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4829 CTX112, a Next-Generation Allogeneic CRISPR-Cas9 Engineered CD19 CAR T Cell with Novel Potency Edits: Data from Phase 1 Dose Escalation Study in Patients with Relapsed or Refractory B-Cell Malignancies

Program: Oral and Poster Abstracts
Session: 704. Cellular Immunotherapies: Early Phase Clinical Trials and Toxicities: Poster III
Hematology Disease Topics & Pathways:
Research, Clinical trials, Clinical Research
Monday, December 9, 2024, 6:00 PM-8:00 PM

Armin Ghobadi, MD1, Joseph P. McGuirk, DO2, Paul Shaughnessy, MD3, Constantine S. Tam, MBBS, MD4, Melanie Allen, MS5*, Chenyi Pan, PhD5*, Ziliang Li, PhD5*, William N. Stevens, MS5*, Annie Weaver, PhD6* and Chan Y. Cheah, MBBS DMSc7

1Division of Oncology, Washington University School of Medicine, St. Louis, MO
2Division of Hematologic Malignancies & Cellular Therapeutics, University of Kansas Medical Center, Kansas City, KS
3Sarah Cannon Transplant and Cellular Therapy Program, Methodist Hospital, San Antonio, TX
4Alfred Hospital and Monash University, Melbourne, VIC, Australia
5CRISPR Therapeutics, Boston, MA
6CRISPR Therapeutics, San Mateo, CA
7Sir Charles Gairdner Hospital, Perth, Western Australia, Australia

Introduction: CRISPR/Cas9 editing allows for advanced CAR T cell engineering, which could prevent common failure modes (e.g., exhaustion, lack of expansion) and potentially result in more efficacious therapies. CTX112 is a next-generation allogeneic CAR T cell therapy with 5 edits, including site-specific insertion of an anti-CD19 CAR transgene into the T-cell receptor (TCR) alpha constant (TRAC) locus using adeno-associated viral delivery, and targeted disruption of 4 genes: TRAC (to prevent graft versus host disease, GvHD), B2M (to remove major histocompatibility complex [MHC] class I expression), TGFBR2 (to overcome immunosuppressive signaling in the tumor microenvironment), and ZC3H12A (also known as Regnase-1, to increase cell expansion and functional persistence). This editing strategy was chosen based on a large scale phenotypic CRISPR screen to identify novel potency edits, and further informed by our first-generation CTX110 data. CTX110, which contains only the TRAC and B2M disruptions, produced durable remissions in patients with large B-cell lymphoma (LBCL) without long-lived CAR T cell persistence.

Methods: NCT05643742 is a phase 1/2, open-label, multicenter study evaluating the safety and efficacy of CTX112 in subjects with relapsed or refractory (r/r) B-cell malignancies. Eligible disease subtypes include LBCL, follicular lymphoma (FL) grade 1-3a, marginal zone lymphoma (MZL), mantle cell lymphoma (MCL), and chronic lymphocytic leukemia (CLL)/small lymphocytic lymphoma (SLL). Patients received standard lymphodepleting chemotherapy (LDC) with fludarabine 30 mg/m2 and cyclophosphamide 500 mg/m2 for 3 days followed by CTX112 infusion. The Phase 1 primary endpoint was the incidence of dose limiting toxicities (DLTs), with secondary endpoints including overall and complete response rates (ORR/CRR) and pharmacokinetics (PK). Data are presented from 9 subjects (3 FL, 2 MZL, 4 LBCL) treated with CTX112 at doses ranging from 30 x 106 (Dose Level [DL] 1) to 300 x 106 (DL3) CAR+ T cells who were followed for >3 months.

