Background
Corcept Therapeutics marketed Korlym® (mifepristone) for treatment of Cushing’s syndrome — a condition caused by excessive cortisol production. Corcept held patents on methods of treating patients with mifepristone in combination with strong CYP3A inhibitors (drugs that slow the metabolism of mifepristone), requiring dose adjustments when the two drug classes are used together. Teva filed an ANDA seeking to market generic mifepristone and submitted a label that largely tracked the Korlym label, including instructions about mifepristone’s interaction with CYP3A inhibitors.
Corcept sued for patent infringement, arguing that Teva’s proposed label would induce physicians to infringe the method-of-treatment patents covering the mifepristone-CYP3A inhibitor combination. Teva argued that its label did not encourage the specific combination claimed in the patent — that the label’s drug interaction warnings were informational rather than instructional. The district court found infringement.
The Court’s Holding
The Federal Circuit affirmed. The court found that Teva’s proposed label would actively induce infringement of Corcept’s method-of-treatment patents because the label’s instructions — including dosing guidance for patients who were also taking CYP3A inhibitors — would encourage physicians to prescribe mifepristone in the combination covered by the patents. The label’s drug interaction section specifically guided physicians on how to adjust mifepristone doses when CYP3A inhibitors were co-administered — language that directly described practicing the claimed method.
The court rejected Teva’s argument that its label should be read to discourage co-administration. The critical question for induced infringement in ANDA cases is whether the label’s instructions will lead physicians to practice the patented method — and when a label includes specific guidance on how to adjust dosing in a combination therapy, that label encourages the claimed combination therapy even if it doesn’t affirmatively recommend it.
Key Takeaways
- In Hatch-Waxman ANDA litigation, a generic drug label that includes specific dosing guidance for a patented drug combination therapy can support induced infringement even if the label doesn’t affirmatively recommend the combination — the key is whether the instructions will lead physicians to practice the claimed method.
- Drug interaction sections of ANDA labels must be carefully drafted to avoid describing the patented combination therapy — if dose adjustment instructions for a co-administered drug combination track the patent’s method claims, the label may support induced infringement.
- Skinny label carve-outs (omitting patented indications) are less effective when the drug interaction information that would need to be omitted is required safety labeling under FDA regulations — creating tension between FDA labeling requirements and patent protection strategy.
- Method-of-treatment patents covering drug combination therapies and dosing adjustment protocols can effectively block generic entry even when the underlying drug compound is off-patent, provided the method claims cover a therapeutically necessary drug combination.
Why It Matters
Corcept Therapeutics v. Teva highlighted a significant strategic tension in pharmaceutical patent litigation between FDA labeling requirements and generic drug market entry. When FDA requires that a generic drug label include drug interaction warnings describing a patented method of use — such as dosing guidance for a combination therapy — the generic manufacturer faces a dilemma: omit the required safety information (potentially risking FDA rejection) or include it (potentially constituting induced infringement).
The decision reinforced the viability of method-of-treatment patents as a means of extending pharmaceutical market exclusivity beyond compound patent expiration — a strategy sometimes called “method patent continuation” or “evergreening” in the pharmaceutical industry. For generic manufacturers, the ruling underscored the complexity of navigating method-of-treatment patents in ANDA proceedings, particularly for drugs used in complex patient populations where combination therapy and dose adjustment are medically necessary and reflected in required labeling.