Phase II Study of Enzalutamide for Patients With Androgen Receptor-Positive Salivary Gland Cancers (Alliance A091404)

The impact of HER2-Low expression in salivary duct carcinoma: Clinicopathologic features, survival outcomes, and association with androgen receptor-targeted therapy

OBJECTIVES

Recent advances in systemic therapy for salivary duct carcinoma (SDC) have been driven by the development of HER2- and androgen receptor (AR)-targeted therapies. Trastuzumab deruxtecan has proven effective not only in HER2-positive but also HER2-low breast and gastro-esophageal cancers. However, the significance of HER2-low expression in SDC remains unknown. This study aimed to investigate the clinicopathologic characteristics, prognostic implications, and impact on efficacy to AR-targeted therapy in HER2-low SDC.

MATERIALS AND METHODS

This was a multi-center, observational study. HER2 status was reclassified as follows: HER2-positive (IHC3+ or 2+/ISH+ ), HER2-low (IHC1+ or 2+/ISH-), and HER2-zero (IHC0). The subjects were compared in three groups: total population, curative treatment cohort, and AR-targeted therapy cohort.

RESULTS

The total population consisted of 526 patients, of whom, 271 (52 %), 184 (35 %), and 71 (13 %) had HER2-positive, -low, and -zero tumors, respectively. Sex, M category, histological origin, Ki67, and p53 expression differed significantly between the HER2-low and HER2-positive cases. No differences in relapse-free or overall survival were observed for HER2 status in the curative treatment cohort; however, in the AR-targeted therapy cohort, the HER2-low group had significantly better response rates (41.6 % vs. 18.9 %, Odds ratio = 0.30, P = 0.012) and longer median progression-free survival (6.9 vs. 4.2 months, Hazard ratio = 1.61, P = 0.029) than those of the HER2-positive group.

CONCLUSION

HER2-low showed different clinicopathologic features from HER2-positive cases, with no prognostic differences observed in patients who underwent curative treatment. Still, HER2-low may be associated with the efficacy of AR-targeted therapy.

Precision medicine in Salivary Gland Carcinoma: Insights from breast and prostate cancer

Salivary Gland Carcinomas (SGC) are a heterogeneous group of diseases with varied histologies, biology, clinical behaviors, and therapeutic approaches. The World Health Organization classifies SGCs into Low Aggression and High Aggression categories. Due to their rarity and unique biology, managing SGCs is challenging, often requiring expert histological diagnosis and treatment based on low-level evidence. Despite recent international guidelines, several critical aspects of SGC management remain unresolved, in particular regarding systemic treatment. Recent discoveries of molecular alterations, such as HER2 amplification, and AR overexpression, have provided diagnostic, prognostic, and predictive biomarkers for alternative treatments. While some targeted treatment have corresponding EMA-approved therapies, others do not. Treatment strategies are further complicated by synchronous alterations, such as AR-positive SGCs with concomitant HER2 amplification. Open questions remain on the optimal use of these drugs, whether in early-stage disease, post-surgery, or in palliative settings. Given the rarity of the disease and the consequent lack of high quality data in literature, it is of importance a cross-fertilization process from other, more common disease such as breast and prostate cancers. In the current narrative review we analyze current evidence on the targeted treatment on salivary gland carcinomas and shared features with breast and prostate cancer.

Clinical trials for patients with salivary gland cancers: A systematic review of worldwide registers and an evaluation of current challenges

BACKGROUND

Clinical trials (CT) are crucial for generating scientific evidence and improving clinical outcomes, but they can be challenging in the context of rare cancers. Salivary gland cancers (SGC) are rare and heterogeneous tumors, without standard-of-care approved systemic therapies. We analyzed completed and ongoing CTs to assess the current state of clinical research activity in the field.

METHODS

ClinicalTrials.gov, WHO-ICTRP, HealthCanadaCT were searched for antineoplastic pharmacological and interventional CT involving patients with SGC from the trials database creation until August 6th, 2024. CT characteristics and status were collected.

RESULTS

134 clinical trials met inclusion criteria. Of these, 78 % were sponsored by non-industry entities. 49 % were conducted at only one site, and 61 % at up to five centers. Only 25 trials (19 %) were multinational, being 15 industry-sponsored, a significantly higher proportion compared to non-industry-sponsored trials(p < 0.01). 16 % CTs were umbrella or basket, and 6 % were randomized, again predominantly industry-sponsored(p < 0.01). Regarding SGC-specific trials, 32 % were open to all patients with SGC, regardless of specific histology. Patients with adenoid cystic, salivary duct, and mucoepidermoid carcinoma had access to 92 %, 66 % and 62 % of trials, respectively. 88 % CT targeted palliative setting, and 38 % incorporated predictive biomarkers. Tyrosine kinase inhibitors were the most studied therapy(26 %), followed by immunotherapy(15 %), chemotherapy and antibody-drug conjugate(12 % each) and androgen-blockade(8 %), among others.

CONCLUSION

Clinical research for patients with SGC relies mainly in non-industry organisations, most of them limited to run trials in one to five sites, in a single country. Further collaboration between investigators is needed, as well as reconsidering inclusion criteria and trial designs.

