Intraocular Invasion by Conjunctival Squamous Cell Carcinoma: Clinical Presentation, Histopathological Findings, and Outcome.

Introduction: Intraocular localization of conjunctival squamous cell carcinoma (SCC) is due to scleral or corneal invasion. Herein, we describe the clinical and histopathological findings in four cases of SCC complicated by intraocular invasion, and we review cases reported in the literature and their management. We retrospectively collected and analyzed clinical characteristics, histopathology, management, and follow-up data from 4 patients with conjunctival SCC complicated by intraocular invasion. We reviewed the literature and summarized cases of intraocular invasion by conjunctival SCC reported over the last 30 years. Case Presentations: Two patients presented with intraocular invasion by conjunctival SCC at diagnosis. The two others developed intraocular invasion as recurrence of conjunctival SCC, previously treated with excisional biopsy and adjuvant radiotherapy. All 4 cases had a previous history of conjunctival surgery, but no history of intraocular surgery. Three patients were managed with modified enucleation, including one that required adjuvant orbital radiotherapy. One patient required orbital exenteration. Histopathology analysis showed a well-differentiated conjunctival SCC in all cases. None developed distant localization after at least 2.5-year follow-up. Discussion/Conclusion: Intraocular invasion is a rare complication of conjunctival SCC. Appropriate treatment in a tertiary center and long-term follow-up are highly recommended.

Divergent local and systemic antitumor response in primary uveal melanomas.

Uveal melanoma (UM) is the most common cancer of the eye. The loss of chromosome 3 (M3) is associated with a high risk of metastases. M3 tumors are more infiltrated by T-lymphocytes than low-risk disomic-3 (D3) tumors, contrasting with other tumor types in which T cell infiltration correlates with better prognosis. Whether these T cells represent an antitumor response and how these T cells would be primed in the eye are both unknown. Herein, we characterized the T cells infiltrating primary UMs. CD8+ and Treg cells were more abundant in M3 than in D3 tumors. CD39+PD-1+CD8+ T cells were enriched in M3 tumors, suggesting specific responses to tumor antigen (Ag) as confirmed using HLA-A2:Melan-A tetramers. scRNAseq-VDJ analysis of T cells evidenced high numbers of proliferating CD39+PD1+CD8+ clonal expansions, suggesting in situ antitumor Ag responses. TCRseq and tumor-Ag tetramer staining characterized the recirculation pattern of the antitumor responses in M3 and D3 tumors. Thus, tumor-Ag responses occur in localized UMs, raising the question of the priming mechanisms in the absence of known lymphatic drainage.

Patient Derived Xenografts (PDX) Models as an Avatar to Assess Personalized Therapy Options in Uveal Melanoma: A Feasibility Study.

Uveal melanoma is the most common primary intraocular malignancy in adults. Up to 50% of UM patients develop metastatic disease, usually in the liver. When metastatic, the prognosis is poor, and few treatment options exist. Here, we investigated the feasibility of establishing patient-derived xenografts (PDXs) from a patient's tumor in order to screen for therapies that the patient could benefit from. Samples obtained from 29 primary tumors and liver metastases of uveal melanoma were grafted into SCID mice. PDX models were successfully established for 35% of primary patient tumors and 67% of liver metastases. The tumor take rate was proportional to the risk of metastases. PDXs showed the same morphology, the same GNAQ/11, BAP1, and SF3B1 mutations, and the same chromosome 3 and 8q status as the corresponding patient samples. Six PDX models were challenged with two compounds for 4 weeks. We show that, for 31% of patients with high or intermediate risk of metastasis, the timing to obtain efficacy results on PDX models derived from their primary tumors was compatible with the selection of the therapy to treat the patient after relapse. PDXs could thus be a valid tool ("avatar") to select the best personalized therapy for one third of patients that are most at risk of relapse.

Immunohistochemical characterisation of the immune landscape in primary uveal melanoma and liver metastases.

