Molecular testing in salivary gland cytopathology: A practical overview in conjunction with the Milan system

Recently, significant advances in the molecular characterization of salivary gland neoplasms have facilitated the classification and diagnosis of specific diagnostic entities. In the highly challenging diagnostic scenario of salivary malignancies, molecular testing is increasingly being adopted in routine practice to refine the cytological diagnosis of salivary lesions. Here, we reviewed the most recent evidence in the field of salivary glands molecular cytopathology.

Molecular analysis using SalvGlandDx improves risk of malignancy estimation and diagnosis of salivary gland cytopathology: An exploratory multicenter study

BACKGROUND

Diagnosis of salivary gland neoplasms is challenging, especially on cytological specimens acquired by fine-needle aspiration. The recently implemented standardized Milan system for reporting salivary gland cytopathology provides an estimated risk of malignancy (ROM); yet, for two of the categories, the diagnosis of the lesion remains unclear. However, a precise diagnosis is desirable for optimal patient management, including planning of surgery and imaging procedures.

METHODS

Cytological specimens (n = 106) were subjected to molecular analysis using the SalvGlandDx panel. The risk of malignancy was calculated for each detected alteration based on the diagnosis of the resection specimen. By taking into account the molecular alterations, their associated ROM, the clinical and cytological features, and the current literature, the Milan category was evaluated.

RESULTS

Of n = 63 technically valid cases, 76% revealed a molecular alteration. A total of 94% of these molecularly altered cases could be assigned to a different Milan category when additionally taking molecular results into account. In only 2% of the salivary gland neoplasms of uncertain malignant potential, in which a molecular alteration was detected, the classification remained salivary gland neoplasms of uncertain malignant potential.

CONCLUSION

Molecular analysis of cytological specimens provides a benefit in classifying salivary gland neoplasms on fine-needle aspiration. It can improve the ROM estimation and thus help to assign cases of formerly unknown malignant potential to clearly benign or malignant categories.

Overall and disease-specific survival of sinonasal adenoid cystic carcinoma: a systematic review and meta-analysis

This meta-analysis aims to investigate the outcome of sinonasal adenoid cystic carcinoma (snAdCC). We followed PRISMA guidelines and included studies reporting 5-year overall survival (OS) rates for snAdCC. Eligible studies were identified through a literature search and assessed using JBI critical appraisal checklist. A total of 17 studies were included comprising 2259 patients (mean age: 58.1 years, 52.7% female, 47.3% male). The meta-analysis demonstrated that the 5-year OS, 10-year OS, and 5-year disease-free survival (DFS) were 68%, 40%, and 47.2%, respectively. Descriptive statistics on study level showed high rates of locally advanced tumor stages at diagnosis: 23% cT3, 53% cT4, 3.4% N+, and 4.2% M+. 29.7% of the tumors were in the nasal cavity, 67.6% in the paranasal sinuses. The maxillary, ethmoid, sphenoid, and frontal sinus were affected in 50.9%, 7.2%, 4%, and 0.5%, of cases. A combination of surgery and radiotherapy was used in 45.4% of the patients and 19.3% of patients received surgery only. In conclusion, these findings emphasize the significance of thorough surveillance for individuals with snAdCC to identify any potential recurrence or progression of the disease.

Challenging Tumor Heterogeneity with HER2, p16 and Somatostatin Receptor 2 Expression in a Case of EBV-Associated Lymphoepithelial Carcinoma of the Salivary Gland

BACKGROUND

Lymphoepithelial carcinoma of the salivary glands (LECSG) is a rare disease in the Western hemisphere that is typically associated with an EBV infection. The molecular mechanisms of LECSG tumorigenesis are poorly understood.

RESULTS

Here we report a case of EBV-associated LECSG with an unusual immunophenotype. The tumor exhibited bi-morphic histological features with a mutually exclusive expression of HER2 and p16. The p16-positive domain of the tumor immunohistochemically co-expressed late membrane protein 1 (LMP-1), while the HER2 positive domain did not. Both tumor regions expressed SSTR2.

METHODS

In situ hybridization confirmed the EBV origin of the tumor while extensive immunohistochemical characterization and the recently established RNA-based next generation sequencing panel ("SalvGlandDx" panel) did not reveal evidence for another salivary gland neoplasm. No HPV co-infection was detected by in situ hybridization or PCR-based screenings and no ERBB2 gene amplification was detected by fluorescence in situ hybridization.

CONCLUSION

These findings suggest tumor heterogeneity and lack of genomic aberrations in EBV-associated LECSGs. The heterogenous and unusual immunohistochemical features explain the diagnostic difficulties and simultaneously extend the immunophenotype spectrum of this tumor entity.

