Significant and durable clinical benefit from trastuzumab in 2 patients with HER2-amplified salivary gland cancer and a review of the literature

Molecular Targeting of the Human Epidermal Growth Factor Receptor-2 (HER2) Genes across Various Cancers

Human epidermal growth factor receptor 2 (HER2) belongs to the ErbB family, a group of four transmembrane glycoproteins with tyrosine kinase activity, all structurally related to epidermal growth factor receptor (EGFR). These tyrosine kinases are involved in the transmission of cellular signals controlling normal cell growth and differentiation. If this transmission goes awry, it can lead to dysregulated growth of the cell. HER2 specifically can be implicated in the pathogenesis of at least eight malignancies. HER2 positivity quickly became a well-characterized indicator of aggressiveness and poor prognosis, with high rates of disease progression and mortality. After realizing the implication of HER2, it first became investigated as a target for treatment in breast cancer, and later expanded to areas of research in other cancer types. To this day, the most therapeutic advancements of anti-HER2 therapy have been in breast cancer; however, there have been strong advancements made in the incorporation of anti-HER2 therapy in other cancer types as well. This comprehensive review dissects HER2 to its core, incorporating the most up to date information. The topics touched upon are discussed in detail and up to 200 published sources from the most highly recognized journals have been integrated. The importance of knowing about HER2 is exemplified by the groundbreaking advancements that have been made, and the change in treatment plans it has brought to the oncological world in the last twenty years. Since its groundbreaking discovery there have been significant breakthroughs in knowledge regarding the actual receptor, the receptors biology, its mechanism of action, and advancements in tests to detect HER2 and significant strides on how to best incorporate targeted treatment. Due to the success of this field thus far, the review concludes by discussing the future of novel anti-HER2 therapy currently in development that everyone should be aware of.

HER2-targeted therapies for salivary gland cancers

Salivary gland cancers (SGCs) are a heterogeneous group of rare tumors including various histological subtypes with different molecular profiling. Human epidermal growth factor receptor 2 (HER2) is one of the most intriguing and studied molecular alterations with prognostic and predictive roles. Indeed, HER2 overexpression is commonly correlated with aggressive histological subtypes and poorer prognosis. However, HER2 may represent the target of personalized treatment. We performed a literature review of use of anti-HER2 targeted agents for treatment of recurrent or metastatic SGCs. The efficacy and safety of anti-HER2 were firstly evaluated in patients affected with other solid tumors, mostly breast and gastric cancers. For SGCs the literature is mainly comprised of case reports or case series and small clinical trials. The most common used drug is trastuzumab in combination with chemotherapy (i.e. taxanes, capecitabine, carboplatin, eribulin) or with another anti-HER2 targeted agent (i.e. pertuzumab). The use of anti-HER2 therapies induces improvement in clinical responses, which are mostly durable. Besides, new anti-HER2 drugs such as antibody-drug conjugates (ADC) (i.e. trastuzumab emtansine, trastuzumab deruxtecan) have been introduced in this setting inducing further therapeutic advances. Anti-HER2 treatment strategy is emerging as potentially effective in selected HER2 overexpressing SGCs. However, prospective and multicentric clinical trials are needed to evaluate the efficacy of these therapeutic regimens within larger cohorts and to assess the most appropriate treatment sequence strategy.

Comprehensive Genome profile testing in head and neck cancer

OBJECTIVE

Head and neck cancer (HNC) is a tumor occurring in various primary sites with limited chemotherapy options for its treatment. Recently, comprehensive genomic profiling (CGP) testing has become clinically widespread. In this study, we examined the utility of CGP in diagnosing and treating HNC.

METHODS

This study included 29 patients with HNC who underwent CGP testing at the Gifu University Hospital between December 2019 and April 2022. We analyzed the types of gene mutations and tumor mutational burden (TMB) based on the CGP results. Squamous cell carcinoma accounted for 55.2%, and other cancers accounted for 44.8%. And we investigated the correlation of prognosis with gene mutations and TMB.

RESULTS

Gene mutations were detected in TP53(48.3%), CDKN2A (27.6%), CDKN2B (17.2%), NOTCH1 (17.2%), PIK3CA (17.2%), ARID1A (13.8%), and NF1 (13.8%). TP53, CDKN2A and CDKN2B mutations significantly decreased survival rate in HNC. Five cases (17.2%) were TMB-high and 82.8% were TMB-low. In SCC cases treated with immune checkpoint inhibitors, TMB-high had better Overall survival than TMB-low. And all patients with TMB-high were oropharyngeal cancer.

