Treatment options for advanced ameloblastoma in the era of precision medicine: A brief review.

Although complete excision is the standard of care for ameloblastoma, a subset of recurrent and/or metastasizing ameloblastomas are difficult to treat surgically. Over the past decade, several recurrent mutations in the mitogen-activated protein kinase pathway genes have been identified in ameloblastoma, based on which the efficacy of targeted therapy has been investigated. However, most of the literature has focused on BRAF V600E mutations, the most common oncogenic mutations in ameloblastoma. Hence, this study aims to review the current knowledge of targetable genetic alterations in ameloblastoma from a broader perspective. In addition, the therapeutic potential of immunotherapy for ameloblastoma will be briefly discussed in the context of tumoral PD-L1 expression and the tumor immune microenvironment.

Current concepts in targeted therapies for benign tumors of the jaw - A review of the literature.

The aim of our study was to review current concepts in targeted therapies for benign tumors of the jaw. Benign odontogenic and maxillofacial bone tumors often require radical surgery, with consequent morbidity that impacts patients' postsurgical quality of life. Currently, targeted therapies and novel nonsurgical therapeutics are being explored for management of non-resectable tumors, with the aim of avoiding surgery or minimizing surgical scope. However, data on clinical applications of targeted therapies for benign tumors of the jaw remain sparse. Therefore, a literature review was conducted, based on the PubMed database, which included in vivo human clinical studies describing clinical application of targeted therapy for benign tumor of the jaw. The review assessed the outcomes of BRAF and MEK inhibitors for treatment of ameloblastoma, RANKL monoclonal antibody for treatment of giant cell tumor, cherubism, aneurysmal bone cyst, and fibrous dysplasia, and tyrosine kinase inhibitor for treatment of odontogenic myxoma and cherubism. Targeted therapies decreased tumor size, slowed down tumor progression, and reduced bone pain. Surgery remains the gold standard, but targeted therapies are promising adjuvant or alternative treatment options for reducing tumor progression and morbidity of tumor surgery.

Differential Outcomes in Codon 12/13 and Codon 61 NRAS-Mutated Cancers in the Phase II NCI-MATCH Trial of Binimetinib in Patients with NRAS-Mutated Tumors.

PURPOSE: Preclinical and clinical data suggest that downstream inhibition with an MEK inhibitor, such as binimetinib, might be efficacious for NRAS-mutated cancers. PATIENTS AND METHODS: Patients enrolled in the NCI-MATCH trial master protocol underwent tumor biopsy and molecular profiling by targeted next-generation sequencing. Patients with NRAS-mutated tumors, except melanoma, were enrolled in subprotocol Z1A, a single-arm study evaluating binimetinib 45 mg twice daily. The primary endpoint was objective response rate (ORR). Secondary endpoints included progression-free survival (PFS) and overall survival (OS). A post hoc analysis examined the association of NRAS mutation type with outcome. RESULTS: In total, 47 eligible patients with a refractory solid tumor harboring a codon 12, 13, or 61 NRAS mutation were treated. Observed toxicity was moderate, and 30% of patients discontinued treatment because of binimetinib-associated toxicity. The ORR was 2.1% (1/47 patients). A patient with malignant ameloblastoma harboring a codon 61 NRAS mutation achieved a durable partial response (PR). A patient with NRAS codon 61-mutated colorectal cancer had an unconfirmed PR, and two other patients with NRAS codon 61-mutated colorectal had stable disease for at least 12 months. In an exploratory analysis, patients with colorectal cancer bearing a NRAS codon 61 mutation (n = 8) had a significantly longer OS (P = 0.03) and PFS (P = 0.007) than those with codon 12 or 13 mutations (n = 16). CONCLUSIONS: Single-agent binimetinib did not show promising efficacy in NRAS-mutated cancers. The observation of increased OS and PFS in patients with codon 61 NRAS-mutated colorectal cancer merits further investigation.

MAID chemotherapy regimen as a treatment strategy for metastatic malignant ameloblastoma: A case report.