Advances in Targeted and Systemic Therapy for Salivary Gland Carcinomas: Current Options and Future Directions

Salivary gland carcinomas (SGCs) represent a rare and heterogeneous group of malignancies accounting for 3-6% of all head and neck cancers. While surgical resection and radiotherapy remain the standard for locoregional control, systemic treatment is indicated for recurrent or metastatic disease. Advances in molecular profiling have identified actionable targets such as NTRK gene fusions, HER2, immune checkpoint regulators, androgen receptors, and RET receptors. These have facilitated the development of targeted therapies, including TRK inhibitors, HER2-directed agents, and androgen receptor modulators, as well as emerging combinations of immunotherapy and chemotherapy. Despite these advancements, challenges such as resistance mechanisms and limited therapeutic efficacy persist. Overall response rates remain relatively low across most systemic therapies, reflecting a persistent unmet clinical need. This review discusses the current landscape of treatment options and explores promising clinical trials and future directions to enhance outcomes for patients with SGCs.

Targeted Therapy in Salivary Gland Cancer: Prevalence of a Selected Panel of Actionable Molecular Alterations in a German Tertiary Referral Center Patient Cohort

OBJECTIVE

Salivary gland carcinomas (SGC) are a heterogeneous group of malignancies, with 24 subtypes defined by the World Health Organization (WHO). The standard of therapy is surgical resection, with adjuvant radiotherapy in most cases. However, disease recurrence (R) or metastasis (M) is common and no active systemic therapies are currently available for RM-SGC resulting in a 5-year survival rate of only 20%.

PATIENTS AND METHODS

Overall, 55 SGC patients with seven different histological tumor subtypes were included in this study. formalin-fixed paraffin-embedded (FFPE) tissue samples were used for immunohistochemical (IHC) staining targeting HER2/neu, androgen receptor (AR), PD-L1, EGFR, panTRK, and TROP2. Fluorescence in situ hybridization (FISH) was performed for detecting HER2/neu amplifications and NTRK1/2/3 translocations in selected cases with relevant HER2/neu and panTRK protein expression, respectively. IHC and FISH results were correlated with patients' clinical and histopathological data.

RESULTS

The overall prevalence of druggable molecular alterations, defined as an immunoreactive score ≥ 9 in at least one of the analyzed targets, was 54.4% with the highest percentage in oncocytic carcinomas (100%) and lowest percentage in acinic cell carcinomas (10%). EGFR overexpression proved to be the most common alteration (32.7% of cases) followed by overexpression of TROP2 (27.3%), AR (10.9%), HER2/neu (7.3%), PD-L1 (1.8%), and panTRK (1.8%). HER2/neu amplifications were found in 50% and NTRK translocations were found in 100% of all cases with elevated Her2/neu and panTRK protein expression, respectively.

CONCLUSIONS

Our data indicate that targeted therapy using e.g., trastuzumab deruxtecan, bicalutamide, pembrolizumab, cetuximab, entrectinib or sacituzumab govitecan might be a promising option especially for a relevant subset of patients with RM-SGC not suitable for salvage surgery. However, evidence from clinical studies regarding response rates to these therapies remains sparse, which underlines the need of multicenter clinical trials.

Targeting CDK7 enhances the antitumor efficacy of enzalutamide in androgen receptor-positive triple-negative breast cancer by inhibiting c-MYC-mediated tumorigenesis

Triple-negative breast cancer (TNBC) is an aggressive subtype of breast cancer. Among TNBC subtypes, the luminal androgen receptor (LAR) subtype expresses high levels of androgen receptor (AR) and generally responds poorly to neoadjuvant chemotherapy. AR has been reported as a promising therapeutic target for the LAR TNBC subtype. Here, we evaluated the preclinical antitumor efficacy of enzalutamide, an AR inhibitor, in TNBC. Enzalutamide had moderate anti-proliferation activity against AR-positive (AR+) TNBC cells (IC50 > 15 µM). To enhance its antitumor efficacy, we performed high-throughput kinome siRNA screening and identified the cell cycle pathway as a potential target. Inhibition of cell cycle progression using the CDK7 inhibitor KRLS-017 showed a synergistic anti-proliferation effect with enzalutamide in AR+ LAR MDA-MB-453 and SUM185 TNBC cells. Downstream target analysis revealed that enzalutamide and KRLS-017 combination dramatically reduced c-MYC expression at both mRNA and protein levels. c-MYC knockdown significantly suppressed growth of MDA-MB-453 and SUM185 cells to a degree comparable to that of enzalutamide and KRLS-017 combination treatment, whereas c-MYC overexpression reversed the synergistic effect. An enhancement in inhibition of tumor growth and suppression of c-MYC expression was further confirmed when enzalutamide combined with KRLS-017 in an MDA-MB-453 mouse model. Our study suggests that KRLS-017 enhances the antitumor efficacy of enzalutamide by inhibiting c-MYC-mediated tumorigenesis and presents a potential new approach for treating AR+ LAR TNBC.