CONCLUSION

Although there were no cases in which effective treatment was actually performed based on the results of CGP, many gene mutations have been detected and several gene mutations correlated with prognosis. Furthermore, TMB can be used as a biomarker to predict the therapeutic effects of immune checkpoint inhibitors in cases of SCC.

Capecitabine is effective as palliative chemotherapy in a patient with androgen receptor and HER2 positive metastatic salivary duct carcinoma. A case report

ABSTRACT

Metastatic salivary duct carcinomas (SDC) are rare tumors and evidence-based guidelines for their treatment have not yet been established. Reports of such cases like ours could be beneficial in the decision-making in the similar clinical circumstances. Here we present the 64-year-old Caucasian man with bone pain and pancytopenia two years after local treatment of SDC, in whom a bone marrow biopsy revealed poorly differentiated carcinoma of salivary origin with nuclear androgen receptor (AR) and human epidermal growth factor receptor 2 (HER2/neu) positivity. Clinical response was achieved with cis-platin based cytotoxic therapy and maintenance hormonal treatment. At progression after 12 months, he was treated with anti-HER2 therapy combined with taxanes. The response lasted for 14 months. Then palliative therapy with capecitabine was introduced. With a relatively sustained quality of life, the response lasted for 15 months.

Rare tumors: a blue ocean of investigation

Advances in novel drugs, therapies, and genetic techniques have revolutionized the diagnosis and treatment of cancers, substantially improving cancer patients' prognosis. Although rare tumors account for a non-negligible number, the practice of precision medicine and development of novel therapies are largely hampered by many obstacles. Their low incidence and drastic regional disparities result in the difficulty of informative evidence-based diagnosis and subtyping. Sample exhaustion due to difficulty in diagnosis also leads to a lack of recommended therapeutic strategies in clinical guidelines, insufficient biomarkers for prognosis/efficacy, and inability to identify potential novel therapies in clinical trials. Herein, by reviewing the epidemiological data of Chinese solid tumors and publications defining rare tumors in other areas, we proposed a definition of rare tumor in China, including 515 tumor types with incidences of less than 2.5/100 000 per year. We also summarized the current diagnosis process, treatment recommendations, and global developmental progress of targeted drugs and immunotherapy agents on the status quo. Lastly, we pinpointed the current recommendation chance for patients with rare tumors to be involved in a clinical trial by NCCN. With this informative report, we aimed to raise awareness on the importance of rare tumor investigations and guarantee a bright future for rare tumor patients.

Epithelial-myoepithelial carcinoma of the maxillofacial and sinonasal region: a systematic review of presenting characteristics, treatment modalities, and associated outcomes

Epithelial-myoepithelial carcinoma (EMC) is a rare salivary gland malignancy. Controversy exists in the literature regarding the effectiveness of treatment modalities employed in the management of EMC. This systematic review was undertaken to understand the presenting characteristics of EMC and identify the most common treatment modalities and their associated outcomes, in order to help guide an evidenced-based approach to the algorithm of care. The MEDLINE (PubMed) and Embase databases were searched (up to February 23, 2022), and the review was performed in accordance with the PRISMA statement. Fifty-seven studies (51 case reports and six case series) describing 91 cases of EMC were included in this review. In the included studies, a slow-growing painless mass was the most common presenting clinical feature. EMC was most frequently treated with surgery alone (65%). Local disease recurrence occurred in 24% of the cases and metastatic disease in 11%. A positive surgical margin was found to be associated with a higher risk of recurrence (P < 0.001), while adjuvant radiotherapy was associated with a decreased risk of local disease recurrence (P = 0.034). Metastatic disease and multimodal therapy were found to be associated with decreased disease-free and overall survival (all P < 0.05). The current literature supports surgery with clear margins as the mainstay of treatment for EMC of the salivary and seromucous glands of the head and neck. In certain situations, radiotherapy may improve disease-free survival.

Management of Malignant Salivary Gland Conditions

Salivary cancers are rare tumors that arise in major and minor salivary glands. Workup almost always includes fine-needle aspiration or core needle biopsy in select cases. Imaging with ultrasound, computed tomography, or MRI is also helpful, particularly with MRI to assess facial nerve involvement or skull base involvement. Preserving function of the facial nerve is of paramount importance, and the standard of care is to not sacrifice facial nerve except in instances of gross encasement and inability to dissect tumor off of the nerve. Adjuvant radiation and chemotherapy offer survival advantages for select patients.