RATIONALE: Ameloblastoma is generally characterized as a benign tumor originating in odontogenic epithelium. However, few cases of metastatic malignant ameloblastoma have also been reported. Due to the low incidence of malignant ameloblastoma, there is no established treatment regimen. To explore effective treatment for malignant ameloblastoma, we reported this case study. PATIENTS CONCERNS: This report described a case of a 28-year-old malignant ameloblastoma female patient with multiple metastasis (brain and lung). DIAGNOSES: The patient presented ameloblastoma of the left mandible in 2012. Three years later, local recurrence and brain metastasis was observed during a follow-up examination. Five years later, malignant ameloblastoma was detected by imaging and immunohistochemistry in the bilateral multiple pulmonary nodules and mediastinal lymph nodes. INTERVENTIONS: The patient was initially treated with tumor resection. Three years later after local recurrence and brain metastasis, she was accepted the extensive mandibulectomy supplemented with brain stereotactic body radiotherapy (SBRT). When diagnosed with pulmonary metastasis, the patient received combined chemotherapy regimen of MAID (mesna, adriamycin, ifosfamide and dacarbazine) for 6 cycles. OUTCOMES: The efficacy evaluation was partial remission (PR) after the 6 cycles of MAID. The last patient follow-up was July 24th 2018, and no evidence of progression was observed. The progression-free survival (PFS) of the patient was more than 9 months. LESSONS: Surgical resection is the optimal treatment for locally recurrent ameloblastoma. SBRT may be an effective treatment for unresectable oligometastasis of malignant ameloblastoma. Finally, combined chemotherapy of MAID showed encouraging effects in the management of metastatic malignant ameloblastoma.

Advancements in MAPK signaling pathways and MAPK-targeted therapies for ameloblastoma: A review.

Numerous signal transduction pathways are closely associated with the occurrence, development, and prognosis of ameloblastoma (AM). Mitogen-activated protein kinase (MAPK) is a serine/threonine-specific protein kinase that transduces intracellular signals in critical cellular phenomena. A number of recent analyses have reported that the MAPK signaling pathway contributes significantly to AM. High-throughput DNA sequencing methods, such as next-generation sequencing using Illumina have yielded advancements in studies on MAPK signaling pathways and their association with AM; in particular, BRAF V600E is mediated by the activation of the Ras/Raf/MAPK pathway. This review discusses advancements in studies on MAPK signaling pathways and MAPK-targeted inhibitors or antibodies, along with the merits and demerits of MAPK-targeted therapies, finally followed by a discussion regarding more efficient potential MAPK-targeted therapies to treat AM with few side effects, thereby providing novel insights into targeted therapy for AM.

Clinical benefit and radiological response with BRAF inhibitor in a patient with recurrent ameloblastoma harboring V600E mutation.

BACKGROUND: Ameloblastoma is a slow-growing neoplasm of the jaw, for which the standard treatment is surgical removal of the lesion with high recurrence rates and elevated morbidity. Systemic therapy is not established in the literature. CASE PRESENTATION: We present a case of a 29-year-old woman diagnosed with an ameloblastoma of the left mandible who had been subjected to several surgical procedures over twenty years due to multiple local recurrences. Molecular testing revealed a BRAF V600E mutation, and vemurafenib was started. She experienced complete resolution of symptoms related to the disease, and image scans evidenced continuous shrinkage of the neoplastic lesion after eleven months of therapy. CONCLUSION: This is the first report showing clinical benefit and radiological response with vemrafenib for recurrent ameloblastoma. Targeted therapy addressing BRAF V600E mutation has the potential to change clinical practice of this rare disease.

Carcinoma primario intraóseo mandibular derivado de un quiste odontogénico / Primary intraosseous mandibular carcinoma arising from an odontogenic cyst

