SUMMIT, NJ (TheStreet) -- Celgene (CELG) - Get Report was known as the savviest collaborative deal maker in biotech. That honorific has to be called into question after Celgene announced a plan Monday to buy a $1 billion, stake in Juno Therapeutics (JUNO) and its CAR-T cancer immunotherapy platform at more than twice Juno's current market value.

Under terms of the 10-year collaboration, Celgene is buying 9.1 million shares of Juno at $93 per share -- a 102% premium to Juno's closing price of $46.30. Juno will also receive a $150 million upfront licensing fee from Celgene.

For its investment, Celgene secures an option to be the ex-U.S. commercialization partner for Juno's platform of CAR-T cancer immunotherapies targeting certain blood cancers, plus other potential co-development and marketing rights.

The partnership is a tremendous show of support for Juno as it battles Novartis (NVS) - Get Report, Kite Pharma (KITE) , Bluebird Bio (BLUE) - Get Report and other companies developing therapies which use re-engineered T cells to identify and kill cancer cells.

But investors will undoubtedly raise questions about the high price paid by Celgene to get into bed with Juno, especially since CAR-T therapies are still years from the market in certain blood cancers and may never be an effective treatment for solid tumors. Celgene's investment feels desperate unless a competitive bidding process forced the company to open the wallet super wide.

"Bottom line is we like that Celgene is making a big commitment to CAR-T as we think this will be an important hematological platform in the future -- but certainly would agree with the likely pending consensus view that the price tag is also big," writes RBC Capital analyst Michael Yee in a note issued after the deal was announced.

Celgene shares closed Monday at $114.91 and were unchanged in after-hours trading. Juno shares are up 40% to $64.34 in after-hours trading.

Adam Feuerstein writes regularly for TheStreet. In keeping with company editorial policy, he doesn't own or short individual stocks, although he owns stock in TheStreet. He also doesn't invest in hedge funds or other private investment partnerships. Feuerstein appreciates your feedback; click here to send him an email.