Sinonasal mucosal melanoma treatment response assessment to immune checkpoint inhibitors using hybrid positron emission tomography imaging

The purpose of this retrospective study was to investigate response of sinonasal mucosal melanoma (SMM) patients to treatment with immune checkpoint inhibitors (ICI), using hybrid PET imaging. Fifteen SMM patients underwent hybrid PET imaging before and three months after initiation of ICI. The disease-specific survival (DSS) was calculated. Quantitative PET parameters of the primary tumor and their association with DSS and therapy response were investigated. Nine of the fifteen (60%) patients responded to ICI therapy. Patients with therapy response depicted on hybrid PET imaging had better DSS than those without (p = 0.0058). Quantitative PET parameters of the initial PET harbored no association with DSS or therapy response. However, these findings lack of sufficient statistical power and must be interpreted with caution. The first restaging PET-imaging after ICI initiation can help stratify patients with regard to DSS.

Acquired resistance to anti-PD1 therapy in patients with NSCLC associates with immunosuppressive T cell phenotype

Immune checkpoint inhibitor treatment has the potential to prolong survival in non-small cell lung cancer (NSCLC), however, some of the patients develop resistance following initial response. Here, we analyze the immune phenotype of matching tumor samples from a cohort of NSCLC patients showing good initial response to immune checkpoint inhibitors, followed by acquired resistance at later time points. By using imaging mass cytometry and whole exome and RNA sequencing, we detect two patterns of resistance¨: One group of patients is characterized by reduced numbers of tumor-infiltrating CD8+ T cells and reduced expression of PD-L1 after development of resistance, whereas the other group shows high CD8+ T cell infiltration and high expression of PD-L1 in addition to markedly elevated expression of other immune-inhibitory molecules. In two cases, we detect downregulation of type I and II IFN pathways following progression to resistance, which could lead to an impaired anti-tumor immune response. This study thus captures the development of immune checkpoint inhibitor resistance as it progresses and deepens our mechanistic understanding of immunotherapy response in NSCLC.

Combinational expression of tumor testis antigens NY-ESO-1, MAGE-A3, and MAGE-A4 predicts response to immunotherapy in mucosal melanoma patients

PURPOSE

Immunotherapy using immune checkpoint inhibitors (ICI) has revolutionized cancer treatment in recent years, particularly in melanoma. While response to immunotherapy is associated with high tumor mutational burden (TMB), PD-L1 expression, and microsatellite instability in several cancers, tumors lacking these biomarkers can still respond to this treatment. Especially, mucosal melanoma, commonly exhibiting low TMB compared to cutaneous melanoma, may respond to immunotherapy with immune checkpoint inhibitors. Therefore, the aim of our study was to investigate novel biomarkers in mucosal melanoma that predict response to combined ipilimumab and nivolumab.

METHODS

We investigated 10 tumor samples from 10 patients (three responders, seven non-responders) before treatment and six tumor samples from five patients after progression using a targeted Next Generation Sequencing (NGS) gene expression panel. The findings were corroborated with an independent method (i.e., immunohistochemical staining) on the same 10 tumor samples before treatment and, to increase the cohort, in addition on three tumor samples before treatment of more recent patients (one responder, two non-responders).

RESULTS

With the targeted gene expression panel, we found the three tumor testis antigens CTAG1B (NY-ESO-1), MAGE-A3, and MAGE-A4 to be predominantly expressed in responding tumors. This marker panel was either not or not completely expressed in non-responders (p < 0.01). Using immunohistochemistry for all three markers, we could confirm the elevated expression in tumors responding to the ipilimumab/nivolumab combination therapy.

CONCLUSION

In conclusion, these three biomarkers await validation in a larger patient cohort and could be easily used in future routine diagnostics to predict the outcome of ipilimumab/nivolumab combination therapy in mucosal melanoma patients.

Clock-like Mutation Signature May Be Prognostic for Worse Survival Than Signatures of UV Damage in Cutaneous Melanoma

Novel treatment modalities comprising immune checkpoint inhibitors and targeted therapies have revolutionized treatment of metastatic melanoma. Still, some patients suffer from rapid progression and decease within months after a diagnosis of stage IV melanoma. We aimed to assess whether genomic alterations may predict survival after the development of stage IV disease, irrespective of received therapy. We analyzed tumor samples of 79 patients with stage IV melanoma using a custom next-generation gene-sequencing panel, MelArray, designed to detect alterations in 190 melanoma-relevant genes. We classified the patients: first, as short survivors (survival ≤6 months after stage IV disease, n = 22) and long survivors (survival >6 months, n = 57); second, by using a cut-off of one year; and third, by comparing the longest surviving 20 patients to the shortest surviving 20. Among analyzed genes, no individual gene alterations, or combinations of alterations, could be dichotomously associated with survival. However, the cohort's mutational profiles closely matched three known mutational signatures curated by the Catalog of Somatic Mutations in Cancer (COSMIC): UV signature COSMIC_7 (cosine-similarity 0.932), clock-like signature COSMIC_5 (cosine-similarity 0.829), and COSMIC_30 (cosine-similarity 0.726). Patients with UV signature had longer survival compared to patients with clock-like and COSMIC 30 (p < 0.0001). Subgroup dichotomization at 6 months showed that 75% of patients with UV signature survived longer than 6 months, and about 75% of patients with clock-like signature survived less than 6 months after development of stage IV disease. In our cohort, clock-like COSMIC_5 mutational signature predicted poor survival while a UV signature COSMIC_7 predicted longer survival. The prognostic value of mutational signatures should be evaluated in prospective studies.