Introducción: el carcinoma de células escamosas primario intraóseo es una neoplasia maligna poco frecuente. Objetivo: presentar un caso clínico de un carcinoma primario intraóseo derivado de un quiste odontogénico en las regiones del cuerpo a la rama mandibular izquierdas. Caso clínico: acude a consulta paciente masculino de 68 años quien refiere una molestia en la mandíbula. Al examen bucal se detecta expansión cortical a nivel del 37. Se realiza estudio de ortopantomografía donde se observó un área radiolúcida con borde definidos, y bajo la impresión diagnóstica de quiste residual se efectúa curetaje y estudio histopatológico, que confirma lo sospechado. Al cabo de unos 4 meses el paciente acude nuevamente refiriendo dolor muy intenso en la región del ángulo mandibular con ligera parestesia del labio inferior izquierdo que se asociaba al examen físico facial, con edema geniano bajo y submandibular, y al examen bucal con movilidad anormal ósea mandibular izquierda. Se realiza ortopantomografía donde se observa imagen radiolúcida de bordes irregulares, poco precisos, y fractura patológica mandibular. Se decide inmovilización y toma de muestra para biopsia, que informa un carcinoma epidermoide moderadamente diferenciado, por lo que se realiza tratamiento quirúrgico radical con manejo del cuello, más radioterapia y quimioterapia posoperatorias. Conclusión: la transformación en un carcinoma primario intraóseo a partir de un quiste residual es una entidad infrecuente en la región maxilofacial. El diagnóstico en el caso presentado se realizó por exclusión. La sintomatología de dolor intenso y parestesia fueron elementos clave en la sospecha diagnóstica. El enfoque oncológico mediante cirugía radical con manejo del cuello, radio y quimioterapia permitieron el control loco-regional(AU)

Introduction: primary intraosseous squamous cell carcinoma is an infrequent malignant neoplasm. Objective: present a clinical case of primary intraosseous carcinoma arising from an odontogenic cyst in body regions to the left mandibular branch. Clinical case: a 68-year-old male patient presented with discomfort in his mandible. Oral examination revealed cortical expansion at the level of 37. Orthopantomography showed a radiolucent area with definite borders. Curettage and histological testing confirmed the preliminary diagnosis of residual cyst. Some four months later the patient presented again with very intense pain in the mandibular angle region with slight paresthesia of the left lower lip area associated on physical facial examination with lower and submandibular genian edema, and on oral examination with abnormal left mandibular bone mobility. Orthopantomography revealed a radiolucent image of irregular, imprecise borders and pathological mandibular fracture. It was decided to immobilize and take a sample for biopsy, which reported moderately differentiated epidermoid carcinoma. Therefore, radical surgical treatment was performed with neck management plus postoperative radiotherapy and chemotherapy. Conclusion: evolution of a residual cyst into a primary intraosseous carcinoma is an infrequent condition in the maxillofacial region. In the case herein presented diagnosis was made by exclusion. The symptoms of intense pain and paresthesia were crucial to the preliminary diagnosis. Application of an oncological approach based on radical surgery with neck management and radio- and chemotherapy resulted in local-regional control(AU)

Pharmacological and surgical therapy for the central giant cell granuloma: A long-term retrospective cohort study.

PURPOSE: This is a retrospective cohort study of patients with a central giant cell granuloma (CGCG) treated at a single center to assess and compare the different surgical and non-surgical approaches. MATERIAL AND METHODS: A cohort with a single histologically proven non-syndrome-related CGCG was selected and reviewed. Patients were allocated to group I (surgery), group II (pharmacotherapy), and group III (pharmacotherapy and surgery). The primary outcome was long-term radiologic response using computed tomography. Secondary outcomes were intermediate radiologic responses and occurrence and severity of side effects. RESULTS: Thirty-three subjects were included in the study. The surgical group (n = 4) included 1 patient with progression during follow-up and a relatively high post-surgical morbidity. Twenty-nine patients started on various pharmacological treatment regimens (groups II and III). Fourteen patients could be managed without additional surgery. One of these lesions showed progression during follow-up. The other 15 lesions underwent additional surgery, and none showed progression during follow-up. Interferon treatment was associated with the most side effects. CONCLUSION: Pharmacological agents have a role in the treatment of aggressive and non-aggressive CGCGs by limiting the renewed progression during long-term follow up and the extent and morbidity of surgical treatment.

Adjuvant Antiangiogenic Treatment for Aggressive Giant Cell Lesions of the Jaw: A 20-Year Experience at Massachusetts General Hospital.