Systemic treatments in recurrent or metastatic salivary gland cancer: a systematic review

BACKGROUND

Salivary gland cancers are infrequent and pose a challenge owing to their histological diversity and varied clinical behavior, making the selection of optimal systemic treatments for advanced or recurrent stages difficult. This systematic review aims to assess overall survival outcomes and systemic treatment responses across four types of salivary cancers.

METHODS

A PubMed and Google Scholar search identified studies involving initially advanced or relapsed cases undergoing systemic treatment. Studies with clear, individualized data on treatment responses and outcomes were selected based on the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) checklist. Of the 723 studies screened, 44 met our inclusion criteria.

RESULTS

A total of 426 cases of recurrent/metastatic salivary gland cancer, mostly salivary duct carcinoma (SDC; n = 219) and adenoid cyst carcinoma (ACC; n = 167), were included. Histomolecular markers were heavily associated with histology, with HER2 overexpression and androgen receptor nuclear expression typically found in SDC and adenocarcinoma not otherwise specified cases and KIT overexpression only in ACC. The response rates were associated with specific receptor blockage, with trastuzumab plus chemotherapy, and bicalutamide being the most effective (overall response rate 80% and 42.8%, respectively). Moreover, the response to treatment positively influenced overall survival (responders 38 versus non-responders 18.7 median months; P < 0.001). In this retrospective analysis of a particular cohort, survival outcomes per histology types showed that anti-human epidermal growth factor receptor 2 therapy was more effective for SDC, while chemotherapy was more effective for ACC.

CONCLUSION

Systemic treatments contribute to the survival of patients with salivary gland cancer at relapsed or newly advanced stages. The response to treatment is heavily influenced by histological subtype and treatment specificity.

Unusual case of extramammary Paget disease of the oral mucosa: A case report and literature review

Paget disease is an intraepithelial neoplastic proliferation, commonly occurring in the breast and apocrine-rich areas, often associated with an underlying internal malignancy. Extramammary Paget disease (EMPD) of the oral cavity is exceedingly rare, with only eight reported cases, four of which were associated with an underlying internal malignancy. Here, we report a case of oral EMPD involving the buccal mucosa and gingiva of an 81-year-old male with no known underlying internal malignancy. The Paget cells were positive for CK7, CK20, CAM5.2, and androgen receptor, but negative for SOX10 and p63. The immunophenotype, association with internal malignancies, and treatment approaches for oral EMPD are reviewed.

Apalutamide and Goserelin for Androgen Receptor-Positive Salivary Gland Carcinoma: A Phase II Nonrandomized Clinical Trial, YATAGARASU

PURPOSE

To assess the efficacy and safety of apalutamide plus goserelin for androgen receptor (AR)-positive unresectable or recurrent/metastatic salivary gland carcinoma.

PATIENTS AND METHODS

This trial was an open-label, single-arm, multicenter phase II study. Patients with histologically confirmed unresectable or recurrent/metastatic salivary gland carcinoma with AR expression were included. The primary endpoint was the overall response rate (ORR) according to RECIST v1.1 by an independent central radiology review in the first 24 response-evaluable (RE) patients who had been observed at least 24 weeks from study initiation (primary RE patients). The efficacy was to be declared when at least 8 of the 24 primary RE patients responded.

RESULTS

A total of 31 patients were enrolled. In the first 24 primary RE patients with a median follow-up of 7.4 months, confirmed ORR by independent central radiology review was 25.0% [6/24 patients; 95% confidence interval, 9.8%-46.7%; P = 0.11 (one-sided)], which did not meet the predefined criteria of efficacy. Clinical benefit rate (ORR + rate of stable disease for at least 24 weeks) and median progression-free survival were 50.0% and 7.4 months, respectively. Both median duration of response and overall survival were not reached. Exploratory analyses showed a better ORR of 54.5% (6/11) in patients with AR positivity ≥70% and no history of prior systemic therapy. Grade 3 or higher treatment-emergent adverse events were reported in 35.5% (11/31), which included skin rash, anemia, leukopenia, and cancer pain.

CONCLUSIONS

Although this study did not meet the predefined efficacy criteria, apalutamide plus goserelin showed clinically meaningful efficacy in a subset of patients with AR-positive salivary gland carcinoma and safety consistent with prior experience in prostate cancer.

The extent of androgen receptor and HER2 expression allows for targeted therapy in most cases of salivary duct carcinoma: analysis of clinical and histopathological data in a tertiary care center

PURPOSE

The incidence of salivary duct carcinoma (SDC) seems to be underestimated due to inaccurate classification. Further, the frequency of SDC patients with targeted therapy options according to current guidelines is unclear. Therefore, this study aimed at (a) describing the proportion of SDC among salivary gland carcinoma (SGC) before and after reclassification of cases initially classified as adenocarcinoma, not otherwise specified (ANOS); and (b) quantifying the frequency of SDC patients with targeted therapy options.

METHODS

All patients with SDC or ANOS treated in a tertiary care center between 1996 and 2023 were identified. Histopathological diagnosis was verified for patients primarily diagnosed with SDC and reviewed for patients initially diagnosed with ANOS. Clinical data for SDC patients were retrieved from clinical charts. Immunohistochemical (IHC) androgen receptor (AR) and HER2 staining was performed.

