SAN DIEGO, Oct. 26, 2017 — Poseida Therapeutics Inc. (“Poseida”), a San Diego-based company translating best-in-class gene therapy technologies into lifesaving cell therapies, today announced that the California Institute for Regenerative Medicine (CIRM) awarded a $19.8 million grant to support the clinical development of Poseida’s P-BCMA-101 product candidate. P-BCMA-101 is a chimeric antigen receptor T cell (CAR-T) immunotherapy currently in a Phase 1 clinical trial as a treatment for relapsed and refractory multiple myeloma.“We are honored that CIRM has recognized the promise of P-BCMA-101 as an immunotherapy for patients with multiple myeloma and is contributing to the advancement of this program in Phase 1 clinical development,” said Eric Ostertag, M.D., Ph.D., chief executive officer of Poseida. “P-BCMA-101 is elegantly designed with several key characteristics, including an exceptionally high concentration of stem cell memory T-cells which has the potential to significantly improve durability of response to treatment.”The P-BMCA-101 product candidate is a CAR-T immunotherapy designed to supercharge a patient’s own T cells to safely and effectively eliminate tumor cells carrying B cell maturation antigen (BCMA), which is expressed on essentially all multiple myeloma cells. P-BCMA-101 modifies a patient’s T cells using a non-viral gene delivery system called piggyBac™, which enables several desirable features, including:

• T stem cell memory: P-BCMA-101 is comprised of an exceptionally high proportion of stem cell memory T cells, resulting in unprecedented durability of response without re-administration of product in multiple preclinical studies.
• Pure product: The addition of a human-derived positive selection gene results in a product that is essentially 100% pure in contrast with lentivirus-based products, which are generally 5-30% pure.
• Safety: piggyBac™ has safer integration profile than lentivirus and is non-oncogenic. In addition, a human-derived safety switch is added such that P-BCMA-101 can be rapidly attenuated or eliminated if significant side effects occur.

“Poseida is developing a promising next generation CAR-T cell therapy which includes many of the desirable attributes of emerging CAR-T cell therapies into a single treatment,” said Maria Millan, M.D., President and CEO of CIRM. “CIRM is pleased to support Poseida in the development of this novel CAR-T therapy which represents a much-needed solution for multiple myeloma.”Additional information about this Phase 1 clinical study of P-BCMA-101 is available at www.clinicaltrials.gov using identifier: NCT03288493About Poseida Therapeutics Inc.Poseida Therapeutics is translating best-in-class gene therapy technologies into lifesaving cell therapies. The company is developing CAR T-cell immunotherapies for cancer, as well as gene therapies for orphan diseases. P-BCMA-101 is Poseida’s lead CAR-T therapy currently in Phase 1 clinical development for the treatment of multiple myeloma. Poseida has assembled a suite of industry-leading gene therapy technologies, including the piggyBac™ DNA Modification System, XTN™ TALEN and NextGEN™ CRISPR site-specific nucleases, and Footprint-Free™ Gene Editing (FFGE). For more information, visit www.poseida.com.Corporate Communications Contact:Jason SparkCanale Communications619-849-6005Jason@canalecomm.com