PURPOSE: To document long-term outcomes using a standardized treatment protocol of enucleation with preservation of vital structures and adjuvant subcutaneous interferon for aggressive giant cell lesions (GCLs) of the jaws. MATERIALS AND METHODS: A retrospective cohort study was designed. We evaluated all patients treated at Massachusetts General Hospital from April 1995 through September 2015 by enucleation with preservation of vital structures and adjuvant daily subcutaneous interferon for aggressive GCLs. The sample included patients with complete medical records consisting of clinical, radiographic, histopathologic, and follow-up data. The exclusion criteria included patients with incomplete records, contraindications to interferon therapy, non-aggressive GCLs, and GCLs associated with syndromes or with hyperparathyroidism. The primary outcome variable was long-term progression-free survival (PFS). The secondary outcome variables were adverse effects and laboratory abnormalities classified by type, frequency, and severity. Predictor variables for recurrence or failure included age, gender, location and features of lesion, type of procedure, duration of interferon treatment, amount of bone fill at end of treatment, and adverse effects. Descriptive statistics, Kaplan-Meier survival analysis, and Cox proportional hazards regression analysis were computed. RESULTS: Of a total of 77 patients, 45 (mean age, 18.8 ± 12.5 years; 29 female patients; 36 in whom the mandible was affected) met the inclusion criteria. The mean duration of interferon therapy was 7.9 ± 2.3 months. After follow-up of 4.8 ± 3.9 years, 6 patients showed progression of the lesion, considered recurrence (13.3% failure rate, 82.6% PFS rate). Most patients had mild (n = 42; 93.3%) and/or moderate (n = 31; 68.8%) side effects, which were readily managed. Adverse effects required stoppage of interferon in 7 patients, whereas no patients had long-term toxicity. No variable was significantly associated with PFS. CONCLUSIONS: The results of this study indicate that enucleation with preservation of vital structures in combination with adjuvant interferon alfa is a reliable treatment for aggressive GCLs of the jaws associated with a low recurrence rate.

[NF-κB signaling pathways and the future perspectives of bone disease therapy using selective inhibitors of NF-κB].

The transcriptional factor nuclear factor κB(NF-κB)regulates the expression of a wide variety of genes that are involved in immune and inflammatory responses, proliferation, and tumorigenesis. NF-κB consists of five members, such as p65(RelA), RelB, c-Rel, p50/p105(NF-κB1), and p52/p100(NF-κB2). There are two distinct NF-κB activation pathways, termed the classical and alternative NF-κB signaling pathways. Since mice lacking both p50 and p52 subunits developed typical osteopetrosis, due to total lack of osteoclasts, NF-κB is also important osteoclast differentiation. A selective NF-κB inhibitor blocked receptor activator of NF-κB ligand(RANKL)-induced osteoclastogenesis both in vitro and in vivo. Recent findings have shown that inactivation of NF-κB enhances osteoblast differentiation in vitro and bone formation in vivo. NF-κB is constitutively activated in many cancers including oral squamous cell carcinoma(OSCC), and is involved in the invasive characteristics of OSCC. A selective NF-κB inhibitor also prevented jaw bone destruction by OSCC by reduced osteoclast numbers in animal model. Thus the inhibition of NF-κB might useful for the treatment of bone diseases, such as arthritis, osteoporosis, periodontitis, and bone invasion by OSCC by inhibiting bone resorption and by stimulating bone formation.

EGFR signaling downstream of EGF regulates migration, invasion, and MMP secretion of immortalized cells derived from human ameloblastoma.

