Effets de l’irradiation à haute dose sur la vascularisation : physiopathologie et conséquences cliniques

Outcomes in dogs undergoing surgical stabilization and non-stereotactic radiation therapy for axial and appendicular bone tumors

Background

Information on dogs that undergo radiation therapy (RT) with non-stereotactic protocols in addition to surgical stabilization with implant placement for treatment of bone tumors is limited.

Objective

Our primary objectives were to describe the clinical characteristics as well as short- and long-term outcomes, including complications, function, and disease progression, in dogs that underwent both surgical stabilization with implant placement and non-stereotactic RT for local treatment of a bone tumor.

Methods

A bi-institutional retrospective case series was performed.

Animals

Eight client-owned dogs that underwent both surgical stabilization with implant placement and non-stereotactic RT for local treatment of a bone tumor were included.

Results

Tumor types included osteosarcoma or suspected osteosarcoma (5), plasma cell tumor (2), and grade 3 fibrosarcoma (1). Radiation protocols were hypofractionated (palliative intent) in 5 dogs and fractionated (definitive intent) in 3 dogs. Five dogs experienced complications following both RT and surgery, including grade 1 complications in two dogs, a grade 2 complication in one dog, both grade 1 and 2 complications in one dog, and both grade 2 and 3 complications in one dog. Clinical signs subjectively improved in all dogs that had outcomes relative to function documented post-surgery/RT (7). Of these 7 dogs, 4 maintained long-term improvement in function and clinical signs, whereas 3 experienced subsequent recurrence/progression of clinical signs at a median of 133 days (range 91-186) postoperatively in association with biomechanical complications (screw loosening), surgical site infection, and local disease progression in 1 dog each; subsequent treatment resulted in improved clinical signs for each of these 3 dogs, such that overall good long-term functional outcomes were experienced. No dogs required amputation or additional vertebral surgery as salvage for local disease control or palliation. The median progression free interval was 206 days (range 25-1078), and the median survival time was 253 days (range 122-1078) with 1 additional dog lost to follow-up at 575 days. Two dogs experienced local disease progression, and 6 dogs experienced systemic disease progression; both dogs that developed local disease progression received palliative intent RT protocols.

Clinical relevance

In this cohort, dogs with primary bone tumors that underwent surgical stabilization with implant placement and hypofractionated or fractionated non-stereotactic RT for local treatment had a low incidence of major complications, good limb function and ambulation post-treatment, and relatively prolonged survival times despite disease progression.

Immune Priming with Spatially Fractionated Radiation Therapy

PURPOSE OF REVIEW

This review aims to summarize the current preclinical and clinical evidence of nontargeted immune effects of spatially fractionated radiation therapy (SFRT). We then highlight strategies to augment the immunomodulatory potential of SFRT in combination with immunotherapy (IT).

RECENT FINDINGS

The response of cancer to IT is limited by primary and acquired immune resistance, and strategies are needed to prime the immune system to increase the efficacy of IT. Radiation therapy can induce immunologic effects and can potentially be used to synergize the effects of IT, although the optimal combination of radiation and IT is largely unknown. SFRT is a novel radiation technique that limits ablative doses to tumor subvolumes, and this highly heterogeneous dose deposition may increase the immune-rich infiltrate within the targeted tumor with enhanced antigen presentation and activated T cells in nonirradiated tumors. The understanding of nontargeted effects of SFRT can contribute to future translational strategies to combine SFRT and IT. Integration of SFRT and IT is an innovative approach to address immune resistance to IT with the overall goal of improving the therapeutic ratio of radiation therapy and increasing the efficacy of IT.

Re-irradiation for recurrent/progressive pediatric brain tumors: from radiobiology to clinical outcomes

INTRODUCTION

Brain tumors are the most common solid tumors in children. Neurosurgical excision, radiotherapy, and/or chemotherapy represent the standard of care in most histopathological types of pediatric central nervous system (CNS) tumors. Even though the successful cure rate is reasonable, some patients may develop recurrence locally or within the neuroaxis.

AREA COVERED

The management of these recurrences is not easy; however, significant advances in neurosurgery, radiation techniques, radiobiology, and the introduction of newer biological therapies, have improved the results of their salvage treatment. In many cases, salvage re-irradiation is feasible and has achieved encouraging results. The results of re-irradiation depend upon several factors. These factors include tumor type, extent of the second surgery, tumor volume, location of the recurrence, time that elapses between the initial treatment, the combination with other treatment agents, relapse, and the initial response to radiotherapy.

EXPERT OPINION

Reviewing the radiobiological basis and clinical outcome of pediatric brain re-irradiation revealed that re-irradiation is safe, feasible, and indicated for recurrent/progressive different tumor types such as; ependymoma, medulloblastoma, diffuse intrinsic pontine glioma (DIPG) and glioblastoma. It is now considered part of the treatment armamentarium for these patients. The challenges and clinical results in treating recurrent pediatric brain tumors were highly documented.

Urinary Bladder Matrix Improves Irradiated Wound Healing in a Murine Model

ABSTRACT

Radiation skin damage is associated with chronic wounds and poor healing. Existing localized treatment modalities have limited benefit. Therefore, there has been increased interest in biologically based solutions. In this study, we aimed to determine the effect of topical urinary bladder matrix (UBM) on chronic irradiated skin wounds using an established murine model. Our findings demonstrated that topical urinary bladder matrix significantly accelerated the healing of irradiated wounds on day 7 (P = 0.0216), day 14 (P = 0.0140), and day 21 (P = 0.0393). Histologically, urinary bladder matrix treatment was associated with higher-quality reorganization and reepithelialization of wounds, an increased density of myofibroblasts (P = 0.0004), and increased collagen deposition (P < 0.0001). In addition, quantitative real-time polymerase chain reaction data demonstrated decreased expression of profibrotic mediators (P = 0.0049). We conclude that urinary bladder matrix may be a useful, noninvasive, adjunctive therapy for the treatment of chronic irradiated skin wounds.

