Upfront rational therapy in BRAF V600E mutated pediatric ameloblastoma promotes ad integrum mandibular regeneration.

ABSTRACT

Ameloblastoma is a neoplasm arising in the craniofacial skeleton. Proliferating odontogenic epithelial cells comprise this benign, yet locally invasive tumor, often causing severe disfiguration. High recurrence rate entails ablative surgical resection, which is the current standard of care, resulting in subsequent critical size osteocutaneous defects. The high incidence of BRAF mutations in ameloblastoma, most notably the BRAF V600E mutation, enabled the use of BRAF inhibiting agent in a neoadjuvant setting. In this investigator-initiated, open-label study, three consecutive pediatric patients, with confirmed BRAF V600E ameloblastoma deemed marginally resectable, were treated with BRAF inhibiting agents, prior to undergoing surgery. The use of upfront BRAF inhibitor treatment resulted in substantial tumor regression, allowing for non-mutilating complete surgical removal, ad integrum bone regeneration and organ preservation. All patients showed a marked radiologic and clinical response to medical treatment, enabling successful conservative surgery. Microscopically, all patients showed evidence of minimal residual tumor with extensive tumor necrosis, fibrosis and generation of new bone. At a median follow-up of 31 months, all patients remained free of disease. Face preservation therapy was achieved in pediatric patients presenting with BRAF V600E mutated ameloblastoma. Our study demonstrates the translational potential of targeted therapy as a neoadjuvant agent. Patient-specific organ preservation therapy should be considered as the new standard of care in ameloblastoma, mainly for children and adolescents.