Cetuximab in the treatment of metastatic mucoepidermoid carcinoma of the salivary glands: a case report and review of literature

Molecular Targets in Salivary Gland Cancers: A Comprehensive Genomic Analysis of 118 Mucoepidermoid Carcinoma Tumors

INTRODUCTION

Salivary gland carcinomas (SGC) are histologically diverse cancers and next-generation sequencing (NGS) to identify key molecular targets is an important aspect in the management of advanced cases.

METHODS

DNA was extracted from paraffin embedded tissues of advanced SGC and comprehensive genomic profiling (CGP) was carried out to evaluate for base substitutions, short insertions, deletions, copy number changes, gene fusions and rearrangements. Tumor mutation burden (TMB) was calculated on approximately 1.25 Mb. Some 324 genes in the FoundationOne CDX panel were analyzed.

RESULTS

Mucoepidermoid carcinoma (MECa) mutations were assessed. CDKN2A and CDKN2B GA were common in mucoepidermoid carcinoma (MECa) (52.5 and 30.5%). PIK3CA was also common in MECa (16.9%). ERBB2 amplification/short variants (amp/SV) were found in MECa (5.9/0%). HRAS GA was common in MECa (14.4%) as well. Other targets, including BAP1, PTEN, and KRAS, were noted but had a low incidence. In terms of immunotherapy (IO)-predictive markers, TMB > 10 was more common in MECa (16.9%). PDL1 high was also seen in MECa (4.20%).

CONCLUSION

SGC are rare tumors with no FDA-approved treatment options. This large dataset reveals many opportunities for IO and targeted therapy contributing to the continuously increased precision in the selection of treatment for these patients.

Mucoepidermoid Carcinoma of the Salivary Gland: Demographics and Comparative Analysis in U.S. Children and Adults with Future Perspective of Management

Background: Salivary gland neoplasms are uncommon in both pediatric and adult populations. Mucoepidermoid carcinoma (MEC) is one of the most common salivary gland tumors and usually presents with atypical clinical features. This study sought to evaluate the demographic and clinical factors affecting outcomes in adults and pediatric populations with MEC that could be used to risk stratification for treatment selection and clinical trial enrollment. Methods: Data on 4507 MEC patients were extracted from the Surveillance Epidemiology and End Result (SEER) database (2000−2018). Patients aged ≤ 18 years were classified into the pediatric population, and those older than 18 years were placed in the adult group. Kaplan−Meier survival curves were created to analyze survival probabilities for various independent factors. Results: The pediatric population comprised 3.7% of the entire cohort, with a predominance of females (51.5%), while the adult population constituted 96.3% of the cohort, with a predominance of female patients (52.2%). Caucasians were the predominant race overall (75.3%), while more African Americans were seen in the pediatric group. In tumor size of <2 cm overall, poorly differentiated tumors with higher metastasis rates were observed more in adults (11.3% and 9.3%) than in the pediatric population (3.0% and 4.8%, p < 0.05). Surgical resection was the most common treatment option (53.9%), making up 63.6% of the pediatric and 53.5% of the adult groups. A combination of surgical resection and radiation was used in 29.8% of the entire cohort while a combination of surgical resection, radiation, and chemotherapy made up only 3.2%. The pediatric group had a lower overall mortality rate (5.5%) than the adult group (28.6%). Females had a higher 5-year survival rate in comparison to males (86.5%, and 73.7%, respectively). Surgical resection led to a more prolonged overall survival and 5-year cancer-specific survival (98.4% (C.I, 93.7−99.6) in the pediatric group and 88.8% (C.I, 87.5−90.0) in the adult group), respectively. Metastasis to the lung, bone, brain, and/or liver was found to have significantly lower survival rates. Multivariate analysis demonstrated that adults (hazard ratio [HR] = 7.4), Asian or Pacific Islander (HR = 0.5), male (HR = 0.8), poorly differentiated histology (HR = 3.8), undifferentiated histology (HR = 4.5), regional spread (HR = 2.1), and distant spread (HR = 3.2) were associated with increased mortality (p < 0.05). Conclusions: Mucoepidermoid carcinoma of the salivary glands primarily affects Whites and is more aggressive in adults than in the pediatric population. Even with surgical resection, the overall survival is poor in the adult population as compared to its pediatric counterparts. Advanced age, larger tumor size, male sex, and lymph node invasion are associated with increased mortality.