Ameloblastoma is an odontogenic tumor characterized by local invasiveness and frequent recurrence. The surrounding stroma, composed of different cell types and extracellular matrix (ECM), may influence ameloblastoma invasive behavior. Furthermore, tumor and stromal cells secrete matrix metalloproteases (MMPs), which, in turn, can modulate the matrix and promote the release of ECM-bound growth factors. Among these growth factors, epidermal growth factor (EGF) and its receptor, EGFR, have already been shown to stimulate MMP synthesis, suggesting that an interdependent mechanism, involving MMP activity and growth factors release, may contribute to tumor invasiveness. The aim of this study was to evaluate the effects of the EGF/EGFR signaling pathway on migration, invasion, and MMP activity, in a primary cell line derived from human ameloblastoma. We established and characterized a primary cell line (AME-1) from a human ameloblastoma sample. This cell line was transduced with human papillomavirus type 16 (HPV16) E6/E7 oncogenes, generating the AME-HPV continuous cell line. EGF, MMP2, and MMP9 expression in ameloblastoma biopsies and in the AME-HPV cell line was analyzed by immunohistochemistry and immunofluorescence, respectively. Migratory activity of EGF-treated AME-HPV cells was investigated using monolayer wound assays and Transwell chambers. EGF-induced invasion was assessed in Boyden chambers coated with Matrigel. Conditioned medium from EGF-treated cells was subjected to zymography. EGFR expression in AME-HPV cells was silenced by small interfering RNA (siRNA), to verify the relationship between this receptor and MMP secretion. Ameloblastoma samples and AME-HPV cells expressed EGF, EGFR, MMP2, and MMP9. AME-HPV cells treated with EGF showed increased rates of migration and invasion, as well as enhanced MMP2 and MMP9 activity. EGFR knockdown decreased MMP2 and MMP9 levels in AME-HPV cells. EGFR signaling downstream of EGF probably regulates migration, invasion, and MMP secretion of ameloblastoma-derived cells.

Identification of recurrent SMO and BRAF mutations in ameloblastomas.

Here we report the discovery of oncogenic mutations in the Hedgehog and mitogen-activated protein kinase (MAPK) pathways in over 80% of ameloblastomas, locally destructive odontogenic tumors of the jaw, by genomic analysis of archival material. Mutations in SMO (encoding Smoothened, SMO) are common in ameloblastomas of the maxilla, whereas BRAF mutations are predominant in tumors of the mandible. We show that a frequently occurring SMO alteration encoding p.Leu412Phe is an activating mutation and that its effect on Hedgehog-pathway activity can be inhibited by arsenic trioxide (ATO), an anti-leukemia drug approved by the US Food and Drug Administration (FDA) that is currently in clinical trials for its Hedgehog-inhibitory activity. In a similar manner, ameloblastoma cells harboring an activating BRAF mutation encoding p.Val600Glu are sensitive to the BRAF inhibitor vemurafenib. Our findings establish a new paradigm for the diagnostic classification and treatment of ameloblastomas.

The use of vismodegib to shrink keratocystic odontogenic tumors in patients with basal cell nevus syndrome.

IMPORTANCE: Keratocystic odontogenic tumors (KCOTs) of the jaw affect more than 65% of patients with basal cell nevus syndrome (BCNS). Surgery frequently causes facial disfigurement and is not always curative. Most BCNS-related and some sporadic KCOTs have malignant activation of the Hedgehog signaling pathway. OBSERVATIONS: We examined the effect of vismodegib (an oral Hedgehog pathway inhibitor) on KCOT size in patients with BCNS enrolled in a clinical trial testing vismodegib for basal cell carcinoma prevention (NCT00957229), using pretreatment and posttreatment magnetic resonance imaging. Four men and 2 women had pretreatment KCOTs (mean longest diameter, 2.0 cm; range, 0.7-3.3 cm), occurring primarily in the mandible. Patients were treated with vismodegib, 150 mg/d, for a mean (SD) of 18.0 (4.8) months (range, 11-24 months). Four patients experienced a size reduction and 2 had no change. Vismodegib reduced the mean longest diameter of KCOTs in all patients by 1.0 cm (95% CI, 0.03-1.94; P = .02) or 50% from baseline. We observed no enlargement of existing KCOTs or new KCOT development. CONCLUSIONS AND RELEVANCE: Vismodegib shrinks some KCOTs in patients with BCNS and may offer an alternative to surgical therapy. These effects were maintained for at least 9 months after drug cessation in 1 patient. Further studies assessing long-term efficacy and optimal maintenance regimens should be performed.

High frequency of BRAF V600E mutations in ameloblastoma.

