A Preclinical Model of Cutaneous Melanoma Based on Reconstructed Human Epidermis

Malignant melanoma is among the tumor entities with the highest increase of incidence worldwide. To elucidate melanoma progression and develop new effective therapies, rodent models are commonly used. While these do not adequately reflect human physiology, two-dimensional cell cultures lack crucial elements of the tumor microenvironment. To address this shortcoming, we have developed a melanoma skin equivalent based on an open-source epidermal model. Melanoma cell lines with different driver mutations were incorporated into these models forming distinguishable tumor aggregates within a stratified epidermis. Although barrier properties of the skin equivalents were not affected by incorporation of melanoma cells, their presence resulted in a higher metabolic activity indicated by an increased glucose consumption. Furthermore, we re-isolated single cells from the models to characterize the proliferation state within the respective model. The applicability of our model for tumor therapeutics was demonstrated by treatment with a commonly used v-raf murine sarcoma viral oncogene homolog B (BRAF) inhibitor vemurafenib. This selective BRAF inhibitor successfully reduced tumor growth in the models harboring BRAF-mutated melanoma cells. Hence, our model is a promising tool to investigate melanoma development and as a preclinical model for drug discovery.

Tracking of Melanoma Cell Plasticity by Transcriptional Reporters

Clonal evolution and cellular plasticity are the genetic and non-genetic driving forces of tumor heterogeneity that in turn determines the tumor cell response towards therapeutic drugs. Several lines of evidence suggest that therapeutic interventions foster the selection of drug resistant neural crest stem-like cells (NCSCs) that establish minimal residual disease (MRD) in melanoma. Here we established a dual reporter system enabling the tracking of NGFR expression and mRNA stability, providing insights into the maintenance of NCSC-states. We observed that the transcriptional reporter that contained a 1kb fragment of the human NGFR promoter was activated only in a minor subset (0.72±0.49%, range 0.3-1.5) and ~2-4% of A375 melanoma cells revealed stable NGFR mRNA. The combination of both reporters provided insights into phenotype switching and revealed that both cellular subsets gave rise to cellular heterogeneity. Moreover, whole transcriptome profiling and gene set enrichment analysis (GSEA) of the minor cellular subset revealed hypoxia-associated programs that might serve as potential drivers of an in vitro switching of NGFR-associated phenotypes and relapse of post-BRAF inhibitor treated tumors. Concordantly, we observed that the minor cellular subset increased in response to dabrafenib over time. In summary, our reporter-based approach provided insights into plasticity and identified a cellular subset that might be responsible for the establishment of MRD in melanoma.

Nuclear Localization of BRAFV600E Is Associated with HMOX-1 Upregulation and Aggressive Behavior of Melanoma Cells

Background: Previously, we have demonstrated that nuclear BRAFV600E is associated with melanoma aggressiveness and vemurafenib resistance. However, the underlying mechanisms of how nuclear localization of BRAFV600E promotes cell aggressiveness have not yet been investigated. Despite therapeutic advancements targeting cutaneous melanoma, unknown cellular processes prevent effective treatment for this malignancy, prompting an urgent need to identify new biological targets. This study aims to explore the association of inducible heme oxygenase 1 (HMOX-1) with nuclear BRAFV600E in promoting melanoma aggressiveness. Methods: Proteomics analysis was performed to identify the interacting partner(s) of nuclear BRAFV600E. Immunohistochemistry was applied to evaluate the levels of HMOX-1 and nuclear BRAFV600E expression in melanoma and adjacent healthy tissues. Immunofluorescence assessed the nuclear localization of BRAFV600E in vemurafenib-resistant A375R melanoma cells. Further study of HMOX-1 knockdown or BRAFV600E overexpression in melanoma cells suggested a role for HMOX-1 in the regulation of cell proliferation in vivo and in vitro. Finally, Western blot analysis was performed to confirm the pathway by which HMOX-1 mediates Akt signaling. Results: Proteomics results showed that HMOX-1 protein expression was 10-fold higher in resistant A375R cells compared to parental counterpart cells. In vitro and in vivo results illustrate that nuclear BRAFV600E promotes HMOX-1 overexpression, whereas HMOX-1 reduction represses melanoma cell proliferation and tumor growth. Mechanistic studies revealed that HMOX-1 was associated with nuclear BRAFV600E localization, thus promoting melanoma proliferation via a persistent activation of the AKT pathway. Conclusions: Our results highlight a previously unknown mechanism in which the nuclear BRAFV600E/HMOX-1/AKT axis plays an essential role in melanoma cell proliferation. Targeting HMOX-1 could be a novel method for treating melanoma patients who develop BRAF inhibitor resistance.

