Shares in United Therapeutics (NSDQ:UTHR) fell today after the biotech company missed expectations on Wall Street with its 1st quarter results.

The Silver Spring, Md.-based company posted profits of $178.6 million, or $3.89 per share, on sales of $370.5 million for the 3 months ended March 31, for bottom-line loss of -24% on sales growth of 0.4% compared with the same period last year.

Adjusted to exclude 1-time items, earnings per share were $3.61, far behind consensus on The Street, where analysts were looking for sales of $399.6 million.

“Our quarterly financial growth trends are slower than we would like as we are seeing more patients stay longer on front-line pulmonary arterial hypertension therapies,” chairman & CEO Martine Rothblatt said in prepared remarks. “Due to the progressive nature of this disease, we believe that this building backlog of PAH patients ultimately will transition to more advanced therapies, such as Orenitram, Tyvaso and Remodulin. As the PAH patient backlog dynamics unfold, we are continuing to invest in our growing product pipeline of late stage programs in cardiopulmonary diseases and oncology and also in regenerative medicine and organ manufacturing to ultimately find a cure for PAH.”

UTHR shares were trading at $114.33 apiece today in morning activity, down -5.6%.

Earlier this month, shares in United took a hit after the company said that the U.S. commercial launch of Remosynch, Medtronic‘s (NYSE:MDT) implantable infusion pump for Remodulin, will be delayed until 2018.

Also in April, the Patent Trial and Appeal Board of the U.S. Patent and Trademark Office ruled that the claims of a United patent that covers Remodulin are unpatenable due to obviousness. SteadyMed (NSDQ:STDY) challenged the patent in October last year.

The patent, No. 8,497,393, relates to the process to purify prostacyclin derivatives, including treprostinil, which is the active ingredient in United’s Remodulin and SteadyMed’s Trevyent.