Biotech firm Isis Pharmaceuticals (IONS -1.52%) announced in a press release Tuesday that the Food and Drug Administration has approved  the company's regulatory application for Kynamro, a treatment for a dangerous form of high cholesterol known as homozygous familial hypercholesterolemia (HoFH). Isis developed Kynamro alongside Genzyme, a division of French pharmaceutical giant Sanofi (SNY 0.68%).

The FDA does want Isis and Genzyme to watch  the drug's long-term safety profile, and to conduct four post-marketing studies. Nonetheless, the approval is good news for the two companies, after the FDA earlier indicated a link between Kynamro and heightened rates of cancerous and liver side effects when the drug was used in rare cases of HoFH.

The FDA's advisory committee voted for approval in a 9-6 vote earlier, setting up Tuesday's regulatory approval. The verdict will allow Isis to collect a $25 million milestone payment, while furthering Sanofi's plans to develop its drug revenues of the future.

Genzyme's CEO and President Dr. David Meeker announced his enthusiasm in the press statement, saying:

As the leader in treatments for rare diseases, we are pleased to bring our expertise to HoFH patients living with this serious condition to better help them manage their disease.

Shares of Isis roared in aftermarket trading, jumping 8.3%.