Tracking of Melanoma Cell Plasticity by Transcriptional Reporters

Clonal evolution and cellular plasticity are the genetic and non-genetic driving forces of tumor heterogeneity that in turn determines the tumor cell response towards therapeutic drugs. Sever-al lines of evidence suggest that therapeutic interventions foster the selection of drug resistant neural crest stem-like cells (NCSCs) that establish minimal residual disease (MRD) in melano-ma. Here we established a dual reporter system enabling the tracking of NGFR expression and mRNA stability, providing insights into the maintenance of NCSC-states. We observed that the transcriptional reporter that contained a 1kb fragment of the human NGFR promoter was acti-vated only in a minor subset (0.72±0.49%, range 0.3-1.5) and ~2-4% of A375 melanoma cells re-vealed stable NGFR mRNA. The combination of both reporters provided insights into pheno-type switching and revealed that both cellular subsets gave rise to cellular heterogeneity. Moreover, whole transcriptome profiling and gene set enrichment analysis (GSEA) of the minor cellular subset revealed hypoxia-associated genes serving as potential drivers of a NGFR-associated phenotype switching in vitro and in relapsed, post-BRAF inhibitor treated tu-mors. Concordantly, we observed that the minor cellular subset increased in response to dabrafenib over time. In summary, our reporter-based approach provided insights into plastici-ty and identified a cellular subset that might be responsible for the establishment of MRD in melanoma.

A case report of anaplastic thyroid cancer and papillary thyroid cancer lymph node metastasis: An unusual presentation as an invasive hypopharyngeal mass

Anaplastic thyroid carcinoma is a rare undifferentiated tumour of the thyroid follicular epithelium. It almost always develops from a pre-existing well-differentiated thyroid cancer with a co-existent thyroid malignancy varying from 5-17% . The co-existence of papillary thyroid cancer (PTC) with anaplastic thyroid cancer is a rare occurrence in metastases outside the primary thyroid lesion. Traditionally, this has been regarded as an aggressive form of cancer associated with a dismal prognosis. Recently the focus has shifted to the development of novel therapies based on the availability of comprehensive genomic profiling platforms (CGP) with a rapid turn-around to identify molecular aberrations in tumours which acts as potential therapeutic targets. In the United Kingdom, we report the case of a 60-year old woman with an unusual presentation of (metastatic) ATC and concomitant papillary thyroid cancer metastasis within a contralateral lymph node. This was initially perceived as a left pyriform fossa mass involving and compressing her left hemi-larynx on clinical and radiological examination. Following the identification of BRAF V600E mutation on CGP, she was started on targeted therapy with the BRAF inhibitor dabrafenib and the MEK inhibitor trametinib and demonstrated excellent clinical and radiological response following 7 months of treatment. She has subsequently undergone total thyroidectomy alongside with bilateral neck dissection, and is due to start radio-active iodine treatment to reduce the risk of recurrence of disease.

Encorafenib plus binimetinib in patients with BRAFV600-mutant non-small cell lung cancer: Phase II PHAROS study design

BRAFV600 oncogenic driver mutations occur in 1–2% of non-small cell lung cancers (NSCLCs) and have been shown to be a clinically relevant target. Preclinical/clinical evidence support the efficacy and safety of BRAF and MEK inhibitor combinations in patients with NSCLC with these mutations. We describe the design of PHAROS, an ongoing, open-label, single-arm, Phase II trial evaluating the BRAF inhibitor encorafenib plus the MEK inhibitor binimetinib in patients with metastatic BRAFV600-mutant NSCLC, as first- or second-line treatment. The primary endpoint is objective response rate, based on independent radiologic review (per RECIST v1.1); secondary objectives evaluated additional efficacy endpoints and safety. Results from PHAROS will describe the antitumor activity/safety of encorafenib plus binimetinib in patients with metastatic BRAFV600-mutant NSCLC.

Dynamic transcriptome analysis reveals signatures of paradoxical effect of vemurafenib on human dermal fibroblasts

