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What happened

Shares of the clinical-stage biotech bluebird bio, Inc. (NASDAQ:BLUE) rose by more than 24% in pre-market trading today as a result of its experimental anti-BCMA CAR T (chimeric antigen receptor T-cell) cell product candidate bb2121 posting some stellar results in an early stage study for relapsed/refractory multiple myeloma.

Although this study was primarily focused on investigating the safety of bb2121 at various doses, Bluebird and its partner Celgene Corp. (NASDAQ:CELG) reported that seven of the first nine evaluable patients responded positively to the therapy. Perhaps even more encouraging, the only patients that have yet to exhibit some form of response (complete response, very good partial response, or partial response) received the lowest dose of bb2121.

Bluebird and Celgene also noted that no serious cases of cytokine release syndrome or neurotoxicity have been observed in the study so far. The pair plans on presenting the data today at the 28th EORTC-NCI-AACR Molecular Targets and Cancer Therapeutics Symposium in Munich, Germany. 

So what

While this study is exceeding small and not exactly geared toward testing the efficacy of bb2121, it's important to keep in mind that these were heavily pre-treated patients with few remaining options from a pharma standpoint. In other words, bb2121 appears to have the potential to be a breakthrough therapy for patients with advanced multiple myeloma.

Now what

Before investors get too excited, though, there are a couple of points to keep in mind. First off, this ongoing dose escalation study won't wrap up until December 2018, according to Put simply, this promising experimental therapy won't hit the market anytime soon.

Next up, bb2121's fairly pristine safety record will almost certainly get dinged up as the study progresses. CAR-T therapies, after all, have a checkered history in terms of safety and have even caused some deaths in clinical trials. 

All in all, these are definitely interesting data. But this rather early peek at the therapy's performance probably isn't a great reason to buy Bluebird's stock today.