Targeted Therapy, Chemotherapy, Immunotherapy and Novel Treatment Options for Different Subtypes of Salivary Gland Cancer

Surgical resection remains the first line treatment for salivary gland cancer (SGC). In the case of locally advanced disease, surgery is followed by adjuvant radiotherapy. Surgical resection should be favored in resectable locoregional recurrent disease as well, and even the complete resection of all distant oligometastases has clinical benefit for the patients. For inoperable and disseminated metastatic disease, a multitude of systemic therapies including chemotherapy, targeted therapy, and immunotherapy are available. In this review, the current therapeutic options for inoperable recurrent or metastatic SGCs are summarized. Systemic treatment can achieve prolonged progression-free and overall survival, while the overall prognosis remains poor. Current clinical trials include only a limited number of patients and mostly combine different histologic subtypes. Additionally, no randomized controlled trial comparing different therapeutic options has been performed. In the future, further studies with a larger patient cohort and ideally only one histologic subtype are needed in order to improve the outcome for SGC patients. However, this may be difficult to accomplish due to the rarity and diversity of the disease. Additionally, molecular analyses need to be performed routinely in order to individualize treatment and to go one step further towards precision medicine.

HER2 and HER3 as Therapeutic Targets in Head and Neck Cancer

ABSTRACT

Work over the past several decades has identified that aberrations in the ErbB signaling pathways are key drivers of oncogenesis, and concurrent efforts to discover targetable vulnerabilities to counter this aberrant oncogenic signaling offer tremendous promise in treating a host of human cancers. These efforts have been centered primarily on EGFR (also known as HER1), leading to the discovery of the first targeted therapies approved for head and neck cancer. More recently, HER2 and HER3 signaling pathways have been identified as highly dysregulated in head and neck cancer. This review highlights the HER2 and HER3 signaling pathways and clinical efforts to target these receptors and their aberrant signaling to treat head and neck squamous cell carcinomas and other head and neck malignancies, including salivary gland carcinomas. This includes the use of small molecule inhibitors and blocking antibodies, both as single agents or as part of multimodal precision targeted and immunotherapies.

Case report: ado-trastuzumab as second-line treatment in HER2 positive salivary duct carcinoma

The objective of this report is to present the use and efficacy of ado-trastuzumab as an advanced line of therapy in salivary duct carcinoma (SDC) patient. An 84-year-old gentleman diagnosed with metastatic salivary duct tumor harboring overexpressed human epidermal growth factor receptor-2 has gone through resection surgery. The first line of treatment included initial doublet chemotherapy combined with trastuzumab, which was continued later as maintenance. PET-CT follow-up for 4 years has demonstrated no evidence of disease. However, upon recurrence, use of Ado-trastuzumab emtansine was prompted as second-line of treatment. This targeted patient-tailored therapy has accomplished a complete response. The effectiveness of ado-trastuzumab emtansine was notable within a short time period of two treatment cycles leading to full recovery. Specific agents aimed at altered oncogenes should be considered as a potential drug of choice in neoadjuvant HER2 positive SDC.

Molecular Markers that Matter in Salivary Malignancy

Despite aggressive initial interventions, recurrent/metastatic salivary gland cancer is not uncommon. Standard chemotherapy has not been shown to have durable clinical benefits. Several potential molecular markers have been identified in different histologic subtypes of salivary cancers. The objective of this review is to highlight the molecular markers that have been targeted in clinical trials for salivary gland cancers.

Predictive modeling of hypoxic head and neck cancers during fractionated radiotherapy with gold nanoparticle radiosensitization

PURPOSE

Intrinsic radioresistance and increased proliferation rates in head and neck cancers (HNCs) are associated with negative radiotherapy (RT) treatment responses. The use of gold nanoparticles (AuNPs) as radiosensitizers could enable total radiation dose reduction and lowered radiation toxicity. AuNP radiosensitization may overcome hypoxia-induced radioresistance and treatment-induced accelerated repopulation of cancer cells in HNCs, improving radiotherapy outcomes.

METHODS

Tumor control was determined by considering individual cancer cell responses in probabilistic computational simulations using HYP-RT software for clinical radiotherapy doses and fractionation schedules along with three different nanoparticle administration schedules. Antagonistic tumor hypoxia and rapid tumor regrowth due to accelerated repopulation of cancers cells were taken into consideration.

RESULTS

Simulations indicate that tumors that are conventionally uncontrollable can be controlled with AuNP radiosensitization. In simulations where the absence of AuNPs required radiotherapy doses above standard clinical prescriptions, reoccurring AuNP administration allowed for radiation dose reductions below standard clinical dose prescriptions. For example, considering a 2 Gy per fraction radiotherapy schedule, tumor control was achieved with 57.2 ± 5.1 Gy (P = <0.0001) for weekly AuNP administration and 53.0 ± 4.0 Gy (P = <0.0001) for biweekly AuNP administration compared to 69.9 ± 5.8 Gy with no radiosensitization.

