Osteonecrosis of the jaw in metastatic renal cell carcinoma (mRCC) patients treated with zolendronic acid and denosumab: An observational retrospective multicenter trial.

Abstract

299 Background: Bone is one of the most common site of metastasis occurring in 30% of metastatic renal cell carcinoma (mRCC) patients (pts)3,4. Skeletal metastases from mRCC are usually osteolytic and associated to high rate of morbidity and complication through skeletal related events (SRE). Bone-targeted therapies (BTT) such as zolendronic acid (ZOL AC) and denosumab (Dmab), shown to decrease the time-to-first and subsequent SREs12. Osteonecrosis of the jaw (ONJ) is a rare but potentially serious adverse event associated with BTT. It occurs in 1-2% of pts treated with BTT and in 10-17% of mRCC pts treated with ZOL AC or Dmab. Vascular endothelial growth factor-Tyrosine kinase inhibitors (VEGF-TKI) represent the backbone treatment for mRCC. Nevertheless, it is unclear whether the association of DMAB and ZOL AC to VEGF-TKITTagents could be associated to higher incidence of ONJ. Methods: We retrospectively collected data, from 2 Italian referring centers for mRCC, about 74 pts with bone metastases from mRCC who received, concurrently or sequentially to VEGF-TKI or immune-oncology (IO), AC ZOL and DMAB from January 2013 to January 2020. All pts provided informed consent for inclusion in the study. Results: All pts received VEGF-TKI as first line treatment. 17 pts received AC ZOL whereas 57 received DMAB. All pts received odontological consultation and orthopantomography before start BTT. The median time of Dmab and AC ZOL exposure was 11.6 months. ONJ occurred in 10/74 pts (7.4%): 6/10 pts were on first line treatment and 4/10 on second line. Treatments administered at the time of ONJ diagnosis were nivolumab (1/10), cabozantinib (2/10), sorafenib (1/10), sorafenib (1/10), sunitinib (4/10) and one pts was off therapy. Conclusions: In this real-life Italian population, treatment with BTT in mRCC pts treated with VEGF-TKI inhibitors and IO is associated to higher incidence of ONJ compared to previous report of pts treated with BTT for bone metastasis and lower compared to previous reports in mRCC. Despite the retrospective collection, we provided one of the largest sample of pts treated concurrently with VEGF-TKI or IO and BTT. Physicians should be careful in the use of BTT combined with other treatments in mRCC pts.