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Objectives: Osteonecrosis of the jaw (ONJ) is a serious adverse event of bone resorption inhibitors (BRIs), such as bisphosphonates and denosumab. Bisphosphonates and denosumab inhibit osteoclast function through different pharmacological effects and bisphosphonates are retained in bone for several months to years. Sequential treatment with bisphosphonates and denosumab might lead to an overlapping treatment effect, due to the addition of the effect of denosumab on the residual bisphosphonate effect. Therefore, the aim of our study was to investigate if switching from denosumab to bisphosphonates is associated with a higher incidence of ONJ., Methods: We retrospectively reviewed records of patients with solid tumors and bone metastases treated with denosumab after prior treatment with bisphosphonates at the University Hospitals Leuven (sequential group). Patients treated with denosumab or bisphosphonates alone were used as control groups., Results: We identified 110 patients sequentially treated with bisphosphonates and denosumab with a median total BRI exposure of 36 months (sequential group). Median bisphosphonates exposure was 16 months and median denosumab exposure was 13 months. About 299 patients were included in the bisphosphonates control group with a median bisphosphonate exposure 19 months. About 6.7% (20/299) of patients developed ONJ. About 240 patients were included in the denosumab control group with a median denosumab exposure 17.5 months. About 10.0% of patients (24/240) developed ONJ. In the sequential group, 15.5% of patients (17/110) developed ONJ. The incidence of ONJ was 1.8% (2/110), 6.3% (6/99), 4.9% (4/82), 5.6% (3/54), and 3.4% (1/29), respectively in the first, second, third, fourth, and fifth year of BRI exposure, an ONJ-incidence similar to ONJ-incidence in the denosumab control group. In a time-to-ONJ-analysis, the curves of the sequential group and the denosumab control group were overlapping. In the sequential group, most of the ONJs occurred in the first year of denosumab exposure and in a matched control group analysis, with correction for median BRI-exposure, ONJ cases tend to occur earlier in the sequential group compared to ONJ cases in the bisphosphonates group., Conclusion: Cancer patients with bone metastases treated with BRIs seem to have a slightly higher risk of ONJ early after switching from bisphosphonates to denosumab compared to patients remaining on bisphosphonates. Nevertheless, based on the global ONJ-incidence, the switch from bisphosphonates to denosumab can be considered as safe as an equivalent exposure to denosumab from the start on.

Background: Several case reports and small case series have suggested a higher incidence of medication-related osteonecrosis of the jaw (MRONJ) in patients treated concomitantly with bone resorption inhibitors (BRIs) and vascular endothelial growth factor receptor tyrosine kinase inhibitors (VEGFR-TKIs), as compared to patients treated with BRIs alone. We aimed to assess ONJ-incidence in patients exposed concomitantly to BRIs and VEGFR-TKIs., Patients and Methods: We reviewed the records of all patients who received VEGFR-TKIs concomitantly with BRIs. Patients, who were treated with BRIs without VEGFR-TKI, served as a control group. Endpoints of the study were total MRONJ-incidence, MRONJ-incidence during the first and second year of exposure, and time-to-ONJ-incidence., Results: Ninety patients were treated concomitantly with BRIs and VEGFR-TKIs with a median BRI-exposure of 5.0 months. Total MRONJ-incidence was 11.1%. During the first year of BRI-exposure (with a median concomitant exposure of 4.0 months), 6 out of 90 patients (6.7%) developed a MRONJ, compared to 1.1% in the control group (odds ratio 5.9; 95%CI 2.0-18.0; p = 0.0035). In Kaplan-Meier estimates, time-to-ONJ-incidence was significantly shorter in patients treated with BRIs and VEGFR-TKIs compared to BRIs alone (hazard ratio 9.5; 95%CI 3.1-29.6; p < 0.0001). MRONJs occurred earlier in patients treated concomitantly compared to patients treated with BRIs only (after a median exposure of 4.5 and 25.0 months, respectively; p = 0.0033)., Conclusion: With a global MRONJ-incidence of 11%, patients receiving concomitant treatment with VEGFR-TKIs and BRIs have a five to ten times higher risk for development of MRONJ compared to patients treated with BRIs alone.

Background: Intimal sarcoma is a rare malignancy that, clinically and radiographically, often mimics pulmonary embolism. The intravascular tumor tends to disseminate rapidly and metastases can be present at first diagnosis., Methods: We reviewed all cases of intimal sarcoma that were diagnosed, treated and followed at the University Hospitals Leuven between April 2006 and April 2016., Results: We identified 13 patients with a median age of 51 years. In 6 patients initial findings were suggestive of thromboembolic disease. Platelet-derived growth factor receptor α (PDGFRA) amplification was the most prevalent molecular finding, present in 11 patients. The MDM2 gene was amplified in 9 cases, and the EGFR gene in 3 patients. The median overall survival was 13 months. 11 patients underwent surgery. In 5 cases with inoperable and/or metastatic disease chemotherapy was given. Treatment with imatinib was initiated in 4 patients., Conclusions: Intimal sarcoma is an extremely rare and aggressive malignancy that has a very poor prognosis. Mimicking thromboembolic disease, diagnosis and treatment can be delayed. Surgery is the mainstay of treatment but is seldom curative. The disease is highly resistant to cytotoxic and targeted treatment. Given the fact that intimal sarcoma commonly expresses more than 1 molecular target, combination therapy might be an option, although toxicity may be a limitation., (© 2017 S. Karger GmbH, Freiburg.)