Clinicopathological significance of EGFR pathway gene mutations and CRTC1/3-MAML2 fusions in salivary gland mucoepidermoid carcinoma

AIMS

Mucoepidermoid carcinoma (MEC) is one of the most common salivary gland carcinomas. Epidermal growth factor receptor (EGFR) signalling pathway gene mutations are important in predicting a patient's prognosis, selecting molecularly targeted drugs and estimating the efficacy of a molecular therapy. However, their significance in MEC have been poorly clarified. CRTC1/3-MAML2 fusions are specific to MEC and may be associated with favourable characteristics in these patients.

METHODS AND RESULTS

We looked for CRTC1/3-MAML2 fusions and gene alterations in the EGFR, RAS family (KRAS, HRAS and NRAS), PIK3CA, BRAF and AKT1 in 101 MEC cases. We also examined mutations in TP53. CRTC1/3-MAML2 fusions were found in 62.4% of the cases. KRAS, HRAS and PIK3CA mutations were detected in 6.9%, 2.0% and 6.9%, respectively, but other EGFR pathway genes were not mutated. In total, gene mutations (RAS/PIK3CA) in the EGFR pathway were detected in 14.9% of the cases. TP53 mutations were found in 20.8%. CRTC1/3-MAML2 fusions were associated with a better prognosis and RAS/PIK3CA mutations a worse prognosis of the patients, respectively, and both were selected as independent prognostic factors for the overall survival of the patients. TP53 mutations had no prognostic impact. CRTC1/3-MAML2 fusion-positive rates were inversely associated with the patients' age and the fusions were found in 82% of patients aged < 30 years.

CONCLUSIONS

RAS/PIK3CA mutations were frequently detected, and may be a biomarker for a poorer prognosis in MEC patients. CTRC1/3-MAML2 fusions were positive in most of the young MEC patients.

Advances and challenges in precision medicine in salivary gland cancer

Salivary gland cancer (SGC) is a rare malignancy consisting of 22 subtypes with different genetic, histological and clinical characteristics. This rarity and heterogeneity makes systemic treatment of recurrent or metastatic (R/M) disease challenging. Use of chemotherapy is scarcely studied and chemotherapy at best has moderate effects. New therapeutic strategies are therefore warranted, but advances made in SGC are lagging behind on advances made in more common cancers. By unraveling tumor characteristics of SGC, such as genetic alterations and protein expression profiles, therapeutic strategies tailored to the patient's tumor can be rationalized. This genomic profiling and mapping of immunohistochemical expression profiles is essential in the search for a suitable treatment approach. Thereby, it alleviates the paucity in systemic treatment options and can significantly alter the prognosis of patients with R/M SGC. This review aims to give a comprehensive overview of known genetic alterations and expression profiles amenable for targeted therapy in every histological subtype of SGC. We discuss the remaining knowledge gaps and the implications of these targets for future studies and personalized treatments, thereby aiding clinicians faced with this rare and heterogeneous type of cancer.

Metastasis of carcinoma ex pleomorphic adenoma to the brain without previous metastasis to the lungs or bones: a case report

Carcinoma ex pleomorphic adenoma is a rare type of cancer of the salivary gland that involves the malignant transformation of a primary or recurrent pleomorphic adenoma, which often metastasises to the lungs or bones, or both. To the best of our knowledge, however, nobody has reported a distant metastasis of this lesion to the brain without such previous metastasis. We report a case in a 64-year-old man.