Adenoid Cystic Carcinoma With Striking Tubular Hypereosinophilia: A Unique Pattern Associated With Nonparotid Location and Both Canonical and Novel EWSR1::MYB and FUS::MYB Fusions

The classification of salivary gland tumors is ever-evolving with new variants of tumors being described every year. Next-generation sequencing panels have helped to prove and disprove prior assumptions about tumors' relationships to one another, and have helped refine this classification. Adenoid cystic carcinoma (AdCC) is one of the most common salivary gland malignancies and occurs at all major and minor salivary gland and seromucous gland sites. Most AdCC are predominantly myoepithelial and basaloid with variable cribriform, tubular, and solid growth. The luminal tubular elements are often less conspicuous. AdCC has largely been characterized by canonical MYB fusions, with MYB::NFIB and rarer MYBL1::NFIB. Anecdotal cases of AdCC, mostly in nonmajor salivary gland sites, have been noted to have unusual patterns, including squamous differentiation and macrocystic growth. Recently, this has led to the recognition of a subtype termed "metatypical adenoid cystic carcinoma." Another unusual histology that we have seen with a wide range of architecture, is striking tubular hypereosinophilia. The hypereosinophilia and luminal cell prominence is in stark contrast to the vast majority of AdCC that are basaloid and myoepithelial predominant. A total of 16 cases with tubular hypereosinophilia were collected, forming morular, solid, micropapillary, and glomeruloid growth, and occasionally having rhabdoid or Paneth-like cells. They were subjected to molecular profiling demonstrating canonical MYB::NFIB (5 cases) and MYBL1::NFIB (2 cases), as well as noncanonical EWSR1::MYB (2 cases) and FUS::MYB (1 case). The remaining 6 cases had either no fusion (3 cases) or failed sequencing (3 cases). All cases were present in nonmajor salivary gland sites, with seromucous glands being the most common. These include sinonasal tract (7 cases), laryngotracheal (2 cases), external auditory canal (2 cases), nasopharynx (1 case), base of tongue (2 cases), palate (1 case), and floor of mouth (1 case). A tissue microarray of 102 conventional AdCC, including many in major salivary gland sites was examined for EWSR1 and FUS by fluorescence in situ hybridization and showed that these novel fusions were isolated to this histology and nonmajor salivary gland location. In summary, complex and striking tubular hypereosinophilia and diverse architectures are present within the spectrum of AdCC, particularly in seromucous gland sites, and may show variant EWSR1/FUS::MYB fusions.

[Salivary gland tumors-an overview : Advances in molecular characterization: Part I]

In den letzten Jahren hat die Charakterisierung der Speicheldrüsenkarzinome einen großen Wandel durchlebt. Morphologisch definierte Entitäten konnten zu einem Großteil auch molekular mit einem oftmals distinkten Genotyp charakterisiert werden. Der erste Teil des Artikels gibt einen Überblick über die Fortschritte der molekularen Charakteristiken des Mukoepidermoidkarzinoms, adenoid-zystischen Karzinoms, Azinuszellkarzinoms, des sekretorischen und intraduktalen Karzinoms sowie des hyalinisierenden klarzelligen Karzinoms. Der molekulare Genotyp kann dabei insbesondere bei der Klassifizierung ungewöhnlicher morphologischer Varianten von großem Nutzen sein. Rekurrente NTRK- oder RET-Genfusionen können dabei nicht nur als diagnostisches Hilfsmittel, sondern auch für eine potenzielle gezielte Therapie genutzt werden.

Expanding the clinicopathological spectrum of TGFBR3-PLAG1 rearranged salivary gland neoplasms with myoepithelial differentiation including evidence of high-grade transformation

PLAG1 rearrangements have been described as a molecular hallmark of salivary gland pleomorphic adenoma (PA), carcinoma ex pleomorphic adenoma (CEPA), and myoepithelial carcinoma (MECA). Several fusion partners have been described, however, commonly no further assignment to the aforementioned entities or a morphological prediction can be made based on the knowledge of the fusion partner alone. In contrast, TGFBR3‐PLAG1 fusion has been specifically described and characterized as an oncogenic driver in MECA, and less common in MECA ex PA. Here, we describe the clinicopathological features of three TGFBR3‐PLAG1 fusion‐positive salivary gland neoplasms, all of which arose in the deep lobe of the parotid gland. Histopathology showed high morphological similarities, encompassing encapsulation, a polylobular growth pattern, bland basaloid and oncocytoid cells with myoepithelial differentiation, and a distinct sclerotic background. All cases showed at least limited, unusual foci of minimal invasion into adjacent salivary gland tissue, including one case with ERBB2 (Her2/neu) amplified, TP53 mutated high‐grade transformation, and lymph node metastases. Of note, all cases illustrated focal ductal differentiation. Classification remains difficult, as morphological overlaps between myoepithelial‐rich cellular PA, myoepithelioma, and MECA were observed. However, evidence of minimal invasion advocates classification as low‐grade MECA. This case series further characterizes the spectrum of uncommon cellular myoepithelial neoplasms harboring TGFBR3‐PLAG1 fusion, which show recurrent minimal invasion of the adjacent salivary gland tissue, a predilection to the deep lobe of the parotid gland, and potential high‐grade transformation.