CONCLUSIONS

AuNPs decreased the predicted RT total doses required to achieve tumor control via total stem cell elimination, offering an optimistic prediction and method for which hypoxia-induced and rapidly growing radioresistant tumors are treated more effectively. Outcomes are also shown to be sensitive to the RT schedule with data for hyperfractionated RT indicating the greatest benefits from radiosensitization.

HER2-positive metastatic, parotid salivary duct carcinoma treated with a trastuzumab/pertuzumab-based chemotherapy: A case report

This case highlights the rare entity, salivary duct carcinoma (SDC), which is difficult to diagnose and manage. It is the first published case of a metastatic, HER2-positive parotid SDC successfully treated by a dual anti-HER2 treatment associated to a chemotherapy.

Systemic therapy in the management of recurrent or metastatic salivary duct carcinoma: A systematic review

BACKGROUND

Salivary duct carcinoma (SDC) is an aggressive subtype of salivary gland cancer. Approximately half of SDC patients will develop recurrences or metastases. Therapeutic palliative therapy is therefore often needed. The majority of SDC tumors expresses the androgen receptor (AR) and one-third expresses human epidermal growth factor receptor 2 (HER2), both are potential therapeutic targets. The aim of this paper is to systematically review and summarize the evidence on systemic palliative therapy for SDC and to provide treatment recommendations.

MATERIALS AND METHODS

Electronic libraries were systematically searched with a broad search strategy to identify studies where SDC patients received systemic therapy. Due to the rarity of SDC no restrictions were placed on study designs.

RESULTS

The search resulted in 2014 articles of which 153 were full-text analyzed. Forty-five studies were included in the analysis, which included in total 256 SDC patients receiving systemic therapy. Two phase 2 trials primarily including SDC patients were identified. The majority of the studies were case series or case reports, resulting in an overall low quality of available evidence. Based on studies including ≥ 5 SDC patients, objective responses to HER2 targeting agents were observed in 60-70%, to AR pathway agents in 18-53% and to chemotherapy in 10-50%.

CONCLUSION

For AR or HER2 positive SDC, agents targeting these pathways are the cornerstone for palliative treatment. Regarding chemotherapy, the combination of carboplatin combined with a taxane is best studied. Regarding other targeted agents and immunotherapy evidence is anecdotal, limiting formulation of treatment recommendations for these antineoplastic agents.

HER2 in Colorectal Carcinoma: Are We There yet?

HER2 (ERBB2) is a member of the ERBB family of receptor tyrosine kinases and functions to drive signaling in the RAS/RAF/MEK/ERK and PI3K/AKT/mTOR pathways. Overall, approximately 2-3% of CRCs exhibit ERBB2 amplification. Multiple phase II clinical trials have now shown that ERBB2 amplification can be predictive of response to anti-ERBB2 targeted therapy. Consequently, recently released guidelines from the National Comprehensive Cancer Network recommend treatment with anti-ERBB2 targeted therapy for RAS wild-type, ERBB2-amplified metastatic CRC. While circumspection is still needed, ERBB2 amplification has now emerged as the next standard-of-care biomarker for metastatic CRC, expanding targeted therapy options for these patients.

Head and Neck Cancers, Version 2.2020, NCCN Clinical Practice Guidelines in Oncology

Treatment is complex for patients with head and neck (H&N) cancers with specific site of disease, stage, and pathologic findings guiding treatment decision-making. Treatment planning for H&N cancers involves a multidisciplinary team of experts. This article describes supportive care recommendations in the NCCN Guidelines for Head and Neck Cancers, as well as the rationale supporting a new section on imaging recommendations for patients with H&N cancers. This article also describes updates to treatment recommendations for patients with very advanced H&N cancers and salivary gland tumors, specifically systemic therapy recommendations.