RESULTS

Among 46 SDC, 34 were primarily diagnosed as SDC and 12 had initially been classified as ANOS. The proportion of SDC among SGC was 12.1% and was rising when comparing the time periods 2000-2015 (7.1-11.5%) versus 2016-2023 (15.4-18.1%). Nuclear AR staining in > 70% of tumor cells was found in 56.8% and HER2 positivity (IHC 3 +) in 36.4% of cases. 70.5% of patients showed AR staining in > 70% of tumor cells and/or HER2 positivity and therefore at least one molecular target. 5-year overall and disease-free survival (DFS) were 62.8% and 41.0%. Multivariate Cox regression revealed positive resection margins (HR = 4.0, p = 0.03) as independent negative predictor for DFS.

CONCLUSIONS

The results suggest a rising SDC incidence and show that the extent of the AR and HER2 expression allows for targeted therapy in most SDC cases.

Case report: Salivary duct carcinoma in a patient with a germline CDH1 pathogenic variant - expanding the spectrum of hereditary cancer predisposition syndromes

Introduction

Recently, an entity known as salivary duct carcinoma with rhabdoid features (SDC-RF) has been associated with somatic CDH1 mutations. Here we present the first known case report of conventional SDC occurring in the setting of a germline CDH1 pathogenic variant accompanied by a somatic loss of heterozygosity at the CDH1 locus.

Case discussion

A 67-year-old man presented with chest and back pain and was found to have osteolytic lesions in the sternum and lumbar spine. Vertebral bone biopsies were positive for metastatic carcinoma of unknown primary. A molecular profiling assay consisting of both whole-exome next-generation sequencing (NGS) as well as immunohistochemistry (IHC) for select clinically-relevant proteins performed on the bone biopsy suggested a triple-negative (ER/PR/ERBB2 negative, by IHC), androgen receptor (AR IHC) positive tumor profile. Additionally, the assay uncovered a coding mutation in the CDH1 gene (c.1792C>T, p.R598*) with genomic loss of the second CDH1 allele. Germline testing returned positive for a heterozygous CDH1 pathogenic variant. PET-CT revealed a tumor in the neck suggestive of the primary malignancy consistent with that of salivary gland origin. The patient was initially treated with carboplatin and paclitaxel, then pembrolizumab, and finally with AR-directed therapy using leuprolide and enzalutamide. These treatments were not successful, and the patient eventually succumbed to his disease.

Conclusion

Molecular testing revealed that our patient had bi-allelic inactivation of the CDH1 gene. We believe our patient developed a somatic mutation in addition to his preexisting germline CDH1 mutation that ultimately predisposed him to SDC. While previous studies have found somatic CDH1 pathogenic variants in SDC-RF, our patient was found to have a germline CDH1 pathogenic variant in the setting of conventional SDC, without rhabdoid features. This case provokes questions regarding tumor genetics and molecular profiling of SDC in patients with germline CDH1 pathogenic variants. Moreover, this case supports the notion that SDC may be the salivary counterpart of other malignancies associated with germline CDH1 pathogenic variants and may possibly expand the spectrum of tumors that arise in this familial cancer-predisposition syndrome.

Exploring Immunological Effects and Novel Immune Adjuvants in Immunotherapy for Salivary Gland Cancers

Salivary gland cancer (SGC) is rare and comprises over 20 histological subtypes. Recently, clinical experience regarding immunotherapies for SGCs has been accumulating, yet their efficacy remains controversial. Understanding the tumor microenvironment (TME), including the expression of immune checkpoint molecules in SGC, is crucial to optimizing immunotherapy. In this review, we demonstrate that high-grade mucoepidermoid carcinoma and salivary duct carcinoma generally exhibit immune-hot TME with high immune cell infiltration, frequent genetic mutations, and robust immune checkpoint molecule expression. In contrast, adenoid cystic carcinomas exhibit an immune-cold TME. While the reported efficacy of immune checkpoint inhibitors (ICIs) for SGCs is generally poor, several studies showed promising clinical efficacy of ICIs, with an objective response rate ranging from 20.0-33.3%, indicating that ICIs might be beneficial for a specific population of SGC. Molecule-targeted therapies including anti-human epidermal growth factor receptor 2 and anti-androgen receptor therapies have shown promising clinical efficacy against SGC. Recent evidence indicates that these molecules could be targets for antigen-specific immunotherapies including chimeric antigen receptor-T therapy and cancer vaccines. This review discusses the current understanding and future directions of immunotherapies for SGCs, including ongoing clinical trials.

