Federal Circuit applied Amgen v. Sanofi, 598 U.S. 594 (2013)in deciding that claims 1-4, 19 and 20 of Baxalta's hemophilia patent, U.S. Patent 7,033,590 ('590), were invalid as lacking an enabling disclosure.

Hemophilia A is a blood clotting disorder where the activity of Factor VIII is functionally absent, thereby impeding the coagulation cascade and the body's ability to effectively form blood clots. Historically, Hemophilia A has been treated by intravenously administering Factor VIII. However, approximately 20–30% of Hemophilia A patients do not benefit from this treatment because their bodies develop Factor VIII inhibitors (i.e., antibodies against Factor VIII). The '590 patent sought to treat hemophilia with antibodies which increase the procoagulant activity of Factor IXa by binding to Factor IX/IXa. The court identified Claim 1 as representative of the claims on appeal and recites:

1. An isolated antibody or antibody fragment thereof that binds Factor IX or Factor IXa and increases the procoagulant activity of Factor IXa.

The inventors used standard techniques to generate thousands of antibodies which were screened for increased Factor IXa activity. Only 1.6% of the screened antibodies increased Factor IXa procoagulant activity. The '590 patent disclosed the amino acid sequences that increased Factor IXa procoagulant activity. The disclosed antibodies were monospecific, i.e., bind to a single antigen. The claim encompassed not only monospecific antibodies but also bispecific antibodies which bind to two different antigens and humanized antibodies with no disclosure of specific antibodies having the necessary Facto IXa binding activity. The district court granted summary judgment of invalidity.

The Federal Circuit affirmed because in its opinion the facts were indistinguishable from those in Amgen, a research project to identify the claimed antibody by preparing antibodies and then identifying first those that bound to Factor IXa and then determining if those antibodies increased the Factor IXa procoagulant activity. Stated differently, the '590 patent inhibited the progress of useful arts by precluding others from developing better/alternative antibodies not enabled by '590 for activating Factor IXa without infringing the '590 claims. See LeRoy v. Tatham, 55 U.S. 156, 175 (1852). Enablement can be tested by determining whether one seeking to make alternative antibodies can avoid repeating a research project similar in scope to that of the inventors. If not, then the claims are not enabled.

In both Amgen and Baxalta the claims effectively claimed a natural law, binding to an antigen to have a therapeutic effect, a defense not raised to date in the antibody cases. The advantage to this defense is that the issue can be decided on a motion to dismiss.

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