USE OF DENOSUMAB IN GIANT-CELL TUMOR AT A PUBLIC HOSPITAL IN SOUTHERN BRAZIL: REPORT OF 13 CASES

Introduction: Giant-cell tumor (GCT) is a rare neoplasia, benign but locally aggressive, that causes significant bone destruction. It represents 4 to 10% of primary tumors of bone and occurs mainly in young adults. Definitive treatment is surgical, with complete tumoral resection followed by autograft, homograft, arthrodesis, unconventional endoprostheses or methylmethacrylate. In most cases, surgery is accompanied by high morbidity and variable recurrence rates, depending in the site, size and type of surgical intervention. The RANK receptor is a key mediator of osteoclastogenesis. Denosumab, a RANKL inhibitor, acts by decreasing tumoral osteoclastic activity and is approved for treatment of GCT when surgery is not possible or is accompanied by high morbidity. Objective: Introduce the service experience using denosumab in patients with GCT. Methods: Reporting of cases based on the review of medical records about all cases of GCT from the Ambulatory Service for Adolescents and Young Adults (AYA), from May 2011 to February 2018. A total of 13 cases were selected. Among the cases, there were two patients with diagnosed pulmonary metastases, whose initial treatment was chemotherapy. Among the other patients, desonumab was elected for the initial treatment in eight cases and in three of them desonumab was started in our institution after prior surgical intervention at other centers. Regarding surgery after use of desonumab, among all patients under treatment, one was still receiving it, one missed follow-up and six underwent surgery. Four patients had not undergone surgery. When AP exams were assessed after the use of desonumab in non-metastatic patients, from the six patients who had undergone surgery, four of them showed changes related only to the use of the drug and without evidence of the disease. By analyzing the metastatic pulmonary patients, one received desonumab for 13 months, with complete pulmonary response. The other one, when diagnosed, had no evidence of recurrence until May 2017. Among the six patients who had received desonumab and had subsequently undergone surgery, four of them remained without evidence of the disease. The use of desonumab was very well tolerated by all patients. Conclusion: We concluded that desonumab treatment of GCT is a relevant one, once we provided a less aggressive treatment and with encouraging results, from complete responses after surgery or without any evidence of the disease, even when surgery is not possible.