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McMillan MT, Khan AJ, Powell SN, Humm J, Deasy JO, Haimovitz-Friedman A. Spatially Fractionated Radiotherapy in the Era of Immunotherapy. Semin Radiat Oncol 2024; 34:276-283. [PMID: 38880536 DOI: 10.1016/j.semradonc.2024.04.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/18/2024]
Abstract
Spatially fractionated radiotherapy (SFRT) includes historical grid therapy approaches but more recently encompasses the controlled introduction of one or more cold dose regions using intensity modulation delivery techniques. The driving hypothesis behind SFRT is that it may allow for an increased immune response that is otherwise suppressed by radiation effects. With both two- and three-dimensional SFRT approaches, SFRT dose distributions typically include multiple dose cold spots or valleys. Despite its unconventional methods, reported clinical experience shows that SFRT can sometimes induce marked tumor regressions, even in patients with large hypoxic tumors. Preclinical models using extreme dose distributions (i.e., half-sparing) have been shown to nevertheless result in full tumor eradications, a more robust immune response, and systemic anti-tumor immunity. SFRT takes advantage of the complementary immunomodulatory features of low- and high-dose radiotherapy to integrate the delivery of both into a single target. Clinical trials using three-dimensional SFRT (i.e., lattice-like dose distributions) have reported both promising tumor and toxicity results, and ongoing clinical trials are investigating synergy between SFRT and immunotherapies.
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Affiliation(s)
| | | | | | - John Humm
- Medical Physics, Memorial Sloan-Kettering Cancer Center, New York, NY
| | - Joseph O Deasy
- Medical Physics, Memorial Sloan-Kettering Cancer Center, New York, NY
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2
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Takashima ME, Berg TJ, Morris ZS. The Effects of Radiation Dose Heterogeneity on the Tumor Microenvironment and Anti-Tumor Immunity. Semin Radiat Oncol 2024; 34:262-271. [PMID: 38880534 DOI: 10.1016/j.semradonc.2024.04.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/18/2024]
Abstract
Radiotherapy elicits dose- and lineage-dependent effects on immune cell survival, migration, activation, and proliferation in targeted tumor microenvironments. Radiation also stimulates phenotypic changes that modulate the immune susceptibility of tumor cells. This has raised interest in using radiotherapy to promote greater response to immunotherapies. To clarify the potential of such combinations, it is critical to understand how best to administer radiation therapy to achieve activation of desired immunologic mechanisms. In considering the multifaceted process of priming and propagating anti-tumor immune response, radiation dose heterogeneity emerges as a potential means for simultaneously engaging diverse dose-dependent effects in a single tumor environment. Recent work in spatially fractionated external beam radiation therapy demonstrates the expansive immune responses achievable when a range of high to low dose radiation is delivered in a tumor. Brachytherapy and radiopharmaceutical therapies deliver inherently heterogeneous distributions of radiation that may contribute to immunogenicity. This review evaluates the interplay of radiation dose and anti-tumor immune response and explores emerging methodological approaches for investigating the effects of heterogeneous dose distribution on immune responses.
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Affiliation(s)
- Maya E Takashima
- Department of Human Oncology, University of Wisconsin School of Medicine and Public Health, Madison, WI
| | - Tracy J Berg
- Department of Human Oncology, University of Wisconsin School of Medicine and Public Health, Madison, WI
| | - Zachary S Morris
- Department of Human Oncology, University of Wisconsin School of Medicine and Public Health, Madison, WI.
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3
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Lu Q, Yan W, Zhu A, Tubin S, Mourad WF, Yang J. Combining spatially fractionated radiation therapy (SFRT) and immunotherapy opens new rays of hope for enhancing therapeutic ratio. Clin Transl Radiat Oncol 2024; 44:100691. [PMID: 38033759 PMCID: PMC10684810 DOI: 10.1016/j.ctro.2023.100691] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2023] [Revised: 10/04/2023] [Accepted: 10/15/2023] [Indexed: 12/02/2023] Open
Abstract
Spatially Fractionated Radiation Therapy (SFRT) is a form of radiotherapy that delivers a single large dose of radiation within the target volume in a heterogeneous pattern with regions of peak dosage and regions of under dosage. SFRT types can be defined by how the heterogeneous pattern of radiation is obtained. Immune checkpoint inhibitors (ICIs) have been approved for various malignant tumors and are widely used to treat patients with metastatic cancer. The efficacy of ICI monotherapy is limited due to the "cold" tumor microenvironment. Fractionated radiotherapy can achieve higher doses per fraction to the target tumor, and induce immune activation (immodulate tumor immunogenicity and microenvironment). Therefore, coupling ICI therapy and fractionated radiation therapy could significantly improve the outcome of metastatic cancer. This review focuses on both preclinical and clinical studies that use a combination of radiotherapy and ICI therapy in cancer.
