What: Shares of Spark Therapeutics (NASDAQ:ONCE), a leader in the field of gene therapy, ripped higher today by more than 50% at one point on tremendous volume. The fuel driving this rocket-like surge was the announcement that the company's lead experimental gene therapy product candidate, SPK-RPE65, met its primary endpoint of improving functional vision in an intervention group, relative to a control group, of patients with RPE65-mediated inherited retinal dystrophies. The company said SPK-RPE65 was also generally well-tolerated, with no serious adverse effects occurring in the experimental group as a result of treatment.  

Source: Wikimedia Commons

So what: On the scientific side of the ledger, gene therapy as a viable treatment modality is finally starting to make headway, at least for some diseases. And Spark's ability to successfully reverse some of the impacts of RPE65-mediated inherited retinal dystrophies with its experimental-stage product is certainly another important achievement for gene therapy as a whole. 

From an investment standpoint, the Street thinks SPK-RPE65 could eventually achieve peak sales of around $600 million, meaning that Spark's shares are presently trading at less than 3 times this estimate, even after today's huge move upwards.

Now what: Given the strength of these late-stage results, Spark's management plans on filing for the therapy's regulatory approval with the U.S. Food and Drug Administration in 2016. Before then, though, I would expect the company to take advantage of this spike in share price to raise funds via a secondary offering, which is almost standard procedure among clinical-stage biotechs following a positive clinical catalyst. Investors that missed this positive clinical catalyst therefore may have a chance to buy shares at a lower price in the days ahead. Stay tuned. 

George Budwell has no position in any stocks mentioned. The Motley Fool has no position in any of the stocks mentioned. Try any of our Foolish newsletter services free for 30 days. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.