Setting a diagnostic benchmark for tumor BRCA testing: detection of BRCA1 and BRCA2 large genomic rearrangements in FFPE tissue - A pilot study

PARP inhibitors are used for treatment of tumors lacking function of the double-strand DNA break repair proteins BRCA1 or BRCA2 and are already approved for several cancer types. Thus, it is clinically crucial to determine germline as well as somatic BRCA1/2 mutations in those patients. The amplicon-based Oncomine BRCA1 and BRCA2 Assay is a test routinely used in diagnostics with FFPE specimens. The assay is validated for the detection of mutations, however, data on its performance in detecting large genomic rearrangements in FFPE tissue, is scarce. We cross-validated Oncomine BRCA1 and BRCA2 Assay in blood samples and/or FFPE tissue with multiplex ligation-dependent probe amplification (MLPA) for exon deletions and with OncoScan and an in-house hybridization-based target capture assay (MelArray) with a customized pipeline for the detection of loss of heterozygosity (LOH) and heterozygous versus complete gene loss. The Oncomine BRCA1 and BRCA2 Assay could detect both exon deletion and mono- and bi-allelic losses of the BRCA1/2 genes. We show that the therapeutically relevant large genomic rearrangements are reliably detected with the amplicon-based Oncomine BRCA1 and BRCA2 Assay in FFPE tumor tissue. Based on our data, we suggest tumor BRCA testing as standard diagnostic prescreening prior to germline BRCA testing.

Who's Driving? Switch of Drivers in Immunotherapy-Treated Progressing Sinonasal Melanoma

Simple Summary

Here, we monitored the course of the disease and treatment of sinonasal melanoma patients. Since treatment options are rare, immunotherapy is often the treatment of choice. However, intrinsic or acquired resistance to treatment may occur. We assessed the mutational status of the tumors and metastases during the course of therapy and recognized a switch of the oncogenic drivers to mutant NRAS in progressing disease. As a switch of drivers (other than the addition of a second driver) has not been reported yet, longitudinal molecular testing and the awareness of molecular heterogeneity of sinonasal melanoma is crucial.

Abstract

Mucosal melanoma can be driven by various driver mutations in genes such as NRAS, KIT, or KRAS. However, some cases present with only weak drivers, or lacking known oncogenic drivers, suggesting immunotherapy over targeted therapy. While resistance mechanisms to immunotherapy in cutaneous melanoma have been uncovered, including alterations in JAK1/2, B2M, or STK11, a switch of oncogenic drivers under immunotherapy has not yet been observed. We report three cases of metastatic sinonasal melanoma that switched oncogenic drivers from KRAS, KIT, or no driver to NRAS during or after immunotherapy, thereby showing progressive disease. One of the cases presented with three spatially separate driver mutations in the primary tumor, whereas the NRAS clone persisted under immunotherapy. In comparison, three different control cases receiving radiotherapy only did not show a change of the detectable molecular drivers in their respective recurrences or metastases. In summary, these data provide an important rationale for longitudinal molecular testing, based on evidence for an unforeseen recurrent event of molecular driver switch to NRAS in progressing sinonasal melanoma. These findings provide the basis for further studies on a potential causal relation of emerging NRAS mutant clones and immunotherapy.

Clinical and Molecular Features of Skin Malignancies in Muir-Torre Syndrome

BACKGROUND

We investigated the mutational landscape of skin tumors in patients with Muir-Torre Syndrome (MTS) a hereditary autosomal dominant mismatch repair disorder of increased cancer susceptibility, and examined mutations other than in the DNA mismatch repair (MMR) genes.

METHODS

This retrospective single-center case series included seven patients with the diagnosis of Muir-Torre Syndrome with precise medical history and family history. Mutational analysis of tumor samples Formalin-fixed paraffin-embedded tissue blocks of skin lesions associated with Muir-Torre Syndrome were used for further analysis. All skin tumors were analyzed with the Oncomine Comprehensive Assay v3 (Life Technologies), which includes 161 of the most relevant cancer driver genes.

