Novo Nordisk A/S v. Caraco Pharmaceutical Laboratories, Ltd., 719 F.3d 1346

Novo Nordisk appeals a district court ruling that claim 4 of the '358 patent is invalid as obvious and that the patent is unenforceable due to inequitable conduct; the court affirms in part and reverses in part.
The patent concerns treating Type II diabetes with combination therapy of repaglinide (an insulin secretagogue) and metformin (an insulin sensitizer).
Prior art showed synergies with other metformin combinations; repaglinide/metformin combination data included the Moses Study (HbA1c and FPG improvements) and a Sturis rat study suggesting synergy.
Novo filed a provisional patent in 1997; the examiner initially rejected as obvious; Novo argued synergy based on the Moses Study and Sturis Declaration; patent issued in 2004 with Claim 4 unchanged.
Caraco filed an ANDA in 2005 and asserted obviousness and inequitable conduct; the district court found claim 4 obvious and the patent unenforceable for inequitable conduct; on appeal, the Federal Circuit affirmed in part and reversed in part.
The opinion discusses burden-shifting in obviousness, the predictability of synergy, the Kappos v. Hyatt question on consideration of new evidence, and the post-Therasense standards for materiality and intent.

Issue	Plaintiff's Argument	Defendant's Argument	Held
Was the burden of persuasion correctly allocated in the obviousness analysis?	Novo argues the court shifted the burden to the patentee after a prima facie showing.	Caraco contends proper burden-shifting allowed considering countervailing evidence of unexpected results.	No reversible error; burden allocation was proper.
Did Caraco prove that the repaglinide/metformin results were expected in view of the prior art?	Novo argues the combination yielded unexpected synergy not anticipated by prior art.	Caraco argued prior art, especially metformin with sulfonylureas, supports expected synergy.	The court affirmed that the district court correctly found the results were expected in light of the prior art.
Should the examiner’s prior findings on synergy have been given deference under Kappos v. Hyatt?	Novo argues the PTO findings should be given deference as in PTO review cases.	Caraco argues deference is inappropriate in this Hatch-Waxman context or that new evidence can alter findings.	Hyatt is inapplicable; no deference owed to PTO findings in this district court patent case.
Did the district court err in finding inequitable conduct by Sturis and Bork?	Novo contends the Sturis Declaration omissions and Bork’s statements were not material or intentional.	Caraco argued materiality and intent under pre- and post-Therasense standards.	The court reversed the inequitable conduct findings as to Sturis and Bork (materiality/intent not upheld).

Pfizer v. Apotex, Inc., 480 F.3d 1345 (Fed. Cir. 2007) (burden of proving invalidity remains with challenger; burden does not shift to patentee)
In re Cyclobenzaprine Hydrochloride Extended-Release Capsule Patent Litig., 676 F.3d 1063 (Fed. Cir. 2012) (reaffirmed proper burden-shifting approach in obviousness; cannot rely solely on prima facie evidence)
Therasense, Inc. v. Becton, Dickinson & Co., 649 F.3d 1276 (Fed. Cir. 2011) (post-Therasense standard for materiality and intent in inequitable conduct)
KSR Int’l Co. v. Teleflex Inc., 550 U.S. 398 (U.S. 2007) (Gives a practical, flexible approach to obviousness; supports real-world considerations)
In re Kao,, 639 F.3d 1057 (Fed. Cir. 2011) (illustrates scope and sufficiency of evidence for nonobviousness across embodiments)
In re Merchant, 575 F.2d 865 (CCPA 1978) (closest prior art; nonobviousness depends on novelty over the closest reference)
In re Lain, 747 F.2d 703 (Fed. Cir. 1984) (considers property of a compound in nonobviousness analysis)
Eisai Co. v. Dr. Reddy’s Labs., Ltd., 533 F.3d 1353 (Fed. Cir. 2008) (unpredictability in chemical arts affects obviousness assessment)
Standard Oil Co. v. Am. Cyanamid Co., 774 F.2d 448 (Fed. Cir. 1985) (inventor’s path not determinative of obviousness; person of ordinary skill standard)