Curcumin Enhances the Antitumoral Effect Induced by the Recombinant Vaccinia Neu Vaccine (rV-neuT) in Mice with Transplanted Salivary Gland Carcinoma Cells

The survival rate for head and neck cancer patients has not substantially changed in the last two decades. We previously showed that two rV-neuT intratumoral injections induced an efficient antitumor response and rejection of transplanted Neu (rat ErbB2/neu oncogene-encoded protein)-overexpressing salivary gland tumor cells in BALB-neuT mice (BALB/c mice transgenic for the rat ErbB2/neu oncogene). However, reiterated poxviral vaccinations increase neutralizing antibodies to viral proteins in humans that prevent immune response against the recombinant antigen expressed by the virus. Curcumin (CUR) is a polyphenol with antineoplastic and immunomodulatory properties. The aim of this study was to employ CUR administration to boost the anti-Neu immune response and anticancer activity induced by one rV-neuT intratumoral vaccination in BALB-neuT mice. Here, we demonstrated that the combined rV-neuT+CUR treatment was more effective at reducing tumor growth and increasing mouse survival, anti-Neu humoral response, and IFN-γ/IL-2 T-cell release in vitro than the individual treatment. rV-neuT+CUR-treated mice showed an increased infiltration of CD4⁺/CD8⁺ T lymphocytes within the tumor as compared to those that received the individual treatment. Overall, CUR enhanced the antitumoral effect and immune response to Neu induced by the rV-neuT vaccine in mice. Thus, the combined treatment might represent a successful strategy to target ErbB2/Neu-overexpressing tumors.

Comprehensive routine diagnostic screening to identify predictive mutations, gene amplifications, and microsatellite instability in FFPE tumor material

Background

Sensitive and reliable molecular diagnostics is needed to guide therapeutic decisions for cancer patients. Although less material becomes available for testing, genetic markers are rapidly expanding. Simultaneous detection of predictive markers, including mutations, gene amplifications and MSI, will save valuable material, time and costs.

Methods

Using a single-molecule molecular inversion probe (smMIP)-based targeted next-generation sequencing (NGS) approach, we developed an NGS panel allowing detection of predictive mutations in 33 genes, gene amplifications of 13 genes and microsatellite instability (MSI) by the evaluation of 55 microsatellite markers. The panel was designed to target all clinically relevant single and multiple nucleotide mutations in routinely available lung cancer, colorectal cancer, melanoma, and gastro-intestinal stromal tumor samples, but is useful for a broader set of tumor types.

Results

The smMIP-based NGS panel was successfully validated and cut-off values were established for reliable gene amplification analysis (i.e. relative coverage ≥3) and MSI detection (≥30% unstable loci). After validation, 728 routine diagnostic tumor samples including a broad range of tumor types were sequenced with sufficient sensitivity (2.4% drop-out), including samples with low DNA input (< 10 ng; 88% successful), low tumor purity (5–10%; 77% successful), and cytological material (90% successful). 75% of these tumor samples showed ≥1 (likely) pathogenic mutation, including targetable mutations (e.g. EGFR, BRAF, MET, ERBB2, KIT, PDGFRA). Amplifications were observed in 5.5% of the samples, comprising clinically relevant amplifications (e.g. MET, ERBB2, FGFR1). 1.5% of the tumor samples were classified as MSI-high, including both MSI-prone and non-MSI-prone tumors.

Conclusions

We developed a comprehensive workflow for predictive analysis of diagnostic tumor samples. The smMIP-based NGS analysis was shown suitable for limited amounts of histological and cytological material. As smMIP technology allows easy adaptation of panels, this approach can comply with the rapidly expanding molecular markers.

The Immune Microenvironment and Neoantigen Landscape of Aggressive Salivary Gland Carcinomas Differ by Subtype

PURPOSE

Salivary gland carcinomas (SGC) are rare, aggressive cancers with high rates of recurrence and distant metastasis. These factors, and a lack of active systemic therapies, contribute to poor clinical outcome. Response rates with immune checkpoint blockade have been low, although clinical data remain sparse. To improve the efficacy of therapies, a more comprehensive understanding of relevant molecular alterations and immunologic processes is needed.

EXPERIMENTAL DESIGN

To characterize the immune microenvironment and neoantigen landscape of SGCs, we performed RNA sequencing (RNA-seq) in 76 tumors representing the three most lethal histologies: adenoid cystic carcinoma (ACC), myoepithelial carcinoma (MECA), and salivary duct carcinoma (SDC). We analyzed transcriptomic profiles, tumor-infiltrating immune cell populations, and measures of T-cell activation/dysfunction. In 37 cases also undergoing exome sequencing, we analyzed somatic mutations and neoantigens.

RESULTS

SDCs exhibited high levels of immune infiltration, with corresponding higher levels of T-cell dysfunction, and higher mutational load. In contrast, ACCs were characterized by an immune-excluded microenvironment, the presence of M2-polarized macrophages and myeloid-derived suppressor cells, and very low mutational load. MECAs were more heterogeneous, with both immune-low and immune-high phenotypes represented. Across all SGCs, levels of immune infiltration were associated with mutation- and fusion-derived neoantigens, and with aggressive clinical behavior.