RESULTS

Eleven skin neoplasms (nine sebaceous tumors, one melanoma, one cutaneous squamous cell carcinoma) were diagnosed in seven patients. In two patients, visceral malignancies preceded the diagnosis of the skin tumors and one patient was diagnosed with a visceral malignancy after a sebaceous tumor. History of familial cancer of Lynch Syndrome (LS) was reported in three patients. The most frequently detected mutation was in the MSH2 gene, followed by mutations in the NOTCH1/2 and TP53 gene. Conclusion, this study provides a molecular analysis of Muir-Torre Syndrome associated and non-associated skin tumors in patients with Muir-Torre Syndrome. Patients with sebaceous lesions should undergo microsatellite instability analysis and accurate evaluation of personal and family history to detect a possible Muir-Torre syndrome. As secondary malignancies may appear years after the first occurrence of sebaceous tumors, lifelong screening is mandatory.

Sequential somatic mutations upon secondary anti-HER2 treatment resistance in metastatic ERBB2S310F mutated extramammary Paget's disease

Metastatic extramammary Paget’s disease is a rare adenocarcinoma with poor prognosis. Several reports of human epidermal growth factor receptor 2 alterations point to its pathogenic role in the disease. However, the occurrence of treatment resistance to anti-HER2 therapy demand the need for further knowledge. We report of a patient with metastatic penoscrotal extramammary Paget’s disease, with an ERBB2^S310F mutation, in which near complete response was achieved upon treatment with trastuzumab and carboplatin. However, after 10 cycles of trastuzumab and carboplatin, widespread metastasis re-occurred. Analysis of a newly developing metastasis revealed additional genomic alterations including ERBB3^A232V and PIK3CA^G106V point mutations as well as MET and CDK6 amplification, providing a potential mechanism of acquired treatment resistance. Therefore, ERBB family inhibitor afatinib was initiated. Unfortunately, the patient succumbed to disease-related complications shortly after treatment initiation. This is the first report of ERBB2^S310F mutated, metastatic extramammary Paget’s disease with secondary resistance to trastuzumab / carboplatin, potentially due to additional acquired genomic alterations. This case contributes to the growing evidence of HER2 in the pathogenesis of metastatic extramammary Paget’s disease and emphasizes the importance of repetitive, genomic analysis in rare diseases.

Morpho-Molecular Assessment Indicates New Prognostic Aspects and Personalized Therapeutic Options in Sinonasal Melanoma

Sinonasal melanoma is a rare subtype of melanoma and little is known about its molecular fingerprint. Systemic treatment options are limited, as targetable BRAF mutations are rare compared to cutaneous melanoma. Currently, metastatic sinonasal melanoma is being treated according to the guidelines of cutaneous melanoma. In this study, we investigated the molecular profile of 19 primary sinonasal melanomas, using a novel customized melanoma-specific next generation sequencing (NGS) panel (MelArray) of 190 genes. Results were correlated to histological and clinical features to further characterize this rare, aggressive type of melanoma and screen for prognostic markers and possible treatment options. Molecular profiles encompassed predominantly mutations in NRAS (25%), whereas KIT or BRAF p.V600 mutations were not detected. Tumor mutational burden was overall low. High level of copy number variations (CNVs) were associated with alterations in DNA-repair genes and shorter distant metastasis-free survival (p = 0.005). Monomorphic (vs. pleomorphic) morphology was found to be significantly associated with worse disease-specific survival (p < 0.001), however no correlation between morphology and molecular aberrations was found. A variety of alterations in different pathways were detected, justifying molecular testing and opening potential personalized treatment options in current study or compassionate use settings.

New Insights into Tumor Heterogeneity: A Case of Solid-Oncocytic Epithelial-Myoepithelial Carcinoma of the Parotid Gland Harboring a HRAS and Heterogeneous Terminating ARID1A Mutation

Epithelial-myoepithelial carcinoma (EMC) can be a challenging diagnosis due to a lack of obvious invasion and bland cytology. We report an unusual case of a low-grade EMC with prominent fibrous stroma, an extensive solid-oncocytic differentiation and limited areas of morphological clearly identifiable characteristic biphasic (tubular) differentiation, clear cells and PAS-positive secretions/calcifications. Both areas were investigated by next generation sequencing (Oncomine comprehensive assay) and revealed a typical concordant HRAS p.Q61R mutation. An additional heterogeneous ARID1A (p.E672*) terminating mutation with loss of heterozygosity, which could be visualized predominantly in the solid-oncocytic differentiation by immunohistochemical loss of ARID1A protein expression, was found. This is the first case of an EMC of the salivary gland to be described with two separate tumor clones involving concordant HRAS and heterogeneous ARID1A mutations. The latter seem to be a "second hit" and was predominantly found in the solid-oncocytic differentiation, suggesting a potential morpho-molecular association.

