that once a prima facie case of anticipation through overlapping ranges is established, it is the patentee’s burden to prove that the claimed range is critical to the operability of the claimed invention. Here, the Court agreed with the PTAB’s finding that Genentech failed to establish that the claimed temperature range was critical to performing protein A chromatography, and upheld the finding of anticipation in view of WO’389.

The Court also upheld the PTAB’s finding of obviousness in view of WO’389, noting that “even a slight overlap in range establishes a prima facie case of obviousness.” The Court determined that Genentech failed to demonstrate “that there is something special about the claimed range” in order to rebut this presumption of obviousness. The Court found that it would have been obvious to select this temperature range because it was known that these impurities were caused by proteolysis of protein A and that proteolysis is affected temperature.

In rebuttal, Genentech offered objective indicia of non-obviousness, including industry praise and recognition, and pointed to a presentation of the claimed invention that had been selected by the American Chemical Society. The Court found this evidence unpersuasive, noting that Genentech failed to establish a nexus between objective indicia of non-obviousness and the claimed method, because there was no evidence that the presentation was selected because of the claimed method.

Because the Court found that the PTAB did not err in its finding of invalidity based on WO’389, it did not address the PTAB’s invalidity findings based on van Sommeren.

The Federal Circuit also rejected Genentech’s constitutionality challenge, pointing to its recent decision in Celgene Corp v. Peter (IP Update, Vol. 22, No. 8), where the Court held that although an IPR differs from district court and pre-AIA US Patent and Trademark Office reexamination proceedings, those differences were not sufficiently substantive or significant such that a “constitutional issue” is created when IPR is applied to pre-AIA patents.

Judge Newman dissented from the Court’s finding of anticipation and obviousness in view of WO’389, arguing that the Court’s analysis was subject to hindsight bias. Newman further stated that “the abutment at 18°C between the claimed chilled temperature range and room temperature does not produce anticipation of the lower range,” and that no reference contemplated, suggested or hinted that chilling a composition below room temperature would eliminate the protein A contamination in the purified solution.

Practice Note: The claim term “about” can be used in a claimed range to allow patent drafters to catch potential infringers just outside the defined range, but may also introduce an overlap with prior art ranges that abut the outer limit of that claimed range.

Amy Mahan, PhDAmy Mahan, PhD
Amy Mahan focuses her practice on intellectual property matters in the life sciences, pharmaceutical and biotechnology sectors. She works on a variety of patent infringement litigation cases involving monoclonal antibody biologics, cell-based immunotherapies and small molecule drugs. Read Amy Mahan's full bio. 

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