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 Agios Pharmaceuticals (NASDAQ:AGIO), a clinical-stage biopharmaceutical company developing cancer therapies, vaulted higher by as much as 27% after the company on Sunday released initial data on its phase 1 study of AG-221, an oral inhibitor of IDH2 mutations, in patients with hematological malignancies (i.e., blood cancers).

So what: According to its press release, Agios' preliminary data for AG-221 demonstrated that the drug was well-tolerated and safe. More importantly, though not the initial goal of its phase 1 study, AG-221 demonstrated promising clinical activity, including complete clinical remissions, even at the lowest-tested dose. Overall, six of seven evaluable patients had an objective response, with three complete responses and two complete remissions with incomplete platelet recovery, and one patient with a partial response.

Now what: I know this is an early stage study that hasn't even had a maximum tolerated dose established yet, and shareholders should really keep this in mind while reviewing the press release so as not to allow their emotions to get the best of them, but WOW -- three complete responses out of seven evaluable patients is incredible! Obviously I'd like to see how well AG-221 translates into a much larger trial as the current sample size is small, and the only true focus of this initial study was safety and tolerability, which look to be met based on its initial data.

This also looks like it could be a nice win for Celgene (NASDAQ:CELG), which is partnered with Agios in the development of AG-221. Celgene hasn't been shy about partnering up with smaller clinical-stage companies, and it appears that, in the early stages at least, this partnership could be paying off. While I would still urge investor caution as these are merely early-stage initial results, I would also waste no time in at least getting Agios added to your watchlist.