CONCLUSIONS

These findings provide new insights into the immune microenvironment and neoantigen landscape of SGCs, showing that mechanisms of immune escape appear to differ by histology. These data nominate potential immunologic vulnerabilities and may help guide the next steps of investigation in precision immunotherapy for these difficult-to-treat cancers.

Prognostic significance of lymphovascular invasion in patients with salivary duct cell carcinoma of the head and neck

The purpose of this study was to evaluate the treatment outcomes of patients who underwent surgery with curative intention after the diagnosis of salivary duct cell carcinoma (SDC) in the head and neck area and to analyse the prognostic factors and treatment failure pattern. Fifty-nine patients treated between March 2003 and December 2018 were enrolled in the study. The mean follow-up period was 45.5 months (range 12-189 months). The 5-year overall survival rate was 54.7% and the 5-year disease-free survival rate was 56.8%. Nineteen recurrences occurred during the study period: four loco-regional recurrences and 15 distant metastases. During the study period, 10 patients died of disease relapse and 5 patients died of other medical caused. On univariate analysis, lymphovascular invasion (LVI) (P=0.031) showed the most significant correlation with mortality. On multivariate Cox regression analysis, LVI showed the most significant correlation with patient survival (P = 0.027). LVI was the most significant prognostic factor related to the 5-year overall survival rate of SDC patients. The development of novel therapeutic agents is necessary to improve the survival rate of these patients with LVI.

Novel therapeutic targets in salivary duct carcinoma uncovered by comprehensive molecular profiling

Salivary duct carcinoma (SDC) is a rare, aggressive salivary gland malignancy, which often presents at an advanced stage. A proportion of SDC are characterized by HER2 amplification and/or overexpression of androgen receptor (AR), which could be targeted in a subset of patients, but the presence of AR splice variant‐7 (AR‐V7) in some SDC cases could result in resistance to anti‐androgen therapy. We evaluated a cohort of 28 cases of SDC for potentially targetable biomarkers and pathways using immunohistochemistry (IHC) and next‐generation sequencing (DNA and RNA) assays. Pathogenic genetic aberrations were found in all but 1 case and affected TP53 (n = 19), HRAS (n = 7), PIK3CA, ERBB2 (HER2), and NF1 (n = 5 each); KMT2C (MLL3) and PTEN (n = 3 each); BRAF (p.V600E), KDM5C and NOTCH1 (n = 2 each). Androgen receptor was expressed in all cases and 13 of 27 harbored the AR‐V7 splice variant (including a case without any other detectable genetic alteration). HER2 IHC was expressed in 11 of 28 cases. The majority of SDC cases had no biomarkers predictive of immunotherapy response: 5 cases exhibited low (1%‐8%) programmed death ligand 1 (PD‐L1) expression in tumor cells, 2 cases exhibited elevated TMB, and no samples exhibited microsatellite instability. Notably, the pre‐treatment biopsies from 2 patients with metastatic disease, who demonstrated clinical responses to anti‐androgen therapy, showed AR expression and no AR splice variants. We conclude that comprehensive molecular profiling of SDCs can guide the selection of patients for targeted therapies involving AR, HER2, PD‐L1, mitogen‐activated protein kinase, and PIK3CA pathways.

Cancers of the Major Salivary Gland

Salivary gland malignancies are rare tumors that comprise multiple histologic entities with diverse clinical behavior. Mucoepidermoid carcinoma is the most frequent primary salivary malignancy, followed by adenoid cystic and acinic cell carcinoma. Although most salivary malignancies are asymptomatic, presentation with a rapidly enlarging mass may be accompanied by pain, functional neurologic deficits, soft-tissue invasion, or nodal enlargement. Assessment of clinical behavior and physical exam greatly contributes to diagnostic workup. Preoperative imaging, to include ultrasound, computed tomography, or magnetic resonance imaging, may assist with surgical planning. Limitations of preoperative fine-needle aspiration cytology mean that, in some cases, definitive histologic diagnosis may not be established until therapeutic surgery is undertaken. Treatment strategies rely on oncologic resection of the primary site with negative margins as well as adjuvant radiotherapy in patients with high-risk features, such as high-grade histology, advanced T class, or perineural invasion. Regional lymphadenectomy is recommended for involved nodal basins. Patients with clinically node-negative disease at high risk for occult nodal metastases may be considered for elective lymphadenectomy or radiotherapy. Use of chemotherapy in the adjuvant setting, in combination with radiotherapy, remains controversial. The rate of objective response to palliative chemotherapy in recurrent or metastatic salivary gland malignancy remains low. In studies that include a significant proportion of adenoid cystic carcinomas, whether disease stability represents an indolent disease process or the true effect of a therapeutic drug may be difficult to discern. Recognition of genetic alterations and protein expression unique to salivary malignancies presents exciting new opportunities for molecularly targeted therapy, although the response to molecularly targeted therapy in studies has been modest thus far.

