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Yvonne Y. Chen is in the Department of Chemical and Biomolecular Engineering, University of California, Los Angeles, Los Angeles, California 90095, USA, in the Department of Microbiology, Immunology, and Molecular Genetics, University of California, Los Angeles, and at the Parker Institute for Cancer Immunotherapy, University of California, Los Angeles.
Harnessing a person’s immune system to target a tumour — a type of treatment called cancer immunotherapy — has emerged as a promising treatment option for cancer. T cells are a type of immune cell that has a surveillance function and the capacity to kill foreign or infected cells that are perceived to pose a threat. These properties have cemented T cells as a central pillar of cancer immunotherapy. The generation of an effective antitumour T-cell response depends crucially on the availability of nutrients such as the amino acid l-arginine1. However, the tumour microenvironment poses a challenge because it is nutrient-poor2. Writing in Nature, Canale et al.3 show that the treatment of mice with metabolically engineered bacteria produces a local, continuous source of l-arginine in the tumour microenvironment that results in strong, long-lasting antitumour T-cell responses when combined with a form of immunotherapy called checkpoint blockade.