TERT promoter mutations are associated with longer progression-free and overall survival in patients with BRAF-mutant melanoma receiving BRAF and MEK inhibitor therapy

BRAF mutations and concurrent alterations in patients with soft tissue sarcoma

BRAF alterations, including V600E and non-V600E mutations and fusions, in soft tissue sarcoma (STS) have been identified in a limited case series. Here, we aimed to evaluate the frequency of BRAF mutations and concurrent alterations in STS to understand their therapeutic action. In this retrospective analysis, we included data from 1964 patients with advanced STS who underwent comprehensive genomic profiling tests at hospitals in Japan between June 2019 and March 2023. The prevalence of BRAF and recurrent concurrent gene alterations were also investigated. BRAF mutations were detected in 24 (1.2%) of 1964 STS patients, with a median age of 47 (range 1-69) years. BRAF V600E was detected in 11 (0.6%) of the 1964 patients with STS, BRAF non-V600E mutations in 9 (4.6%), and BRAF fusions were detected in 4 (0.2%). BRAF V600E was identified in 4 (0.2%) cases of malignant peripheral nerve sheath tumors. The most common concurrent alteration was CDKN2A (11 cases, 45.8%), and the frequency was equivalent to that of the BRAF V600E (5/11 cases, 45.5%) and non-V600E (5/9 cases, 55.6%) groups. Recurrent concurrent alterations, such as TERT promoter mutations (7 cases, 29.2%), were detected at the same frequency in the V600E and non-V600E groups. In contrast, TP53 alterations (4/9 cases, 44.4%) and mitogen-activated protein kinase (MAPK)-activating genes, including NF1, GNAQ, and GNA11 (3/9 cases, 33.3%), were identified as relatively higher in the non-V600E group than in the V600E group (each 1/11 case, 9.1%). We identified BRAF alterations at a rate of 1.2% in all patients with advanced STS. Among them, BRAF V600E and BRAF fusions account for 45.8% and 16.7%, respectively. Collectively, our findings support the clinical characteristics and therapeutic strategies for patients with BRAF-altered advanced STS.

BRAF Mutations in Melanoma: Biological Aspects, Therapeutic Implications, and Circulating Biomarkers

Melanoma is an aggressive form of skin cancer resulting from the malignant transformation of melanocytes. Recent therapeutic approaches, including targeted therapy and immunotherapy, have improved the prognosis and outcome of melanoma patients. BRAF is one of the most frequently mutated oncogenes recognised in melanoma. The most frequent oncogenic BRAF mutations consist of a single point mutation at codon 600 (mostly V600E) that leads to constitutive activation of the BRAF/MEK/ERK (MAPK) signalling pathway. Therefore, mutated BRAF has become a useful target for molecular therapy and the use of BRAF kinase inhibitors has shown promising results. However, several resistance mechanisms invariably develop leading to therapeutic failure. The aim of this manuscript is to review the role of BRAF mutational status in the pathogenesis of melanoma and its impact on differentiation and inflammation. Moreover, this review focuses on the mechanisms responsible for resistance to targeted therapies in BRAF-mutated melanoma and provides an overview of circulating biomarkers including circulating tumour cells, circulating tumour DNA, and non-coding RNAs.

pTERT C250T mutation: A potential biomarker of poor prognosis in metastatic melanoma

Melanoma is the most aggressive form of skin cancer and the leading cause of death from cutaneous tumors. Several studies have associated alterations in the TERT promoter region (pTERT) with gene overexpression, aggressiveness and poor prognosis of the disease. The aim of this study was to clarify the role of pTERT molecular status in paired samples of primary melanoma and metastasis using tissue and plasma to establish a correlation with disease progression and survival. A total of 88 FFPE tissue samples from 53 patients with advanced melanoma were analyzed. Of these, 35 had paired samples. We also examined cfDNA samples from plasma of 25 patients. We detected a good correlation between primary tumors and metastases in pTERT mutation and methylation status. We were also able to identify pTERT mutations in plasma samples that correlated with mutational status in tissue samples. Interestingly, the C250T mutation was associated with worse survival and higher TERT mRNA expression, compared to the other most common mutation: C228T. In addition, hyper-methylation of the promoter region seems to be related to the progression of pTERT wild type (WT) patients. These results suggest that TERT gene alterations plays an important role during tumor progression, with the detection of the C250T mutation in tissue and plasma as a potential biomarker of poor prognosis in patients with advanced melanoma.

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.

BIBR1532 Affects Endometrial Cell Proliferation, Migration, and Invasion in Endometriosis via Telomerase Inhibition and MAPK Signaling

OBJECTIVES

The effect of telomerase inhibitor BIBR1532 on endometriotic cells was investigated to explore the inhibitory effect of targeting telomerase on endometriosis.

DESIGN

In vitro primary cell culture study. Participants/Materials: Primary endometrial cells derived from eutopic and ectopic endometrium in patients with endometriosis.

SETTING

The study was conducted in the university hospital.

