NEW YORK — Researchers from Weill Cornell Medicine, Cedars-Sinai Medical Center, and Roswell Park Comprehensive Cancer Center have developed genetically engineered CAR T cells that target bladder cancer. The study, published on June 26, 2026, in the Journal of Experimental Medicine, demonstrated that direct delivery of these CAR T cells via a catheter controlled bladder tumors in mice.

The researchers created CAR T cells with high specificity for bladder cancer cells and delivered them directly to the bladder. These CAR T cells were generated to recognize a protein called MUC16, which is highly expressed on the surface of many bladder cancer cells, including types resistant to existing therapies. MUC16 is largely absent from normal bladder cells and other healthy tissues.

These CAR T cells killed MUC16-positive tumors grown in the lab from patient-derived bladder cancer cells. The team tested the ability of these CAR T cells to control the growth of human bladder cancer cells implanted in the bladders of mice. When administered directly into the bladder, the CAR T cells reduced tumor growth and extended survival in mice. The CAR T cells were ineffective when administered intravenously in mice and did not spread into the rest of the body in mice when delivered intravesically.

Bladder cancer treatment typically involves surgical removal of the tumor, followed by chemotherapy or immunotherapy. Parwiz Abrahimi, a urologic oncologist at Cedars-Sinai Medical Center and the first author of the study, said, "For patients facing high-risk bladder cancer, options have historically been limited, highly morbid and life-altering." Abrahimi added, "This reality has driven a critical, renewed interest in developing effective bladder-sparing approaches."

Jedd Wolchok, a professor at Weill Cornell Medicine and co-leader of the study, said, "Using a compartmentalized delivery system allows us to overcome this hurdle and hopefully come one step closer to broader use of CAR and transgenic T cells for common solid tumors, like bladder cancer." The study was also co-led by Professor Taha Merghoub of Weill Cornell Medicine and Professor Renier J. Brentjens of Roswell Park Comprehensive Cancer Center.

Merghoub said, "Our findings establish MUC16 as a clinically relevant target for CAR T cell therapy in bladder cancer, and highlight that intravesical delivery, a commonly used administration route in urological practice, represents a feasible, effective, and readily easy-to-implement strategy for adoptive CAR T cell transfer." He added, "This approach could be useful for both initial treatment of bladder cancer as well as treatment refractory subsets of tumors, offering an attractive therapeutic option for patients who may have limited therapeutic alternatives besides bladder removal."

CAR T cells are immune cells genetically engineered to express an artificial receptor protein capable of specifically targeting cancer cells. While successfully used to treat many different types of blood cancer, their success against solid tumors has been limited due to challenges including poor tumor infiltration and off-target toxicity. The direct delivery of these cells to the bladder addresses these challenges.

Approximately 80,000 new cases of bladder cancer are diagnosed in the U.S. each year, and around 600,000 new cases are diagnosed worldwide annually.