A shift towards in vivo-engineered cell therapies has accompanied major workforce reductions at two US biotechs in recent days.
ArsenalBio has cut 99 jobs, while TScan Therapeutics plans to reduce its workforce by around 75%, as both refocus on programmes designed to engineer patients’ cells directly inside the body.
In vivo focus
ArsenalBio announced its restructuring on 31 August, halting development of its ex vivo autologous cell therapies for solid tumours and retaining a core team to pursue an in vivo CAR-T strategy.
The 99 job cuts represent the majority of a workforce that stood at 127 employees following earlier reductions in 2025.
Ken Drazan, Co-Founder, Chairman and CEO, ArsenalBio, said the company would apply its foundational understanding of T-cell biology to in vivo work, “where we believe our technology will advance the field and help patients win”.
TScan announced its reorganisation on 2 September as it moved to prioritise its in vivo solid tumour programme. The company has two candidates in development and aims to begin phase 1 trials in the fourth quarter of 2027.
In the same announcement, TScan said it would pause further enrolment in its phase 3 ALLOHA-2 trial in blood cancers, citing insufficient capital to complete the study.
The cuts are expected to generate $55m in cumulative cost savings and extend the company’s cash runway. TScan is also seeking partners for its haematology and autoimmune disease programmes.
Growing industry interest
The restructurings add to growing interest in in vivo cell therapies across the pharmaceutical industry, with several major drugmakers expanding their presence in the field.
In 2025, AbbVie acquired in vivo CAR-T developer Capstan Therapeutics for up to $2.1bn, while Eli Lilly expanded its footprint through its acquisition of Kelonia Therapeutics in April 2026.
Johnson & Johnson has also entered a collaboration with Sail Biomedicines to develop in vivo CAR-T therapies for immune-mediated diseases.
Why make the move?
Growing interest in the space is largely driven by the potential advantages of in vivo therapies over conventional cell therapies.
By carrying out cell engineering inside the patient, in vivo approaches could eliminate several of the complex manufacturing and delivery steps required for conventional treatments.
Developers hope this could reduce treatment costs, simplify delivery and make cell therapies easier to scale across healthcare systems.
Featured image: Achmad Khoeron on Adobe Stock
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