Targeted therapy with trastuzumab for epidermal growth factor receptor 2 (HER2)-positive advanced salivary duct carcinoma: A case report

Herein we report two cases of advanced and/or metastatic salivary duct carcinoma that relapsed after standard first-line chemotherapy. As overexpression of human epidermal growth factor receptor 2 (HER2) (3+) was observed by immunohistochemistry, the patients were treated with trastuzumab plus paclitaxel. One patient showed a complete response lasting over 2.5 years after the commencement of therapy; however, the other patient had no response to trastuzumab combined therapy. Dual fluorescence in situ hybridization was performed after the initiation of chemotherapy; the first case was positive for HER2 gene amplification, while the second case was negative. Our experiences suggest that therapy with HER2 blockers should be considered as options for treatment of HER2-positive salivary duct carcinoma. However, HER2 protein overexpression and gene amplification should be investigated further as therapeutic biomarkers.

The Role of Ancillary Techniques in Salivary Gland Cytopathology Specimens

Salivary gland tumor aspiration cytology is a useful preoperative test to guide the most appropriate clinical and surgical management for these patients. Although salivary gland cytology is often useful to distinguish between non-neoplastic lesions, benign neoplasms and malignant neoplasms, there remain many challenges in this area. Specifically, these tumors are uncommon and may have considerable morphologic overlap, especially in the setting of a malignant tumor. This article reviews some of the immunohistochemical and molecular characteristics of more common salivary gland neoplasms that pathologists and cytotechnologists may encounter. When used in combination with morphologic features, such ancillary testing can be useful to further refine the differential diagnosis, more strongly favor a particular entity, or in some instances confidently provide a specific diagnosis.

Trastuzumab-Based Combination Chemotherapy in Patients with Human Epidermal Growth Factor Receptor-2-Positive Metastatic Carcinoma ex Pleomorphic Adenoma

Background

Carcinoma ex pleomorphic adenoma (CXPA) is a rare histologic subtype of lacrimal gland and submandibular gland cancer. Currently, there is no standard treatment for metastatic CXPA, although some case reports have explored the role of targeted agents in chemotherapy. A few histopathologic analyses have shown that some of these tumors overexpress human epidermal growth factor receptor-2 (HER2), suggesting a potential role for HER2-based therapy. We report here two cases of metastatic CXPA that were treated with trastuzumab-based chemotherapy (IRB approved) with rapid and significant responses.

Case Report 1

A 66-year-old male was diagnosed as HER2-positive CXPA of the right lacrimal gland with multiple bone and lymph node metastases. Combination chemotherapy with trastuzumab (Tmab) and nanoparticle albumin-bound paclitaxel (nabPTX) was initiated. A rapid response was confirmed, and after seven cycles of treatment, CR(complete response) was achieved.

Case Report 2

A 67-year-old female was diagnosed with HER2 positive CXPA of the right submandibular gland. Multiple pulmonary metastatic lesions were detected after surgery, and combination chemotherapy with Tmab and nab-PTX was initiated. A rapid partial response (PR) was confirmed, and she eventually became disease-free.

Conclusion

In the absence of definitive clinical trials, which are unlikely to be performed due to the rarity of HER2-positive CXPA, therapeutic information must be obtained from case reports. Some reports, such as this one, have suggested a potential utility of trastuzumab-based chemotherapy.

Salivary gland tumors: Molecular characterization and therapeutic advances for metastatic disease

Salivary gland cancers represent a rare group of tumors composed by over 20 histological subtypes. Initially treated as one single disease, its diagnosis, prognosis, and treatment are currently being stratified based on morphology. More recently, insight has been provided on the molecular characterization of each subtype, further improving diagnostic accuracy and paving the way for personalized therapy. In this article, we provide a comprehensive review of recent breakthroughs, preliminary results of novel therapy, and future directions on the treatment of these complex malignancies.

