Emphasizing the need for a reasonable expectation of success in finding a claim invalid based on obviousness, the US Court of Appeals for the Federal Circuit affirmed the lower court's decision that Dr. Reddy's Laboratories (DRL) failed to prove the asserted claim was invalid. Genzyme Corporation v. Dr. Reddy's Laboratories, Ltd., Case No. 2017 WL 6418934 (Fed. Cir., Dec. 18, 2017) (Chen, J).
Asserted claim 19 of US Patent No. 7,897,590 is directed to "a method to obtain progenitor and/or stem cells" by (1) administering G-CSF to a subject; (2) administering plerixafor or a pharmaceutically acceptable salt thereof to the subject, in an amount effective to mobilize the progenitor and/or stem cells; and (3) harvesting the progenitor and/or stem cells.
Under normal conditions, stem cells are anchored to the bone marrow through a bond between CXCR-4 located on the stem cell and a protein (SDF-1) produced in the bone marrow. Plerixafor disrupts this bond, releasing the stem cell from the bone marrow into the bloodstream, so that the stem cells can then be collected from a patient's blood.
DRL argued that claim 19 of the '590 patent was obvious in view of either (1) Hendrix and US Patent No. 5,824,304, or (2) WO 00/45814 (WO '814) and the '304 patent.
Hendrix disclosed an increase in white blood cells (WBCs) in the peripheral blood of HIV patients after an administration of plerixafor and hypothesized that the binding of plerixafor to CXCR4 may inhibit the chemotactic effects of SDF-1 causing release of WBCs from the endothelium and/or stem cells from bone marrow. WO '814 also disclosed that administration of plerixafor elevated WBC levels. The '304 patent taught that administering an agent that inhibits binding between the VLA-4 receptor on stem cells and the VCAM-1 ligand found in the bone marrow could increase the number of stem cells in peripheral blood, and that G-CSF mobilized stem cells from the marrow to the peripheral blood by stimulating the production of stem cells.
DRL argued that the only difference between the claimed invention and the '304 patent was the use of plerixafor, and that Hendrix and/or WO '814 would have led a person of skill in the art to use plerixafor to mobilize stem cells, noting that Hendrix hypothesized that plerixafor could be used to mobilize stem cells from bone marrow.
The district court rejected DRL's arguments. First, the court found that Hendrix (and WO '814) and the '304 patent were not analogous art—Hendrix and WO '814 taught use of plerixafor for use in treatment of HIV, whereas the '304 patent was related to the field of mobilizing stem cells for harvest and transplantation—and that DRL failed to show that a person of skill in the art would have pursued CXCR-4 over other possible stem cell mobilizers. Second, the district court found that even if Hendrix were deemed analogous art, DRL failed to show that a person of ordinary skill would have had a reasonable expectation of success in achieving the claimed invention by combining the prior art, because of unpredictability in the art and a history of failure in the field of stem cell mobilization.
In affirming, the Federal Circuit noted that CXCR-4 is in a completely different receptor family than VLA-4, and there was no evidence or expectation that CSCR-4 and VLA-4 would behave similarly concerning mobilization. The Federal Circuit also found that the district court reasonably rejected DRL's attempts to draw an analogy between the two results based on ample evidence showing that an increased WBC count did not necessarily correlate to stem cell mobilization. Finally, the Federal Circuit noted that the district court's finding of a high degree of unpredictability in the art also ran counter to an expectation of success.
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