Poseida sells $50M stake to Astellas, extending cash runway as gene therapy programs reviewed

Japanese pharma Astellas is taking a stake in Poseida Therapeutics for $50 million to get a first shot at a solid tumor CAR-T cell therapy. But elsewhere, Poseida’s pipeline is facing delays and a regrouping after Takeda walked away from a gene therapy partnership.

Astellas will put up the $50 million in exchange for an 8.8% stake in Poseida, the San Diego-based biotech working on cell and gene therapies for cancer and rare diseases. The subject of the deal is P-MUC1C-ALLO1, an allogeneic CAR-T cell therapy that Poseida is developing for solid tumors. Astellas wants first dibs on partnering options for the med.

The deal includes $25 million in exchange for 8,333,333 shares of Poseida’s common stock at $3 apiece through a private placement plus a one-time $25 million payment for the right of exclusive first negotiation for P-MUC1C-ALLO1. Astellas will also snag a board observer seat and certain rights to any potential change in control of Poseida.

P-MUC1C-ALLO1 is in phase 1 development for solid tumors, an indication that has seen limited success for CAR-T therapies compared to blood cancers. While many existing CAR-Ts—such as Novartis’ Kymriah and Gilead’s Yescarta—use a patients’ own cells, Poseida is developing off-the-shelf treatments from healthy donors to avoid unwanted immune reactions and speed up the time to treatment. The open-label early-stage trial for Poseida’s therapy is expected to enroll 100 people with primary study completion slated for 2026.

The deal is a nice boost for Poseida, which in July officially announced that a gene therapy deal with Takeda was terminated. The pair had been working on a hemophilia A therapy, which Poseida said is being re-evaluated as it comes back into the biotech’s fold, according to a Monday business update.

Investors reacted positively to the news of Astellas' stake, sending Poseida's shares up 23% to $2, compared to $1.63 at the previous close. 

Poseida still has some tough decisions ahead. The entire gene therapy program is being re-evaluated “to determine which programs it will prioritize and progress internally,” according to the update. The company is considering whether future development of its gene therapy programs should be done “through business development.”

But the Astellas deal at least adds some runway to Poseida’s cash position into early 2025. The company did not provide an update today, but in May reported cash and equivalents of $247.2 million that would run into mid-2024.

"The strategic investment by Astellas, together with our disciplined capital expenditure, cost control initiatives and expected payments and milestones from the Roche collaboration, put us on a firm financial foundation," said CFO Johanna Mylet.

Those Roche programs are now facing a slight delay for data, however, as Poseida retools dosing based on the findings already collected. “The data we have generated has led us to find improvements that we believe have the potential to greatly benefit our allogeneic portfolio,” according to Kristin Yarema, Ph.D., Poseida’s president of cell therapy.

"We have implemented a number of these already in our clinical-stage programs, as we continue steady progress in dose-ranging and explore approaches such as raising conditioning lymphodepletion to emerging industry norms and exploring additional dosing and administration options,” Yarema continued.

The Roche collaboration involves the allogeneic CAR-T therapy P-BCMA-ALLO1, which is in phase 1 testing for relapsed/refractory multiple myeloma. A clinical update is expected at a medical meeting this year, but due to the implementation of a new dosing regimen, this readout will be limited and a further update is planned for mid-2024.

The companies are also working together on P-CD19CD20-ALLO1 in B-cell malignancies, which was just cleared for human testing in June. Site start-up is underway now and dosing is expected in early 2024.

Poseida CEO Mark Gergen acknowledged the delays and said the changes will be highlighted at upcoming medical meetings this fall “with plans for a more robust clinical update to follow in mid-2024."