E-Poster Presentation ESA-SRB-ANZBMS 2021

Clinical and radiologic responses of central giant cell granuloma to denosumab: a 6-year observational cohort study (#758)

Yoon Ji Jina Rhou 1 , Che-Jen Wang 2 , Minh Nguyen 1 , Lydia Lim 3 , Jane Holmes-Walker 1 , Craig Munns 4 , Christian M Girgis 1
  1. Diabetes and Endocrinology, Westmead Hospital, Sydney, NSW, Australia
  2. Dental and Maxillofacial Surgery, Prince of Wales Hospital, Sydney, NSW, Australia
  3. Oral and Maxillofacial Surgery, Westmead Hospital, Sydney, NSW, Australia
  4. Institute of Endocrinology and Diabetes, The Children’s Hospital at Westmead, Sydney, NSW, Australia

611384bf8cc90-Figure+1.pngBackground:

Central giant cell granuloma (CGCG) is a rare tumour of the jaw occurring in young adults. Surgery is associated with high morbidity and recurrence rates. Denosumab is effective targeted therapy in a related but distinct, more aggressive entity, giant cell tumour of bone (GCTB). Experience in CGCG, a more indolent condition, is limited. 

Aims:

To evaluate the safety and efficacy of denosumab in the management of CGCG, and recurrence risk post-cessation, using a more conservative treatment and monitoring regimen than used for GCTB. 

Methods:

In this observational cohort study of all denosumab-treated CGCG at a tertiary referral centre (2015-2021), patients received denosumab 120mg using a modified regimen with less frequent dosing than used for GCTB to reduce the risk of adverse effects. Patients were followed for up to 72 months with standardised, low-radiation protocol: 3-monthly clinical, biochemical and radiological assessment (orthopantomogram +/- cone beam CT). Responses, complications and recurrence rates were evaluated. 

Results:

Eight patients, median age 21 [IQR 6] years, received denosumab, median initial course 13 [10] doses. Responses were seen after 5.5 [4.5] doses (Fig.1): radiopacification representing intralesional ossification in all and radiological size reduction in three. Response was variable. Recurrence post-discontinuation occurred in 4 of 7 completing therapy after 12 [6.5] months. Larger baseline size, aggressive subtype and initial treatment <12 doses predicted recurrence. There was no osteonecrosis of the jaw and hypocalcaemia occurred in one receiving modified treatment regimen. Post-denosumab cessation rebound hypercalcaemia was mild and self-limiting in adults. 

Conclusions:

This is the largest cohort of a diverse population of denosumab-treated CGCG and demonstrates the efficacy of denosumab at more conservative dosing than used in GCTB. Recurrence was predicted by larger baseline size, aggressive subtype and short initial treatment. This study supports the use of modified-dose denosumab in CGCG. Long-term low-dose radiological monitoring is required.