Combined Gemcitabine and Immune-Checkpoint Inhibition Conquers Anti-PD-L1 Resistance in Low-Immunogenic Mismatch Repair-Deficient Tumors
Tumors arising in the context of Lynch Syndrome or constitutional mismatch repair deficiency are hypermutated and have a good response towards immune-checkpoint inhibitors (ICIs), including α-PD-L1 antibodies. However, in most cases, resistance mechanisms evolve. To improve outcomes and prevent resi...
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MDPI AG
2021-06-01
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| Series: | International Journal of Molecular Sciences |
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| Online Access: | https://www.mdpi.com/1422-0067/22/11/5990 |
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| author | Inken Salewski Julia Henne Leonie Engster Bjoern Schneider Heiko Lemcke Anna Skorska Peggy Berlin Larissa Henze Christian Junghanss Claudia Maletzki |
| author_facet | Inken Salewski Julia Henne Leonie Engster Bjoern Schneider Heiko Lemcke Anna Skorska Peggy Berlin Larissa Henze Christian Junghanss Claudia Maletzki |
| author_sort | Inken Salewski |
| collection | DOAJ |
| description | Tumors arising in the context of Lynch Syndrome or constitutional mismatch repair deficiency are hypermutated and have a good response towards immune-checkpoint inhibitors (ICIs), including α-PD-L1 antibodies. However, in most cases, resistance mechanisms evolve. To improve outcomes and prevent resistance development, combination approaches are warranted. Herein, we applied a combined regimen with an α-PD-L1 antibody and gemcitabine in a preclinical tumor model to activate endogenous antitumor immune responses. Mlh1<sup>−/−</sup> mice with established gastrointestinal tumors received the α-PD-L1 antibody (clone 6E11; 2.5 mg/kg bw, i.v., q2wx3) and gemcitabine (100 mg/kg bw, i.p., q4wx3) in mono- or combination therapy. Survival and tumor growth were recorded. Immunological changes in the blood were routinely examined via multi-color flow cytometry and complemented by ex vivo frameshift mutation analysis to identify alterations in Mlh1<sup>−/−</sup>-tumor-associated target genes. The combined therapy of α-PD-L1 and gemcitabine prolonged median overall survival of Mlh1<sup>−/−</sup> mice from four weeks in the untreated control group to 12 weeks, accompanied by therapy-induced tumor growth inhibition, as measured by <sup>[18F]</sup>-FDG PET/CT. Plasma cytokine levels of IL13, TNFα, and MIP1β were increased and also higher than in mice receiving either monotherapy. Circulating splenic and intratumoral myeloid-derived suppressor cells (MDSCs), as well as M2 macrophages, were markedly reduced. Besides, residual tumor specimens from combi-treated mice had increased numbers of infiltrating cytotoxic T-cells. Frameshift mutations in <i>APC</i>, <i>Tmem60</i>, and <i>Casc3</i> were no longer detectable upon treatment, likely because of the successful eradication of single mutated cell clones. By contrast, novel mutations appeared. Collectively, we herein confirm the safe application of combined chemo-immunotherapy by long-term tumor growth control to prevent the development of resistance mechanisms. |
| first_indexed | 2024-03-10T10:48:08Z |
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| institution | Directory Open Access Journal |
| issn | 1661-6596 1422-0067 |
| language | English |
| last_indexed | 2024-03-10T10:48:08Z |
| publishDate | 2021-06-01 |
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| series | International Journal of Molecular Sciences |
| spelling | doaj.art-cb1083984d91488ebc7cf0c4f00ad4172023-11-21T22:26:49ZengMDPI AGInternational Journal of Molecular Sciences1661-65961422-00672021-06-012211599010.3390/ijms22115990Combined Gemcitabine and Immune-Checkpoint Inhibition Conquers Anti-PD-L1 Resistance in Low-Immunogenic Mismatch Repair-Deficient TumorsInken Salewski0Julia Henne1Leonie Engster2Bjoern Schneider3Heiko Lemcke4Anna Skorska5Peggy Berlin6Larissa Henze7Christian Junghanss8Claudia Maletzki9Department of Medicine, Clinic III–Hematology, Oncology, Palliative Medicine, Rostock University Medical Center, University of Rostock, 18057 Rostock, GermanyDepartment of Medicine, Clinic III–Hematology, Oncology, Palliative Medicine, Rostock University Medical Center, University of Rostock, 18057 Rostock, GermanyDepartment of Medicine, Clinic III–Hematology, Oncology, Palliative Medicine, Rostock University Medical Center, University of Rostock, 18057 Rostock, GermanyInstitute of Pathology, Rostock University Medical Center, University of Rostock, 18057 Rostock, GermanyDepartment of Cardiac Surgery, Reference and Translation Center for Cardiac Stem Cell Therapy (RTC), Rostock University Medical Center, University of Rostock, 18057 Rostock, GermanyDepartment of Cardiac Surgery, Reference and Translation Center for Cardiac Stem Cell Therapy (RTC), Rostock University Medical Center, University of Rostock, 18057 Rostock, GermanyDivision of Gastroenterology and Endocrinology, Department of Medicine II, Rostock University Medical Center, University of Rostock, 18057 Rostock, GermanyDepartment of Medicine, Clinic III–Hematology, Oncology, Palliative Medicine, Rostock University Medical Center, University of Rostock, 18057 Rostock, GermanyDepartment of Medicine, Clinic III–Hematology, Oncology, Palliative Medicine, Rostock University Medical Center, University of Rostock, 18057 Rostock, GermanyDepartment of Medicine, Clinic III–Hematology, Oncology, Palliative Medicine, Rostock University Medical Center, University of Rostock, 18057 Rostock, GermanyTumors arising in the context of Lynch Syndrome or constitutional mismatch repair deficiency are hypermutated and have a good response towards immune-checkpoint inhibitors (ICIs), including α-PD-L1 antibodies. However, in most cases, resistance mechanisms evolve. To improve outcomes and prevent resistance development, combination approaches are warranted. Herein, we applied a combined regimen with an α-PD-L1 antibody and gemcitabine in a preclinical tumor model to activate endogenous antitumor immune responses. Mlh1<sup>−/−</sup> mice with established gastrointestinal tumors received the α-PD-L1 antibody (clone 6E11; 2.5 mg/kg bw, i.v., q2wx3) and gemcitabine (100 mg/kg bw, i.p., q4wx3) in mono- or combination therapy. Survival and tumor growth were recorded. Immunological changes in the blood were routinely examined via multi-color flow cytometry and complemented by ex vivo frameshift mutation analysis to identify alterations in Mlh1<sup>−/−</sup>-tumor-associated target genes. The combined therapy of α-PD-L1 and gemcitabine prolonged median overall survival of Mlh1<sup>−/−</sup> mice from four weeks in the untreated control group to 12 weeks, accompanied by therapy-induced tumor growth inhibition, as measured by <sup>[18F]</sup>-FDG PET/CT. Plasma cytokine levels of IL13, TNFα, and MIP1β were increased and also higher than in mice receiving either monotherapy. Circulating splenic and intratumoral myeloid-derived suppressor cells (MDSCs), as well as M2 macrophages, were markedly reduced. Besides, residual tumor specimens from combi-treated mice had increased numbers of infiltrating cytotoxic T-cells. Frameshift mutations in <i>APC</i>, <i>Tmem60</i>, and <i>Casc3</i> were no longer detectable upon treatment, likely because of the successful eradication of single mutated cell clones. By contrast, novel mutations appeared. Collectively, we herein confirm the safe application of combined chemo-immunotherapy by long-term tumor growth control to prevent the development of resistance mechanisms.https://www.mdpi.com/1422-0067/22/11/5990immune checkpoint inhibitorMMR deficiencyin vivo imagingtumor microenvironmentgenetic modelcoding microsatellite mutations |
| spellingShingle | Inken Salewski Julia Henne Leonie Engster Bjoern Schneider Heiko Lemcke Anna Skorska Peggy Berlin Larissa Henze Christian Junghanss Claudia Maletzki Combined Gemcitabine and Immune-Checkpoint Inhibition Conquers Anti-PD-L1 Resistance in Low-Immunogenic Mismatch Repair-Deficient Tumors International Journal of Molecular Sciences immune checkpoint inhibitor MMR deficiency in vivo imaging tumor microenvironment genetic model coding microsatellite mutations |
| title | Combined Gemcitabine and Immune-Checkpoint Inhibition Conquers Anti-PD-L1 Resistance in Low-Immunogenic Mismatch Repair-Deficient Tumors |
| title_full | Combined Gemcitabine and Immune-Checkpoint Inhibition Conquers Anti-PD-L1 Resistance in Low-Immunogenic Mismatch Repair-Deficient Tumors |
| title_fullStr | Combined Gemcitabine and Immune-Checkpoint Inhibition Conquers Anti-PD-L1 Resistance in Low-Immunogenic Mismatch Repair-Deficient Tumors |
| title_full_unstemmed | Combined Gemcitabine and Immune-Checkpoint Inhibition Conquers Anti-PD-L1 Resistance in Low-Immunogenic Mismatch Repair-Deficient Tumors |
| title_short | Combined Gemcitabine and Immune-Checkpoint Inhibition Conquers Anti-PD-L1 Resistance in Low-Immunogenic Mismatch Repair-Deficient Tumors |
| title_sort | combined gemcitabine and immune checkpoint inhibition conquers anti pd l1 resistance in low immunogenic mismatch repair deficient tumors |
| topic | immune checkpoint inhibitor MMR deficiency in vivo imaging tumor microenvironment genetic model coding microsatellite mutations |
| url | https://www.mdpi.com/1422-0067/22/11/5990 |
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