[Uveal Melanoma: Molecular and Genetic Mechanisms of Development and Therapeutic Approaches].

Uveal melanoma (UM) is a neuroectodermal tumor that results from malignant transformation of melanocytes in the eye uvea, including the iris, the ciliary body, and the choroid. UM accounts for 5% of all melanoma cases and is extremely aggressive with half of the UM patients developing metastases within the first 1-2 years after tumor development. Molecular mechanisms of UM carcinogenesis are poorly understood, but are known to differ from those of skin melanoma. Activating mutations of the GNAQ and GNA11 genes, which code for the large G protein subunits Gq and G11, respectively, are found in 90% of UM patients. The Gaq/PKC/MAPK signaling pathway is a main signaling cascade that leads to the transformation of melanocytes of the uveal tract, and major regulators of the cascade provide targets for the development of drugs. Metastatic UM (MUM) is most often associated with mutations of BAP1, EIF1AX, GNA11, GNAQ, and SF3B1. A combination of a commercial expression test panel of 15 genes and a mutation panel of 7 genes, supplemented with data on the size of the primary tumor, is highly efficient in predicting the risk of metastasis. The risk of metastasis determines the choice of therapy and the patient follow-up regimen. However, no systemic therapy for MUM has been developed to date. New drugs undergoing clinical trials are mostly targeted drugs designed to inhibit the protein products of mutant genes or immunotherapeutic agents designed to stimulate the immune response against specific antigens. In addition to these approaches, potential therapeutic targets of epigenetic regulation of UM development are considered in the review.

Malignant blue melanoma.

Malignant blue melanomas (MBMs) arise from blue nevi and all related intradermal melanocytic proliferations. They harbor specific, mutually exclusive mutations in the G-coupled protein pathway, mainly involving GNAQ or GNA11. Other rare genetic drivers include CYSLTR2 or PCLB4 mutations. PKC and GRM1-gene fusions have been recently added to this list. MBMs have a predilection for the scalp area, presenting as rapidly growing nodules within a pre-existing lesion. Histopathologically, these tumors are located in the dermis and subcutaneous fat and consist of large nodules or expanding dense sheets. Tumor necrosis is commonly seen. Large spindle-shaped and epithelioid melanocytes with high-grade cytological atypia and frequent mitotic figures are at higher magnification. A benign blue nevus or intermediate-grade blue melanocytoma is frequently found on the side of the central mass. Loss of nuclear BAP1 immunoreactivity is a poor prognostic factor.

Similarities and differences between brain and skin GNAQ p.R183Q driven capillary malformations.

Capillary malformations (CM) are congenital vascular irregularities of capillary and venous blood vessels that appear in the skin, leptomeninges of the brain, and the choroid of the eye in the disorder known as Sturge Weber Syndrome (SWS). More common are non-syndromic CM found only in the skin, without brain or ocular involvement. A somatic activating mutation in GNAQ (p.R183Q) is found in ~ 90% of syndromic and non-syndromic CM specimens and is present in CD31pos endothelial cells isolated from brain and skin CM specimens. Endothelial expression of the GNAQ p.R183Q variant is sufficient to form CM-like vessels in mice. Given the distinct features and functions of blood vessels in the brain versus the skin, we examined the features of CM vessels in both tissues to gain insights into the pathogenesis of CM. Herein, we present morphologic characteristics of CM observed in specimens from brain and skin. The GNAQ p.R183Q variant allelic frequency in each specimen was determined by droplet digital PCR. Sections were stained for endothelial cells, tight junctions, mural cells, and macrophages to assess the endothelium as well as perivascular constituents. CM blood vessels in brain and skin were enlarged, exhibited fibrin leakage and reduced zona occludin-1 and claudin-5, and were surrounded by MRC1pos/LYVE1pos macrophages. In contrast, the CMs from brain and skin differ in endothelial sprouting activity and localization of mural cells. These characteristics might be helpful in the development of targeted and/or tissue specific therapies to prevent or reverse non-syndromic and syndromic CM.

Similarities and differences between brain and skin GNAQ p.R183Q driven capillary malformations.

