Flt3L-mediated tumor cDC1 expansion enhances immunotherapy by priming stem-like CD8+ T cells in lymph nodes

Junyun Lai; Cheok Weng Chan; Jesse D Armitage; Katherine M Audsley; Yu-Kuan Huang; Emily B Derrick; Laura S Carstensen; Christina M Scheffler; Matt E Jones; Kevin Sek; Nicola Principe; Joelle S Kim; Imran G House; Amanda X Y Chen; Kah Min Yap; Jim Middelburg; Isabelle Munoz; Dat Nguyen; Junming Tong; Thang X Hoang; Kirsten L Todd; Maximilien Evrard; Jonathan Chee; Laura K Mackay; Alistair R R Forrest; Ian A Parish; Anthony Bosco; Jason Waithman; Paul A Beavis; Phillip K Darcy

doi:10.1038/s41590-026-02419-4

Flt3L-mediated tumor cDC1 expansion enhances immunotherapy by priming stem-like CD8⁺ T cells in lymph nodes

Nat Immunol. 2026 Mar;27(3):530-542. doi: 10.1038/s41590-026-02419-4. Epub 2026 Feb 10.

Authors

Junyun Lai^#^{1

2}, Cheok Weng Chan^#^{1

2}, Jesse D Armitage^#^{1

2

3

4}, Katherine M Audsley^{1

2}, Yu-Kuan Huang^{1

2}, Emily B Derrick^{1

2}, Laura S Carstensen^{1

2}, Christina M Scheffler^{1

2}, Matt E Jones⁵, Kevin Sek^{1

2}, Nicola Principe⁶, Joelle S Kim^{1

2}, Imran G House^{1

2}, Amanda X Y Chen^{1

2}, Kah Min Yap^{1

2}, Jim Middelburg^{1

2}, Isabelle Munoz^{1

2}, Dat Nguyen^{1

2}, Junming Tong^{1

2}, Thang X Hoang^{1

2}, Kirsten L Todd^{1

2}, Maximilien Evrard⁷, Jonathan Chee⁶, Laura K Mackay⁷, Alistair R R Forrest⁵, Ian A Parish^{1

2}, Anthony Bosco^{8

9}, Jason Waithman¹⁰, Paul A Beavis^{11

12}, Phillip K Darcy^{13

14

15}

Affiliations

¹ Cancer Immunology Program, Peter MacCallum Cancer Centre, Melbourne, Victoria, Australia.
² Sir Peter MacCallum Department of Oncology, The University of Melbourne, Parkville, Victoria, Australia.
³ School of Biomedical Sciences, The University of Western Australia, Perth, Western Australia, Australia.
⁴ The Kids Research Institute Australia, The University of Western Australia, Perth, Western Australia, Australia.
⁵ Harry Perkins Institute of Medical Research, QEII Medical Centre and Centre for Medical Research, The University of Western Australia, Perth, Western Australia, Australia.
⁶ Institute for Respiratory Health, National Centre for Asbestos Related Diseases, The University of Western Australia, Perth, Western Australia, Australia.
⁷ Department of Microbiology and Immunology at the Peter Doherty Institute for Infection and Immunity, The University of Melbourne, Parkville, Victoria, Australia.
⁸ Asthma and Airway Disease Research Center, University of Arizona, Tucson, AZ, USA.
⁹ Department of Immunobiology, The University of Arizona College of Medicine, Tucson, AZ, USA.
¹⁰ School of Biomedical Sciences, The University of Western Australia, Perth, Western Australia, Australia. jason.waithman@uwa.edu.au.
¹¹ Cancer Immunology Program, Peter MacCallum Cancer Centre, Melbourne, Victoria, Australia. paul.beavis@petermac.org.
¹² Sir Peter MacCallum Department of Oncology, The University of Melbourne, Parkville, Victoria, Australia. paul.beavis@petermac.org.
¹³ Cancer Immunology Program, Peter MacCallum Cancer Centre, Melbourne, Victoria, Australia. phil.darcy@petermac.org.
¹⁴ Sir Peter MacCallum Department of Oncology, The University of Melbourne, Parkville, Victoria, Australia. phil.darcy@petermac.org.
¹⁵ Department of Immunology, Monash University, Clayton, Victoria, Australia. phil.darcy@petermac.org.

^# Contributed equally.

Abstract

Immune checkpoint blockade (ICB) evokes antitumor immunity through the reinvigoration of T cell responses. T cell differentiation status controls response, with less differentiated cells having an enhanced capacity to proliferate after ICB. Given that conventional type 1 dendritic cells (cDC1) maintain precursor exhausted T cells (T_PEX), we hypothesized that expansion of cDC1s with Flt3L could enhance responses to ICB. Here we show that treatment with Fms-related tyrosine kinase 3 ligand (Flt3L) expands CD62L⁺SLAMF6⁺CD8⁺ T cells in the tumor through a mechanism that requires XCR1⁺ dendritic cells to traffic to the tumor-draining lymph node. The combination of Flt3L and anti-CTLA-4 enhanced therapeutic responses. Combination therapy is associated with the emergence of a CD8⁺ T cell subset characterized by the expression of Il21r and oligoclonal expansion of CD8⁺ T cells within tumors through a mechanism that is dependent on lymph node egress.

MeSH terms

Animals
CD8-Positive T-Lymphocytes* / immunology
CTLA-4 Antigen / antagonists & inhibitors
CTLA-4 Antigen / immunology
Cell Line, Tumor
Dendritic Cells* / immunology
Humans
Immune Checkpoint Inhibitors / pharmacology
Immune Checkpoint Inhibitors / therapeutic use
Immunotherapy* / methods
Lymph Nodes* / immunology
Membrane Proteins* / immunology
Membrane Proteins* / metabolism
Mice
Mice, Inbred C57BL

Substances

flt3 ligand protein
Membrane Proteins
Immune Checkpoint Inhibitors
CTLA-4 Antigen