What happened

Shares of Akcea Therapeutics (NASDAQ:AKCA) soared 60% on Monday after the biopharmaceutical company announced that it had agreed to be bought out by Ionis Pharmaceuticals (NASDAQ:IONS).

So what

Ionis will acquire the 24% of Akcea's stock it doesn't already own for $18.15 per share, a premium of about 63% compared to its closing price on Friday. The all-cash deal values Akcea at roughly $500 million.

Two people in business suits shaking hands

Ionis Pharmaceuticals and Akcea Therapeutics are joining forces. Image source: Getty Images.

The purchase will enable Ionis to capture more of the potential profits from Akcea's product pipeline and allow it to access Akcea's $390 million in cash reserves. Ionis also expects cost cuts to boost the combined company's profitability. "This acquisition is another step forward in Ionis' evolution and creates a stronger, more efficient organization to the benefit of all stakeholders," Ionis CEO Brett Monia said in a press release.

Now what

The deal follows the release of positive phase 2 data for Akcea's experimental treatment for hypertriglyceridemia, which showed significant reductions in triglyceride levels among study participants. Akcea also recently released promising phase 2 data for a potential treatment for certain cardiovascular diseases, which also demonstrated significant reductions in triglyceride levels among patients.

Ionis and Akcea say that together, they will be able to accelerate the development of these therapies. "We believe becoming one company -- with one vision and one set of strategic priorities, led by one team -- will deliver significant strategic value, enhancing the future success of our company, accelerating our next phase of growth and positioning us to most effectively deliver our medicines to patients," Monia said.