Capillary malformations (CM) are congenital vascular irregularities of capillary and venous blood vessels that appear in the skin, leptomeninges of the brain, and the choroid of the eye in the disorder known as Sturge Weber Syndrome (SWS). More common are non-syndromic CM found only in the skin, without brain or ocular involvement. A somatic activating mutation in GNAQ (p.R183Q) is found in ~90% of syndromic and non-syndromic CM specimens and is present in CD31pos endothelial cells isolated from brain and skin CM specimens. Endothelial expression of the GNAQ p.R183Q variant is sufficient to form CM-like vessels in mice. Given the distinct features and functions of blood vessels in the brain versus the skin, we examined the features of CM vessels in both tissues to gain insights into the pathogenesis of CM. Herein, we present morphologic characteristics of CM observed in specimen from brain and skin. The GNAQ p.R183Q variant allelic frequency in each specimen was determined by droplet digital PCR. Sections were stained for endothelial cells, tight junctions, mural cells, and macrophages to assess the endothelium as well as perivascular constituents. CM blood vessels in brain and skin were enlarged, exhibited fibrin leakage and reduced zona occludin-1, and were surrounded by MRC1pos/LYVE1pos macrophages. In contrast, the CMs from brain and skin differ in endothelial sprouting activity and localization of mural cells. These characteristics might be helpful in the development of targeted and/or tissue specific therapies to prevent or reverse non-syndromic and syndromic CM.

Impact of Driver Mutations on Metastasis-Free Survival in Uveal Melanoma: A Meta-Analysis.

The prognosis of uveal melanoma is significantly influenced by the risk of metastasis, which varies according to clinical and genetic features. Driver mutations can predict the likelihood of disease progression and survival, although the data in the literature are inconsistent. This meta-analysis aimed to evaluate the prognostic significance of driver mutations, including GNAQ, GNA11, BAP1, and SF3B1, in the advancement of uveal melanoma. A comprehensive search of databases yielded relevant studies, and data from 13 studies (848 eyes) were synthesized to assess the impact of these mutations on metastasis-free survival. The BAP1 mutation and negative immunohistochemistry were associated with a higher risk of metastasis (logHR = 1.44, 95% CI 1.05-1.83). GNAQ, GNA11, and SF3B1 mutations did not show a significant increase in risk. In summary, BAP1 has proven to reliably predict the likelihood of disease progression in uveal melanoma, while further studies are needed to establish the significance of other driver mutations.

GNA14 and GNAQ somatic mutations cause spinal and intracranial extra-axial cavernous hemangiomas.

Extra-axial cavernous hemangiomas (ECHs) are complex vascular lesions mainly found in the spine and cavernous sinus. Their removal poses significant risk due to their vascularity and diffuse nature, and their genetic underpinnings remain incompletely understood. Our approach involved genetic analyses on 31 tissue samples of ECHs employing whole-exome sequencing and targeted deep sequencing. We explored downstream signaling pathways, gene expression changes, and resultant phenotypic shifts induced by these mutations, both in vitro and in vivo. In our cohort, 77.4% of samples had somatic missense variants in GNA14, GNAQ, or GJA4. Transcriptomic analysis highlighted significant pathway upregulation, with the GNAQ c.626A>G (p.Gln209Arg) mutation elevating PI3K-AKT-mTOR and angiogenesis-related pathways, while GNA14 c.614A>T (p.Gln205Leu) mutation led to MAPK and angiogenesis-related pathway upregulation. Using a mouse xenograft model, we observed enlarged vessels from these mutations. Additionally, we initiated rapamycin treatment in a 14-year-old individual harboring the GNAQ c.626A>G (p.Gln209Arg) variant, resulting in gradual regression of cutaneous cavernous hemangiomas and improved motor strength, with minimal side effects. Understanding these mutations and their pathways provides a foundation for developing therapies for ECHs resistant to current therapies. Indeed, the administration of rapamycin in an individual within this study highlights the promise of targeted treatments in treating these complex lesions.

