Over six years ago, the Federal Circuit vacated a preliminary injunction against Lupin, finding that a substantial question of invalidity of U.S. Patent No. 6,866,866 had been raised, allowing Lupin to continue its at-risk launch of a metformin hydrochloride extended-release tablet.1 Following this decision, Lupin reached a settlement with the patentee and related parties (Andrx) that acknowledged Lupin’s right to enter the generic market, as of September 1, 2011, over nine years before the expiration of the ‘866 patent.
Recently, in a final written decision in an inter partes review, the Patent and Trial Appeal Board (PTAB) denied Aurobindo’s challenge of the validity of the ‘866 patent, reasoning that the PTAB is not bound by the Federal Circuit’s findings on appeal from a preliminary injunction.2 The Federal Circuit’s finding that Lupin raised a substantial question of validity was of no help to Aurobindo in its PTAB proceedings.
In the Federal Circuit appeal and PTAB proceedings, Lupin and Aurobindo respectively argued that claim 1 of the ‘866 patent was obvious from the combination of Timmons and Cheng, two published patent applications. Also, in both proceedings, Andrx did not dispute that Cheng discloses all of the limitations of claim 1 except for the Tmax limitation (“the dosage form provides a mean time to maximum plasma concentration (Tmax) of the metformin from 5.5 to 7.5 hours after administration following dinner”).
The PTAB criticized Aurobindo because its Tmax limitation arguments were based entirely on the findings of the Federal Circuit in Sciele, and its evidence of record did not provide a factual basis for its argument that the combination of Timmons and Cheng renders the Tmax limitation obvious, particularly the calculations that resulted in the court’s opinion in Sciele that “Timmons discloses a range of possible mean Tmax between 4.67 and 6.33 hours” were not made of record before the PTAB. The PTAB observed that even if Timmons discloses a range of possible mean Tmax between 4.67 and 6.33 hours, that does not allow a conclusion that Timmons discloses a mean Tmax between 5.5 and 7.5 hours. While the PTAB agreed with the Federal Circuit that based on the teaching of Timmons, a skilled artisan would have been motivated to lower the Tmax, it found insufficient evidence that the skilled artisan would have targeted the specific mean Tmax range recited in claim 1. The PTAB further observed that 4.67-6.33 hours as disclosed in Timmons does not include 6.34-7.5 hours, which is over half of the range recited in claim 1. Thus, the PTAB concluded that Aurobindo had not made a sufficient showing that a person of ordinary skill in the art would have been motivated to make a dosage form that provides a mean Tmax between 5.5 and 7.5 hours and had not shown by a preponderance of the evidence that claim 1 of the ‘866 patent is obvious over Timmons and Cheng.