Douglas H. Carsten

Douglas Carsten’s practice focuses on life sciences patent litigation. The co-chair of the firm’s global life sciences practice has handled billion-dollar patent cases involving pharmaceuticals, biologics, medical devices, diagnostic products and more.

He represents longtime biotechnology client United Therapeutics Corp. in its HatchWaxman patent infringement suit against Liquidia Technologies. United Therapeutics Corporation v. Liquidia Technologies, Inc., 1-20-cv-00755 (D. Del., filed June 4, 2020), IPR2020-00770 IPR2020- 00769 (PTAB, filed March 30, 2020), IPR2021-00406 (PTAB, filed Jan. 7, 2020), 22-2133, (CAFC, filed Sept. 1, 2022).

United alleged that Liquidia’s proposed product, Yutrepia, infringes three patents related to United’s Tyvaso (treprostinil) product, which treats pulmonary arterial hypertension.

Carsten and his team filed the suit in response to Liquidia’s FDA application to market a generic formulation of United’s Tyvaso. Following the bench trial in March 2022, Judge Richard Andrews ruled that Liquidia’s product infringes a United patent that relates to a method of administering treprostinil via inhalation.

Carsten said securing the ruling came down to two things: having good experts on United’s side and effective cross of the opponent’s experts. United’s experts effectively demonstrated to the court that based on the disclosure of the patent, a person ordinarily skilled in the art was able to make the invention as claimed within a month and with little experimentation, he said.

“The one-two punch of effective, real-world expert testimony of someone who actually went into the lab, coupled with effective cross-examination, set out a path that we like to think the judge was able to really understand,” Carsten said.

After Liquidia sought inter partes review (IPR) of the patent, the Patent Trial & Appeal Board invalidated the patent in a final written decision. However, Judge Andrews stated that the IPR decision has no impact on his decision and issued an order delaying Liquidia’s FDA approval. United is expected to file an appeal of the PTAB decision in the Federal Circuit.

The judge found another patent to be invalid, and that case is also on appeal. Oral arguments were scheduled for May 3.

United had $873 million in net product sales for Tyvaso in 2022. Beyond the multimillion-dollar stakes, Carsten said, the case is also about protecting innovation.

“It does come down to protecting the IP and innovation that these great companies are doing on a day-to-day basis. Standing in front of a judge, saying, ‘We are innovating,’ doesn’t cut it. The proof is in the pudding — you can’t claim to be innovating when you’re violating someone else’s IP,” he said.

—Jennifer Chung Klam