Abscopal effect following nivolumab induction in a patient with metastatic renal cell carcinoma-unique pathological features of the primary specimen: A case report

Abscopal effect with fever of unknown cause during radiotherapy: Two case reports and review of the literature

The abscopal effect is a rare phenomenon that is defined as regression of tumor lesions distant from irradiation targets. At our department, two cases with an abscopal effect with fever of unknown cause (FUC) and an inflammatory response during radiotherapy were encountered. Radiotherapy is a local treatment; therefore, it rarely causes systemic side effects during radiotherapy, and if a patient develops a fever during radiotherapy, it is frequently considered tumor fever. We experienced 2 cases of FUC during irradiation followed by abscopal effect. The obvious relationship between the abscopal effect and the fever remains to be clarified. However, FUC during radiotherapy may be a hint to the abscopal effect, considering that immune response and cytokines are closely related to the abscopal effect.

HDAC-an important target for improving tumor radiotherapy resistance

Radiotherapy is an important means of tumor treatment, but radiotherapy resistance has been a difficult problem in the comprehensive treatment of clinical tumors. The mechanisms of radiotherapy resistance include the repair of sublethal damage and potentially lethal damage of tumor cells, cell repopulation, cell cycle redistribution, and reoxygenation. These processes are closely related to the regulation of epigenetic modifications. Histone deacetylases (HDACs), as important regulators of the epigenetic structure of cancer, are widely involved in the formation of tumor radiotherapy resistance by participating in DNA damage repair, cell cycle regulation, cell apoptosis, and other mechanisms. Although the important role of HDACs and their related inhibitors in tumor therapy has been reviewed, the relationship between HDACs and radiotherapy has not been systematically studied. This article systematically expounds for the first time the specific mechanism by which HDACs promote tumor radiotherapy resistance in vivo and in vitro and the clinical application prospects of HDAC inhibitors, aiming to provide a reference for HDAC-related drug development and guide the future research direction of HDAC inhibitors that improve tumor radiotherapy resistance.

Abscopal Effects in Metastatic Cancer: Is a Predictive Approach Possible to Improve Individual Outcomes?

Patients with metastatic cancers often require radiotherapy (RT) as a palliative therapy for cancer pain. RT can, however, also induce systemic antitumor effects outside of the irradiated field (abscopal effects) in various cancer entities. The occurrence of the abscopal effect is associated with a specific immunological activation in response to RT-induced cell death, which is mainly seen under concomitant immune checkpoint blockade. Even if the number of reported apscopal effects has increased since the introduction of immune checkpoint inhibition, its occurrence is still considered rare and unpredictable. The cases reported so far may nevertheless allow for identifying first biomarkers and clinical patterns. We here review biomarkers that may be helpful to predict the occurrence of abscopal effects and hence to optimize therapy for patients with metastatic cancers.

Immunostimulatory Effects of Radiotherapy for Local and Systemic Control of Melanoma: A Review

Recently, modern therapies involving immune checkpoint inhibitors, cytokines, and oncolytic virus have been developed. Because of the limited treatment effect of modern therapy alone, the immunostimulatory effect of radiotherapy attracted increasing attention. The combined use of radiotherapy and modern therapy has been examined clinically and non-clinically, and its effectiveness has been confirmed recently. Because melanomas have high immunogenicity, better therapeutic outcomes are desired when using immunotherapy. However, sufficient therapeutic effects have not yet been achieved. Thus far, radiotherapy has been used only for local control of tumors. Although extremely rare, radiotherapy has also been reported for systemic control, i.e., abscopal effect. This is thought to be due to an antitumor immune response. Therefore, we herein summarize past information on not only the mechanism of immune effects on radiotherapy but also biomarkers reported in case reports on abscopal effects. We also reviewed the animal model suitable for evaluating abscopal effects. These results pave the way for further basic research or clinical studies on new treatment methods for melanoma. Currently, palliative radiation is administered to patients with metastatic melanoma for local control. If it is feasible to provide both systemic and local control, the treatment benefit for the patients is very large.

Possible abscopal effect after discontinuation of nivolumab in metastatic renal cell carcinoma

INTRODUCTION

Renal cell carcinoma has been considered radioresistant. Recently, several studies have reported the efficacy of combination therapy using radiotherapy and immune checkpoint inhibitors.

CASE PRESENTATION

In 1999, a 56-year-old woman underwent left nephrectomy (clear cell carcinoma, pT1bN0M0). Seventeen years postoperatively, recurrence in the left lung hilum was observed. Despite administration of three molecular target drugs, all treatments were terminated due to adverse events. Nivolumab was initiated in December 2016. In August 2017, subcutaneous and lung metastases were observed. Moreover in January 2018, right renal metastasis was noted. After 22 cycles of nivolumab treatment, metastasis in the iliac bone was observed, and the patient was subjected to conventional palliative external beam radiation therapy. Five months after radiotherapy, there was significant reduction in multiple metastases. Here, we reported the case presenting with possible abscopal effect.

CONCLUSION

Radiotherapy combined with immune checkpoint inhibitors may induce systemic effects against metastatic renal carcinoma.