[Circumscribed choroidal hemangioma and non-pigmented choroidal melanoma: clinical, instrumental and molecular genetic features]. / Otgranichennaya gemangioma i bespigmentnaya melanoma khorioidei: kliniko-instrumental'nye i molekulyarno-geneticheskie osobennosti.

Circumscribed choroidal hemangioma (CCH) and early non-pigmented choroidal melanoma (CM) have similar clinical, ultrasound and morphometric features, which in some cases makes their differential diagnosis difficult. There are few studies in the literature devoted to a comparative analysis of the molecular genetic features of CCH and non-pigmented CM, and the results of those studies are contradictory. PURPOSE: This study attempts to develop a method of non-invasive molecular genetic differential diagnostics of CCH and non-pigmented CM. MATERIAL AND METHODS: Based on the results of clinical and instrumental examination methods, 60 patients (60 eyes) with CCH (n=30) and non-pigmented CM (n=30) were included in this prospective study. The control group consisted of 30 individuals without intraocular tumors. Mutations in the GNAQ/GNA11 genes were determined by real-time PCR using the analysis of genomic circulating tumor DNA isolated from peripheral blood plasma. The average follow-up period was 12.1±1.8 months. RESULTS: The study revealed a significant association of mutations in exons 4 and 5 of the GNAQ/GNA11 genes with the presence of non-pigmented CM (27/30; 90%). These mutations were not detected in the group of patients with CCH. Mutations in exons 4 and 5 of the GNAQ/GNA11 genes were also not detected in the control group of healthy individuals. CONCLUSION: This study proposes a method of non-invasive and low-cost differential diagnostics based on molecular genetic analysis and detection of mutations in exons 4 and 5 of the GNAQ and GNA11 genes, which are specific for CM (90%).

MRC1 and LYVE1 expressing macrophages in vascular beds of GNAQ p.R183Q driven capillary malformations in Sturge Weber syndrome.

Sturge-Weber syndrome (SWS), a neurocutaneous disorder, is characterized by capillary malformations (CM) in the skin, brain, and eyes. Patients may suffer from seizures, strokes, and glaucoma, and only symptomatic treatment is available. CM are comprised of enlarged vessels with endothelial cells (ECs) and disorganized mural cells. Our recent finding indicated that the R183Q mutation in ECs leads to heightened signaling through phospholipase Cß3 and protein kinase C, leading to increased angiopoietin-2 (ANGPT2). Furthermore, knockdown of ANGPT2, a crucial mediator of pro-angiogenic signaling, inflammation, and vascular remodeling, in EC-R183Q rescued the enlarged vessel phenotype in vivo. This prompted us to look closer at the microenvironment in CM-affected vascular beds. We analyzed multiple brain histological sections from patients with GNAQ-R183Q CM and found enlarged vessels devoid of mural cells along with increased macrophage-like cells co-expressing MRC1 (CD206, a mannose receptor), CD163 (a scavenger receptor and marker of the monocyte/macrophage lineage), CD68 (a pan macrophage marker), and LYVE1 (a lymphatic marker expressed by some macrophages). These macrophages were not found in non-SWS control brain sections. To investigate the mechanism of increased macrophages in the perivascular environment, we examined THP1 (monocytic/macrophage cell line) cell adhesion to EC-R183Q versus EC-WT under static and laminar flow conditions. First, we observed increased THP1 cell adhesion to EC-R183Q compared to EC-WT under static conditions. Next, using live cell imaging, we found THP1 cell adhesion to EC-R183Q was dramatically increased under laminar flow conditions and could be inhibited by anti-ICAM1. ICAM1, an endothelial cell adhesion molecule required for leukocyte adhesion, was strongly expressed in the endothelium in SWS brain histological sections, suggesting a mechanism for recruitment of macrophages. In conclusion, our findings demonstrate that macrophages are an important component of the perivascular environment in CM suggesting they may contribute to the CM formation and SWS disease progression.

EHMT2 promotes tumorigenesis in GNAQ/11-mutant uveal melanoma via ARHGAP29-mediated RhoA pathway.

