Radiographical efficacy of systemic treatment for bone metastasis from renal cell carcinoma

Practical management of renal cell carcinoma: integrating current approaches with advances in bone metastasis treatment

Renal cell carcinoma (RCC) is a common type of tumor that can develop in the kidney. It is responsible for around one-third of all cases of neoplasms. RCC manifests itself in a variety of distinct subtypes. The most frequent of which is clear cell RCC, followed by papillary and chromophobe RCC. RCC has the potential for metastasis to a variety of organs; nevertheless, bone metastases are one of the most common and potentially fatal complications. These bone metastases are characterized by osteolytic lesions that can result in pathological fractures, hypercalcemia, and other complications, which can ultimately lead to a deterioration in quality of life and an increase morbidity. While nephrectomy remains a foundational treatment for RCC, emerging evidence suggests that targeted therapies, including tyrosine kinase inhibitors and T cell checkpoint inhibitors, may offer effective alternatives, potentially obviating the need for adjuvant nephrectomy in certain cases of metastatic RCC Bone metastases continue to be a difficult complication of RCC, which is why more research is required to enhance patient outcome.

Extracellular vesicles secreted from bone metastatic renal cell carcinoma promote angiogenesis and endothelial gap formation in bone marrow in a time-dependent manner in a preclinical mouse model

Introduction

Bone is a major metastatic site of renal cell carcinoma (RCC). Recently, it is well recognized that bone metastatic tumor cells remodel bone marrow vasculature. However, the precise mechanism underlying cell-cell communication between bone metastatic RCC and the cells in bone marrow remains unknown. Extracellular vesicles (EVs) reportedly play crucial roles in intercellular communication between metastatic tumor cells and bone marrow. Therefore, we conducted the current study to clarify the histological alteration in vascular endothelium in bone marrow induced by EVs secreted from bone metastatic RCC cells as well as association between angiogenesis in bone marrow and bone metastasis formation.

Materials and methods

We established a bone metastatic RCC cell line (786-O BM) by in vivo selection and observed phenotypic changes in tissues when EVs were intravenously injected into immunodeficient mice. Proteomic analysis was performed to identify the protein cargo of EVs that could contribute to histological changes in bone. Tissue exudative EVs (Te-EVs) from cancer tissues of patients with bone metastatic RCC (BM-EV) and those with locally advanced disease (LA-EV) were compared for in vitro function and protein cargo.

Results

Treatment of mice with EVs from 786-O BM promoted angiogenesis in the bone marrow in a time-dependent manner and increased the gaps of capillary endothelium. 786-O BM EVs also promoted tube formation in vitro. Proteomic analysis of EVs identified aminopeptidase N (APN) as a candidate protein that enhances angiogenesis. APN knockdown in 786-O BM resulted in reduced angiogenesis in vitro and in vivo. When parental 786-O cells were intracardially injected 12 weeks after treatment with786-O BM EVs, more bone metastasis developed compared to those treated with EVs from parental 786-O cells. In patient samples, BM-EVs contained higher APN compared to LA-EV. In addition, BM-EVs promoted tube formation in vitro compared to LA-EVs.

Conclusion

EVs from bone metastatic RCC promote angiogenesis and gap formation in capillary endothelium in bone marrow in a time-dependent manner.

Establishment and Validation of a Machine Learning Prediction Model Based on Big Data for Predicting the Risk of Bone Metastasis in Renal Cell Carcinoma Patients

Purpose

Since the prognosis of renal cell carcinoma (RCC) patients with bone metastasis (BM) is poor, this study is aimed at using big data to build a machine learning (ML) model to predict the risk of BM in RCC patients.

Methods

A retrospective study was conducted on 40,355 RCC patients in the SEER database from 2010 to 2017. LASSO regression and multivariate logistic regression analysis was performed to determine independent risk factors of RCC-BM. Six ML algorithm models, including LR, GBM, XGB, RF, DT, and NBC, were used to establish risk models for predicting RCC-BM. The prediction performance of ML models was weighed by 10-fold cross-validation.

