Immunostimulatory effects of targeted thorium-227 conjugates as single agent and in combination with anti-PD-L1 therapy
Background Targeted thorium-227 conjugates (TTCs) are an emerging class of targeted alpha therapies (TATs). Their unique mode of action (MoA) is the induction of difficult-to-repair clustered DNA double-strand breaks. However, thus far, their effects on the immune system are largely unknown. Here, w...
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| Language: | English |
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BMJ Publishing Group
2021-10-01
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| Series: | Journal for ImmunoTherapy of Cancer |
| Online Access: | https://jitc.bmj.com/content/9/10/e002387.full |
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| author | Pascale Lejeune Véronique Cruciani Axel Berg-Larsen Andreas Schlicker Anne Mobergslien Lisa Bartnitzky Sandra Berndt Sabine Zitzmann-Kolbe Claudia Kamfenkel Stefan Stargard Stefanie Hammer Jennifer S Jørgensen Malene Jackerott Carsten H Nielsen Christoph A Schatz Hartwig Hennekes Jenny Karlsson Alan S Cuthbertson Dominik Mumberg Urs B Hagemann |
| author_facet | Pascale Lejeune Véronique Cruciani Axel Berg-Larsen Andreas Schlicker Anne Mobergslien Lisa Bartnitzky Sandra Berndt Sabine Zitzmann-Kolbe Claudia Kamfenkel Stefan Stargard Stefanie Hammer Jennifer S Jørgensen Malene Jackerott Carsten H Nielsen Christoph A Schatz Hartwig Hennekes Jenny Karlsson Alan S Cuthbertson Dominik Mumberg Urs B Hagemann |
| author_sort | Pascale Lejeune |
| collection | DOAJ |
| description | Background Targeted thorium-227 conjugates (TTCs) are an emerging class of targeted alpha therapies (TATs). Their unique mode of action (MoA) is the induction of difficult-to-repair clustered DNA double-strand breaks. However, thus far, their effects on the immune system are largely unknown. Here, we investigated the immunostimulatory effects of the mesothelin-targeted thorium-227 conjugate (MSLN-TTC) in vitro and in vivo in monotherapy and in combination with an inhibitor of the immune checkpoint programmed death receptor ligand 1 (PD-L1) in immunocompetent mice.Methods The murine cell line MC38 was transfected with the human gene encoding for MSLN (hMSLN) to enable binding of the non-cross-reactive MSLN-TTC. The immunostimulatory effects of MSLN-TTC were studied in vitro on human cancer cell lines and MC38-hMSLN cells. The efficacy and MoA of MSLN-TTC were studied in vivo as monotherapy or in combination with anti-PD-L1 in MC38-hMSLN tumor-bearing immunocompetent C57BL/6 mice. Experiments were supported by RNA sequencing, flow cytometry, immunohistochemistry, mesoscale, and TaqMan PCR analyses to study the underlying immunostimulatory effects. In vivo depletion of CD8+ T cells and studies with Rag2/Il2Rg double knockout C57BL/6 mice were conducted to investigate the importance of immune cells to the efficacy of MSLN-TTC.Results MSLN-TTC treatment induced upregulation of DNA sensing pathway transcripts (IL-6, CCL20, CXCL10, and stimulator of interferon genes (STING)-related genes) in vitro as determined by RNASeq analysis. The results, including phospho-STING activation, were confirmed on the protein level. Danger-associated molecular pattern molecules were upregulated in parallel, leading to dendritic cell (DC) activation in vitro. MSLN-TTC showed strong antitumor activity (T:C 0.38, p<0.05) as a single agent in human MSLN-expressing MC38 tumor-bearing immunocompetent mice. Combining MSLN-TTC with anti-PD-L1 further enhanced the efficacy (T:C 0.08, p<0.001) as evidenced by the increased number of tumor-free surviving animals. MSLN-TTC monotherapy caused migration of CD103+ cDC1 DCs and infiltration of CD8+ T cells into tumors, which was enhanced on combination with anti-PD-L1. Intriguingly, CD8+ T-cell depletion decreased antitumor efficacy.Conclusions These in vitro and in vivo data on MSLN-TTC demonstrate that the MoA of TTCs involves activation of the immune system. The findings are of relevance for other targeted radiotherapies and may guide clinical combination strategies. |
| format | Article |
| id | doaj-art-05e7344e8ce54a129a43af0ebbd6ec6f |
| institution | DOAJ |
| issn | 2051-1426 |
| language | English |
| publishDate | 2021-10-01 |
| publisher | BMJ Publishing Group |
| record_format | Article |
| series | Journal for ImmunoTherapy of Cancer |