Proteomic identification of a marker signature for MAPKi resistance in melanoma

MAPK inhibitors (MAPKi) show outstanding clinical response rates in melanoma patients harbouring BRAF mutations, but resistance is common. The ability of melanoma cells to switch from melanocytic to mesenchymal phenotypes appears to be associated with therapeutic resistance. High-throughput, subcellular proteome analyses and RNAseq on two panels of primary melanoma cells that were either sensitive or resistant to MAPKi revealed that only 15 proteins were sufficient to distinguish between these phenotypes. The two proteins with the highest discriminatory power were PTRF and IGFBP7, which were both highly upregulated in the mesenchymal-resistant cells. Proteomic analysis of CRISPR/Cas-derived PTRF knockouts revealed targets involved in lysosomal activation, endocytosis, pH regulation, EMT, TGFβ signalling and cell migration and adhesion, as well as a significantly reduced invasive index and ability to form spheres in 3D culture. Overexpression of PTRF led to MAPKi resistance, increased cell adhesion and sphere formation. In addition, immunohistochemistry of patient samples showed that PTRF expression levels were a significant biomarker of poor progression-free survival, and IGFBP7 levels in patient sera were shown to be higher after relapse.

[Benefits of Molecular Analyses in Thyroid Carcinoma]

Benefits of Molecular Analyses in Thyroid Carcinoma Abstract. The widespread access to neck ultrasonography has led to high detection rates of thyroid nodules, whose vast majority will remain clinically silent. In daily practice it is a challenge to filter out the thyroid nodules that require medical attention. This is usually achieved by a combination of sonomorphologic criteria and fine-needle aspiration cytology. In recent years, there is a trend toward deescalation in diagnostic and therapeutic measures for thyroid nodules. Some authors even advocate active surveillance instead of surgical approaches for very low-risk thyroid carcinoma. This approach requires an accurate assessment of the malignant potential of each thyroid nodule. As recent studies have allowed better understanding of molecular pathogenesis of thyroid cancer, the mutational profile of thyroid nodules has emerged as a new tool for assessment of thyroid nodules. Its exact clinical application in daily routine remains, however, unclear.

SMAD signaling promotes melanoma metastasis independently of phenotype switching

The development of metastatic melanoma is thought to require the dynamic shifting of neoplastic cells between proliferative and invasive phenotypes. Contrary to this conventional "phenotype switching" model, we now show that disease progression can involve malignant melanoma cells simultaneously displaying proliferative and invasive properties. Using a genetic mouse model of melanoma in combination with in vitro analyses of melanoma cell lines, we found that conditional deletion of the downstream signaling molecule Smad4, which abrogates all canonical TGF-β signaling, indeed inhibits both tumor growth and metastasis. Conditional deletion of the inhibitory signaling factor Smad7, however, generated cells that are both highly invasive and proliferative, indicating that invasiveness is compatible with a high proliferation rate. In fact, conditional Smad7 deletion led to sustained melanoma growth and at the same time promoted massive metastasis formation, a result consistent with data indicating that low SMAD7 levels in patient tumors are associated with a poor survival. Our findings reveal that modulation of SMAD7 levels can overcome the need for phenotype switching during tumor progression and may thus represent a novel therapeutic target in metastatic disease.

Microcrystalline Tyrosine and Aluminum as Adjuvants in Allergen-Specific Immunotherapy Protect from IgE-Mediated Reactivity in Mouse Models and Act Independently of Inflammasome and TLR Signaling

Allergen immunotherapy (AIT) is the only modality that can modify immune responses to allergen exposure, but therapeutic coverage is low. One strategy to improve AIT safety and efficacy is the use of new or improved adjuvants. This study investigates immune responses produced by microcrystalline tyrosine (MCT)–based vaccines as compared with conventional aluminum hydroxide (alum). Wild-type, immune-signaling–deficient, and TCR-transgenic mice were treated with different Ags (e.g., OVA and cat dander Fel d 1), plus MCT or alum as depot adjuvants. Specific Ab responses in serum were measured by ELISA, whereas cytokine secretion was measured both in culture supernatants by ELISA or by flow cytometry of spleen cells. Upon initiation of AIT in allergic mice, body temperature and further clinical signs were used as indicators for anaphylaxis. Overall, MCT and alum induced comparable B and T cell responses, which were independent of TLR signaling. Alum induced stronger IgE and IL-4 secretion than MCT. MCT and alum induced caspase-dependent IL-1β secretion in human monocytes in vitro, but inflammasome activation had no functional effect on inflammatory and Ab responses measured in vivo. In sensitized mice, AIT with MCT-adjuvanted allergens caused fewer anaphylactic reactions compared with alum-adjuvanted allergens. As depot adjuvants, MCT and alum are comparably effective in strength and mechanism of Ag-specific IgG induction and induction of T cell responses. The biocompatible and biodegradable MCT seems therefore a suitable alternative adjuvant to alum-based vaccines and AIT.