Salivary gland carcinoma: Towards a more personalised approach

Salivary Gland carcinomas (SGCs) are rare tumors accounting for less than 1% of all cancers with 21 histologically diverse subtypes. The rarity of the disease presents a challenge for clinicians to conduct large size randomized controlled trials. Surgery and radiotherapy remain the only curative treatment for localized disease, whereas treatments for recurrent and metastatic disease remain more challenging with very disappointing results for chemotherapy. The different histological subtypes harbor various genetic alterations, some pathognomonic with a diagnostic impact for pathologists in confirming a difficult diagnosis and others with therapeutic implications regardless of the histologic subtype. Current international guidelines urge pathologists to identify androgen receptor status, HER-2 expression that could be determined by immunohistochemistry, and TRK status in patients with non-adenoid cystic salivary gland carcinoma that are eligible to initiate a systemic treatment, in order to offer them available targeted therapies or refer them to clinical trials based on their mutational profile. A more advanced molecular profiling by next generation sequencing would offer a larger panel of molecular alterations with possible therapeutic implications such as NOTCH, PI3K, BRAF, MYB, and EGFR. In the following review, we present the most common genetic alterations in SGCs as well as actionable mutations with the latest available data on therapeutic options and upcoming clinical trials.

Translational Insights in the Landscape of Salivary Gland Cancers: Ready for a New Era?

Salivary gland carcinomas (SGCs) are rare neoplasms, representing less than 10% of all head and neck tumors, but they are extremely heterogeneous from the histological point of view, their clinical behavior, and their genetics. The guidelines regarding their treatment include surgery in most cases, which can also play an important role in oligometastatic disease. Where surgery cannot be used, systemic therapy comes into play. Systemic therapy for many years has been represented by polychemotherapy, but recently, with the affirmation of translational research, it can also count on targeted therapy, at least in some subtypes of SGCs. Interestingly, in some SGC histotypes, predominant mutations have been identified, which in some cases behave as "driver mutations", namely mutations capable of governing the carcinogenesis process. Targeting these driver mutations may be an effective therapeutic strategy. Nonetheless, it is not always possible to have drugs suitable for targeting driver mutations-and targeting driver mutations is not always accompanied by a clinical benefit. In this review, we will analyze the main mutations predominant in the various histotypes of SGCs.

Analysis of B7-H4 Expression Across Salivary Gland Carcinomas Reveals Adenoid Cystic Carcinoma-Specific Prognostic Relevance

B7-H4 (VTCN1), a member of the B7 family, is overexpressed in several types of cancer. Here we investigated the pattern of expression of B7-H4 in salivary gland carcinomas (SGC) and assessed its potential as a prognostic marker and therapeutic target. Immunohistochemistry (IHC) analyses were performed in a cohort of 340 patient tumors, composed of 124 adenoid cystic carcinomas (ACC), 107 salivary duct carcinomas (SDC), 64 acinic cell carcinomas, 36 mucoepidermoid carcinomas (MEC), 9 secretory carcinomas (SC), as well as 20 normal salivary glands (controls). B7-H4 expression was scored and categorized into negative (<5% expression of any intensity), low (5%-70% expression of any intensity or >70% with weak intensity), or high (>70% moderate or strong diffuse intensity). The associations between B7-H4 expression and clinicopathologic characteristics, as well as overall survival, were assessed. Among all tumors, B7-H4 expression was more prevalent in ACC (94%) compared with those of SC (67%), MEC (44%), SDC (32%), and acinic cell carcinomas (0%). Normal salivary gland tissue did not express B7-H4. High expression of B7-H4 was found exclusively in ACC (27%), SDC (11%), and MEC (8%). In SDC, B7-H4 expression was associated with female gender (P = .002) and lack of androgen receptor expression (P = .012). In ACC, B7-H4 expression was significantly associated with solid histology (P < .0001) and minor salivary gland primary (P = .02). High B7-H4 expression was associated with a poorer prognosis in ACC, regardless of clinical stage and histologic subtype. B7-H4 expression was not prognostic in the non-ACC SGC evaluated. Our comparative study revealed distinct patterns of B7-H4 expression according to SGC histology, which has potential therapeutic implications. B7-H4 expression was particularly high in solid ACC and was an independent prognostic marker in this disease but not in the other SGC assessed.

Pathological nodal status as a main predictive factor of survival and treatment outcomes of submandibular salivary gland cancers: A 25-year single center experience

INTRODUCTION

Aim of this study was to explore the survival predictive factors and treatment outcomes in a cohort of SGC patients treated at a single center over a period of 25 years.

MATERIALS AND METHODS

Patients who had received primary treatment for SGC were enroled. Outcomes evaluated were: overall survival (OS), disease specific survival (DSS), recurrence free survival (RFS), locoregional recurrence free survival (LRFS) and distant metastasis free survival (DFS).

RESULTS

A total of 40 patients with SGC were enroled in the study. The most common tumor was the adenoid cystic carcinoma (60% of cases). Cumulative OS for 5-and 10-year follow up period was 81% and 60%, respectively. Thirteen patients (32.5%) developed distant metastases during follow-up. Nodal status, high-grade histology, tumor stage and adjuvant radiation-therapy (RT) were significant variables on multivariate analysis for survival and treatment outcomes.

