Company: PGEN
Filing Date: 2025-03-19
Form Type: 10-K
Source: 0001356090-25-000007
Chunk: 25

Company: PRECIGEN, INC.
Filing Date: 2025-03-19
Form: 10-K
Item: Item 1
Chunk 25
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 prior lines of therapy across all arms. Patients had significantly advanced stage disease with a high baseline tumor burden with most patients having distant metastases, including liver, spleen, bladder and lung.

PRGN-3005 treatment was well-tolerated with low incidence of treatment related adverse events (TRAEs), no dose limiting toxicities (DLTs), and no neurotoxicity. The most common side effects for the IV and IP arms without lymphodepletion were abdominal pain, fever and decreased absolute lymphocyte count (ALC). Serious Adverse Events included five incidences of Cytokine Release Syndrome (CRS), with no incidence of CRS greater than Grade 2. One patient with CRS required specific intervention which was resolved following standard CRS management after 24 hours. There was no use of tocilizumab or dexamethasone or kill switch.

PRGN-3005 administered via either IP or IV infusion resulted in a dose-dependent expansion and encouraging persistence in peripheral blood. Best responses in patients treated without lymphodepletion were stable disease with complete responses 

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observed in certain individual target lesions. Incorporating lymphodepletion prior to IV infusion led to an encouraging anti-tumor activity with a decrease in tumor burden in 67% (6/9) of patients and stable or partial response in 90% of the individual target lesions in these patients.

Subsequently, we initiated the Phase 1b dose expansion study of PRGN-3005 UltraCAR-T at Dose Level 3 with lymphodepletion prior to IV infusion. As part of the strategic prioritization of our pipeline announced in August 2024, we have paused enrollment in the Phase 1b clinical trial of PRGN-3005.

PRGN-3006

PRGN-3006 is an investigational autologous CAR-T therapy that utilizes our UltraCAR-T platform to express a CAR to target CD33, mbIL15 and a kill switch for better precision and control.

CD33, also known as Siglec-3, is a single pass transmembrane glycoprotein and a member of the sialic acid-binding immunoglobulin-like lectin super-family. CD33 is an attractive target for immunotherapy because it is over-expressed on AML blasts and leukemic stem cells, or LSCs, but is not expressed on normal blood stem cells, also known as hematopoietic stem cells. Approximately 85-90 percent of AML patients express CD33 on their tumor cells. In