Heme Oxygenase-1 is a Key Molecule Underlying Differential Response of TW-37-Induced Apoptosis in Human Mucoepidermoid Carcinoma Cells

TW-37 is a small-molecule inhibitor of Bcl-2 family proteins, which can induce anti-cancer activities in various types of cancer. In the current study, we investigated the potential molecular mechanism underlying the differential response to TW-37-induced apoptosis in two human mucoepidermoid carcinoma (MEC) cell lines. The differential response and underlying molecular mechanism of human MEC cells to TW-37 was evaluated by trypan blue exclusion assay, western blotting, 4’, 6-diamidino-2-phenylindole staining, annexin V/propidium iodide double staining, analysis of the sub-G1 population, human apoptosis array, and measurements of intracellular reactive oxygen species (ROS). TW-37 decreased cell viability and induced apoptosis in YD-15 cells, but not in MC3 cells. Proteome profiling using a human apoptosis array revealed four candidate proteins and of these, heme oxygenase-1 (HO-1) was mainly related to the differential response to TW-37 of YD-15 and MC3 cells. TW-37 also led to a significant increase in intracellular levels of ROS in YD-15 cells, which is associated with apoptosis induction. The ectopic expression of HO-1 recovered YD-15 cells from TW-37-induced apoptosis by reducing intracellular levels of ROS. The expression of HO-1 was reduced through both transcriptional and post-translational modification during TW-37-mediated apoptosis. We conclude that HO-1 is a potential indicator to estimate response to TW37-induced apoptosis in human MEC.

Interfering with bromodomain epigenome readers as therapeutic option in mucoepidermoid carcinoma

PURPOSE

Emerging evidence indicates that bromodomains comprise a conserved class of epigenome readers involved in cancer development and inflammation. Bromodomains are associated with epigenetic modifications of gene transcription through interactions with lysine residues of histone tails. Particularly, the bromodomain and extra-terminal domain (BET) family member BRD4 has been found to be involved in the control over oncogenes, including c-MYC, and in the maintenance of downstream inflammatory processes. The objective of this study was to evaluate the effect of pharmacologically displacing BRD4 in mucoepidermoid carcinoma (MEC) cells.

METHODS

We assessed the presence of BRD4 levels in a panel of human MEC tissue samples in conjunction with histological grading and clinical information. In vitro studies were carried out using human MEC-derived cell lines. The BET inhibitor iBET762 was administered to MEC cells to assess the impact of disrupted BRD4 signaling on colony forming capacities and cell cycle status. The activation of cellular senescence induced by iBET762 was determined by immunohistochemical staining for p16^ink4. Flow cytometry was used to identify populations of cancer stem cells in MEC-derived cell lines.

RESULTS

We found that primary human MECs and MEC-derived cell lines are endowed with high BRD4 expression levels compared to those in normal salivary glands. We also found that, by displacing BRD4 from chromatin using the BET inhibitor iBET762, MEC cells lose their colony forming capacities and undergo G1 cell cycle arrest and senescence. Finally, we found that targeted displacement of BRD4 from chromatin results in depletion of cancer stem cells from the overall MEC cell populations.

CONCLUSIONS

Our findings indicate that bromodomain-mediated gene regulation constitutes an epigenetic mechanism that is deregulated in MEC cells and that the use of BET inhibitors may serve as a feasible therapeutic strategy to manage MECs.

Lower gingival squamous cell carcinoma with brain metastasis during long-term cetuximab treatment: A case report

Long-term cetuximab treatment can lead to acquired resistance, and tumor progression and/or new lesions often occur. The present report describes a case of lower gingival squamous cell carcinoma with brain metastasis during long-term cetuximab treatment in a 60-year-old man, including findings of an immunohistochemical study. The resected primary tumors, biopsy of the lung metastasis before administration of cetuximab, and brain metastasis specimens mediated by cetuximab were immunohistochemically examined. Histologically, the metastatic brain lesion showed hyperkeratinizing tumor cells with deeply stained irregular nuclei with necrotizing tumor cells, and a decrease in cell density was exhibited in part of the tumor nest. Moreover, the brain lesion was less malignant compared with the primary tumor and metastatic lung lesions. Immunohistochemically, the metastatic brain lesions showed low expression of epidermal growth factor receptor (EGFR) and high expression of N-cadherin compared with the primary tumor and metastatic lung lesions. These results suggest that acquired resistance to cetuximab may be associated with low EGFR expression and increased epithelial-to-mesenchymal transition potential.

