During a virtual event, trial investigators reported on the clinical progress of three therapies included in the company's UltraCAR-T platform: PRGN-3005, PRGN-3006, and PRGN-3007. In addition, presentations were given relating to two therapies in its AdenoVerse immunotherapy platform: PRGN-2009 off-the-shelf (OTS) AdenoVerse Immunotherapy and PRGN-2012 OTS AdenoVerse Immunotherapy.

The following data was presented:

• In the lymphodepletion cohort of an ongoing trial, a 50% (3 out of 6 patients) objective response rate (ORR) was observed in relapsed or refractory acute myeloid leukemia patients treated with PRGN-3006 at the two lowest dose levels (comprising a single administration of four to 28 million UltraCAR-T cells).
• A 40% ORR (2 out of 5) and 60% disease control rate (3 out of 5) was observed in recurrent or metastatic human papilloma virus-associated cancer patients treated in the PRGN-2009 combination arm of an ongoing trial.

• Preliminary PRGN-2012 phase I data shows encouraging clinical activity, including ongoing reduction of the need for surgical intervention at the most recent follow-up, up to 12 weeks after PRGN-2012 treatment.
• PRGN-3005 and PRGN-3006 UltraCAR-T demonstrated favorable safety profiles with no dose-limiting toxicities or neurotoxicity, dose-dependent in vivo expansion, and durable persistence.
• PRGN-2009 and PRGN-2012 AdenoVerse immunotherapies demonstrated favorable safety profiles with no dose-limiting toxicities, strong antigen-specific immune response, and a lack of a significant neutralizing antibody response upon repeat administrations.

UltraCAR-T therapies are composed of genetically modified autologous T cells that simultaneously express an antigen-specific CAR, membrane-bound interleukin-15 (IL-15), and a kill switch.

Including the gene-encoding, membrane-bound IL-15 slows the aging of UltraCAR-T cells and leads to increased expansion of cells in vivo. The kill switch allows for rapid destruction of UltraCAR-T cells in the event of adverse events, which increases the safety profile of the therapy, the company said.

Precigen received clearance from the U.S. Food and Drug Administration last year for manufacturing UltraCAR-T therapies.