| spelling | doaj-art-05e7344e8ce54a129a43af0ebbd6ec6f2025-08-20T03:08:06ZengBMJ Publishing GroupJournal for ImmunoTherapy of Cancer2051-14262021-10-0191010.1136/jitc-2021-002387Immunostimulatory effects of targeted thorium-227 conjugates as single agent and in combination with anti-PD-L1 therapyPascale Lejeune0Véronique Cruciani1Axel Berg-Larsen2Andreas Schlicker3Anne Mobergslien4Lisa Bartnitzky5Sandra Berndt6Sabine Zitzmann-Kolbe7Claudia Kamfenkel8Stefan Stargard9Stefanie Hammer10Jennifer S Jørgensen11Malene Jackerott12Carsten H Nielsen13Christoph A Schatz14Hartwig Hennekes15Jenny Karlsson16Alan S Cuthbertson17Dominik Mumberg18Urs B Hagemann19Bayer AG, Berlin, GermanyBayer AS, Oslo, NorwayBayer AS, Oslo, NorwayBayer AG, Berlin, GermanyBayer AS, Oslo, NorwayBayer AG, Berlin, GermanyBayer AG, Berlin, GermanyBayer AG, Berlin, GermanyBayer AG, Berlin, GermanyBayer AG, Berlin, GermanyBayer AG, Berlin, GermanyMinerva Imaging ApS, Copenhagen, DenmarkMinerva Imaging ApS, Copenhagen, DenmarkMinerva Imaging ApS, Copenhagen, DenmarkBayer AG, Berlin, GermanyBayer AG, Berlin, GermanyBayer AS, Oslo, NorwayBayer AS, Oslo, NorwayBayer AG, Berlin, GermanyBayer AG, Berlin, GermanyBackground Targeted thorium-227 conjugates (TTCs) are an emerging class of targeted alpha therapies (TATs). Their unique mode of action (MoA) is the induction of difficult-to-repair clustered DNA double-strand breaks. However, thus far, their effects on the immune system are largely unknown. Here, we investigated the immunostimulatory effects of the mesothelin-targeted thorium-227 conjugate (MSLN-TTC) in vitro and in vivo in monotherapy and in combination with an inhibitor of the immune checkpoint programmed death receptor ligand 1 (PD-L1) in immunocompetent mice.Methods The murine cell line MC38 was transfected with the human gene encoding for MSLN (hMSLN) to enable binding of the non-cross-reactive MSLN-TTC. The immunostimulatory effects of MSLN-TTC were studied in vitro on human cancer cell lines and MC38-hMSLN cells. The efficacy and MoA of MSLN-TTC were studied in vivo as monotherapy or in combination with anti-PD-L1 in MC38-hMSLN tumor-bearing immunocompetent C57BL/6 mice. Experiments were supported by RNA sequencing, flow cytometry, immunohistochemistry, mesoscale, and TaqMan PCR analyses to study the underlying immunostimulatory effects. In vivo depletion of CD8+ T cells and studies with Rag2/Il2Rg double knockout C57BL/6 mice were conducted to investigate the importance of immune cells to the efficacy of MSLN-TTC.Results MSLN-TTC treatment induced upregulation of DNA sensing pathway transcripts (IL-6, CCL20, CXCL10, and stimulator of interferon genes (STING)-related genes) in vitro as determined by RNASeq analysis. The results, including phospho-STING activation, were confirmed on the protein level. Danger-associated molecular pattern molecules were upregulated in parallel, leading to dendritic cell (DC) activation in vitro. MSLN-TTC showed strong antitumor activity (T:C 0.38, p<0.05) as a single agent in human MSLN-expressing MC38 tumor-bearing immunocompetent mice. Combining MSLN-TTC with anti-PD-L1 further enhanced the efficacy (T:C 0.08, p<0.001) as evidenced by the increased number of tumor-free surviving animals. MSLN-TTC monotherapy caused migration of CD103+ cDC1 DCs and infiltration of CD8+ T cells into tumors, which was enhanced on combination with anti-PD-L1. Intriguingly, CD8+ T-cell depletion decreased antitumor efficacy.Conclusions These in vitro and in vivo data on MSLN-TTC demonstrate that the MoA of TTCs involves activation of the immune system. The findings are of relevance for other targeted radiotherapies and may guide clinical combination strategies.https://jitc.bmj.com/content/9/10/e002387.full |
| spellingShingle | Pascale Lejeune Véronique Cruciani Axel Berg-Larsen Andreas Schlicker Anne Mobergslien Lisa Bartnitzky Sandra Berndt Sabine Zitzmann-Kolbe Claudia Kamfenkel Stefan Stargard Stefanie Hammer Jennifer S Jørgensen Malene Jackerott Carsten H Nielsen Christoph A Schatz Hartwig Hennekes Jenny Karlsson Alan S Cuthbertson Dominik Mumberg Urs B Hagemann Immunostimulatory effects of targeted thorium-227 conjugates as single agent and in combination with anti-PD-L1 therapy Journal for ImmunoTherapy of Cancer |
| title | Immunostimulatory effects of targeted thorium-227 conjugates as single agent and in combination with anti-PD-L1 therapy |
| title_full | Immunostimulatory effects of targeted thorium-227 conjugates as single agent and in combination with anti-PD-L1 therapy |
| title_fullStr | Immunostimulatory effects of targeted thorium-227 conjugates as single agent and in combination with anti-PD-L1 therapy |
| title_full_unstemmed | Immunostimulatory effects of targeted thorium-227 conjugates as single agent and in combination with anti-PD-L1 therapy |
| title_short | Immunostimulatory effects of targeted thorium-227 conjugates as single agent and in combination with anti-PD-L1 therapy |
| title_sort | immunostimulatory effects of targeted thorium 227 conjugates as single agent and in combination with anti pd l1 therapy |
| url | https://jitc.bmj.com/content/9/10/e002387.full |
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