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Affiliation(s)
- Qiuxia Lu
- Foshan Fosun Chancheng Hospital, P.R. China
- Junxin Precision Oncology Group, P.R. China
| | - Weisi Yan
- Baptist Health System, Lexington, KY, United States
- Junxin Precision Oncology Group, P.R. China
| | - Alan Zhu
- Mayo Clinic Alix School of Medicine, Scottsdale, AZ, United States
| | - Slavisa Tubin
- Albert Einstein Collage of Medicine New York, Center for Ion Therapy, Medaustron, Austria
| | - Waleed F. Mourad
- Department of Radiation Medicine Markey Cancer Center, University of Kentucky - College of Medicine, United States
| | - Jun Yang
- Foshan Fosun Chancheng Hospital, P.R. China
- Junxin Precision Oncology Group, P.R. China
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Bertho A, Iturri L, Brisebard E, Juchaux M, Gilbert C, Ortiz R, Sebrie C, Jourdain L, Lamirault C, Ramasamy G, Pouzoulet F, Prezado Y. Evaluation of the Role of the Immune System Response After Minibeam Radiation Therapy. Int J Radiat Oncol Biol Phys 2023; 115:426-439. [PMID: 35985455 DOI: 10.1016/j.ijrobp.2022.08.011] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2022] [Revised: 07/23/2022] [Accepted: 08/05/2022] [Indexed: 01/11/2023]
Abstract
PURPOSE Minibeam radiation therapy (MBRT) is an innovative technique that uses a spatial dose modulation. The dose distribution consists of high doses (peaks) in the path of the minibeam and low doses (valleys). The underlying biological mechanism associated with MBRT efficacy remains currently unclear and thus we investigated the potential role of the immune system after treatment with MBRT. METHODS AND MATERIALS Rats bearing an orthotopic glioblastoma cell line were treated with 1 fraction of high dose conventional radiation therapy (30 Gy) or 1 fraction of the same mean dose in MBRT. Both immunocompetent (F344) and immunodeficient (Nude) rats were analyzed in survival studies. Systemic and intratumoral immune cell population changes were studied with flow cytometry and immunohistochemistry (IHC) 2 and 7 days after the irradiation. RESULTS The absence of response of Nude rats after MBRT suggested that T cells were key in the mode of action of MBRT. An inflammatory phenotype was observed in the blood 1 week after irradiation compared with conventional irradiation. Tumor immune cell analysis by flow cytometry showed a substantial infiltration of lymphocytes, specifically of CD8 T cells and B cells in both conventional and MBRT-treated animals. IHC revealed that MBRT induced a faster recruitment of CD8 and CD4 T cells. Animals that were cured by radiation therapy did not suffer tumor growth after reimplantation of tumoral cells, proving the long-term immunity response generated after a high dose of radiation. CONCLUSIONS Our findings show that MBRT can elicit a robust antitumor immune response in glioblastoma while avoiding the high toxicity of a high dose of conventional radiation therapy.
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Affiliation(s)
- Annaig Bertho
- CNRS UMR3347, Inserm U1021, Signalisation Radiobiologie et Cancer, Institut Curie, Université PSL, Orsay, France; CNRS UMR3347, Inserm U1021, Signalisation Radiobiologie et Cancer, Université Paris-Saclay, Orsay, France.
| | - Lorea Iturri
- CNRS UMR3347, Inserm U1021, Signalisation Radiobiologie et Cancer, Institut Curie, Université PSL, Orsay, France; CNRS UMR3347, Inserm U1021, Signalisation Radiobiologie et Cancer, Université Paris-Saclay, Orsay, France
| | | | - Marjorie Juchaux
- CNRS UMR3347, Inserm U1021, Signalisation Radiobiologie et Cancer, Institut Curie, Université PSL, Orsay, France; CNRS UMR3347, Inserm U1021, Signalisation Radiobiologie et Cancer, Université Paris-Saclay, Orsay, France
| | - Cristèle Gilbert
- CNRS UMR3347, Inserm U1021, Signalisation Radiobiologie et Cancer, Institut Curie, Université PSL, Orsay, France; CNRS UMR3347, Inserm U1021, Signalisation Radiobiologie et Cancer, Université Paris-Saclay, Orsay, France
| | - Ramon Ortiz
- CNRS UMR3347, Inserm U1021, Signalisation Radiobiologie et Cancer, Institut Curie, Université PSL, Orsay, France; CNRS UMR3347, Inserm U1021, Signalisation Radiobiologie et Cancer, Université Paris-Saclay, Orsay, France
| | - Catherine Sebrie
- Service Hospitalier Frédéric Joliot, CEA, CNRS, Inserm, BIOMAPS Université Paris-Saclay, Orsay, France
| | - Laurene Jourdain
- Service Hospitalier Frédéric Joliot, CEA, CNRS, Inserm, BIOMAPS Université Paris-Saclay, Orsay, France
| | - Charlotte Lamirault
- Département de Recherche Translationnelle, CurieCoreTech-Experimental Radiotherapy (RadeXp), Institut Curie, PSL University, Paris, France
| | - Gabriel Ramasamy
- Département de Recherche Translationnelle, CurieCoreTech-Experimental Radiotherapy (RadeXp), Institut Curie, PSL University, Paris, France
| | - Frédéric Pouzoulet
- Département de Recherche Translationnelle, CurieCoreTech-Experimental Radiotherapy (RadeXp), Institut Curie, PSL University, Paris, France; Inserm U1288, Laboratoire de Recherche Translationnelle en Oncologie, Institut Curie, PSL University, Université Paris-Saclay, Orsay, France
| | - Yolanda Prezado
- CNRS UMR3347, Inserm U1021, Signalisation Radiobiologie et Cancer, Institut Curie, Université PSL, Orsay, France; CNRS UMR3347, Inserm U1021, Signalisation Radiobiologie et Cancer, Université Paris-Saclay, Orsay, France
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Baiocco G, Bartzsch S, Conte V, Friedrich T, Jakob B, Tartas A, Villagrasa C, Prise KM. A matter of space: how the spatial heterogeneity in energy deposition determines the biological outcome of radiation exposure. RADIATION AND ENVIRONMENTAL BIOPHYSICS 2022; 61:545-559. [PMID: 36220965 PMCID: PMC9630194 DOI: 10.1007/s00411-022-00989-z] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/09/2022] [Accepted: 08/03/2022] [Indexed: 05/10/2023]
Abstract
The outcome of the exposure of living organisms to ionizing radiation is determined by the distribution of the associated energy deposition at different spatial scales. Radiation proceeds through ionizations and excitations of hit molecules with an ~ nm spacing. Approaches such as nanodosimetry/microdosimetry and Monte Carlo track-structure simulations have been successfully adopted to investigate radiation quality effects: they allow to explore correlations between the spatial clustering of such energy depositions at the scales of DNA or chromosome domains and their biological consequences at the cellular level. Physical features alone, however, are not enough to assess the entity and complexity of radiation-induced DNA damage: this latter is the result of an interplay between radiation track structure and the spatial architecture of chromatin, and further depends on the chromatin dynamic response, affecting the activation and efficiency of the repair machinery. The heterogeneity of radiation energy depositions at the single-cell level affects the trade-off between cell inactivation and induction of viable mutations and hence influences radiation-induced carcinogenesis. In radiation therapy, where the goal is cancer cell inactivation, the delivery of a homogenous dose to the tumour has been the traditional approach in clinical practice. However, evidence is accumulating that introducing heterogeneity with spatially fractionated beams (mini- and microbeam therapy) can lead to significant advantages, particularly in sparing normal tissues. Such findings cannot be explained in merely physical terms, and their interpretation requires considering the scales at play in the underlying biological mechanisms, suggesting a systemic response to radiation.