Constitutive activation of GNAQ/11 is the initiative oncogenic event in uveal melanoma (UM). Direct targeting GNAQ/11 has yet to be proven feasible as they are vital for a plethora of cellular functions. In search of genetic vulnerability for UM, we found that inhibition of euchromatic histone lysine methyltransferase 2 (EHMT2) expression or activity significantly reduced the proliferation and migration capacity of cancer cells. Notably, elevated expression of EHMT2 had been validated in UM samples. Furthermore, Kaplan-Meier survival analysis indicated high EHMT2 protein level was related to poor recurrence-free survival and a more advanced T stage. Chromatin immunoprecipitation sequencing analysis and the following mechanistic investigation showed that ARHGAP29 was a downstream target of EHMT2. Its transcription was suppressed by EHMT2 in a methyltransferase-dependent pattern in GNAQ/11-mutant UM cells, leading to elevated RhoA activity. Rescuing constitutively active RhoA in UM cells lacking EHMT2 restored oncogenic phenotypes. Simultaneously blocking EHMT2 and GNAQ/11 signaling in vitro and in vivo showed a synergistic effect on UM growth, suggesting the driver role of these two key molecules. In summary, our study shows evidence for an epigenetic program of EHMT2 regulation that influences UM progression and indicates inhibiting EHMT2 and MEK/ERK simultaneously as a therapeutic strategy in GNAQ/11-mutant UM.

Multidisciplinary approach and treatment of acral and mucosal melanoma.

Acral and mucosal melanoma are uncommon variants of melanoma. Acral melanoma has an age-adjusted incidence of approximately 1.8 cases per million individuals per year, accounting for about 2% to 3% of all melanoma cases. On the other hand, mucosal melanoma, with an incidence of 2.2 cases per million per year, makes up around 1.3% of all melanoma cases. These melanomas, in addition to being biologically and clinically distinct from cutaneous melanoma, share certain clinical and pathologic characteristics. These include a more aggressive nature and a less favorable prognosis. Furthermore, they exhibit a different mutational pattern, with KIT mutations being more prevalent in acral and mucosal melanomas. This divergence in mutational patterns may partially account for the relatively poorer prognosis, particularly to immune checkpoint inhibitors. This review explores various aspects of acral and mucosal melanoma, including their clinical presentation, pathologic features, mutational profiles, current therapeutic approaches, outcomes associated with systemic therapy, and potential strategies to address resistance to existing treatments.

The clinico-pathological spectrum of plaque-type blue naevi and their potential for malignant transformation.

AIMS: Plaque-type blue naevi are rare melanocytic tumours presenting as large, pigmented plaques at birth or during childhood. There is a risk for malignant transformation, but no larger comprehensive studies exist and the diagnosis is challenging, especially on limited biopsy material. The aim is to describe the clinicopathological features and behaviour of the disease more comprehensively. METHODS AND RESULTS: We retrieved eight plaque-type blue naevi, presenting as large, pigmented plaques (median = 7 cm; range = 3-26) most frequently affecting the scalp (four) followed by the cheek, arm, abdominal wall and gluteal cleft (one each), with a slight female predilection. Median age at time of biopsy was 39.5 years (range = 15-90), but three tumours had been present at birth and one since childhood. Histopathologically, the tumours were poorly circumscribed and composed of cellular fascicles of uniform spindle cells in a background of variably prominent pigmented dendritic cells affecting dermis and subcutaneous tissues. The majority had mutations in GNAQ. One tumour showed malignant transformation, characterised by an expansile nodule of pleomorphic epithelioid melanocytes with rhabdoid morphology, high mitotic activity and areas of necrosis. This patient developed metastatic melanoma to lymph nodes. All patients are alive with a median follow-up of 60 months. CONCLUSION: Plaque-type blue naevi are diagnostically challenging tumours with risk for malignant transformation. Awareness and familiarity with the salient clinicopathological features are necessary for reliable diagnosis, and long-term clinical follow-up is required to monitor for malignant transformation.

Anastomosing haemangioma of the mediastinum: Clinicopathological series with radiological and genetic characterisation.