CONCLUSIONS

Submandibular gland carcinomas represent rare and heterogenous tumor group regarding histological appearance and locoregional and distant metastatic potential. Tumor histological grade, AJCC tumor stage and nodal status were the strongest predictive factors for survival and treatment outcomes. RT improved OS and locoregional treatment outcome, but not DFS. Elective neck dissection (END) could be beneficial for selected cases of SGC. Superselective neck dissection of levels I-IIa may be the level of dissection for END. Distant metastases were the main cause of death and treatment failure. Prognostic factors for poor DMFS were AJCC stage III and IV, high tumor grade and nodal status.

Proceedings from the Melanoma Research Foundation Mucosal Melanoma Meeting (December 16, 2022, New York, USA)

Mucosal melanoma remains a rare cancer with high mortality and a paucity of therapeutic options. This is due in significant part to its low incidence leading to limited patient access to expert care and downstream clinical/basic science data for research interrogation. Clinical challenges such as delayed and at times inaccurate diagnoses, and lack of consensus tumor staging have added to the suboptimal outcomes for these patients. Clinical trials, while promising, have been difficult to activate and accrue. While individual institutions and investigators have attempted to seek solutions to such problems, international, national, and local partnership may provide the keys to more efficient and innovative paths forward. Furthermore, a mucosal melanoma coalition would provide a potential network for patients and caregivers to seek expert opinion and advice. The Melanoma Research Foundation Mucosal Melanoma Meeting (December 16, 2022, New York, USA) highlighted the current clinical challenges faced by patients, providers, and scientists, identified current and future clinical trial investigations in this rare disease space, and aimed to increase national and international collaboration among the mucosal melanoma community in an effort to improve patient outcomes. The included proceedings highlight the clinical challenges of mucosal melanoma, global clinical trial experience, basic science advances in mucosal melanoma, and future directions, including the creation of shared rare tumor registries and enhanced collaborations.

The evolving landscape of salivary gland tumors

Salivary gland cancers are a rare, histologically diverse group of tumors. They range from indolent to aggressive and can cause significant morbidity and mortality. Surgical resection remains the mainstay of treatment, but radiation and systemic therapy are also critical parts of the care paradigm. Given the rarity and heterogeneity of these cancers, they are best managed in a multidisciplinary program. In this review, the authors highlight standards of care as well as exciting new research for salivary gland cancers that will strive for better patient outcomes.

Beyond Prostate Cancer: An Androgen Receptor Splice Variant Expression in Multiple Malignancies, Non-Cancer Pathologies, and Development

Multiple studies have demonstrated the importance of androgen receptor (AR) splice variants (SVs) in the progression of prostate cancer to the castration-resistant phenotype and their utility as a diagnostic. However, studies on AR expression in non-prostatic malignancies uncovered that AR-SVs are expressed in glioblastoma, breast, salivary, bladder, kidney, and liver cancers, where they have diverse roles in tumorigenesis. AR-SVs also have roles in non-cancer pathologies. In granulosa cells from women with polycystic ovarian syndrome, unique AR-SVs lead to an increase in androgen production. In patients with nonobstructive azoospermia, testicular Sertoli cells exhibit differential expression of AR-SVs, which is associated with impaired spermatogenesis. Moreover, AR-SVs have been identified in normal cells, including blood mononuclear cells, neuronal lipid rafts, and the placenta. The detection and characterization of AR-SVs in mammalian and non-mammalian species argue that AR-SV expression is evolutionarily conserved and that AR-SV-dependent signaling is a fundamental regulatory feature in multiple cellular contexts. These discoveries argue that alternative splicing of the AR transcript is a commonly used mechanism that leads to an expansion in the repertoire of signaling molecules needed in certain tissues. Various malignancies appropriate this mechanism of alternative AR splicing to acquire a proliferative and survival advantage.

Targeted treatment in a case series of AR+, HRAS/PIK3CA co-mutated salivary duct carcinoma

Background and purpose

A subgroup of salivary duct carcinoma (SDC) harbor overexpression of the androgen receptor (AR), and co-occurring mutations in the HRAS- and PIK3CA-genes. The impact of genomic complexity on targeted treatment strategies in advanced cancer is unknown.

Materials and methods

We analyzed molecular and clinical data from an institutional molecular tumor board (MTB) to identify AR+, HRAS/PIK3CA co-mutated SDC. Follow-up was performed within the MTB registrational study or retrospective chart review after approval by the local ethics committee. Response was assessed by the investigator. A systematic literature search was performed in MEDLINE to identify additional clinically annotated cases.

Results

4 patients with AR+ HRAS/PIK3CA co-mutated SDC and clinical follow-up data were identified from the MTB. An additional 9 patients with clinical follow-up were identified from the literature. In addition to AR overexpression and HRAS and PIK3CA-alterations, PD-L1 expression and Tumor Mutational Burden > 10 Mutations per Megabase were identified as additional potentially targetable alterations. Among evaluable patients, androgen deprivation therapy (ADT) was initiated in 7 patients (1 Partial Response (PR), 2 Stable Disease (SD), 3 Progressive Disease (PD), 2 not evaluable), tipifarnib was initiated in 6 patients (1 PR, 4 SD, 1 PD). One patient each was treated with immune checkpoint inhibition (Mixed Response) and combination therapies of tipifarnib and ADT (SD) and alpelisib and ADT (PR).