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Affiliation(s)
- Giorgio Baiocco
- Radiation Biophysics and Radiobiology Group, Physics Department, University of Pavia, Pavia, Italy.
| | - Stefan Bartzsch
- Institute for Radiation Medicine, Helmholtz Centre Munich, Munich, Germany
- Department of Radiation Oncology, Technical University of Munich, Munich, Germany
| | - Valeria Conte
- Istituto Nazionale Di Fisica Nucleare INFN, Laboratori Nazionali Di Legnaro, Legnaro, Italy
| | - Thomas Friedrich
- Department of Biophysics, GSI Helmholtz Centre for Heavy Ion Research, Darmstadt, Germany
| | - Burkhard Jakob
- Department of Biophysics, GSI Helmholtz Centre for Heavy Ion Research, Darmstadt, Germany
| | - Adrianna Tartas
- Biomedical Physics Division, Institute of Experimental Physics, University of Warsaw, Warsaw, Poland
| | - Carmen Villagrasa
- IRSN, Institut de Radioprotection et de Sûreté Nucléaire, Fontenay aux Roses, France
| | - Kevin M Prise
- Patrick G Johnston Centre for Cancer Research, Queen's University Belfast, Belfast, UK
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Microbeam Radiation Therapy controls local growth of radioresistant melanoma and treats out-of-field locoregional metastasis. Int J Radiat Oncol Biol Phys 2022; 114:478-493. [DOI: 10.1016/j.ijrobp.2022.06.090] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2021] [Revised: 06/17/2022] [Accepted: 06/24/2022] [Indexed: 11/21/2022]
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7
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Barnes MJ, Paino J, Day LR, Butler D, Häusermann D, Pelliccia D, Crosbie JC. SyncMRT: a solution to image-guided synchrotron radiotherapy for quality assurance and pre-clinical trials. JOURNAL OF SYNCHROTRON RADIATION 2022; 29:1074-1084. [PMID: 35787575 PMCID: PMC9255576 DOI: 10.1107/s1600577522004829] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/09/2021] [Accepted: 05/05/2022] [Indexed: 06/15/2023]
Abstract
In this work, a new image guidance system and protocols for delivering image-guided radiotherapy (IGRT) on the Imaging and Medical Beamline (IMBL) at the ANSTO Australian Synchrotron are introduced. The image guidance methods used and the resulting accuracy of tumour alignment in in vivo experiments are often under-reported. Image guidance tasks are often complex, time-consuming and prone to errors. If unchecked, they may result in potential mis-treatments. We introduce SyncMRT, a software package that provides a simple, image guidance tool-kit for aligning samples to the synchrotron beam. We have demonstrated sub-millimetre alignment using SyncMRT and the small-animal irradiation platform (the DynamicMRT system) on the IMBL. SyncMRT has become the standard for carrying out IGRT treatments on the IMBL and has been used in all pre-clinical radiotherapy experiments since 2017. Further, we introduce two quality assurance (QA) protocols to synchrotron radiotherapy on the IMBL: the Winston-Lutz test and hidden target test. It is shown that the presented QA tests are appropriate for picking up geometrical setup errors and assessing the end-to-end accuracy of the image guidance process. Together, these tools make image guidance easier and provide a mechanism for reporting the geometric accuracy of synchrotron-based IGRT treatments. Importantly, this work is scalable to other delivery systems, and is in continual development to support the upcoming veterinary radiotherapy trials on the IMBL.
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Affiliation(s)
- M. J. Barnes
- ANSTO Australian Synchrotron, Kulin Nation, Clayton, Victoria, Australia
- Peter MacCallum Cancer Centre, Kulin Nation, Melbourne, Victoria, Australia
- School of Science, RMIT Univeristy, Kulin Nation, Melbourne, Victoria, Australia
- Illawarra Health and Medical Research Institute, Dharawal Nation, Wollongong, New South Wales, Australia
| | - J. Paino
- Illawarra Health and Medical Research Institute, Dharawal Nation, Wollongong, New South Wales, Australia
- Centre for Medical Radiation Physics, University of Wollongong, Dharawal Nation, Wollongong, New South Wales, Australia
| | - L. R. Day
- School of Science, RMIT Univeristy, Kulin Nation, Melbourne, Victoria, Australia
| | - D. Butler
- Australian Radiation Protection and Nuclear Safety Agency (ARPANSA), Kulin Nation, Yallambie, Victoria, Australia
| | - D. Häusermann
- ANSTO Australian Synchrotron, Kulin Nation, Clayton, Victoria, Australia
| | - D. Pelliccia
- Instruments and Data Tools, Kulin Nation, Melbourne, Victoria, Australia
| | - J. C. Crosbie
- School of Science, RMIT Univeristy, Kulin Nation, Melbourne, Victoria, Australia
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Wang L, Jiang J, Chen Y, Jia Q, Chu Q. The roles of CC chemokines in response to radiation. Radiat Oncol 2022; 17:63. [PMID: 35365161 PMCID: PMC8974090 DOI: 10.1186/s13014-022-02038-x] [Citation(s) in RCA: 20] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2021] [Accepted: 03/20/2022] [Indexed: 01/21/2023] Open
Abstract
Radiotherapy is an effective regimen for cancer treatment alone or combined with chemotherapy or immunotherapy. The direct effect of radiotherapy involves radiation-induced DNA damage, and most studies have focused on this area to improve the efficacy of radiotherapy. Recently, the immunomodulatory effect of radiation on the tumour microenvironment has attracted much interest. Dying tumour cells can release multiple immune-related molecules, including tumour-associated antigens, chemokines, and inflammatory mediators. Then, immune cells are attracted to the irradiated site, exerting immunostimulatory or immunosuppressive effects. CC chemokines play pivotal roles in the trafficking process. The CC chemokine family includes 28 members that attract different immune subsets. Upon irradiation, tumour cells or immune cells can release different CC chemokines. Here, we mainly discuss the importance of CCL2, CCL3, CCL5, CCL8, CCL11, CCL20 and CCL22 in radiotherapy. In irradiated normal tissues, released chemokines induce epithelial to mesenchymal transition, thus promoting tissue injury. In the tumour microenvironment, released chemokines recruit cancer-associated cells, such as tumour-infiltrating lymphocytes, myeloid-derived suppressor cells and tumour-associated macrophages, to the tumour niche. Thus, CC chemokines have protumour and antitumour properties. Based on the complex roles of CC chemokines in the response to radiation, it would be promising to target specific chemokines to alleviate radiation-induced injury or promote tumour control.