AIMS: Anastomosing haemangiomas are benign tumours with anastomosing vascular channels that may mimic angiosarcoma. While anastomosing haemangiomas have been described in diverse locations, particularly the abdominal/paraspinal region, data on anastomosing haemangiomas in the mediastinum remain limited. We report the clinicopathological, radiological and molecular characteristics of the largest single-institutional series of mediastinal anastomosing haemangiomas. METHODS AND RESULTS: In our pathology archives in 2011-23, we reviewed all vascular lesions involving the mediastinum and identified seven anastomosing haemangiomas. Clinical information was abstracted from medical charts; available radiological imaging was reviewed. Targeted DNA-based next-generation sequencing (447 genes, including GNAQ and GNA11) was performed on five cases. The seven patients included five women and two men, with an age range of 55-77 (median = 72) years. Of the six tumours with available radiology, two each were in the prevascular, visceral and paravertebral mediastinum, with lobulated peripheral enhancement in all tumours examined with contrast enhancement. Six patients underwent tumour resection; one patient received proton radiotherapy. Microscopically, each tumour was solitary and characterised by anastomosing capillary-sized vessels lined by hobnail endothelial cells. Fibrin microthrombi, hyaline globules and extramedullary haematopoiesis were common. In the five tumours analysed by next-generation sequencing, GNAQ p.Q209P was identified in one tumour; no additional reportable alterations were identified in the remaining cases. No recurrence was noted in the four patients with available follow-up of 3-58 (median = 9.5) months after resection. CONCLUSION: While mediastinal anastomosing haemangiomas can microscopically mimic angiosarcoma, awareness of this entity and radiological correlation may help to circumvent this diagnostic pitfall.

Capillary malformations in a child caused by a novel HRAS mutation.

A 6-year-old boy with multiple capillary malformations of the port-wine birthmark (PWB) type on the right leg since birth presented with a varicose vein and segmental overgrowth of the affected leg. Genetic testing on affected skin confirmed the presence of a somatic novel pathogenic HRAS 30 bp in-frame duplication/insertion in the switch II domain. This case illustrates the phenotypic overlap of different genotypes and shows that somatic HRAS pathogenic variants, especially in-frame duplications/insertions, must be added to the list of the underlying causes in capillary malformations.

Driver mutations in GNAQ and GNA11 genes as potential targets for precision immunotherapy in uveal melanoma patients.

Uveal melanoma (UM) is the most common ocular malignancy in adults. Nearly 95% of UM patients carry the mutually exclusive mutations in the homologous genes GNAQ (amino acid change Q209L/Q209P) and GNA11 (aminoacid change Q209L). UM is located in an immunosuppressed organ and does not suffer immunoediting. Therefore, we hypothesize that driver mutations in GNAQ/11 genes could be recognized by the immune system. Genomic and transcriptomic data from primary uveal tumors were collected from the TCGA-UM dataset (n = 80) and used to assess the immunogenic potential for GNAQ/GNA11 Q209L/Q209P mutations using a variety of tools and HLA type information. All prediction tools showed stronger GNAQ/11 Q209L binding to HLA than GNAQ/11 Q209P. The immunogenicity analysis revealed that Q209L is likely to be presented by more than 73% of individuals in 1000 G databases whereas Q209P is only predicted to be presented in 24% of individuals. GNAQ/11 Q209L showed a higher likelihood to be presented by HLA-I molecules than almost all driver mutations analyzed. Finally, samples carrying Q209L had a higher immune-reactive phenotype. Regarding cancer risk, seven HLA genotypes with low Q209L affinity show higher frequency in uveal melanoma patients than in the general population. However, no clear association was found between any HLA genotype and survival. Results suggest a high potential immunogenicity of the GNAQ/11 Q209L variant that could allow the generation of novel therapeutic tools to treat UM like neoantigen vaccinations.

Photoperiod Induces the Epigenetic Change of the GNAQ Gene in OVX+E2 Ewes.