Ameloblastoma is a benign but locally infiltrative odontogenic neoplasm. Although ameloblastomas rarely metastasise, recurrences together with radical surgery often result in facial deformity and significant morbidity. Development of non-invasive therapies has been precluded by a lack of understanding of the molecular background of ameloblastoma pathogenesis. When addressing the role of ERBB receptors as potential new targets for ameloblastoma, we discovered significant EGFR over-expression in clinical samples using real-time RT-PCR, but observed variable sensitivity of novel primary ameloblastoma cells to EGFR-targeted drugs in vitro. In the quest for mutations downstream of EGFR that could explain this apparent discrepancy, Sanger sequencing revealed an oncogenic BRAF V600E mutation in the cell line resistant to EGFR inhibition. Further analysis of the clinical samples by Sanger sequencing and BRAF V600E-specific immunohistochemistry demonstrated a high frequency of BRAF V600E mutations (15 of 24 samples, 63%). These data provide novel insight into the poorly understood molecular pathogenesis of ameloblastoma and offer a rationale to test drugs targeting EGFR or mutant BRAF as novel therapies for ameloblastoma.

Metastatic cancer identified in osteonecrosis specimens of the jaws in patients receiving intravenous bisphosphonate medications.

PURPOSE: The aim of the present study was to investigate the microscopic presence of metastatic cancer in jaw specimens clinically and histologically diagnosed as having osteonecrosis in patients receiving intravenous bisphosphonate medications. PATIENTS AND METHODS: A retrospective cohort multicenter study was designed. Patients from the University of Tennessee Medical Center, New York University Medical Center, and New York Center for Orthognathic and Maxillofacial Surgery were enrolled who had been treated with intravenous bisphosphonate medications for an underlying diagnosis of cancer and who had been clinically diagnosed with bisphosphonate-related osteonecrosis of the jaws (BRONJ). The institutional review boards approved the present study. The primary predictor variable was the clinical presence of BRONJ. The primary outcome variable was the microscopic presence of metastatic cancer in the osteonecrotic jaw specimens. RESULTS: A total of 744 sites of BRONJ were clinically diagnosed. Of these sites, 552 (74%) were diagnosed in patients who had received intravenous bisphosphonate medications. Of these 552 sites, 357 (65%) underwent microscopic evaluation through biopsy, sequestrectomy, or resection with curative intent. Of the 357 sites of BRONJ subjected to microscopic analysis, 19 (5.3%) sites were diagnosed with 20 cancers in 16 patients. CONCLUSIONS: Albeit rare, the presence of cancer in a BRONJ specimen represents 1 explanation for the development of osteonecrosis in patients exposed to intravenous bisphosphonate medications in whom a clinical diagnosis of BRONJ has been applied. Additional molecular information is needed to provide an explanation for this observation.

[A case of brain abscess secondary to bisphosphonate-related osteonecrosis of the jaws in metastatic bone lesions from breast carcinoma].

Bisphosphonates have been used clinically as highly effective drugs in the treatment of hypercalcemia of malignancy, and bone metastasis of solid cancers. Despite these benefits, however, the emergence of bisphosphonate-related osteonecrosis of the jaws has become a growing and significant problem in a subset of patients receiving these drugs. We report a rare case of brain abscess secondary to BRONJ in metastatic bone lesions from breast carcinoma.

Intralesional corticosteroid injections in the treatment of central giant cell lesions of the jaws: a meta-analytic study.

OBJECTIVE: The aim of this study was to evaluate the response of treatment of central giant cell lesion to intralesional corticosteroid injections. STUDY DESIGN: Review of articles indexed in PubMed on the topic between the years 1988 and 2011, and development of a descriptive meta-analysis of the results. RESULTS: Sample of 41 patients primarily treated with intralesional corticosteroid injections was obtained, with a male female ratio of 1:0.95, being 23 aggressive and 18 non-aggressive central giant cell lesions. Triamcinolone acetonide and triamcinolone hexacetonide were the drugs used, and 78.0% cases were considered as good result, 14.6% were considered as moderate response and 7.3% were considered as negative result to treatment. Considering the aggressiveness, 88.9% of non-aggressive lesions presented a good response to treatment, in aggressive central giant cell lesions, 69.6% presented a good response to intralesional corticosteroid injections. CONCLUSION: In view of the results analyzed, intralesional corticosteroid injections could be considered as first treatment option for central giant cell lesion.