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Trappetti V, Fazzari J, Fernandez-Palomo C, Smyth L, Potez M, Shintani N, de Breuyn Dietler B, Martin OA, Djonov V. Targeted Accumulation of Macrophages Induced by Microbeam Irradiation in a Tissue-Dependent Manner. Biomedicines 2022; 10:biomedicines10040735. [PMID: 35453485 PMCID: PMC9025837 DOI: 10.3390/biomedicines10040735] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2022] [Revised: 03/08/2022] [Accepted: 03/18/2022] [Indexed: 02/01/2023] Open
Abstract
Radiation therapy (RT) is a vital component of multimodal cancer treatment, and its immunomodulatory effects are a major focus of current therapeutic strategies. Macrophages are some of the first cells recruited to sites of radiation-induced injury where they can aid in tissue repair, propagate radiation-induced fibrogenesis and influence tumour dynamics. Microbeam radiation therapy (MRT) is a unique, spatially fractionated radiation modality that has demonstrated exceptional tumour control and reduction in normal tissue toxicity, including fibrosis. We conducted a morphological analysis of MRT-irradiated normal liver, lung and skin tissues as well as lung and melanoma tumours. MRT induced distinct patterns of DNA damage, reflecting the geometry of the microbeam array. Macrophages infiltrated these regions of peak dose deposition at variable timepoints post-irradiation depending on the tissue type. In normal liver and lung tissue, macrophages clearly demarcated the beam path by 48 h and 7 days post-irradiation, respectively. This was not reflected, however, in normal skin tissue, despite clear DNA damage marking the beam path. Persistent DNA damage was observed in MRT-irradiated lung carcinoma, with an accompanying geometry-specific influx of mixed M1/M2-like macrophage populations. These data indicate the unique potential of MRT as a tool to induce a remarkable accumulation of macrophages in an organ/tissue-specific manner. Further characterization of these macrophage populations is warranted to identify their organ-specific roles in normal tissue sparing and anti-tumour responses.
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Affiliation(s)
- Verdiana Trappetti
- Institute of Anatomy, University of Bern, Baltzerstarsse 2, 3012 Bern, Switzerland; (V.T.); (J.F.); (C.F.-P.); (M.P.); (N.S.); (B.d.B.D.); (O.A.M.)
| | - Jennifer Fazzari
- Institute of Anatomy, University of Bern, Baltzerstarsse 2, 3012 Bern, Switzerland; (V.T.); (J.F.); (C.F.-P.); (M.P.); (N.S.); (B.d.B.D.); (O.A.M.)
| | - Cristian Fernandez-Palomo
- Institute of Anatomy, University of Bern, Baltzerstarsse 2, 3012 Bern, Switzerland; (V.T.); (J.F.); (C.F.-P.); (M.P.); (N.S.); (B.d.B.D.); (O.A.M.)
| | - Lloyd Smyth
- Department of Obstetrics and Gynaecology, Royal Women’s Hospital, University of Melbourne, Melbourne, VIC 3052, Australia;
| | - Marine Potez
- Institute of Anatomy, University of Bern, Baltzerstarsse 2, 3012 Bern, Switzerland; (V.T.); (J.F.); (C.F.-P.); (M.P.); (N.S.); (B.d.B.D.); (O.A.M.)
- Department of Immunology, H. Lee Moffitt Cancer Center and Research Institute, 12902 USF Magnolia Drive, Tampa, FL 33612, USA
| | - Nahoko Shintani
- Institute of Anatomy, University of Bern, Baltzerstarsse 2, 3012 Bern, Switzerland; (V.T.); (J.F.); (C.F.-P.); (M.P.); (N.S.); (B.d.B.D.); (O.A.M.)
| | - Bettina de Breuyn Dietler
- Institute of Anatomy, University of Bern, Baltzerstarsse 2, 3012 Bern, Switzerland; (V.T.); (J.F.); (C.F.-P.); (M.P.); (N.S.); (B.d.B.D.); (O.A.M.)
| | - Olga A. Martin
- Institute of Anatomy, University of Bern, Baltzerstarsse 2, 3012 Bern, Switzerland; (V.T.); (J.F.); (C.F.-P.); (M.P.); (N.S.); (B.d.B.D.); (O.A.M.)
- Division of Radiation Oncology, Peter MacCallum Cancer Centre, 305 Grattan St., Melbourne, VIC 3000, Australia
- Department of Oncology, University of Melbourne, Parkville, VIC 3010, Australia
| | - Valentin Djonov
- Institute of Anatomy, University of Bern, Baltzerstarsse 2, 3012 Bern, Switzerland; (V.T.); (J.F.); (C.F.-P.); (M.P.); (N.S.); (B.d.B.D.); (O.A.M.)
