CD5-Deleted Chimeric Antigen Receptor Cells (Senza5™ CART5) to Enhance Immunotherapy Against T-Cell Non-Hodgkin Lymphoma: A First-in-Human Phase I Clinical Trial

Background and Significance: Outcomes for relapsed or refractory (RR) T-cell lymphomas (TCL) are poor with standard therapies and cure is elusive. While in B-cell malignancies CAR T-cell (CART) therapy has changed the treatment paradigm, its development in TCL faces many challenges, mainly related to the fact that normal and malignant T cells share similar antigens. This can result in fratricide during CART manufacture and T-cell aplasia after CART treatment. To overcome these obstacles, we used CRISPR-Cas9 CD5 short-guide RNA to delete CD5 (Senza5™) in T cells and created a 4-1BB costimulated anti-CD5 CAR product (CART5). This product (Senza™ CART5) features two T-cell populations: CD5 knocked out (CD5KO) CAR5+ T cells that will exert the anti-tumor effect and CD5KO CAR-neg T cells which are expected to provide anti-infective (e.g., EBV, CMV) immunity in case of T-cell toxicity. Preclinically, Senza™ CART5 demonstrated increased CART5 expansion and enhanced antitumor efficacy in TCL xenograft models compared to wild-type (WT) CART5.

Study Design and Methods: In this single-center first-in human phase I trial, we will determine the recommended phase 2 dose (RP2D) of Senza5™ CART5 cells in participants with relapsed or refractory CD5 positive T cell NHL based on their safety, tolerability, pharmacokinetics. Participants will be treated on one of 5 dose levels (DL) of Senza5™ CART5 cells. The dose levels will be determined using a Bayesian Optimal Interval (BOIN) design. Participants will receive 3x10⁶ (DL -1) to 1.25x10⁸ (DL4) CART5+ cells based on the assigned DL, preceded by lymphodepletion with fludarabine 25 mg/m² and cyclophosphamide 250 mg/m² (Flu/Cy) IV daily on days -5 to -3 (or bendamustine 90mg/m2 IV daily on days -5 and -4 if contraindications to or unavailability of Flu/Cy). For participants with a WBC <1000/μL lymphodepletion may be omitted.

We will assign cohorts of up to 3 participants sequentially to a dose level based on the number of dose-limiting toxicities (DLTs) observed at the current dose level under a pre-specified scheme assuming a targeted DLT rate of ≤0.3. The RP2D will be determined based on feasibility, safety, and efficacy data. Patients 18 years or older with confirmed RR CD5-positive non-leukemic T-cell lymphoma with ≥50% expression of CD5 on malignant cells and no circulating malignant CD5+ cells as determined by peripheral blood flow cytometry will be eligible if they have an adequate performance status (ECOG PS 0-2) and organ function. Participants must have a sufficient cell dose for an autologous hematopoietic cell transplant (HCT) available or be human leukocyte antigen-typed and have an identified stem cell donor that could provide immune function backup in the event of T-cell aplasia. Patients with prior allogeneic HCT are currently excluded.

The study will continue to enroll and treat participants until a maximum of 9 participants are infused and evaluable for DLT assessments at a given dose level, or a maximum of 30 DLT-evaluable participants from all dose levels are infused. The primary objective is to determine the RP2D of Senza5™ CART5 cells. Secondary objectives include safety as determined by frequency and severity of treatment-related adverse events, as well as efficacy by assessing overall and complete response rates, duration of response, progression-free and overall survival. Manufacturing feasibility will be determined by the frequency of product release failures and occurrence of dose failures (inability to meet targeted dose). Exploratory objectives will evaluate the persistence and trafficking of Senza5™ CART5 cells in blood and tumor by characterizing the kinetics of the infused cells by flow cytometry and qPCR. We will perform gene expression profiling of the tumor and tumor microenvironment and measure systemic soluble cytokines before and after treatment. We will also assess the impact of treatment on normal T cells, and the persistence of CD5KO untransduced T cells that are infused as part of the Senza5™ CART5 product by multicolor flow cytometry, qPCR, and single-cell RNA/TCR sequencing.

The trial is registered at clinicaltrials.gov as NCT06420089 and open to accrual. Enrollment is ongoing.

Barta:Kyowa Kirin: Consultancy; Janssen: Membership on an entity's Board of Directors or advisory committees; Acrotech: Consultancy; BMS: Consultancy; Daiichi Sankyo: Consultancy. Ruella:Vittoria Biotherapeutics: Current equity holder in private company, Patents & Royalties; AbClon Inc.: Other: Consultancy, Research Funding. Svoboda:BMS: Honoraria; Merck: Honoraria; TG Therapeutics: Honoraria; Abbvie: Honoraria; Atara: Honoraria; GenMab: Honoraria; Adaptive: Honoraria, Research Funding; Seagen: Honoraria; Incyte: Research Funding. Carter:Ispen: Honoraria. Chong:AstraZeneca: Consultancy, Research Funding; Nurix: Research Funding; Genentech/Roche: Research Funding; CARGO: Research Funding; AbbVie: Research Funding; Beigene: Consultancy; Genmab: Research Funding. Landsburg:Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; ADC Therapeutics: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; GenMab: Honoraria; Calithera: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding. Nasta:Caribou Biosciences: Research Funding; Takeda: Research Funding; ONO therapeutics: Research Funding; MERCK: Other: DSMB; GenMab: Membership on an entity's Board of Directors or advisory committees; Roche: Research Funding; Pharmacyclics: Research Funding; FortySeven/Gilead: Research Funding; Loxo/Lilly: Research Funding; ATAEA: Research Funding; ASTEX: Research Funding; ADCT: Membership on an entity's Board of Directors or advisory committees; Acrotech: Membership on an entity's Board of Directors or advisory committees. Patel:Vittoria Biotherapeutics: Current Employment. Ghilardi:Vittoria Biotherapeutics: Honoraria. Yang:Vittoria Biotherapeutics: Current Employment. Qian:Vittoria Biotherapeutics: Current Employment. Nimmagadda:Vittoria Biotherapeutics: Current Employment. Vu:Vittoria Biotherapeutics: Current Employment. Peddada:Vittoria Biotherapeutics: Current Employment. Snook:Vittoria Biotherapeutics: Current Employment. Siciliano:Vittoria Biotherapeutics: Current Employment, Current equity holder in publicly-traded company. Mazanet:Vittoria Biotherapeutics: Current Employment.