Sensitizing mucoepidermoid carcinomas to chemotherapy by targeted disruption of cancer stem cells

Mucoepidermoid carcinoma (MEC) is the most common malignancy of salivary glands. The response of MEC to chemotherapy is unpredictable, and recent advances in cancer biology suggest the involvement of cancer stem cells (CSCs) in tumor progression and chemoresistance and radioresistance phenotype. We found that histone acetyltransferase inhibitors (HDACi) were capable of disrupting CSCs in MEC. Furthermore, administration of HDACi prior to Cisplatin (two-hit approach) disrupts CSCs and sensitizes tumor cells to Cisplatin. Our findings corroborate to emerging evidence that CSCs play a key role in tumor resistance to chemotherapy, and highlights a pharmacological two-hit approach that disrupts tumor resistance to conventional therapy.

More than a headache: a case of cetuximab-induced aseptic meningitis

While the wide belief is that monoclonal antibodies, due to their large size, would not be able to penetrate the blood-brain barrier, we present a rare case of aseptic meningitis induced by intravenous cetuximab administration. A 58-year-old man with tonsillar squamous cell cancer presented with headache and fever, which started approximately 1 h after his first dose of cetuximab (loading dose of 400 mg/m(2) equalling 800 mg). CT scan of the head was non-revealing and laboratory tests including complete blood count, serum comprehensive metabolic panel and coagulation profile were within normal limits. Aseptic meningitis in the setting of cetuximab therapy has been reported on 6 previous occasions. Consistent with these prior reports, it is interesting to note that this case also occurred after administration of the initial higher loading dose of Cetuximab. This is of interest as Cetuximab is more frequently being dosed at 500 mg/m(2) (higher dose) every 2 weeks in colorectal cancer.

Aberrantly activated AREG-EGFR signaling is required for the growth and survival of CRTC1-MAML2 fusion-positive mucoepidermoid carcinoma cells

Salivary gland tumors (SGT) are a group of highly heterogeneous head and neck malignancies with widely varied clinical outcomes and no standard effective treatments. The CRTC1-MAML2 fusion oncogene, encoded by a recurring chromosomal translocation t(11;19)(q14-21;p12-13), is a frequent genetic alteration found in >50% of mucoepidermoid carcinomas (MEC), the most common malignant SGT. In this study, we aimed to define the role of the CRTC1-MAML2 oncogene in the maintenance of MEC tumor growth and to investigate critical downstream target genes and pathways for therapeutic targeting of MEC. By performing gene expression analyses and functional studies via RNA interference and pharmacological modulation, we determined the importance of the CRTC1-MAML2 fusion gene and its downstream AREG-EGFR signaling in human MEC cancer cell growth and survival in vitro and in vivo using human MEC xenograft models. We found that CRTC1-MAML2 fusion oncogene was required for the growth and survival of fusion-positive human MEC cancer cells in vitro and in vivo. The CRTC1-MAML2 oncoprotein induced the upregulation of the epidermal growth factor receptor (EGFR) ligand Amphiregulin (AREG) by co-activating the transcription factor CREB, and AREG subsequently activated EGFR signaling in an autocrine manner that promoted MEC cell growth and survival. Importantly, CRTC1-MAML2-positive MEC cells were highly sensitive to EGFR signaling inhibition. Therefore, our study revealed that aberrantly activated AREG-EGFR signaling is required for CRTC1-MAML2-positive MEC cell growth and survival, suggesting that EGFR-targeted therapies will benefit patients with advanced, unresectable CRTC1-MAML2-positive MEC.

