Liquidia loses patent ruling on YUTREPIA PH-ILD indication

Liquidia Corporation has suffered a partial defeat in its Hatch-Waxman litigation with United Therapeutics, after the US District Court for the District of Delaware ruled that claims 1 and 14 of United Therapeutics' '327 patent are both valid and infringed by YUTREPIA (treprostinil) inhalation powder. The remaining four claims asserted against Liquidia were found invalid.

The two surviving claims broadly cover the treatment of pulmonary hypertension associated with interstitial lung disease (PH-ILD) using inhaled treprostinil, encompassing dry powder formulations. The court has directed both parties to submit a proposed form of judgment, including their preferred remedies, within one week. United Therapeutics has previously asked for injunctive relief that could restrict YUTREPIA's availability on the market, a request that now moves closer to resolution.

What the ruling means for YUTREPIA

YUTREPIA received FDA approval in 2025 for two indications: pulmonary arterial hypertension (PAH) and PH-ILD. The PAH approval is not directly implicated by the '327 patent litigation. However, the PH-ILD label is now at material risk. Liquidia's chief executive Roger Jeffs acknowledged the ruling but signalled the company would not go quietly: "We respectfully disagree with the Court's decision regarding claims 1 and 14 and are fully prepared to pursue all available appellate options." The company also confirmed it intends to submit a supplement to YUTREPIA's New Drug Application to the FDA specifically to remove PH-ILD from the label, a pre-emptive step that could limit the scope of any injunction.

Potential remedies range from that voluntary label narrowing at the milder end to a broader restriction on product availability at the more severe. Liquidia said it cannot reasonably estimate the financial exposure at this stage, given the range of variables including further proceedings and possible appeals.

Competitive and regulatory context

The Hatch-Waxman framework governs patent disputes arising from abbreviated drug applications and is the standard litigation pathway when a generic or follow-on competitor challenges a branded product's exclusivity. United Therapeutics' Tyvaso DPI, also an inhaled dry powder treprostinil approved for both PAH and PH-ILD, is the direct commercial rival to YUTREPIA. The two products compete for the same patient population, and the patent dispute reflects the commercial stakes in a market where pulmonary hypertension treatments can carry substantial annual list prices.

From a regulatory read-across perspective, a label removal via NDA supplement is a well-established manoeuvre in Hatch-Waxman disputes. Its success in limiting injunctive relief is not guaranteed, however: courts have at times found that voluntary label changes made in the shadow of litigation do not fully insulate a defendant from broader injunctive remedies, particularly where the infringing product remains on the market in a commercially significant form. Appellate options through the Court of Appeals for the Federal Circuit, which specialises in patent matters, could extend the timeline by two to three years.

Liquidia also markets a generic treprostinil injection for PAH and is developing L606, an investigational extended-release nebuliser formulation of treprostinil. Neither pipeline asset is affected by the current ruling, though the litigation cloud over YUTREPIA is likely to weigh on investor sentiment until the remedy phase is resolved.