What happened

Shares of drugmaker Dova Pharmaceuticals (NASDAQ:DOVA) rose by 86.5% in September, according to data provided by S&P Global Market Intelligence.

This added to Dova's big gains in 2019, piggybacking on a June jump of 59.9%. Year to date, the company's shares have skyrocketed 271.2%. And it's all thanks to one drug.

An eyedropper drips clear liquid into a test tube.

Dova Pharmaceuticals' outperformance is due to the success of a single drug, Doptelet. Image source: Getty Images.

So what

The big winner for Dova has been Doptelet, a treatment for adults who don't have enough platelets in their blood. Platelets are the blood cells that cause clotting, so people who don't have enough -- a condition known as thrombocytopenia -- can be at risk of excessive bleeding due to injury or surgery.

Doptelet was already approved to treat thrombocytopenia in adult patients with chronic liver disease who were about to undergo surgery. As you can imagine, that's a very limited pool of potential patients. In June, however, the Food and Drug Administration gave additional approval to Doptelet for use in patients with chronic immune thrombocytopenia (ITP) who have had an insufficient response to a previous treatment. That caused Dova's stock to soar.

It also attracted the interest of drugmaker Swedish Orphan Biovitrum (OTC:SWTUY), also known as Sobi, which focuses on rare diseases with a major interest in hematology (blood disorders). Sobi agreed to acquire Dova for $27.50 a share, a 36% premium, to gain access to the company's platelet treatments and additional U.S. market exposure. The deal also offers Dova shareholders an additional "$1.50 per share upon approval of Doptelet for use in Chemotherapy-Induced Thrombocytopenia (CIT)" by the FDA.

Now what

If you're a Dova shareholder, congratulations -- this is about the best possible outcome one can get when purchasing shares of a small biotech company. Right now, the stock price is hovering around $28.20 per share, meaning the market is assigning about a 50-50 chance of getting that CIT approval from the FDA. But the difference between today's price and the full $29 per share is just 2.8%, so most Dova investors will probably just want to sell at the current price rather than wait around.

If you're not already a Dova shareholder, there's no real point to buying the stock now. Consider taking a look elsewhere in the sector.