Although we don't believe in timing the market or panicking over market movements, we do like to keep an eye on big changes -- just in case they're material to our investing thesis.

What: Shares of Receptos (UNKNOWN:RCPT.DL), a clinical-stage biopharmaceutical company focused on developing therapies to treat various immune disorders, rocketed higher by as much as 40% after reporting positive phase 2 study results for RPC1063, its oral investigational treatment for relapsing multiple sclerosis, or RMS.

So what: According to Receptos' press release, which came just after the market close yesterday, in the phase 2 portion of its RADIANCE trial RPC1063 met its primary endpoint of reduction in MRI brain lesion activity. Most importantly, RPC1063 was deemed safe and well-tolerated. Specifically, the goal of the study was a reduction in the cumulative number of total gadolinium-enhancing lesions as determined by an MRI from the 12th week of treatment to the 24th week. As noted, patients experienced statistically significant gadolinium-enhancing lesion reductions of 86% at both the 0.5 mg and 1 mg dose. A phase 3 study involving RPC1063 is already under way per the Special Protocol Assessment pathway, and will pit RPC1063 against Biogen Idec's Avonex across 1,200 patients with relapsing multiple sclerosis.

Now what: There's no other way to look at this as anything but good news for Receptos and its shareholders. I will say that RMS is a tough disease to treat and Biogen Idec has quite the stranglehold on MS-based market share, so Receptos is going to have quite the fight on its hands even if RPC1063 does eventually gain approval. I am, however, always a bit leery of companies that only have one or two drugs in the development pipeline as a single failure can wipe out a lot of shareholder value. In this case Receptos is studying RPC1063 in RMS and ulcerative colitis, and RPC4046 as a possible treatment for eosinophilic esophagitis. Two investigational drugs and only three indications means there's a lot riding on Receptos' nearly $900 million valuation. For now, I'm happily sticking to the sidelines.