- Correspondence:
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10
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Bertho A, Iturri L, Prezado Y. Radiation-induced immune response in novel radiotherapy approaches FLASH and spatially fractionated radiotherapies. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2022; 376:37-68. [PMID: 36997269 DOI: 10.1016/bs.ircmb.2022.11.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
The last several years have revealed increasing evidence of the immunomodulatory role of radiation therapy. Radiotherapy reshapes the tumoral microenvironment can shift the balance toward a more immunostimulatory or immunosuppressive microenvironment. The immune response to radiation therapy appears to depend on the irradiation configuration (dose, particle, fractionation) and delivery modes (dose rate, spatial distributions). Although an optimal irradiation configuration (dose, temporal fractionation, spatial dose distribution, etc.) has not yet been determined, temporal schemes employing high doses per fraction appear to favor radiation-induced immune response through immunogenic cell death. Through the release of damage-associated molecular patterns and the sensing of double-stranded DNA and RNA breaks, immunogenic cell death activates the innate and adaptive immune response, leading to tumor infiltration by effector T cells and the abscopal effect. Novel radiotherapy approaches such as FLASH and spatially fractionated radiotherapies (SFRT) strongly modulate the dose delivery method. FLASH-RT and SFRT have the potential to trigger the immune system effectively while preserving healthy surrounding tissues. This manuscript reviews the current state of knowledge on the immunomodulation effects of these two new radiotherapy techniques in the tumor, healthy immune cells and non-targeted regions, as well as their therapeutic potential in combination with immunotherapy.
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A Brief Overview of the Preclinical and Clinical Radiobiology of Microbeam Radiotherapy. Clin Oncol (R Coll Radiol) 2021; 33:705-712. [PMID: 34454806 DOI: 10.1016/j.clon.2021.08.011] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2021] [Revised: 07/27/2021] [Accepted: 08/17/2021] [Indexed: 11/23/2022]
Abstract
Microbeam radiotherapy (MRT) is the delivery of spatially fractionated beams that have the potential to offer significant improvements in the therapeutic ratio due to the delivery of micron-sized high dose and dose rate beams. They build on longstanding clinical experience of GRID radiotherapy and more recently lattice-based approaches. Here we briefly overview the preclinical evidence for MRT efficacy and highlight the challenges for bringing this to clinical utility. The biological mechanisms underpinning MRT efficacy are still unclear, but involve vascular, bystander, stem cell and potentially immune responses. There is probably significant overlap in the mechanisms underpinning MRT responses and FLASH radiotherapy that needs to be further defined.
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12
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Trappetti V, Fazzari JM, Fernandez-Palomo C, Scheidegger M, Volarevic V, Martin OA, Djonov VG. Microbeam Radiotherapy-A Novel Therapeutic Approach to Overcome Radioresistance and Enhance Anti-Tumour Response in Melanoma. Int J Mol Sci 2021; 22:7755. [PMID: 34299373 PMCID: PMC8303317 DOI: 10.3390/ijms22147755] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2021] [Revised: 07/15/2021] [Accepted: 07/17/2021] [Indexed: 12/19/2022] Open
Abstract
Melanoma is the deadliest type of skin cancer, due to its invasiveness and limited treatment efficacy. The main therapy for primary melanoma and solitary organ metastases is wide excision. Adjuvant therapy, such as chemotherapy and targeted therapies are mainly used for disseminated disease. Radiotherapy (RT) is a powerful treatment option used in more than 50% of cancer patients, however, conventional RT alone is unable to eradicate melanoma. Its general radioresistance is attributed to overexpression of repair genes in combination with cascades of biochemical repair mechanisms. A novel sophisticated technique based on synchrotron-generated, spatially fractionated RT, called Microbeam Radiation Therapy (MRT), has been shown to overcome these treatment limitations by allowing increased dose delivery. With MRT, a collimator subdivides the homogeneous radiation field into an array of co-planar, high-dose microbeams that are tens of micrometres wide and spaced a few hundred micrometres apart. Different preclinical models demonstrated that MRT has the potential to completely ablate tumours, or significantly improve tumour control while dramatically reducing normal tissue toxicity. Here, we discuss the role of conventional RT-induced immunity and the potential for MRT to enhance local and systemic anti-tumour immune responses. Comparative gene expression analysis from preclinical tumour models indicated a specific gene signature for an 'MRT-induced immune effect'. This focused review highlights the potential of MRT to overcome the inherent radioresistance of melanoma which could be further enhanced for future clinical use with combined treatment strategies, in particular, immunotherapy.
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Affiliation(s)
- Verdiana Trappetti
- Institute of Anatomy, University of Bern, 3012 Bern, Switzerland; (V.T.); (J.M.F.); (C.F.-P.); (M.S.); (O.A.M.)
| | - Jennifer M. Fazzari
- Institute of Anatomy, University of Bern, 3012 Bern, Switzerland; (V.T.); (J.M.F.); (C.F.-P.); (M.S.); (O.A.M.)
| | - Cristian Fernandez-Palomo
- Institute of Anatomy, University of Bern, 3012 Bern, Switzerland; (V.T.); (J.M.F.); (C.F.-P.); (M.S.); (O.A.M.)
| | - Maximilian Scheidegger
- Institute of Anatomy, University of Bern, 3012 Bern, Switzerland; (V.T.); (J.M.F.); (C.F.-P.); (M.S.); (O.A.M.)
| | - Vladislav Volarevic
- Department of Genetics, Department of Microbiology and Immunology, Faculty of Medical Sciences, University of Kragujevac, 34000 Kragujevac, Serbia;
| | - Olga A. Martin
- Institute of Anatomy, University of Bern, 3012 Bern, Switzerland; (V.T.); (J.M.F.); (C.F.-P.); (M.S.); (O.A.M.)
- Peter MacCallum Cancer Centre, Division of Radiation Oncology, Melbourne, VIC 3000, Australia
- University of Melbourne, Parkville, VIC 3010, Australia
| | - Valentin G. Djonov
- Institute of Anatomy, University of Bern, 3012 Bern, Switzerland; (V.T.); (J.M.F.); (C.F.-P.); (M.S.); (O.A.M.)