Co-existence of BRAF and NRAS driver mutations in the same melanoma cells results in heterogeneity of targeted therapy resistance

Acquired chemotherapeutic resistance of cancer cells can result from a Darwinistic evolution process in which heterogeneity plays an important role. In order to understand the impact of genetic heterogeneity on acquired resistance and second line therapy selection in metastatic melanoma, we sequenced the exomes of 27 lesions which were collected from 3 metastatic melanoma patients treated with targeted or non-targeted inhibitors. Furthermore, we tested the impact of a second NRAS mutation in 7 BRAF inhibitor resistant early passage cell cultures on the selection of second line therapies.We observed a rapid monophyletic evolution of melanoma subpopulations in response to targeted therapy that was not observed in non-targeted therapy. We observed the acquisition of NRAS mutations in the BRAF mutated patient treated with a BRAF inhibitor in 1 of 5 of his post-resistant samples. In an additional cohort of 5 BRAF-inhibitor treated patients we detected 7 NRAS mutations in 18 post-resistant samples. No NRAS mutations were detected in pre-resistant samples. By sequencing 65 single cell clones we prove that NRAS mutations co-occur with BRAF mutations in single cells. The double mutated cells revealed a heterogeneous response to MEK, ERK, PI3K, AKT and multi RTK - inhibitors.We conclude that BRAF and NRAS co-mutations are not mutually exclusive. However, the sole finding of double mutated cells in a resistant tumor is not sufficient to determine follow-up therapy. In order to target the large pool of heterogeneous cells in a patient, we think combinational therapy targeting different pathways will be necessary.

Targeted next-generation-sequencing for reliable detection of targetable rearrangements in lung adenocarcinoma-a single center retrospective study

Oncogenic rearrangements leading to targetable gene fusions are well-established cancer driver events in lung adenocarcinoma. Accurate and reliable detection of these gene fusions is crucial to select the appropriate targeted therapy for each patient. We compared the targeted next-generation-sequencing Oncomine Focus Assay (OFA; Thermo Fisher Scientific) with conventional ALK FISH and anti-Alk immunohistochemistry in a cohort of 52 lung adenocarcinomas (10 ALK rearranged, 18 non-ALK rearranged, and 24 untested cases). We found a sensitivity and specificity of 100% for detection of ALK rearrangements using the OFA panel. In addition, targeted next generation sequencing allowed us to analyze a set of 23 driver genes in a single assay. Besides EML4-ALK (11/52 cases), we detected EZR-ROS1 (1/52 cases), KIF5B-RET (1/52 cases) and MET-MET (4/52 cases) fusions. All EML4-ALK, EZR-ROS1 and KIF5B-RET fusions were confirmed by multiplexed targeted next generation sequencing assay (Oncomine Solid Tumor Fusion Transcript Kit, Thermo Fisher Scientific). All cases with EML4-ALK rearrangement were confirmed by Alk immunohistochemistry and all but one by ALK FISH. In our experience, targeted next-generation sequencing is a reliable and timesaving tool for multiplexed detection of targetable rearrangements. Therefore, targeted next-generation sequencing represents an efficient alternative to time-consuming single target assays currently used in molecular pathology.

TLR4 as a negative regulator of keratinocyte proliferation

TLR4 is an innate immune receptor with expression in human skin, keratinocytes as well as squamous cell carcinoma (SCC) of the skin. In the present study we investigate the role of TLR4 as a negative regulator of keratinocyte proliferation. We present here that the expression of TLR4 increased with the differentiation of cultured keratinocytes in a passage-dependent manner or under calcium-rich conditions. Moreover, the down-regulation of TLR4 by specific knockdown increased the proliferation of HaCaT keratinocytes in vitro. In addition, subcutaneously injected HaCaT keratinocytes with shTLR4 formed growing tumors in nude mice. In contrast, we observed lower proliferation and increased migration in vitro of the SCC13 cell line stably overexpressing TLR4 in comparison to SCC13 TLR4 negative cells. In vivo, SCC13 TLR4-overexpressing tumors showed delayed growth in comparison to TLR4 negative tumors. The overexpression of TLR4 in SCC13 tumor cells was followed by phosphorylation of ERK1/2 and JNK and increased expression of ATF3. In gene expression arrays, the overexpression of TLR4 in tumor cells correlated with gene expression of ATF-3, IL-6, CDH13, CXCL-1 and TFPI. In summary, TLR4 negatively regulates the proliferation of keratinocytes and its overexpression reduces tumor growth of SCC cells.

CYFIP1 is directly controlled by NOTCH1 and down-regulated in cutaneous squamous cell carcinoma

Squamous cell carcinoma of the skin (SCC) represents one of the most common cancers in the general population and is associated with a substantial risk of metastasis. Previous work uncovered the functional role of CYFIP1 in epithelial tumors as an invasion inhibitor. It was down-regulated in some cancers and correlated with the metastatic properties of these malignant cells. We investigated its role and expression mechanisms in SCC. We analyzed the expression of CYFIP1 in patient derived SCC, primary keratinocytes and SCC cell lines, and correlated it to the differentiation and NOTCH1 levels. We analyzed the effects of Notch1 manipulation on CYFIP1 expression and confirmed the biding of Notch1 to the CYFIP1 promoter. CYFIP1 expression was down-regulated in SCC and correlated inversely with histological differentiation of tumors. As keratinocyte differentiation depends on Notch1 signaling, we investigated the influence of Notch1 on CYFIP1 expression. CYFIP1 mRNA was highly increased in human Notch1-overexpressing keratinocytes. Further manipulation of the Notch1 pathway in keratinocytes impacted CYFIP1 levels and chromatin immunoprecipitation assay confirmed the direct binding of Notch1 to the CYFIP1 promoter. CYFIP1 may be a link between loss of differentiation and invasive potential in malignant keratinocytes of cutaneous squamous cell carcinoma.

