JPMorgan's Cory Kasimov and Jefferies' Biren Amin called Bluebird Bio (BLUE) the "star" of the weekend at the American Society of Hematology conference. Well, they've got another one in their camp: TheStreet's own Jim Cramer.

Speaking on CNBC's "Mad Dash" segment, Cramer pointed to the massive gains in Bluebird stock. Shares were up as much as 30% in premarket trading, but have since cooled to "just" 20%, with shares trading near $204 in Monday's regular session.

Bluebird has made some excellent progress in its CAR-T treatments and that gives reason for hope. While there is no proven cure for cancer, these immunotherapy treatments are showing a lot of promising technology, Cramer reasoned.

"Bluebird is a fabulous technology company" in the biotech industry, he said, adding that it is "the standout" from the ASH conference this year. Bluebird is coming up with some concrete breakthroughs with this technology and that's great. It's providing "good hope," not false hope, explained Cramer, who also manages the Action Alerts PLUS charitable trust portfolio.

Goldman Sachs wasn't the only one to up its price target on Bluebird following its presentation, but it did give BLUE the highest target, at $309. Analysts rate it a conviction buy, with their price target implying about 50% upside.

Cramer also pointed out some other stock moves from the sector. Celgene (CELG) is up 2.5% and BioMarin (BMRN) is up 7%, while Spark Therapeutics (ONCE) is down a whopping 42%.

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At the time of publication, Cramer's Action Alerts PLUS had no position in any security mentioned.

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