Background Vemurafenib (PLX4032) is one of the most frequently used treatments for late-stage melanoma patients with the BRAFV600E mutation; however, acquired resistance to the drug poses as a major challenge. It remains to be determined whether off-target effects of vemurafenib on normal stroma components could reshape the tumor microenvironment in a way that contributes to cancer progression and drug resistance. Methods By using temporally-resolved RNA- and ATAC-seq, we studied the early molecular changes induced by vemurafenib in human dermal fibroblast (HDF), a main stromal component in melanoma and other tumors with high prevalence of BRAFV600 mutations. Results Transcriptomics analyses revealed a stepwise up-regulation of proliferation signatures, together with a down-regulation of autophagy and proteolytic processes. The gene expression changes in HDF strongly correlated in an inverse way with those in BRAFV600E mutant malignant melanoma (MaMel) cell lines, consistent with the observation of a paradoxical effect of vemurafenib, leading to hyperphosphorylation of MEK1/2 and ERK1/2. The transcriptional changes in HDF were not strongly determined by alterations in chromatin accessibility; rather, an already permissive chromatin landscape seemed to facilitate the early accessibility to MAPK/ERK-regulated transcription factor binding sites. Combinatorial treatment with the MEK inhibitor trametinib did not preclude the paradoxical activation of MAPK/ERK signaling in HDF. When administered together, vemurafenib partially compensated for the reduction of cell viability and proliferation induced by trametinib. These paradoxical changes were restrained by using the third generation BRAF inhibitor PLX8394, a so-called paradox breaker compound. However, the advantageous effects on HDF during combination therapies were also lost. Conclusions Vemurafenib induces paradoxical changes in HDF, enabled by a permissive chromatin landscape. These changes might provide an advantage during combination therapies, by compensating for the toxicity induced in stromal cells by less specific MAPK/ERK inhibitors. Our results highlight the relevance of evaluating the effects of the drugs on non-transformed stromal components, carefully considering the implications of their administration either as mono- or combination therapies.

The role of a new ALK isoform in the diagnosis and targeted therapy of skin melanoma

Contemporary discoveries of fundamental science in recent decades in the field of oncology have led to the emergence of new highly effective anticancer drugs: targeted drugs and immune checkpoint inhibitors, use of which has made a breakthrough in the treatment of oncological diseases, including skin melanoma. Melanoma is still one of the most cancerous tumors. The number of patients resistant to targeted therapy and immunotherapy increases in the world every year. Oncologists have practically no leverage to influence the disease after the development of resistance to this type of therapy. In this regard, scientists around the world are looking for new application points for targeted drugs. Nowadays, the most common treatment method is BRAF inhibitors, since the BRAF mutation is detected in 40–60 % of patients with skin melanoma. However, the resistance to BRAF inhibitor therapy occur in half cases after 6–8 months. To overcome the resistance to the target therapy is one the most important issue, the studying of new isoform of anaplastic lymphoma kinase (ALK) may help to solve this problem.Purpose of the study – to order the data of the leading researchers of a new isoform of ALK, and reveal the most promising directions for its further progress.In the article, there are comparisons and analyses the 6 of the largest studies over the past 5 years devoted to a new isoform of ALK.The joint inhibition of the new ALK isoform and BRAFV600 showed positive results in several studies with different levels of ALKATI expression (alternative initiation of ALK transcription). The new ALK isoform can stimulate oncogenesis only within a certain “threshold” level of expression. Immunohistochemical examination cannot be the main method for determining the expression of a new ALK isoform due to low sensitivity. In almost all studies, tumors with ALK translocation responded to therapy with ALK inhibitors.Even though that the role of the new ALK isoform has been studied in recent years, the optimal method for evaluating the expression of ALKATI in routine practice has not yet been determined. Additional studies are also needed to understand the effectiveness of the use of ALК inhibitors in combination with BRAF and ERK inhibitors. Of interest is the blockade of extracellular vesicles and the study of the role of interleukin-3 in the inhibition of ALKATI.

Nachweis der BRAF-V600E-Mutation beim metastasierten kolorektalen Karzinom

ZusammenfassungRingversuche sind ein wichtiges Instrument zur Qualitätssicherung. Dies betrifft in zunehmendem Maße auch die molekulare Diagnostik in der Pathologie, von deren Ergebnissen Therapieentscheidungen in der Präzisionsonkologie direkt abhängen. Beim metastasierten kolorektalen Karzinom (mKRK) stand bisher der Nachweis von KRAS-und NRAS-Mutationen im Vordergrund, deren Abwesenheit eine Therapie mit EGFR-blockierenden Antikörpern ermöglicht. Nun ist BRAF als weiterer prädiktiver Marker hinzugekommen, da mKRK Patienten mit einer BRAF-V600E-Mutation nach systemischer Vortherapie von einer Behandlung mit Encorafenib (einem BRAF-Inhibitor) in Kombination mit Cetuximab (Anti-EGFR-Antikörper) profitieren. Aufgrund der 2020 erfolgten Zulassung für diese Behandlung ist es wichtig, dass der diagnostische Nachweis einer BRAF-V600E-Mutation zuverlässig in den Pathologien durchgeführt werden kann. Daher wurde dieser Ringversuch durchgeführt, bei dem der Nachweis der BRAF-V600E-Mutation entweder mittels Immunhistochemie oder molekularer Verfahren erfolgen konnte. Die Ergebnisse des Ringversuchs belegen eindeutig, dass derzeit die molekulare BRAF-V600E-Bestimmung dem immunhistologischen Nachweis überlegen ist.