Ingenol Mebutate Signals via PKC/MEK/ERK in Keratinocytes and Induces Interleukin Decoy Receptors IL1R2 and IL13RA2

Squamous cell carcinoma (SCC) is the second most common human skin cancer and the second leading cause of skin cancer-related death. Recently, a new compound, ingenol mebutate, was approved for treatment of actinic keratosis, a precursor of SCC. As the mechanism of action is poorly understood, we have further investigated the mechanism of ingenol mebutate-induced cell death. We elucidate direct effects of ingenol mebutate on primary keratinocytes, patient-derived SCC cells, and a SCC cell line. Transcriptional profiling followed by pathway analysis was performed on ingenol mebutate-treated primary keratinocytes and patient-derived SCC cells to find key mediators and identify the mechanism of action. Activation of the resulting pathways was confirmed in cells and human skin explants and supported by a phosphorylation screen of treated primary cells. The necessity of these pathways was demonstrated by inhibition of certain pathway components. Ingenol mebutate inhibited viability and proliferation of all keratinocyte-derived cells in a biphasic manner. Transcriptional profiling identified the involvement of PKC/MEK/ERK signaling in the mechanism of action and inhibition of this signaling pathway rescued ingenol mebutate-induced cell death after treatment with 100 nmol/L ingenol mebutate, the optimal concentration for the first peak of response. We found the interleukin decoy receptors IL1R2 and IL13RA2 induced by ingenol mebutate in a PKC/MEK/ERK-dependent manner. Furthermore, siRNA knockdown of IL1R2 and IL13RA2 partially rescued ingenol mebutate-treated cells. In conclusion, we have shown that ingenol mebutate-induced cell death is mediated through the PKCδ/MEK/ERK pathway, and we have functionally linked the downstream induction of IL1R2 and IL13RA2 expression to the reduced viability of ingenol mebutate-treated cells.

S100A8/A9 stimulates keratinocyte proliferation in the development of squamous cell carcinoma of the skin via the receptor for advanced glycation-end products

Squamous cell carcinoma (SCC) is the most common neoplasm in organ transplant recipients (OTR) on long-term immunosuppression and occurs 60- to 100-fold more frequently than in the general population. Here, we present the receptor for advanced glycation end products (RAGE) and S100A8/A9 as important factors driving normal and tumor keratinocyte proliferation. RAGE and S100A8/A9 were transcriptionally upregulated in SCC compared to normal epidermis, as well as in OTR compared to immunocompetent patients (IC) with SCC. The proliferation of normal and SCC keratinocytes was induced by exposure to exogenous S100A8/A9 which in turn was abolished by blocking of RAGE. The migratory activities of normal and SCC keratinocytes were also increased upon exposure to S100A8/A9. We demonstrated that exogenous S100A8/A9 induces phosphorylation of p38 and SAPK/JNK followed by activation of ERK1/2. We hypothesize that RAGE and S100A8/A9 contribute to the development of human SCC by modulating keratinocyte growth and migration. These processes do not seem to be impaired by profound drug-mediated immunosuppression in OTR.

The oncogene ATF3 is potentiated by cyclosporine A and ultraviolet light A

Cutaneous squamous cell carcinoma (SCC) represents the most important cutaneous complication following organ transplantation. It develops mostly on sun-exposed areas. A recent study showed the role of activating transcription factor 3 (ATF3) in SCC development following treatment with calcineurin inhibitors. It has been reported that ATF3, which may act as an oncogene, is under negative calcineurin/nuclear factor of activated T cells (NFAT) control and is upregulated by calcineurin inhibitors. Still, these findings do not fully explain the preferential appearance of SCC on chronically sun-damaged skin. We analyzed the influence of UV radiation on ATF3 expression and its potential role in SCC development. We found that ATF3 is a specifically induced AP1 member in SCC of transplanted patients. Its expression was strongly potentiated by combination of cyclosporine A and UVA treatment. UVA induced ATF3 expression through reactive oxygen species-mediated nuclear factor erythroid 2-related factor 2 (NRF2) activation independently of calcineurin/NFAT inhibition. Activated NRF2 directly binds to ATF3 promoter, thus inducing its expression. These results demonstrate two mechanisms that independently induce and, when combined together, potentiate the expression of ATF3, which may then force SCC development. Taking into account the previously defined role of ATF3 in the SCC development, these findings may provide an explanation and a mechanism for the frequently observed burden on SCCs on sun-exposed areas of the skin in organ transplant recipients treated by calcineurin inhibitors.