Astellas had already done several smaller deals that, in retrospect, look like preparation for the Agensys acquisition, aggressively building up its antibody R&D capabilities. In addition, Astellas' initial forays into MAb research for rheumatoid arthritis and other autoimmune diseases were moving into clinical development just as Agensys' pipeline was starting to flow.

After initially perusing individual products, Astellas told Price that it wanted to, in his words, "move the discussions up to a forward position about an acquisition of the entire company." Did this surprise him? "Well, some," he says.

"We wanted to supplement our small-molecule oncology development [in survivin inhibitors] with antibody technology we didn't already have in-house," says Astellas' Fitzsimmons. "Agensys has a discovery platform based on targets that are unique in human tumors." Together, the Astellas' small-molecule capabilities and Agensys' antibody targets might yield a separate oncology development program.

Japanese pharmas have been criticized for overpaying during their recent biotech shopping spree (even with the weak dollar). The Astellas offer of $387 million, up front, got a mixed reception.

"The price is about right for an early-stage biotech in oncology," says AVOS's Jim Wahl. But he added that, by contrast, Merck paid $350 million for NovaCardia last year and got a promising heart drug in Phase III trials.

Some critics hastened to note that Astellas missed out on Agensys' lead compound, a MAb targeting prostate, pancreas, and bladder cancers. Agensys had already signed a codevelopment deal with Merck, and that product is set to start Phase II in early 2009. Agensys had also previously outlicensed one proprietary target and a bunch of antibodies to Genentech.

Decision Resources' Innes is bullish on the buy. "Astellas got a strong antibody technology with wide utility for oncology—and potentially for autoimmune diseases, which are its primary focus," she says. "This arms them with an extra engine that should add significant value to their portfolio. If they make it to market, those antibodies could conceivably work in a lot of indications." Of course, Innes adds, they have to make it to proof-of-concept first.

AVOS's Davis Walp casts a colder eye. "What Astellas is left with is the promise of the platform drugs, and all of that might ultimately pay off very handsomely," he says. "But not between now and 2012."

Astellas doubled down last April, with a $100 million up-front purchase (plus $660 in milestones) of CoMentis' small-molecule Alzheimer's development program. This agreement slipped under the radar mainly due to the frenzy of other Japanese deals that month. Agensys got the San Francisco–based biotech's entire beta-secretase inhibitor platform, including its lead compound, set for Phase II trials next year.

This early-stage debut in the exploding Alzheimer's category is basically another high-stakes crapshoot. (The platform inhibits plaque-producing amyloid-beta, an increasingly controversial Alzheimer's target.) And last month, Astellas announced that it had inked a $160 million milestone deal with Maxygen for worldwide rights to commercialize drugs against autoimmune disorders and transplant rejection created from the Northern California biotech's development program focusing on T cell–inhibiting Maxy-4 proteins. With this deal, Astellas hopes to secure its transplant-rejection franchise—circa 2018.