MannKind shares slide 22% as FDA delays review of Tyvaso DPI new drug application

Inhalable insulin specialist MannKind Corp. (NASDAQ:MNKD) announced that the FDA is extending its deadline to review United Therapeutics’ (NASDAQ:UTHR) new drug application (NDA) for Tyvaso DPI from February to May.

MannKind is developing Tyvaso DPI (treprostinil) in collaboration with United Therapeutics.

The drug candidate Tyvaso DPI would potentially treat pulmonary arterial hypertension and pulmonary hypertension associated with interstitial lung disease.

MNKD shares fell 22.54% to $2.84 in afternoon trading, while UTHR shares dipped 13.81% to $166.45.

FDA has asked for additional information about the pulmonary safety of Tyvaso DPI related to a pending citizen petition filed in July 2021. The petition questions the safety of fumaryl diketopiperazine (FDKP), an excipient used in Tyvasson DPI. The excipient is also used in MannKind’s inhalable insulin product Afrezza.

The petition requests that FDA require additional testing of FDKP, which it describes as an “irritant” potentially associated with “a serious risk of acute bronchospasm in patients with chronic lung disease, such as asthma and chronic obstructive pulmonary disease.”

On Oct. 15, 2021, the FDA issued a complete response letter for Tyvaso DPI outlining its decision to decline approval of the NDA at that time based on an open inspection problem associated with third-party testing of the treprostinil drug substance.

FDA approved an inhalation solution form of Tyvaso in 2009. An indication followed in 2021 for the treatment of pulmonary hypertension associated with interstitial lung disease.