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bioRxiv · 10.1101/2025.07.02.662726

A stress-NRF2 response axis polarises tumor macrophages and undermines immunotherapy

Schaer, D. J.·Schulthess-Lutz, N.·Baselgia, L.·Kunasingam, K.·Humar, R.·Hansen, K.·Vallelian, F.
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Abstract

Tumor-associated macrophages (TAMs) can switch between immune-activating and cancer-promoting states; yet, the stress pathways that lock them into pro-cancerous states remain obscure. In MC38 colon tumors, repeated anti-CD40 or radiotherapy created necrosis that split TAMs into peripheral Cxcl9+ and peri-necrotic Spp1+ subsets. Spatial transcriptomics, single-cell RNA-seq, and Keap1-deficient mice showed that the latter are NRF2high "stress-TAMs", with immunosuppressive and tumor-promoting activity. The same NRF2 activation gradient separates pro-inflammatory CXCL9+ and anti-inflammatory SPP1+ TAMs across diverse human cancers. NRF2high TAMs silence IFN-STAT1 programmes, lose MHC-II and chemokine expression, fail to expand T cells, drive tumor cell invasion in 3D co-cultures, and foster metastasis. Constitutive hematopoietic NRF2 activation accelerated the growth of therapy-naive MMTV-PyMT breast tumors and markedly impaired anti-CD40 efficacy in MC38 subcutaneous and lung-metastasis models. Conversely, macrophage-specific Nrf2 deletion restored immunogenic TAMs and potentiated anti-CD40 and anti-PD-1 treatments. Thus, NRF2 constitutes a stress-response axis that fixes TAMs in a pro-cancer, therapy-resistant state; inhibiting it could revive the macrophage-T-cell amplification loop and broaden immunotherapy responses. GRAPHICAL ABSTRACT O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=139 SRC="FIGDIR/small/662726v1_ufig1.gif" ALT="Figure 1"> View larger version (63K): org.highwire.dtl.DTLVardef@728b03org.highwire.dtl.DTLVardef@4a473org.highwire.dtl.DTLVardef@c8a209org.highwire.dtl.DTLVardef@60681_HPS_FORMAT_FIGEXP M_FIG C_FIG

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Schaer, D. J., Schulthess-Lutz, N., Baselgia, L., Kunasingam, K., Humar, R., Hansen, K., Vallelian, F.. 2025-07-07. A stress-NRF2 response axis polarises tumor macrophages and undermines immunotherapy. https://doi.org/10.1101/2025.07.02.662726

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