Clinical features of brain metastasis from salivary gland tumors

Salivary gland tumors comprise a group of 24 tumor subtypes with a wide range of clinical behaviors and propensities for metastasis. Several prognostic factors have been identified that help predict the development of systemic metastases, most commonly to the lung, liver, or bone. Metastases to the brain are rare. To better understand the behavior of salivary gland tumors that metastasise to the brain, we performed a retrospective cohort analysis on a series of patients to highlight features of their medical and surgical management. From 2007 to 2011, a database of 4117 elective craniotomies were queried at a single institution to identify patients surgically treated for salivary gland metastases to the brain. Three patients were identified. Histologic subtypes included salivary duct carcinoma, poorly differentiated carcinoma, and papillary mucinous adenocarcinoma. They had all undergone previous treatment for their primary malignancy. The mean time to intracranial metastasis was 48 months from initial diagnosis (range, 14-91 months). Treatment for intracranial metastases included surgical resection, whole brain radiation, stereotactic radiosurgery, and chemotherapy. Intracranial metastases from salivary gland tumors are rare, present years after diagnosis of the primary tumor, and are treatable with multimodality therapy.

Ligand-directed profiling: applications to target drug discovery in cancer

BACKGROUND

Generation of targeted therapy remains a major challenge in medicine. The development of drugs that can discriminate between tumor cells and non-malignant cells would improve efficacy and reduce general side effects. Phage display allows identification of specific supramolecular complexes that can target therapeutic compounds or imaging agents, both in vitro and in vivo. The use of phage display to identify molecules expressed on the surface of human cancer cells without bias, as well as to provide initial steps toward identification of a ligand/receptor-based map of the human microvasculature, has broad implications for drug discovery in general, especially for cancer therapy.

OBJECTIVE/METHOD

In this review, we discuss the use of phage display technology as a ligand-directed targeting strategy and its applications to drug discovery.

CONCLUSION

Compared to other existing drug discovery platforms, phage display technology has the advantage to provide valuable clues pointing to target proteins in an unbiased biological context. The result from various display library screenings indicates that in many cases the selected peptide motifs mimic biological ligands. Analysis of peptide motifs targeting a receptor provides a basis for rational drug design of targeted peptidomimetics.

Activation of the EGFR/ERK pathway in high-grade mucoepidermoid carcinomas of the salivary glands

Background:

Mucoepidermoid carcinoma (MEC) shows differences in biological behaviour depending mainly on its histological grade. High-grade tumours usually have an aggressive biological course and they require additional oncological treatment after surgery.

Methods:

In a series of 43 MECs of the salivary glands, we studied the epidermal growth factor receptor (EGFR) gene by using dual-colour chromogenic in situ hybridisation (CISH). Moreover, we assessed the protein expressions of the EGFR and the activated extracellular signal-regulated kinases (pERK1/2) by using immunohistochemistry. These results were correlated with the histological grade of the tumours and the outcome of the patients.

Results:

The CISH study demonstrated a high-EGFR gene copy number, with balanced chromosome 7 polysomy, in 8 out of 11 high-grade MECs (72.7%), whereas 27 low-grade and 15 intermediate-grade tumours had a normal EGFR gene copy number (P<0.001). The EGFR gene gains correlated with disease-free interval (P=0.003) and overall survival of the patients (P=0.019). The EGFR protein expression had a significant correlation with the histological grade of the tumours but not with the outcome of the patients. The pERK1/2 expression correlated with histological grade of tumours (P<0.001), disease-free interval (P=0.004) and overall survival (P=0.001).

Conclusions:

The EGFR/ERK pathway is activated in high-grade MECs with aggressive behaviour. Patients with these tumours who require oncological treatment in addition to surgery could benefit from EGFR and mitogen-activated protein kinase pathway inhibitors.