Results: The study population was enriched for patients with high-risk characteristics, including: 1) primary refractory disease or early relapse to first-line therapy (78%); 2) high tumor burden (SPD > 4000 mm2, 56%); and 3) high disease prognostic index score (IPI, FLIPI, MZL-IPI ≥3) or elevated lactate dehydrogenase (67%). No DLTs or adverse events (AEs) of GvHD, hemophagocytic lymphohistiocytosis, or grade (Gr) ≥3 infections were observed. All Gr ≥3 cytopenias resolved within 30 days following CTX112 infusion. Cytokine release syndrome (CRS) Gr 1/2 was reported in 4/9 (44%) pts with no CRS Gr ≥3. Immune effector cell-associated neurotoxicity syndrome (ICANS) Gr 1 was reported in 2/9 pts (22%) with no Gr ≥2. When comparing CTX112 vs. CTX110 at DL3, the mean Cmax with CTX112 was 7-fold higher (26,235 vs. 3,773 copies/μg) with significantly higher levels detected at D14, leading to a 10-fold increase in mean AUC (133,701 vs.13,830 copies/μg*days). The ORR and CRR (Lugano 2014 criteria) were 6/9 (67%) and 4/9 (44%) respectively. 4 patients have achieved responses lasting for more than 6 months, including 1 patient treated at DL1 who remains in complete remission over a year after CTX112 infusion.

Conclusions: These data provide the first clinical evidence that disruptions in the genes encoding Regnase-1 and transforming growth factor beta receptor 2 can lead to increased expansion and functional persistence of CAR T cells. Compared with first-generation allogeneic CAR T therapies like CTX110, CTX112 results in better efficacy at lower doses, higher response rates, and improved PK. Across multiple Non-Hodgkin lymphoma subtypes, treatment with CTX112 resulted in clinically meaningful responses without requiring the increased intensity LDC used with other allogeneic CAR T cells. Dose optimization within disease-specific cohorts is ongoing. These data demonstrate that CTX112 has the potential to be a highly effective allogeneic CAR T cell therapy for B-cell malignancies.

Disclosures: Ghobadi: Genentech: Research Funding; Wugen Inc: Consultancy; CRISPR Therapeutics: Consultancy; Bristol Myers Squibb: Consultancy; ATARABio: Consultancy; Amgen: Consultancy, Research Funding; Kite (Gilead company): Consultancy, Honoraria, Research Funding. McGuirk: Envision: Consultancy; Novartis: Consultancy; Allo Vir: Consultancy; Autolus: Consultancy; BMS: Consultancy; Kite: Consultancy; NEKTAR therapeutics: Consultancy; CRISPR therapeutics: Consultancy; Caribou bio: Consultancy; Sana technologies: Consultancy; Legend biotech: Consultancy. Shaughnessy: Autolus, Sanofi: Consultancy; BMS: Speakers Bureau; Sanofi: Speakers Bureau. Tam: AbbVie, BeiGene, Janssen: Research Funding; AbbVie, BeiGene, Janssen, LOXO: Honoraria. Allen: CRISPR Therapeutics: Current Employment, Current equity holder in publicly-traded company. Pan: CRISPR Therapeutics: Current Employment, Current equity holder in publicly-traded company. Li: CRISPR Therapeutics: Current Employment, Current equity holder in publicly-traded company. Stevens: CRISPR Therapeutics: Current Employment, Current equity holder in publicly-traded company. Weaver: CRISPR Therapeutics: Current Employment, Current equity holder in publicly-traded company. Cheah: Dizal: Consultancy, Honoraria; Lilly: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; MSD: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Janssen: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; AstraZeneca: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel expenses, Speakers Bureau; Sobi: Consultancy, Honoraria; Regeneron: Consultancy, Honoraria; Gilead: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; BeiGene: Consultancy, Honoraria, Other: travel expenses, Speakers Bureau; Menarini: Consultancy, Honoraria; AbbVie: Consultancy, Honoraria, Research Funding, Speakers Bureau; Roche: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel expenses, Research Funding, Speakers Bureau; Genmab: Consultancy, Honoraria, Speakers Bureau; BMS: Consultancy, Honoraria, Research Funding.

*signifies non-member of ASH