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13
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Smyth LML, Crosbie JC, Sloggett C, Rogers PAW, Donoghue JF. Spatially Fractionated X-Ray Microbeams Elicit a More Sustained Immune and Inflammatory Response in the Brainstem than Homogenous Irradiation. Radiat Res 2021; 196:355-365. [PMID: 34270776 DOI: 10.1667/rade-20-00082.1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2020] [Accepted: 06/22/2021] [Indexed: 11/03/2022]
Abstract
Synchrotron microbeam radiation therapy (MRT) is a preclinical irradiation technique which could be used to treat intracranial malignancies. The goal of this work was to discern differences in gene expression and the predicted regulation of molecular pathways in the brainstem after MRT versus synchrotron broad-beam radiation therapy (SBBR). Healthy C57BL/6 mice received whole-head irradiation with median acute toxic doses of MRT (241 Gy peak dose) or SBBR (13 Gy). Brains were harvested 4 and 48 h postirradiation and RNA was extracted from the brainstem. RNA-sequencing was performed to identify differentially expressed genes (false discovery rate < 0.01) relative to nonirradiated controls and significantly regulated molecular pathways and biological functions were identified (Benjamini-Hochberg corrected P < 0.05). Differentially expressed genes and regulated pathways largely reflected a pro-inflammatory response 4 h after both MRT and SBBR which was sustained at 48 h postirradiation for MRT. Pathways relating to radiation-induced viral mimicry, including HMGB1, NF-κB and interferon signaling cascades, were predicted to be uniquely activated by MRT. Local microglia, as well as circulating leukocytes, including T cells, were predicted to be activated by MRT. Our findings affirm that the transcriptomic signature of MRT is distinct from broad-beam radiotherapy, with a sustained inflammatory and immune response up to 48 h postirradiation.
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Affiliation(s)
- Lloyd M L Smyth
- Department of Obstetrics & Gynaecology, University of Melbourne, Royal Women's Hospital, Parkville, Australia
| | | | - Clare Sloggett
- Melbourne Bioinformatics, University of Melbourne, Parkville, Australia
| | - Peter A W Rogers
- Department of Obstetrics & Gynaecology, University of Melbourne, Royal Women's Hospital, Parkville, Australia
| | - Jacqueline F Donoghue
- Department of Obstetrics & Gynaecology, University of Melbourne, Royal Women's Hospital, Parkville, Australia
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14
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Hasan N, Sham NFR, Karim MKA, Fuad SBSA, Hasani NAH, Omar E, Ibahim MJ. Development of custom lead shield and strainer for targeted irradiation for mice in the gamma cell chamber. Sci Rep 2021; 11:14559. [PMID: 34267293 PMCID: PMC8282798 DOI: 10.1038/s41598-021-93964-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2021] [Accepted: 07/05/2021] [Indexed: 11/09/2022] Open
Abstract
We presented a development of a custom lead shield and mouse strainer for targeted irradiation from the gamma-cell chamber. This study was divided into two parts i.e., to (i) fabricate the shield and strainer from a lead (Pb) and (ii) optimize the irradiation to the mice-bearing tumour model with 2 and 8 Gy absorbed doses. The lead shielding was fabricated into a cuboid shape with a canal on the top and a hole on the vertical side for the beam path. Respective deliveries doses of 28 and 75 Gy from gamma-cell were used to achieve 2 and 8 Gy absorbed doses at the tumour sites.
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Affiliation(s)
- Nurhaslina Hasan
- Faculty of Medicine, Universiti Teknologi MARA, 47200, Sungai Buloh, Selangor, Malaysia
- Faculty of Dentistry, Universiti Teknologi MARA, 47200, Sungai Buloh, Selangor, Malaysia
| | | | | | | | | | - Effat Omar
- Faculty of Medicine, Universiti Teknologi MARA, 47200, Sungai Buloh, Selangor, Malaysia
| | - Mohammad Johari Ibahim
- Faculty of Medicine, Universiti Teknologi MARA, 47200, Sungai Buloh, Selangor, Malaysia.
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15
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Forrester HB, Lobachevsky PN, Stevenson AW, Hall CJ, Martin OA, Sprung CN. Abscopal Gene Expression in Response to Synchrotron Radiation Indicates a Role for Immunological and DNA Damage Response Genes. Radiat Res 2021; 194:678-687. [PMID: 32991732 DOI: 10.1667/rade-19-00014.1] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2019] [Accepted: 08/24/2020] [Indexed: 11/03/2022]
Abstract
Abscopal effects are an important aspect of targeted radiation therapy due to their implication in normal tissue toxicity from chronic inflammatory responses and mutagenesis. Gene expression can be used to determine abscopal effects at the molecular level. Synchrotron microbeam radiation therapy utilizing high-intensity X rays collimated into planar microbeams is a promising cancer treatment due to its reported ability to ablate tumors with less damage to normal tissues compared to conventional broadbeam radiation therapy techniques. The low scatter of synchrotron radiation enables microbeams to be delivered to tissue effectively, and is also advantageous for out-of-field studies because there is minimal interference from scatter. Mouse legs were irradiated at a dose rate of 49 Gy/s and skin samples in the out-of-field areas were collected. The out-of-field skin showed an increase in Tnf expression and a decrease in Mdm2 expression, genes associated with inflammation and DNA damage. These expression effects from microbeam exposure were similar to those found with broadbeam exposure. In immune-deficient Ccl2 knockout mice, we identified a different gene expression profile which showed an early increase in Mdm2, Tgfb1, Tnf and Ccl22 expression in out-of-field skin that was not observed in the immune-proficient mice. Our results suggest that the innate immune system is involved in out-of-field tissue responses and alterations in the immune response may not eliminate abscopal effects, but could change them.