Clinical Utility of In Situ Hybridization Assays in Head and Neck Neoplasms

Head and neck pathology present a unique set of challenges including the morphological diversity of the neoplasms and presentation of metastases of unknown primary origin. The detection of human papillomavirus and Epstein-Barr virus associated with squamous cell carcinoma and newer entities like HPV-related carcinoma with adenoid cystic like features have critical prognostic and management implications. In salivary gland neoplasms, differential diagnoses can be broad and include non-neoplastic conditions as well as benign and malignant neoplasms. The detection of specific gene rearrangements can be immensely helpful in reaching the diagnosis in pleomorphic adenoma, mucoepidermoid carcinoma, secretory carcinoma, hyalinizing clear cell carcinoma and adenoid cystic carcinoma. Furthermore, molecular techniques are essential in diagnosis of small round blue cell neoplasms and spindle cell neoplasms including Ewing sarcoma, rhabdomyosarcoma, synovial sarcoma, biphenotypic sinonasal sarcoma, dermatofibrosarcoma protuberans, nodular fasciitis and inflammatory myofibroblastic tumor. The detection of genetic rearrangements is also important in lymphomas particularly in identifying 'double-hit' and 'triple-hit' lymphomas in diffuse large B cell lymphoma. This article reviews the use of in situ hybridization in the diagnosis of these neoplasms.

Trastuzumab Emtansine for the Treatment of HER-2 Positive Carcinoma Ex-pleomorphic Adenoma Metastatic to the Brain: A Case Report

Background: Carcinoma Ex-pleomorphic adenoma is a malignant transformation of the common benign neoplasm of the salivary glands, “pleomorphic adenoma.” Only two cases were ever reported with brain metastases, with absence of good evidence guiding management of such cases.

Case Presentation: A 61-year-old woman presenting with facial paralysis was found to have carcinoma ex-pleomorphic adenoma of the parotid gland. Twenty months after local treatment, she developed brain metastases, treated with whole brain radiation therapy. The patient then had progressive intracranial disease after the end of radiation therapy in addition to the appearance of liver metastases. Pathology showed overexpression of HER2, so she was treated with Trastuzumab Emtansine (TDM1). Follow-up imaging revealed significant decrease in the number and size of the metastatic brain lesions in keeping with a good response to TDM1 treatment.

Conclusion: Prognosis of metastatic carcinoma ex-pleomorphic adenoma is very poor, and there is no clear management for such cases. We present a case of carcinoma ex-pleomorphic adenoma with brain and liver metastases with a very good response to TDM1 treatment.

Second-Line Treatment of HER2-Positive Salivary Gland Tumor: Ado-Trastuzumab Emtansine (T-DM1) after Progression on Trastuzumab

Patients with salivary duct cancer (SDC) and HER2 overexpression could receive trastuzumab in combination with chemotherapy for metastatic disease. No standard treatment exists for patients with HER2-positive metastatic SDC after progression. We report an excellent patient response to second-line treatment with T-DM1 after progression on paclitaxel plus trastuzumab.

Salivary duct carcinoma: An aggressive salivary gland malignancy with opportunities for targeted therapy

Salivary duct carcinoma (SDC) is a rare, aggressive salivary malignancy that is often diagnosed at an advanced stage. Previously, little was known about outcomes of this disease due to its rarity. In the past several years, much has been learned about salivary duct carcinoma after publication of outcomes from several large single-institution series and national database searches. Recent studies of genomic alterations have helped elucidate the biology and pathogenesis of this aggressive disease. Here we review outcomes of the disease, effects of treatment, prognostic factors, and genomic alterations in SDC. Studies of targeted therapy and promising future directions are also discussed.

Risk of Development of Second Primary Head and Neck Cancer following an Index Breast Cancer

Objective Many head and neck cancers (HNCs) have genomic features seen in breast malignancy. We sought to analyze the risk of second primary HNC following an index breast cancer. Study Design Retrospective cohort study. Setting National database from the SEER registry (Surveillance, Epidemiology, and End Results). Subjects and Methods Within the SEER database, 223,423 women diagnosed with index breast cancer from 1992 to 2002 were identified. We calculated standard incidence ratios (SIRs) for all head and neck sites with 10-year follow-up. Results Women diagnosed with an index breast cancer did not exhibit higher likelihood of developing second primary HNC (SIR = 0.99; 95% CI, 0.90-1.07). The risk was determined for each subsite of the head and neck, and salivary gland cancer presented the highest risk. Patients with index breast cancer were 83% more likely to develop salivary gland cancer than what would be expected in the general population (SIR = 1.83; 95% CI, 1.49-2.22). An overall trend of increased risk was observed for salivary gland cancers between 1992 and 2002. There was no significant higher risk observed for the other head and neck subsites. Conclusion Patients with index breast cancer did not have a higher-than-expected risk of developing HNC. We did find an increased incidence of salivary gland cancers among patients with index breast cancer. Patients were 80% more likely to develop salivary gland cancer than that expected within the population. These findings warrant further investigation on the relationship between salivary gland and breast malignancy.