GNAQ, a member of the alpha subunit encoding the q-like G protein, is a critical gene in cell signaling, and multiple studies have shown that upregulation of GNAQ gene expression ultimately inhibits the proliferation of gonadotropin-releasing hormone (GnRH) neurons and GnRH secretion, and ultimately affects mammalian reproduction. Photoperiod is a key inducer which plays an important role in gene expression regulation by affecting epigenetic modification. However, fewer studies have confirmed how photoperiod induces epigenetic modifications of the GNAQ gene. In this study, we examined the expression and epigenetic changes of GNAQ in the hypothalamus in ovariectomized and estradiol-treated (OVX+E2) sheep under three photoperiod treatments (short photoperiod treatment for 42 days, SP42; long photoperiod treatment for 42 days, LP42; 42 days of short photoperiod followed by 42 days of long photoperiod, SP-LP42). The results showed that the expression of GNAQ was significantly higher in SP-LP42 than in SP42 and LP42 (p < 0.05). Whole genome methylation sequencing (WGBS) results showed that there are multiple differentially methylated regions (DMRs) and loci between different groups of GNAQ. Among them, the DNA methylation level of DMRs at the CpG1 locus in SP42 was significantly higher than that of SP-LP42 (p < 0.01). Subsequently, we confirmed that the core promoter region of the GNAQ gene was located with 1100 to 1500 bp upstream, and the DNA methylation level of all eight CpG sites in SP42 was significantly higher than those in LP42 (p < 0.01), and significantly higher than those in SP-LP42 (p < 0.01), except site 2 and site 4 in the first sequencing fragment (p < 0.05) in the core promoter region. The expression of acetylated GNAQ histone H3 was significantly higher than that of the control group under three different photoperiods (p < 0.01); the acetylation level of sheep hypothalamic GNAQ genomic protein H3 was significantly lower under SP42 than under SP-LP42 (p < 0.05). This suggests that acetylated histone H3 binds to the core promoter region of the GNAQ gene, implying that GNAQ is epigenetically regulated by photoperiod through histone acetylation. In summary, the results suggest that photoperiod can induce DNA methylation in the core promoter region and histone acetylation in the promoter region of the GNAQ gene, and hypothesize that the two may be key factors in regulating the differential expression of GNAQ under different photoperiods, thus regulating the hypothalamus-pituitary-gonadal axis (HPGA) through the seasonal estrus in sheep. The results of this study will provide some new information to understand the function of epigenetic modifications in reproduction in sheep.

High-throughput chemogenetic drug screening reveals PKC-RhoA/PKN as a targetable signaling vulnerability in GNAQ-driven uveal melanoma.

Uveal melanoma (UM) is the most prevalent cancer of the eye in adults, driven by activating mutation of GNAQ/GNA11; however, there are limited therapies against UM and metastatic UM (mUM). Here, we perform a high-throughput chemogenetic drug screen in GNAQ-mutant UM contrasted with BRAF-mutant cutaneous melanoma, defining the druggable landscape of these distinct melanoma subtypes. Across all compounds, darovasertib demonstrates the highest preferential activity against UM. Our investigation reveals that darovasertib potently inhibits PKC as well as PKN/PRK, an AGC kinase family that is part of the "dark kinome." We find that downstream of the Gαq-RhoA signaling axis, PKN converges with ROCK to control FAK, a mediator of non-canonical Gαq-driven signaling. Strikingly, darovasertib synergizes with FAK inhibitors to halt UM growth and promote cytotoxic cell death in vitro and in preclinical metastatic mouse models, thus exposing a signaling vulnerability that can be exploited as a multimodal precision therapy against mUM.

Somatic mutation spectrum of a Chinese cohort of pediatrics with vascular malformations.