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Affiliation(s)
- Helen B Forrester
- Centre for Innate Immunity and Infectious Diseases, Hudson Institute of Medical Research, Clayton, Australia.,Monash University, Clayton, Australia.,School of Science, RMIT University, Melbourne, Australia
| | - Pavel N Lobachevsky
- Research Division, Peter MacCallum Cancer Centre, Melbourne, Australia.,Sir Peter MacCallum Department of Oncology, The University of Melbourne, Melbourne, Australia.,Advanced Analytical Technologies, Melbourne, Australia
| | - Andrew W Stevenson
- Australian Synchrotron, ANSTO, Clayton, Australia.,CSIRO Manufacturing, Clayton, Australia
| | | | - Olga A Martin
- Division of Radiation Oncology, Peter MacCallum Cancer Centre, Melbourne, Australia.,Sir Peter MacCallum Department of Oncology, The University of Melbourne, Melbourne, Australia
| | - Carl N Sprung
- Centre for Innate Immunity and Infectious Diseases, Hudson Institute of Medical Research, Clayton, Australia.,Monash University, Clayton, Australia
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16
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Zhang W, Shen Y, Huang H, Pan S, Jiang J, Chen W, Zhang T, Zhang C, Ni C. A Rosetta Stone for Breast Cancer: Prognostic Value and Dynamic Regulation of Neutrophil in Tumor Microenvironment. Front Immunol 2020; 11:1779. [PMID: 32849640 PMCID: PMC7426521 DOI: 10.3389/fimmu.2020.01779] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2020] [Accepted: 07/03/2020] [Indexed: 12/21/2022] Open
Abstract
Increasing evidence has revealed that the initiation and progression of breast cancer are greatly affected by the immune environment. Neutrophils are the most abundant leucocytes in circulation and act as the spearhead in inflammation, including in breast cancer. Circulating neutrophils are closely related to the prognosis of breast cancer patients, and tumor-infiltrating neutrophils have varied functions at different stages of breast cancer, such as antitumor or tumor-promoting neutrophils, which are termed N1 and N2 neutrophils, respectively. In this review, we will discuss the utility of circulating neutrophils for predicting prognosis and therapeutic efficacy and the underlying mechanisms of their chemotaxis, the dynamic regulation of their antitumor or protumor functions and their different spatial distributions in tumor microenvironment. Finally, we also discuss the possibility of targeting neutrophils as a therapeutic strategy in breast cancer.
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Affiliation(s)
- Wei Zhang
- Department of Endocrinology, Zhejiang Provincial People's Hospital, People's Hospital of Hangzhou Medical College, Hangzhou, China
| | - Yimin Shen
- Department of Cardiology, Second Affiliated Hospital, Zhejiang University, Hangzhou, China.,Key Laboratory of Tumour Microenvironment and Immune Therapy of Zhejiang Province, Second Affiliated Hospital, Zhejiang University, Hangzhou, China
| | - Huanhuan Huang
- Key Laboratory of Tumour Microenvironment and Immune Therapy of Zhejiang Province, Second Affiliated Hospital, Zhejiang University, Hangzhou, China.,Department of Breast Surgery, Second Affiliated Hospital, Zhejiang University, Hangzhou, China
| | - Sheng Pan
- School of Medicine, Chu Kochen Honors College, Zhejiang University, Hangzhou, China
| | - Jingxin Jiang
- Key Laboratory of Tumour Microenvironment and Immune Therapy of Zhejiang Province, Second Affiliated Hospital, Zhejiang University, Hangzhou, China.,Department of Breast Surgery, Second Affiliated Hospital, Zhejiang University, Hangzhou, China
| | - Wuzhen Chen
- Key Laboratory of Tumour Microenvironment and Immune Therapy of Zhejiang Province, Second Affiliated Hospital, Zhejiang University, Hangzhou, China.,Department of Breast Surgery, Second Affiliated Hospital, Zhejiang University, Hangzhou, China
| | - Ting Zhang
- Key Laboratory of Tumour Microenvironment and Immune Therapy of Zhejiang Province, Second Affiliated Hospital, Zhejiang University, Hangzhou, China
| | - Chao Zhang
- Department of Anatomy, School of Medicine, Zhejiang University, Hangzhou, China
| | - Chao Ni
- Key Laboratory of Tumour Microenvironment and Immune Therapy of Zhejiang Province, Second Affiliated Hospital, Zhejiang University, Hangzhou, China.,Department of Breast Surgery, Second Affiliated Hospital, Zhejiang University, Hangzhou, China
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17
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Conventional dose rate spatially-fractionated radiation therapy (SFRT) treatment response and its association with dosimetric parameters-A preclinical study in a Fischer 344 rat model. PLoS One 2020; 15:e0229053. [PMID: 32569277 PMCID: PMC7307781 DOI: 10.1371/journal.pone.0229053] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2020] [Accepted: 05/21/2020] [Indexed: 12/15/2022] Open
Abstract
Purpose To identify key dosimetric parameters that have close associations with tumor treatment response and body weight change in SFRT treatments with a large range of spatial-fractionation scale at dose rates of several Gy/min. Methods Six study arms using uniform tumor radiation, half-tumor radiation, 2mm beam array radiation, 0.3mm minibeam radiation, and an untreated arm were used. All treatments were delivered on a 320kV x-ray irradiator. Forty-two female Fischer 344 rats with fibrosarcoma tumor allografts were used. Dosimetric parameters studied are peak dose and width, valley dose and width, peak-to-valley-dose-ratio (PVDR), volumetric average dose, percentage volume directly irradiated, and tumor- and normal-tissue EUD. Animal survival, tumor volume change, and body weight change (indicative of treatment toxicity) are tested for association with the dosimetric parameters using linear regression and Cox Proportional Hazards models. Results The dosimetric parameters most closely associated with tumor response are tumor EUD (R2 = 0.7923, F-stat = 15.26*; z-test = -4.07***), valley (minimum) dose (R2 = 0.7636, F-stat = 12.92*; z-test = -4.338***), and percentage tumor directly irradiated (R2 = 0.7153, F-stat = 10.05*; z-test = -3.837***) per the linear regression and Cox Proportional Hazards models, respectively. Tumor response is linearly proportional to valley (minimum) doses and tumor EUD. Average dose (R2 = 0.2745, F-stat = 1.514 (no sig.); z-test = -2.811**) and peak dose (R2 = 0.04472, F-stat = 0.6874 (not sig.); z-test = -0.786 (not sig.)) show the weakest associations to tumor response. Only the uniform radiation arm did not gain body weight post-radiation, indicative of treatment toxicity; however, body weight change in general shows weak association with all dosimetric parameters except for valley (minimum) dose (R2 = 0.3814, F-stat = 13.56**), valley width (R2 = 0.2853, F-stat = 8.783**), and peak width (R2 = 0.2759, F-stat = 8.382**). Conclusions For a single-fraction SFRT at conventional dose rates, valley, not peak, dose is closely associated with tumor treatment response and thus should be used for treatment prescription. Tumor EUD, valley (minimum) dose, and percentage tumor directly irradiated are the top three dosimetric parameters that exhibited close associations with tumor response.