Conclusion

Available data further support comprehensive molecular profiling of SDC. Combination therapies, PI3K-inhibitors and immune therapy warrant further investigation, ideally in clinical trials. Future research should consider this rare subgroup of SDC.

Targeting human EGFR 2 (HER2) in salivary gland carcinoma

INTRODUCTION

Human epidermal growth factor receptor 2 (HER2) protein overexpression, gene amplification, and activating mutations have been identified in a subset of salivary gland carcinoma (SGC) histologies (HER2-positive), especially in salivary duct carcinoma, and represent an important therapeutic target.

AREAS COVERED

The evidence for targeting HER2 in the adjuvant setting is limited to small retrospective series. Conversely, there are prospective trials supporting the use of anti-HER2 therapy in patients with unresectable, recurrent, or metastatic HER2-positive SGC, including trastuzumab plus docetaxel, trastuzumab plus pertuzumab, trastuzumab-pkrb plus nanoxel, trastuzumab emtansine (T-DM1), and trastuzumab deruxtecan (T-Dxd).

EXPERT OPINION

HER2-targeting should be considered for patients with advanced HER2-positive SGC. There are no data to guide the selection of one anti-HER2 agent over another in the palliative setting. Trastuzumab plus docetaxel can be considered for patients with a high disease burden, while trastuzumab plus pertuzumab is a good option for patients with low disease burden or borderline performance status. T-DM1 or T-Dxd can be considered upon disease progression on trastuzumab-combination therapies, although these antibody-drug conjugates can also be used upfront. Future research should investigate predictive biomarkers, the combination of HER2 and androgen blockade, and the application of novel therapies from breast cancer.

A molecular guide to systemic therapy in salivary gland carcinoma

Salivary gland carcinomas (SGC) are a rare and variable group of head and neck cancers with historically poor response to cytotoxic chemotherapy and immunotherapy in the recurrent, advanced, and metastatic settings. In the last decade, a number of targetable molecular alterations have been identified in SGCs including HER2 upregulation, androgen receptor overexpression, Notch receptor activation, NTRK gene fusions, and RET alterations which have dramatically improved treatment outcomes in this disease. Here, we review the landscape of precision therapy in SGC including current options for systemic management, ongoing clinical trials, and promising future directions.

'Toxic Masculinity': What Is Known about the Role of Androgen Receptors in Head and Neck Squamous Cell Carcinoma

Head and neck squamous cell carcinoma (HNSCC), the most prevalent cancer in the head and neck region, develops from the mucosal epithelium of the upper aerodigestive tract. Its development directly correlates with alcohol and/or tobacco consumption and infection with human papillomavirus. Interestingly, the relative risk for HNSCC is up to five times higher in males, so it is considered that the endocrine microenvironment is another risk factor. A gender-specific risk for HNSCC suggests either the existence of specific risk factors that affect only males or that females have defensive hormonal and metabolic features. In this review, we summarized the current knowledge about the role of both nuclear and membrane androgen receptors (nAR and mARs, respectively) in HNSCC. As expected, the significance of nAR is much better known; it was shown that increased nAR expression was observed in HNSCC, while treatment with dihydrotestosterone increased proliferation, migration, and invasion of HNSCC cells. For only three out of five currently known mARs-TRPM8, CaV1.2, and OXER1-it was shown either their increased expression in various types of HNSCC or that their increased activity enhanced the migration and invasion of HNSCC cells. The primary treatments for HNSCC are surgery and radiotherapy, but targeted immunotherapies are on the rise. On the other hand, given the evidence of elevated nAR expression in HNSCC, this receptor represents a potential target for antiandrogen therapy. Moreover, there is still plenty of room for further examination of mARs' role in HNSCC diagnosis, prognosis, and treatment.

Metastatic Salivary Duct Carcinoma with ERBB2 Amplification and Sequential Response to Ado-Trastuzumab Emtansine and Neratinib: A Case Report

Introduction

Salivary duct carcinoma (SDC) is an aggressive and rare subtype of salivary gland carcinoma. Surgical excision and radiotherapy are standard of care for early cancer. Chemotherapies with taxanes and platinum show overall response rates between 39% and 50%. SDCs are often associated with an overexpression of the androgen receptor (AR) and HER2/neu which have recently become druggable targets.

Case Presentation

Here, we report on an 84-year-old male patient with metastatic SDC of the right parotid gland. In 2017, he underwent a right total parotidectomy, a right neck dissection, and an infratemporal fossa clearance followed by 6 weeks of radiotherapy. In 2018, due to metastatic spread in the lungs, bones, and pararenal gland, a pathological workup of the tumor tissue was performed and revealed both AR and HER2 overexpression, respectively. Consequently, he underwent androgen deprivation therapy and, due to asymptomatic progression, sequentially human epidermal growth factor receptor 2 (HER-2)-targeted therapy with ado-trastuzumab emtansine and neratinib, which led to stable disease during the course of about 18 months. The electronically captured patient-reported outcome had demonstrated a good tolerance of all three therapeutic lines.