Results

The study investigated 40,355 patients diagnosed with RCC in the SEER database, where 1,811 (4.5%) were BM patients. Independent risk factors for BM were tumor grade, T stage, N stage, liver metastasis, lung metastasis, and brain metastasis. Among the RCC-BM risk prediction models established by six ML algorithms, the XGB model showed the best prediction performance (AUC = 0.891). Therefore, a network calculator based on the XGB model was established to individually assess the risk of BM in patients with RCC.

Conclusion

The XGB risk prediction model based on the ML algorithm performed a good prediction effect on BM in RCC patients.

Case report: Complete remission of bone metastasis from renal cell carcinoma in histopathological examination after treatment with immune checkpoint inhibitors

Recently, the prognosis of metastatic renal cell carcinoma (mRCC) has improved owing to the development of immunotherapy using immune checkpoint inhibitors (ICIs). However, there have been few studies on the therapeutic effect of ICIs in bone metastases from renal cell carcinoma (RCC). We report a case in which pulmonary and humeral metastases from RCC were significantly ameliorated using ICIs, while surgery for a pathological fracture of the humerus significantly improved the patient’s quality of life (QoL). A 70-year-old man who underwent a left nephrectomy for RCC developed multiple pulmonary metastases and humeral metastasis with a pathological fracture one year after surgery, and combined treatment with nivolumab and ipilimumab was initiated. After four courses of ICI treatment, multiple pulmonary metastases had almost disappeared, and the tumor at the fracture site had shrunk remarkably. However, the shoulder joint function had decreased due to the fracture, worsening his QoL. Therefore, he underwent surgery and returned to normal daily life one month after. Postoperative histopathological examination of bone and soft tissue at the fracture site revealed no malignancy. To our knowledge, this is the first case report of complete remission of bone metastasis of RCC based on histopathological examination with ICI treatment.

Immune Checkpoint Inhibitor Therapy for Bone Metastases: Specific Microenvironment and Current Situation

The treatment of bone metastases is a thorny issue. Immunotherapy may be one of the few hopes for patients with unresectable bone metastases. Immune checkpoint inhibitors are the most commonly used immunotherapy drugs currently. In this review, the characteristics and interaction of bone metastases and their immune microenvironment were systematically discussed, and the relevant research progress of the immunological mechanism of tumor bone metastasis was reviewed. On this basis, we expounded the clinical application of immune checkpoint inhibitors for bone metastasis of common tumors, including non-small-cell lung cancer, renal cell carcinoma, prostate cancer, melanoma, and breast cancer. Then, the deficiencies and limitations in current researches were summarized. In-depth basic research on bone metastases and optimization of clinical treatment is needed.

Clinical outcomes and prognostic factors following the surgical resection of renal cell carcinoma spinal metastases

The efficacy of surgical resection in metastatic renal cell carcinoma is an active and important research field in the postcytokine era. Bone metastases, especially in the spine, compromise patient performance status. Metastasectomy is indicated, if feasible, because it helps to achieve the best clinical outcomes possible compared with other treatments. This study examined the postoperative survival and prognostic factors in patients who underwent metastasectomy of spinal lesions. The retrospective study included 65 consecutive patients with metastatic renal cell carcinomas who were operated on by spinal metastasectomy between 1995 and 2017 at our institution. The cancer‐specific survival times from the first spinal metastasectomy to death or the last follow‐up (≥3 years) were determined using Kaplan‐Meier analysis. Potential factors influencing survival were analyzed using Cox proportional hazard models. Planned surgical resection of all the spine tumors was achieved in all patients. Of these, 38 had complete metastasectomy of all visible metastases, including extraspinal lesions. In all patients, the estimated median cancer‐specific survival time was 100 months. The 3‐, 5‐, and 10‐year cancer‐specific survival rates were 77%, 62%, and 48%, respectively. The survival times after spinal metastasectomy were similar in both cytokine and postcytokine groups. In multivariate analyses, postoperative disability, the coexistence of liver metastases, multiple spinal metastases, and incomplete metastasectomy were significant risk factors associated with short‐term survival. Complete metastasectomy, including extraspinal metastases, was associated with improved cancer‐specific survival. Proper patient selection and complete metastasectomy provide a better prognosis in metastatic renal cell carcinoma patients.