CAR T Cell Therapy Targeting IGHV4-34 B Cell Malignancies

Contributed to the development of CART4-34, a precision CAR T cell therapy targeting IGHV4-34+ B cell malignancies, published in Science Translational Medicine (2026). My work focused on solving a transduction efficiency bottleneck in CAR T cell manufacturing.

This project was part of the work published in Science Translational Medicine in February 2026, conducted during my time in the Ruella Lab at the Center for Cellular Immunotherapies at Penn.

The Paper

Current CAR T cell therapies for B cell malignancies target CD19, an antigen expressed across the entire B cell lineage. This causes on-target, off-tumor depletion of healthy B cells, leaving patients immunocompromised, and creates a route for relapse when tumor cells downregulate CD19.

This work presents CART4-34, a CAR T cell therapy that targets the IGHV4-34 B cell receptor instead. Because IGHV4-34 is highly enriched on malignant B cells and largely absent from the healthy B cell pool, CART4-34 can eliminate tumor cells with much greater precision while sparing normal B cells. The study demonstrates its specific cytotoxicity toward IGHV4-34+ malignant B cells in vitro, robust antitumor activity in xenograft mouse models, improved immune synapse morphology through CAR hinge domain optimization, and the ability to target patient-derived Systemic Lupus Erythematosus (SLE) B cells ex vivo without depleting healthy B cells or affecting total IgG levels.

My Contribution

My work focused on solving a manufacturing bottleneck that needed to be resolved before CART4-34 could be used in the more advanced experiments described in the paper. The issue was transduction efficiency: the step where a lentiviral vector delivers the CAR construct into T cells. Low transduction efficiency meant most T cells in a batch were not expressing the CAR, which undermined downstream experiments and posed a real obstacle to clinical translation.

To address this, I systematically tested commercially available transduction efficiency boosters with and without RetroNectin. RetroNectin is a recombinant protein that co-localizes lentiviral particles and T cells on the same surface via the VLA-4 integrin receptor and a heparin binding domain, increasing the chance of successful viral entry. The boosters tested were Poloxamer 407 (P407), beta-mercaptoethanol (BME), Polybrene, and LentiBOOST. Transduction efficiency was measured using a truncated EGFR reporter gene in the CART4-34 construct, detected by flow cytometry with an anti-EGFR antibody, across eight total conditions.

RetroNectin combined with Poloxamer 407 produced the highest transduction efficiency at 35.6% EGFR positivity, compared to 13.6% without RetroNectin and 18.7% with RetroNectin alone. P407 is a nonionic surfactant hypothesized to reduce electrostatic repulsion between the negatively charged T cells and lentiviral particles, complementing the physical co-localization that RetroNectin provides. A subsequent 16-day CART4-34 expansion under the optimized conditions showed strong sustained growth and high EGFR positivity throughout, validating the protocol for use in the larger study.

This work was presented as a poster at the University of Pennsylvania CURF Fall Research Expo in September 2024 and was ultimately instrumental in the subsequent work that led to the STM publication.

Publication and Poster

Chimeric antigen receptor T cells against the IGHV4-34 B cell receptor specifically eliminate neoplastic and autoimmune B cells Cohen, Bochi-Layec, Lemoine, Jenks, Bayat et al. Science Translational Medicine, 2026.

Poster — Penn CURF Fall Research Expo, 2024.

Skills Used

  • CAR T cell manufacturing and lentiviral transduction
  • Flow cytometry (EGFR reporter assay)
  • Cell culture and expansion protocols
  • Experimental design and data analysis