Current Controversies on the Pathogenesis of Medication-Related Osteonecrosis of the Jaw

Medication-related osteonecrosis of the jaw (MRONJ) was first reported more than a decade ago. Since then, numerous cases have been diagnosed. Currently, there are three groups of drugs related to MRONJ: bisphosphonates, denosumab and anti-angiogenic drugs. As MRONJ can lead to debilitating clinical sequels and limited effective treatment options are available, much research has been done in understanding its pathophysiology. Until now, the exact pathogenesis of MRONJ has not been fully elucidated. While history of invasive dental procedures or local trauma may be present, some cases occur spontaneously without any preceding factors. This review aims to examine and discuss the three main hypotheses for the pathogenesis of MRONJ, namely suppressed bone turnover, cellular toxicity and infection.

Osteonecrosis of the Jaw in Patients With Metastatic Renal Cell Cancer Treated With Bisphosphonates and Targeted Agents: Results of an Italian Multicenter Study and Review of the Literature

Osteonecrosis of the jaw (ONJ) associated with the use of bisphosphonates has been rarely reported in metastatic renal cell cancer (RCC) patients. Since the introduction of combined therapies consisting of nitrogen-containing bisphosphonates (NBPs) and targeted agents, an increasing number of RCC patients were reported to develop ONJ, suggesting that therapeutic angiogenesis suppression might increase the risk of ONJ in NBPs users. We performed a multicenter retrospective study and reviewed literature data to assess the occurrence and to investigate the nature of ONJ in RCC patients taking NBPs and targeted agents. Nine Italian Centers contributed to the data collection. Patients with exposed and nonexposed ONJ were eligible for the study if they had been taking NBPs and were receiving targeted agents at the time of ONJ diagnosis. Forty-four RCC patients were studied. Patients were mostly male (82%), with a median age of 63 years (range, 45-85 years). Zoledronic acid (93%) and sunitinib (80%) were the most frequently used NBP and antiangiogenic agent, respectively. Other agents included Pamidronate, ibandronate, sorafenib, bevacizumab, mammalian target of rapamycin inhibitors. Forty-nine sites of ONJ were encountered, with the mandible being the preferred site of ONJ (52%); both jaws were affected in 5 cases (12%). The most common precipitating event was dental/periodontal infection (34%), followed by tooth extraction (30%). Oral triggers of ONJ were missing in 10 cases (23%). This unexpectedly high number of ONJ cases, in comparison with literature data, suggests that frequency of ONJ in RCC patients might be largely underestimated and suggests a potential role for targeted agents in the incremental risk of ONJ.

Epidemiology, clinical manifestations, risk reduction and treatment strategies of jaw osteonecrosis in cancer patients exposed to antiresorptive agents

ABSTRACT: Osteonecrosis of the jaws (ONJ) is an adverse side event of bisphosphonates and denosumab, antiresorptive agents that effectively reduce the incidence of skeletal-related events in patients with metastatic bone cancer and multiple myeloma. Available data suggest that 0–27.5% of individuals exposed to antiresorptive agents can develop ONJ. There is increasing evidence that avoidance of surgical trauma and infection to the jawbones can minimize the risk of ONJ, but there are still a significant number of individuals who develop ONJ in the absence of these risk factors. Bone necrosis is almost irreversible and there is no definitive cure for ONJ with the exclusion, in certain cases, of surgical resection. However, most ONJ individuals are affected by advanced incurable cancer and are often managed with minimally invasive nonsurgical interventions in order to control jawbone infections and painful symptoms. This article summarizes current knowledge of ONJ epidemiology, manifestations, risk-reduction and therapeutic strategies. Further research is needed in order to determine individual predisposition to ONJ and clarify the effectiveness of available treatments.

Concomitant oral tyrosine kinase inhibitors and bisphosphonates in advanced renal cell carcinoma with bone metastases

BACKGROUND

The presence of bone metastases in patients with metastatic renal cell carcinoma treated with oral tyrosine kinase inhibitors (TKIs) is associated with poorer outcome as compared with patients without bone involvement. Concomitant bisphosphonates could probably improve outcomes but also induce osteonecrosis of the jaw (ONJ).

METHODS

Retrospective study on all the renal cell carcinoma patients with bone metastases treated with sunitinib or sorafenib between November 2005 and June 2012 at the University Hospitals Leuven and AZ Groeninge in Kortrijk.

RESULTS

Seventy-six patients were included in the outcome analysis: 49 treated with concomitant bisphosphonates, 27 with TKI alone. Both groups were well balanced in terms of prognostic and predictive markers. Response rate (38% vs 16% partial responses, P=0.028), median progression-free survival (7.0 vs 4.0 months, P=0.0011) and median overall survival (17.0 vs 7.0 months, P=0.022) were significantly better in patients receiving bisphosphonates. The incidence of ONJ was 10% in patients treated with TKI and bisphosphonates.

CONCLUSION

Concomitant use of bisphosphonates and TKI in renal cell carcinoma patients with bone involvement probably improves treatment efficacy, to be confirmed by prospective studies, but is associated with a high incidence of ONJ.