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18
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Tubin S, Yan W, Mourad WF, Fossati P, Khan MK. The future of radiation-induced abscopal response: beyond conventional radiotherapy approaches. Future Oncol 2020; 16:1137-1151. [PMID: 32338046 DOI: 10.2217/fon-2020-0063] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Advances in the immunological pharmaceuticals, such as checkpoint inhibitors and agonists, have positive implications for the future of the radiotherapy abscopal response. A once rare phenomenon, whereby distant nonirradiated tumor sites regressed after radiotherapy alone, may become more common when combined with the immune modulating agents. Radiotherapy can increase neoantigen expression, increased tumor PD-L1 expression, increase MHC class I expression, reverse exhausted CD8 T cells and increase tumor-infiltrating tumors within the tumor microenvironment. These changes in the tumor and the tumor microenvironment after radiotherapy could potentiate responses to anti-CTL-4, anti-PD-L1/PD-1 and other immunotherapy agents. Thus, advances in checkpoint inhibitors have increased interest in re-evaluation of the role of conventional radiotherapy approaches on the immune system. We reviewed newer nonconventional approaches such as SBRT-PATHY, GRID, FLASH, carbon ion and proton therapy and their role in eliciting immune responses. We believe that combining these novel radiation methods may enhance the outcome with the newly US FDA approved immune modulating agents.
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Affiliation(s)
- Slavisa Tubin
- MedAustron Center for Ion Therapy and Research, Marie Curie Strasse 5, A-2700 Wiener Neustadt, Austria
| | - Weisi Yan
- Department of Radiation Oncology, Thomas Jefferson University, 11th St, Philadelphia, PA 19107, USA
| | - Waleed F Mourad
- Department of Radiation Medicine, Markey Cancer Center, University of Kentucky, Medical Center, MN 150 - Lexington, KY 40536-0298, USA
| | - Piero Fossati
- MedAustron Center for Ion Therapy and Research, Marie Curie Strasse 5, A-2700 Wiener Neustadt, Austria
| | - Mohammad K Khan
- Department of Radiation Oncology, Emory University School of Medicine, Winship Cancer Institute, 1365-C Clifton Road, Atlanta, GA 30322, USA
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19
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Fernandez-Palomo C, Fazzari J, Trappetti V, Smyth L, Janka H, Laissue J, Djonov V. Animal Models in Microbeam Radiation Therapy: A Scoping Review. Cancers (Basel) 2020; 12:cancers12030527. [PMID: 32106397 PMCID: PMC7139755 DOI: 10.3390/cancers12030527] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2020] [Revised: 02/19/2020] [Accepted: 02/21/2020] [Indexed: 01/04/2023] Open
Abstract
BACKGROUND Microbeam Radiation Therapy (MRT) is an innovative approach in radiation oncology where a collimator subdivides the homogeneous radiation field into an array of co-planar, high-dose beams which are tens of micrometres wide and separated by a few hundred micrometres. OBJECTIVE This scoping review was conducted to map the available evidence and provide a comprehensive overview of the similarities, differences, and outcomes of all experiments that have employed animal models in MRT. METHODS We considered articles that employed animal models for the purpose of studying the effects of MRT. We searched in seven databases for published and unpublished literature. Two independent reviewers screened citations for inclusion. Data extraction was done by three reviewers. RESULTS After screening 5688 citations and 159 full-text papers, 95 articles were included, of which 72 were experimental articles. Here we present the animal models and pre-clinical radiation parameters employed in the existing MRT literature according to their use in cancer treatment, non-neoplastic diseases, or normal tissue studies. CONCLUSIONS The study of MRT is concentrated in brain-related diseases performed mostly in rat models. An appropriate comparison between MRT and conventional radiotherapy (instead of synchrotron broad beam) is needed. Recommendations are provided for future studies involving MRT.
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Affiliation(s)
| | - Jennifer Fazzari
- Institute of Anatomy, University of Bern, 3012 Bern, Switzerland; (C.F.-P.); (J.F.); (V.T.); (J.L.)
| | - Verdiana Trappetti
- Institute of Anatomy, University of Bern, 3012 Bern, Switzerland; (C.F.-P.); (J.F.); (V.T.); (J.L.)
| | - Lloyd Smyth
- Department of Obstetrics & Gynaecology, University of Melbourne, 3057 Parkville, Australia;
| | - Heidrun Janka
- Medical Library, University Library Bern, University of Bern, 3012 Bern, Switzerland;
| | - Jean Laissue
- Institute of Anatomy, University of Bern, 3012 Bern, Switzerland; (C.F.-P.); (J.F.); (V.T.); (J.L.)
| | - Valentin Djonov
- Institute of Anatomy, University of Bern, 3012 Bern, Switzerland; (C.F.-P.); (J.F.); (V.T.); (J.L.)
- Correspondence: ; Tel.: +41-31-631-8432
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