Arsenal Biosciences is implementing a strategic shift to focus on in vivo CAR T therapies, resulting in a workforce reduction of 99 employees.

As of September 2025, Arsenal Biosciences had 127 employees after a previous downsizing of 50%. As part of this shift, the company will look for strategic alternatives for its assets and technologies. The biotech company previously led by its lead asset AB-2100, an autologous integrated circuit cell therapy for renal cell carcinoma, has dropped both AB-2100 and AB-1015 from its pipeline page. The company's most mature candidate is now AB-3028, which is in early clinical development for prostate cancer. Arsenal Biosciences partnered with Bristol Myers Squibb in late 2020 for programmable cell therapies for cancer indications. The deal involved an upfront payment of $70 million and undisclosed milestones, one tranche of which was paid out in January 2025 after the pharma company exercised an exclusive option to license one program.