{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,6,22]],"date-time":"2026-06-22T05:49:11Z","timestamp":1782107351858,"version":"3.54.5"},"reference-count":25,"publisher":"Frontiers Media SA","license":[{"start":{"date-parts":[[2026,6,22]],"date-time":"2026-06-22T00:00:00Z","timestamp":1782086400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":["frontiersin.org"],"crossmark-restriction":true},"short-container-title":["Front. Immunol."],"abstract":"<jats:sec>\n                    <jats:title>Background<\/jats:title>\n                    <jats:p>Inducible nitric oxide synthase (iNOS) and its product nitric oxide (NO) were historically linked to poor melanoma outcomes, yet recent evidence shows NO supports anti-tumor immunity. This study examines how iNOS shapes anti\u2013PD-1 efficacy, particularly through interferon signaling.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Methods<\/jats:title>\n                    <jats:p>\n                      B16-D5 melanoma tumors were implanted in wild-type (WT) and iNOS knockout (KO) mice to compare tumor growth and response to anti\u2013PD-1 therapy. Flow cytometry, apoptosis assays, and RNA sequencing assessed NO production, PD-L1 expression, and interferon-related gene activation.\n                      <jats:italic>In vitro<\/jats:italic>\n                      , melanoma cells were treated with NO donors (DETA NONOate, SNAP) to assess proliferation and apoptosis. Peripheral blood mononuclear cells from 27 melanoma patients receiving anti\u2013PD-1 therapy were analyzed with multiparameter flow cytometry to correlate NO-associated immune subsets with progression-free survival (PFS).\n                    <\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Results<\/jats:title>\n                    <jats:p>\n                      Tumors grew significantly faster in iNOS KO mice, and anti\u2013PD-1 therapy had no effect, demonstrating that iNOS-derived NO contributes to treatment efficacy. NO donors inhibited melanoma proliferation and induced apoptosis\n                      <jats:italic>in vitro<\/jats:italic>\n                      . Transcriptomic analysis showed anti\u2013PD-1 upregulated interferon pathway genes (STAT1, IRF1, IFNB1) in WT but not iNOS KO mice. In patients, a NO-producing dendritic-cell subset (DAF-FM\n                      <jats:sup>+<\/jats:sup>\n                      CD11c\n                      <jats:sup>+<\/jats:sup>\n                      ) was associated with improved PFS (hazard ratio 0.453; 95% CI\u00a0=\u00a00.270-0.992; p=0.048), indicating a NO-dependent enhancement of interferon-driven immune activity.\n                    <\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Conclusion<\/jats:title>\n                    <jats:p>iNOS-derived NO is necessary for effective anti\u2013PD-1 immunotherapy in melanoma, promoting interferon signaling and immune activation. Loss of iNOS impairs tumor control and immune responsiveness, supporting NO as a potential biomarker and therapeutic adjunct to be explored while challenging assumptions about its deleterious role in melanoma.<\/jats:p>\n                  <\/jats:sec>","DOI":"10.3389\/fimmu.2026.1837275","type":"journal-article","created":{"date-parts":[[2026,6,22]],"date-time":"2026-06-22T05:38:09Z","timestamp":1782106689000},"update-policy":"https:\/\/doi.org\/10.3389\/crossmark-policy","source":"Crossref","is-referenced-by-count":0,"title":["iNOS is a key mediator of anti-PD-1 melanoma therapy response"],"prefix":"10.3389","volume":"17","author":[{"given":"Quang Tam","family":"Nguyen","sequence":"first","affiliation":[{"name":"Department of Cutaneous Oncology, H. Lee Moffitt Cancer Center and Research Institute","place":["Tampa, FL, United States"]},{"name":"Department of Immunology, H. 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Lee Moffitt Cancer Center and Research Institute","place":["Tampa, FL, United States"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Saurabh","family":"Garg","sequence":"additional","affiliation":[{"name":"The Immuno-Oncology Program, H. Lee Moffitt Cancer Center and Research Institute","place":["Tampa, FL, United States"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Vishanna","family":"Balkaran","sequence":"additional","affiliation":[{"name":"Department of Cutaneous Oncology, H. Lee Moffitt Cancer Center and Research Institute","place":["Tampa, FL, United States"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Trisha","family":"Bhathivi","sequence":"additional","affiliation":[{"name":"Department of Cutaneous Oncology, H. Lee Moffitt Cancer Center and Research Institute","place":["Tampa, FL, United States"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Alejandra","family":"Chamizo","sequence":"additional","affiliation":[{"name":"Department of Cutaneous Oncology, H. Lee Moffitt Cancer Center and Research Institute","place":["Tampa, FL, United States"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Christopher W.","family":"Dukes","sequence":"additional","affiliation":[{"name":"Department of Immunology, H. Lee Moffitt Cancer Center and Research Institute","place":["Tampa, FL, United States"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Kimberly","family":"Ward","sequence":"additional","affiliation":[{"name":"Department of Cutaneous Oncology, H. Lee Moffitt Cancer Center and Research Institute","place":["Tampa, FL, United States"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Andrew S.","family":"Brohl","sequence":"additional","affiliation":[{"name":"Department of Cutaneous Oncology, H. Lee Moffitt Cancer Center and Research Institute","place":["Tampa, FL, United States"]},{"name":"Department of Oncologic Sciences, University of South Florida Morsani School of Medicine","place":["Tampa, FL, United States"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Lilit","family":"Karapetyan","sequence":"additional","affiliation":[{"name":"Department of Cutaneous Oncology, H. Lee Moffitt Cancer Center and Research Institute","place":["Tampa, FL, United States"]},{"name":"The Immuno-Oncology Program, H. Lee Moffitt Cancer Center and Research Institute","place":["Tampa, FL, United States"]},{"name":"Department of Oncologic Sciences, University of South Florida Morsani School of Medicine","place":["Tampa, FL, United States"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Nikhil I.","family":"Khushalani","sequence":"additional","affiliation":[{"name":"Department of Cutaneous Oncology, H. Lee Moffitt Cancer Center and Research Institute","place":["Tampa, FL, United States"]},{"name":"Department of Oncologic Sciences, University of South Florida Morsani School of Medicine","place":["Tampa, FL, United States"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Zeynep","family":"Eroglu","sequence":"additional","affiliation":[{"name":"Department of Cutaneous Oncology, H. 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Lee Moffitt Cancer Center and Research Institute","place":["Tampa, FL, United States"]},{"name":"Department of Oncologic Sciences, University of South Florida Morsani School of Medicine","place":["Tampa, FL, United States"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"James J.","family":"Mul\u00e9","sequence":"additional","affiliation":[{"name":"Department of Immunology, H. Lee Moffitt Cancer Center and Research Institute","place":["Tampa, FL, United States"]},{"name":"The Immuno-Oncology Program, H. Lee Moffitt Cancer Center and Research Institute","place":["Tampa, FL, United States"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Joseph","family":"Markowitz","sequence":"additional","affiliation":[{"name":"Department of Cutaneous Oncology, H. Lee Moffitt Cancer Center and Research Institute","place":["Tampa, FL, United States"]},{"name":"Department of Immunology, H. 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