METHODS

Paired eutopic and ectopic endometrial cells were collected from 6 patients from January 2018 to July 2021. A TRAP assay was performed to detect the telomerase activity of the cells. MTT, cell cycle, apoptosis, migration, and invasion assays were performed to study the inhibitory effect of BIBR1532. Enrichment analysis was performed to identify the key pathways involved in endometriosis progression and telomerase action. Then, Western blotting was used to investigate the expression of related proteins.

RESULTS

BIBR1532 treatment significantly inhibited the growth of eutopic and ectopic endometrial cells, with apoptosis and cell cycle signaling involved. Migration and invasion, important characteristics for the establishment of ectopic lesions, were also inhibited by BIBR1532. The MAPK signaling cascade, related to telomerase and endometriosis, was decreased in eutopic and ectopic endometrial stromal cells with the treatment of BIBR1532.

LIMITATIONS

The severe side effects of telomerase inhibitors might be the main obstacle to clinical application, so it is necessary to find better drug delivery methods in vivo.

CONCLUSIONS

The telomerase inhibitor BIBR1532 affects endometrial cell proliferation, migration, and invasion in endometriosis.

TERT expression is associated with metastasis from thin primaries, exhausted CD4+ T cells in melanoma and with DNA repair across cancer entities

Telomerase reverse transcriptase (TERT) promoter mutations occur frequently in cancer, have been associated with increased TERT expression and cell proliferation, and could potentially influence therapeutic regimens for melanoma. As the role of TERT expression in malignant melanoma and the non-canonical functions of TERT remain understudied, we aimed to extend the current knowledge on the impact of TERT promoter mutations and expression alterations in tumor progression by analyzing several highly annotated melanoma cohorts. Using multivariate models, we found no consistent association for TERT promoter mutations or TERT expression with the survival rate in melanoma cohorts under immune checkpoint inhibition. However, the presence of CD4+ T cells increased with TERT expression and correlated with the expression of exhaustion markers. While the frequency of promoter mutations did not change with Breslow thickness, TERT expression was increased in metastases arising from thinner primaries. As single-cell RNA-sequencing (RNA-seq) showed that TERT expression was associated with genes involved in cell migration and dynamics of the extracellular matrix, this suggests a role of TERT during invasion and metastasis. Co-regulated genes found in several bulk tumors and single-cell RNA-seq cohorts also indicated non-canonical functions of TERT related to mitochondrial DNA stability and nuclear DNA repair. This pattern was also evident in glioblastoma and across other entities. Hence, our study adds to the role of TERT expression in cancer metastasis and potentially also immune resistance.

TERT Expression Induces Resistance to BRAF and MEK Inhibitors in BRAF-Mutated Melanoma In Vitro

Because BRAF-mutated melanomas are addicted to the Mitogen Activated Protein Kinase (MAPK) pathway they show a high response rate to BRAF and MEK inhibitors. However, the clinical responses to these inhibitors are often short-lived with the rapid onset of resistance to treatment. Deciphering the molecular mechanisms driving resistance has been the subject of intense research. Recent in vitro and clinical data have suggested a link between expression of telomerase and resistance to targeted therapy in melanoma. TERT promoter mutations are the main mechanism for the continuous upregulation of telomerase in melanoma and co-occur frequently with BRAF alterations. To understand how TERT promoter mutations could be associated with resistance to targeted therapy in melanoma, we conducted translational and in vitro studies. In a cohort of V600E-BRAF-mutated melanoma patients, we showed that the TERT promoter mutation status and TERT expression tended to be associated with response to BRAF and MEK inhibitors. We demonstrated that TERT overexpression in BRAF-mutated melanoma cells reduced sensitivity to BRAF and MEK independently of TERT's telomer maintenance activity. Interestingly, inhibition of TERT reduced growth of BRAF-mutated melanoma including resistant cells. TERT expression in melanoma can therefore be a new biomarker for resistance to MAPK inhibitors as well as a novel therapeutic target.

Clinical and pathological characteristics of familial melanoma with germline TERT promoter variants

Around 10% of melanoma occur in patients with a suspected familial predisposition. TERT promoter mutations are the most common somatic hotspot mutations in human cancers. However, only two families with germline mutations have been identified to date. We present detailed histological, clinical and molecular pathologic analyses of affected patients and details of newly identified individuals in one of these previously reported families. TERT (NM_198253.3) Chr.5:1,295,161T>C (c.-57 T>C) promoter variants were detected in all melanoma-affected (n=18) and one non-diseased family member. Median age at diagnosis was 30 years (n=18, range 16-46 years, 2 unknown). While most primary melanoma arose on the upper extremities (n=7, 21%) and were superficial spreading melanoma (SSM, n=8, 24%), many primary melanoma also originated from non UV-exposed mucosal (n=2, 6%) and acral (n=4, 12%) locations. One SSM sample harboured a Chr.5:1,295,228C>T TERT promoter region in addition to the germline Chr.5:1,295,161T>C variant, arguing additional pathway activation can support tumor pathogenesis. Patients treated with BRAF inhibitor and/or immune checkpoint inhibition (ICI) showed responses, although of limited duration. One mucosal melanoma harboured both a KIT copy number gain and an activating c.1727 p.Leu576Pro mutation. Following modest response to ICI, subsequent KIT inhibitor (imatinib) therapy demonstrated an ongoing complete pathological response (currently 7 months).