BEDMINSTER, N.J.— Drug companies are fond of saying that every patient counts, but in the world of orphan diseases, entire business plans are built around the idea.

That is why Andrew E. Jablonski, a 26-year-old from Lincoln, Nebraska, was a guest of honor this month at NPS Pharmaceuticals, a small New Jersey company that is about to begin selling Gattex, its only approved drug. Mr. Jablonski, who was born missing most of his intestines and has a condition known as short bowel syndrome, is central to the company’s mission to win over the tiny pool of patients— fewer than 5,000 nationwide— that the drug is intended to treat.

Over the last two years, NPS has carefully tended its relationship with Mr. Jablonski, helping to finance his nonprofit, the Short Bowel Syndrome Foundation, and flying company leaders to visit him in Lincoln. On January 15th, he met with the chief executive and strategized with marketing employees about how to promote Gattex to his social network of 1,000 patients and caregivers.

“It’s a nice, close relationship,” Mr. Jablonski said. “I’m an asset to them, as they are an asset to me.”

NPS hopes that Gattex will ultimately bring in hundreds of millions of dollars in annual sales and help establish the company in the increasingly hot orphan drug market, where companies can charge premium prices to treat overlooked diseases with little or no competition. NPS expects to charge about $300,000 a year for Gattex, a breathtaking price tag that is nonetheless on par with other ultra-orphan drugs on the market.

Development of these drugs is increasingly attractive to pharmaceutical companies, which are searching for new sources of revenue as sales of more traditional, mass-market drugs have been lost to generic competition. The orphan drug market was worth more than $50 billion in 2011 and turns out blockbusters at the same rate as the broader industry, according to a recent Thomson Reuters analysis. Pfizer opened a rare disease unit in 2010, and in 2011, Sanofi acquired the biotech company Genzyme, considered one of the pioneers of the orphan drug industry.

As orphan drugs have become increasingly popular, companies have honed their marketing techniques, knowing that they cannot afford to lose a single patient. Following in the footsteps of drug makers like Vertex, which makes the cystic fibrosis drug Kalydeco, NPS has formed close bonds with advocates like Mr. Jablonski and hired so-called patient care coordinators who will do everything from making sure that Gattex is delivered to patients’ doorsteps to writing appeal letters if an insurer refuses to pay for it.

Much is riding on the drug’s success: Gattex is the centerpiece of a comeback plan for NPS, which nearly folded six years ago after a previous drug, to treat osteoporosis, failed to win approval from the Food and Drug Administration. After that setback, the company closed its Utah office and laid off nearly all of its more than 400 employees. NPS has since shifted its focus to orphan drugs and now employs about 140 people, including 27 new sales representatives hired to sell Gattex.

Read more at The New York Times.  Written by Katie Thomas.