Conclusion

In conclusion, since effective standard therapeutic treatment options for SDC may often not be tolerable in older patients, the implementation of personalized and adaptive treatments, especially in patients with rare tumor types, might offer valuable treatment options.

The Therapeutic Landscape of Salivary Gland Malignancies-Where Are We Now?

Salivary gland malignancies (SGMs) account for less than 5% of new diagnoses in head and neck tumors. If feasible, surgery is the preferred treatment modality. Nevertheless, some malignancies have a tendency of recurrence, with possible distant metastasis. Alternative treatment strategies, such as primary radiation or chemotherapeutics, often present low response rates. As a result, there is an unmet need for novel therapeutic approaches. Nowadays, target-based therapies (e.g., small inhibitors and immunotherapy) are used by the medical oncologist for possible treatment of advanced SGMs. Based on recent published trials, some novel treatments may provide additional disease control for some patients. However, sample sizes are small, the general findings are unsatisfactory, and a lot of uncertainties remain to be elucidated. Nevertheless, research shows that patients do not benefit from blind administration of systemic treatments and therefore a more personalized approach is highly needed. The aim of this review paper is to summarize the most recent advances in the biological understanding and molecular pathways of salivary gland cancers, the association of these pathways with the current treatments used and their implications for more personalized targeted-based therapies.

Survival benefit of HER2-targeted or androgen deprivation therapy in salivary duct carcinoma

Background

The efficacy and safety of human epidermal growth factor receptor 2 (HER2)-targeted therapy and androgen deprivation therapy (ADT) for locally advanced or recurrent or metastatic (LA/RM) salivary duct carcinoma (SDC) have been reported in prospective studies. However, the survival benefit of these therapies to conventional therapy remains controversial, and whether HER2-targeted therapy or ADT should be chosen in HER2- and androgen receptor (AR)-positive SDC patients remains unknown.

Methods

Overall, 323 LA/RM SDC patients treated at seven institutions between August 1992 and June 2020 were retrospectively enrolled. The primary aim was to analyze the effect of HER2-targeted therapy and ADT on overall survival from the diagnosis of LA/RM disease to death from any cause (OS1). The secondary indicators included the overall response rate (ORR), clinical benefit rate (CBR), overall survival from therapy initiation for LA/RM disease (OS2), progression-free survival (PFS), time to second progression (PFS2), duration of response (DoR), and duration of clinical benefit (DoCB) of HER2-targeted therapy or ADT as first-line therapy for HER2-positive/AR-positive SDC.

Results

Patients treated with HER2-targeted therapy or ADT had longer OS1 than those treated without these therapies (Median OS1: historical control, 21.6 months; HER2-targeted therapy, 50.6 months; ADT, 32.8 months; HER2-targeted therapy followed by ADT, 42.4 months; and ADT followed by HER2-targeted therapy, 45.2 months, p < 0.001). Among HER2-positive/AR-positive SDC patients, although HER2-targeted therapy had better ORR, CBR, and PFS than those of ADT as first-line therapy, we found no significant differences between HER2-targeted therapy and ADT regarding OS2, PFS2, DoR, and DoCB.

Conclusion

Patients treated with HER2-targeted therapy and ADT showed longer survival in LA/RM SDC. HER2-targeted therapy can be recommended prior to ADT for HER2-positive/AR-positive SDC. It is warranted to establish a biomarker that could predict the efficacy of clinical benefit or better response in ADT.

Biweekly administration of cetuximab in Japanese patients with recurrent or metastatic head and neck cancer

BACKGROUND

Cetuximab (Cmab) plays an important role in the treatment for recurrent or metastatic head and neck cancer (R/M HNC). To date, however, no safety data on biweekly administration of cetuximab at a dose of 500 mg/m² (biweekly Cmab) for Japanese HNC patients have been available.

METHODS

We retrospectively reviewed the clinical records of five R/M HNC patients who received biweekly Cmab in our institute between January 2016 and September 2021 and compared the safety profile between two phases of weekly 250 mg/m² and biweekly 500 mg/m² Cmab in the identical patients.

RESULTS

All patients initially received Cmab in combination with chemotherapy. Chemotherapy consisted of paclitaxel plus carboplatin in two patients, cisplatin + 5-FU in one patient, and paclitaxel in two patients. Three patients switched treatment schedule from weekly Cmab to biweekly Cmab, while two patients received biweekly Cmab after completion of chemotherapy. The main reason for switching to biweekly Cmab was an unacceptably long commuting time to the hospital. The median duration of Cmab was 217 days (49-321) during weekly Cmab with or without chemotherapy and 42 days (28-175) during biweekly Cmab. Median dose of biweekly Cmab was 4 (3-12). During biweekly Cmab, worsened (Grade ≥ 2) toxicities were observed in two patients: one with grade 2 dry skin and the second with grade 2 skin infection. None developed grade ≥ 3 adverse events or discontinued treatment due to Cmab-related adverse events.

CONCLUSION

Biweekly Cmab was well tolerated and did not demonstrate severe toxicities related to Cmab for R/M HNC.