Neoadjuvant stereotactic ablative radiotherapy (SABR) for soft tissue sarcomas of the extremities

BACKGROUND

Soft tissue sarcomas (STS) comprise a diverse group of mesenchymal malignancies that require multidisciplinary care. Although surgery remains the primary form of treatment for those with localized disease, radiation therapy (RT) is often incorporated either in the neo- or adjuvant setting. Given the development of modern RT techniques and alternative dosing schedules, stereotactic ablative radiotherapy (SABR) has emerged as a promising technique. However, the current role of SABR in the treatment of STS of the extremities remains uncertain.

METHODS AND MATERIALS

This was a single-center, prospective, single-arm phase II trial. Patients with localized STS who were candidates for limb-preservation surgery were included. Experimental treatment consisted of SABR with 40 Gy in 5 fractions, administered on alternate days, followed by surgery after a minimum interval of 4 weeks. The primary outcome was the rate of wound complication. Secondary outcomes included 2-year local control (LC), metastasis-free survival (MFS), cancer-specific survival (CSS), and overall survival (OS) rates (and other toxicities).

RESULTS

Twenty-five patients were enrolled between October 2015 and November 2019 and completed the treatment protocol. The median rate of histopathologic regression was 65% (range 0-100) and 20.8% of tumors presented pathologic complete response (pCR). Wound complications were observed in 7/25 patients (28%). Three patients underwent disarticulation by vascular occlusion after plastic reconstruction and one patient was amputated by grade 3 limb dysfunction. After a median follow up of 20.7 months, the 2-year estimated risk of local recurrence, distant metastasis and cause-specific death were 0%, 44.7% and 10.6% respectively.

CONCLUSIONS

Neoadjuvant SABR appears to improve the pCR for patients with eSTS, with acceptable rate of wound complications. Nevertheless, this benefit should be weighed against the risk of late of vascular toxicity with SABR regimen since, even in a short median follow-up, a higher rate of amputation than expected was observed. A larger sample size with longer follow-up is necessary to conclude the overall safety of this strategy.

Potential Second-Hits in Hereditary Hemorrhagic Telangiectasia

Hereditary hemorrhagic telangiectasia (HHT) is an autosomal dominant genetic disorder that presents with telangiectases in skin and mucosae, and arteriovenous malformations (AVMs) in internal organs such as lungs, liver, and brain. Mutations in ENG (endoglin), ACVRL1 (ALK1), and MADH4 (Smad4) genes account for over 95% of HHT. Localized telangiectases and AVMs are present in different organs, with frequencies which differ among affected individuals. By itself, HHT gene heterozygosity does not account for the focal nature and varying presentation of the vascular lesions leading to the hypothesis of a “second-hit” that triggers the lesions. Accumulating research has identified a variety of triggers that may synergize with HHT gene heterozygosity to generate the vascular lesions. Among the postulated second-hits are: mechanical trauma, light, inflammation, vascular injury, angiogenic stimuli, shear stress, modifier genes, and somatic mutations in the wildtype HHT gene allele. The aim of this review is to summarize these triggers, as well as the functional mechanisms involved.

Distributions of intravenous injected iodine nanoparticles in orthotopic u87 human glioma xenografts over time and tumor therapy

Aim: To analyze the localization, distribution and effect of iodine nanoparticles (INPs) on radiation therapy (RT) in advanced intracerebral gliomas over time after intravenous injection. Materials & methods: Luciferase/td-tomato expressing U87 human glioma cells were implanted into mice which were injected intravenously with INPs. Mice with gliomas were followed for tumor progression and survival. Immune-stained mouse brain sections were examined and quantified by confocal fluorescence microscopy. Results: INPs injected intravenously 3 days prior to RT, compared with 1 day, showed greater association with CD31-staining structures, accumulated inside tumor cells more, covered more of the tumor cell surface and trended toward increased median survival. Conclusion: INP persistence and redistribution in tumors over time may enable greater RT enhancement and clinically relevant hypo-fractionated-RT and may enhance INP efficacy.

Advances in Radiobiology of Stereotactic Ablative Radiotherapy

Radiotherapy (RT) has been developed with remarkable technological advances in recent years. The accuracy of RT is dramatically improved and accordingly high dose radiation of the tumors could be precisely projected. Stereotactic radiosurgery (SRS) and stereotactic body radiotherapy (SBRT), also known as stereotactic ablative radiotherapy (SABR), are rapidly becoming the accepted practice in treating solid small sized tumors. Compared with the conventional fractionation external beam radiotherapy (EBRT), SABR with very high dose per fraction and hypo-fractionated irradiation yields convincing and satisfied therapeutic effects with low toxicity, since tumor cells could be directly ablated like radiofrequency ablation (RFA). The impressive clinical efficacy of SABR is greater than expected by the linear quadratic model and the conventional radiobiological principles, i.e., 4 Rs of radiobiology (reoxygenation, repair, redistribution, and repopulation), which may no longer be suitable for the explanation of SABR's ablation effects. Based on 4 Rs of radiobiology, 5 Rs of radiobiology emphasizes the intrinsic radiosensitivity of tumor cells, which may correlate with the responsiveness of SABR. Meanwhile, SABR induced the radiobiological alteration including vascular endothelial injury and the immune activation, which has been indicated by literature reported to play a crucial role in tumor control. However, a comprehensive review involving these advances in SABR is lacking. In this review, advances in radiobiology of SABR including the role of the 4 Rs of radiobiology and potential radiobiological factors for SABR will be comprehensively reviewed and discussed.