BACKGROUND: Somatic mutations of cancer driver genes are found to be responsible for vascular malformations with clinical manifestations ranging from cutaneous birthmarks to life-threatening systemic anomalies. Till now, only a limited number of cases and mutations were reported in Chinese population. The purpose of this study was to describe the somatic mutation spectrum of a cohort of Chinese pediatrics with vascular malformations. METHODS: Pediatrics diagnosed with various vascular malformations were collected between May 2019 and October 2020 from Beijing Children's Hospital. Genomic DNA of skin lesion of each patient was extracted and sequenced by whole-exome sequencing to identify pathogenic somatic mutations. Mutations with variant allele frequency less than 5% were validated by ultra-deep sequencing. RESULTS: A total of 67 pediatrics (33 males, 34 females, age range: 0.1-14.8 years) were analyzed. Exome sequencing identified somatic mutations of corresponding genes in 53 patients, yielding a molecular diagnosis rate of 79.1%. Among 29 PIK3CA mutations, 17 were well-known hotspot p.E542K, p.E545K and p.H1047R/L. Non-hotspot mutations were prevalent in patients with PIK3CA-related overgrowth spectrum, accounting for 50.0% (11/22) of detected mutations. The hotspot GNAQ p.R183Q and TEK p.L914F mutations were responsible for the majority of port-wine stain/Sturge-Weber syndrome and venous malformation, respectively. In addition, we identified a novel AKT1 p.Q79K mutation in Proteus syndrome and MAP3K3 p.E387D mutation in verrucous venous malformation. CONCLUSIONS: The somatic mutation spectrum of vascular malformations in Chinese population is similar to that reported in other populations, but non-hotspot PIK3CA mutations may also be prevalent. Molecular diagnosis may help the clinical diagnosis, treatment and management of these pediatric patients with vascular malformations.

Darovasertib, a novel treatment for metastatic uveal melanoma.

The FDA granted orphan drug designation to darovasertib, a first-in-class oral, small molecular inhibitor of protein kinase C (PKC), for the treatment of uveal melanoma, on 2 May 2022. Primary uveal melanoma has a high risk of progressing to metastatic uveal melanoma, with a poor prognosis. The activation of the PKC and mitogen-activated protein kinase pathways play an essential role in the pathogenesis of uveal melanoma, and mutations in the G protein subunit alpha q (GNAQ), and G protein subunit alpha11 (GNA11) genes are considered early events in the development of uveal melanoma. Compared to other PKC inhibitors, such as sotrastaurin and enzastaurin, darovasertib is significantly more potent in inhibiting conventional (α, ß) and novel (δ, ϵ, η, θ) PKC proteins and has a better tolerability and safety profile. Current Phase I/II clinical trials indicated that darovasertib, combined with the Mitogen-activated protein kinase/Extracellular (MEK) inhibitors, binimetinib or crizotinib, produced a synergistic effect of uveal melanoma. In this article, we summarize the development of drugs for treating uveal melanomas and discuss problems associated with current treatments. We also discuss the mechanism of action, pharmacokinetic profile, adverse effects, and clinical trial for darovasertib, and future research directions for treating uveal melanoma.

GNAQ R183Q somatic mutation contributes to aberrant arteriovenous specification in Sturge-Weber syndrome through Notch signaling.

Episcleral vasculature malformation is a significant feature of Sturge-Weber syndrome (SWS) secondary glaucoma, the density and diameter of which are correlated with increased intraocular pressure. We previously reported that the GNAQ R183Q somatic mutation was located in the SWS episclera. However, the mechanism by which GNAQ R183Q leads to episcleral vascular malformation remains poorly understood. In this study, we investigated the correlation between GNAQ R183Q and episcleral vascular malformation via surgical specimens, human umbilical vein endothelial cells (HUVECs), and the HUVEC cell line EA.hy926. Our findings demonstrated a positive correlation between episcleral vessel diameter and the frequency of the GNAQ R183Q variant. Furthermore, the upregulation of genes from the Notch signaling pathway and abnormal coexpression of the arterial marker EphrinB2 and venous marker EphB4 were demonstrated in the scleral vasculature of SWS. Analysis of HUVECs overexpressing GNAQ R183Q in vitro confirmed the upregulation of Notch signaling and arterial markers. In addition, knocking down of Notch1 diminished the upregulation of arterial markers induced by GNAQ R183Q. Our findings strongly suggest that GNAQ R183Q leads to malformed episcleral vasculatures through Notch-induced aberrant arteriovenous specification. These insights into the molecular basis of episcleral vascular malformation will provide new pathways for the development of effective treatments for SWS secondary glaucoma.