After receiving an unsolicited acquisition proposal from an unnamed Big Pharma in 2023, Poseida reached out to inform partner Roche of the offer, at which point the Swiss pharma said it wasn’t interested in buying the biotech at the time.
Fast forward to Nov. 26, 2024, and Poseida announced that Roche was acquiring the cell therapy biotech for total equity value of $1.5 billion.
So, what changed?
The roots of the acquisition trace back to August 2022, when Roche paid $110 million upfront to team up with Poseida, a partnership that has been revised and expanded multiple times since.
In April of the next year, San Diego-based Poseida received the acquisition offer from an unnamed pharma company, prompting then-CEO Mark Gergen—now the biotech’s executive chair—to reach out to Roche’s former global head of partnering, James Sabry, Ph.D., according to a Securities and Exchange Commission (SEC) filing.
At that time, Sabry indicated that an acquisition wasn’t of current interest to Roche, but that the Big Pharma may want to expand the partnership in the future, which could later lead to interest in a buyout. The pharma then declined to participate in any further discussions regarding a possible acquisition.
A few months later, the unnamed pharma withdrew its acquisition proposal because the company wanted to wait for additional data from Poseida’s lead program.
In August 2023, Japan-based Astellas entered the picture. The Big Pharma made a $50 million private financing investment in Poseida and became a board observer. The next year, on May 1, Astellas paid Poseida $50 million in cash, throwing in up to $550 million in biobucks, to develop two cell therapy candidates for solid tumors.
Six days later, Poseida’s Gergen had a call with Roche’s Sabry in which the biotech CEO asked if the pharma had any interest in a potential financing transaction. Sabry said Roche was evaluating how it could help Poseida.
At the end of May 2024, Gergen had another call with Sabry. During that discussion, the Roche leader said the pharma company was working on a proposal that it would share by the end of June. Sabry’s retirement was then announced May 28, with Roche’s business development head Boris Zaïtra taking over Sabry’s duties.
Soon after, Zaïtra spoke with Poseida's leadership and said Roche needed more time to evaluate all options.
On Aug. 27, Zaïtra called Gergen with Roche’s proposal to acquire Poseida at $5.75 per share in cash, offering a significant premium on Poseida’s common stock price that had closed at $2.81 that day.
Poseida’s board met and determined that the offer was “insufficient to merit further engagement” and Gergen rejected the proposal, according to the SEC filing.
A few days later, Poseida announced the launch of the phase 1b part of its clinical trial for P-BCMA-ALLO1, an investigational stem cell memory T-cell based allogenic CAR-T cell therapy for advanced multiple myeloma, triggering a $20 million milestone payout from Roche to Poseida.
In mid-September, Roche representatives called Gergen with a new acquisition offer: $7.50 per share plus a contingent value right to receive aggregate payments of up to $5.50 per share if Poseida hit certain milestones. At the time, Poseida’s closing share price was $2.95.
Shortly thereafter, Poseida’s P-BCMA-ALLO1 snared a regenerative medicine advanced therapy tag from the FDA. When Poseida’s board met, the company once again decided to reject Roche’s offer, determining that Roche would need to hike up the upfront value, plus propose a total per-share value in the teens, in order for Poseida to accept.
Discussions between the two companies continued, extending to include a possible partnership expansion into the autoimmune landscape.
On Oct. 17, Poseida announced that Roche nominated a new allogeneic CAR-T development candidate for hematologic malignancies under the pair’s agreement, triggering a $15 million payment from Roche to Poseida.
At the end of October, Poseida’s board delivered an acquisition counterproposal to Roche with an upfront price of $9.50 per share and a contingent value right with aggregate payments of up to $7 per share.
Roche came back with an offer of $9 per share upfront plus a contingent value right with up to two developmental milestone payments of $1.50 per share each, an offer Poseida rejected.
Poseida engaged in discussions with “another pharmaceutical company that was familiar with Poseida and its hematology assets from participating in a prior partnering process,” according to the SEC documents. The pharma—called “party X” in the documents—told Poseida it was not interested in acquiring the company after viewing a presentation from Poseida on Nov. 14.
Poseida also asked Astellas if it wanted to put in an offer, and the Big Pharma responded that it did not.
Ultimately, Roche and Poseida agreed on a price of $9 a share in cash, plus a further $4 per share tied to the achievement of certain milestones. Yesterday, Roche commenced a tender offer for all of Poseida's outstanding shares.
The takeover will establish off-the-shelf cell therapies, which Roche has said can democratize CAR-Ts, as a new core capability for the Swiss drugmaker.