BACKGROUND: The immune landscape of uveal melanoma liver metastases (UMLM) has not been sufficiently studied. METHODS: Immune cell infiltrates (ICIs), PD-1 and PD-L1 were characterised in 62 UMLM and 28 primary uveal melanomas (PUM). ICI, PD-1 and PD-L1 were scored as: (1) % tumoral area occupied by tumour-infiltrating lymphocytes or macrophages (TILs, TIMs) and (2) % perTumoral (perT) area. ICIs and other variables including histopathologic growth patterns (HGPs), replacement and desmoplastic, of UMLM were analysed for their prognostic value. RESULTS: ICIs recognised by haematoxylin-eosin-saffron (HES) and IHC (e.g., T cells (CD3), B cells (CD20). Macrophages (CD68), (CD163), were primarily localised to the perT region in PUM and UMLM and were more conspicuous in UMLM. HES, CD3, CD4, FoxP3, CD8, CD20, PD-1 TILs were scant (<5%). TIMs were more frequent, particularly in UMLM than in PUM. Both CD68+ TIMs and HGPs remained significant on multivariate analysis, influencing overall (OS) and metastasis-specific overall survival (MSOS). CD68 + , CD163+ and CD20+ perT infiltrates in UMLM predicted increased OS and MSOS on univariate analysis. CONCLUSIONS: TILs and PD-L1 have no predictive value in PUM or UMLM. CD68+ and CD163+TIMs, CD20+ perT lymphocytes, and HGPs are important prognostic factors in UMLMs.

FAK Inhibitor-Based Combinations with MEK or PKC Inhibitors Trigger Synergistic Antitumor Effects in Uveal Melanoma.

Uveal Melanoma (UM) is a rare and malignant intraocular tumor with dismal prognosis. Even if radiation or surgery permit an efficient control of the primary tumor, up to 50% of patients subsequently develop metastases, mainly in the liver. The treatment of UM metastases is challenging and the patient survival is very poor. The most recurrent event in UM is the activation of Gαq signaling induced by mutations in GNAQ/11. These mutations activate downstream effectors including protein kinase C (PKC) and mitogen-activated protein kinases (MAPK). Clinical trials with inhibitors of these targets have not demonstrated a survival benefit for patients with UM metastasis. Recently, it has been shown that GNAQ promotes YAP activation through the focal adhesion kinase (FAK). Pharmacological inhibition of MEK and FAK showed remarkable synergistic growth-inhibitory effects in UM both in vitro and in vivo. In this study, we have evaluated the synergy of the FAK inhibitor with a series of inhibitors targeting recognized UM deregulated pathways in a panel of cell lines. The combined inhibition of FAK and MEK or PKC had highly synergistic effects by reducing cell viability and inducing apoptosis. Furthermore, we demonstrated that these combinations exert a remarkable in vivo activity in UM patient-derived xenografts. Our study confirms the previously described synergy of the dual inhibition of FAK and MEK and identifies a novel combination of drugs (FAK and PKC inhibitors) as a promising strategy for therapeutic intervention in metastatic UM.

Circulating Tumor DNA as a Prognostic Factor in Patients With Resectable Hepatic Metastases of Uveal Melanoma.

OBJECTIVE: We report here the results of a prospective study of circulating tumor DNA (ctDNA) detection in patients undergoing uveal melanoma (UM) liver metastases resection (NCT02849145). BACKGROUND: In UM patients, the liver is the most common and often only site of metastases. Local treatments of liver metastases, such as surgical resection, have a likely benefit in selected patients. METHODS: Upon enrollment, metastatic UM patients eligible for curative liver surgery had plasma samples collected before and after surgery. GNAQ / GNA11 mutations were identified in archived tumor tissue and used to quantify ctDNA by droplet digital polymerase chain reaction which was then associated with the patient's surgical outcomes. RESULTS: Forty-seven patients were included. Liver surgery was associated with a major increase of cell-free circulating DNA levels, with a peak 2 days after surgery (∼20-fold). Among 40 evaluable patients, 14 (35%) had detectable ctDNA before surgery, with a median allelic frequency of 1.1%. These patients experienced statistically shorter relapse-free survival (RFS) versus patients with no detectable ctDNA before surgery (median RFS: 5.5 vs 12.2 months; hazard ratio=2.23, 95% CI: 1.06-4.69, P =0.04), and had a numerically shorter overall survival (OS) (median OS: 27.0 vs 42.3 months). ctDNA positivity at postsurgery time points was also associated with RFS and OS. CONCLUSIONS: This study is the first to report ctDNA detection rate and prognostic impact in UM patients eligible for surgical resection of their liver metastases. If confirmed by further studies in this setting, this noninvasive biomarker could inform treatment decisions in UM patients with liver metastases.

Cytidine analogs are synthetic lethal with base excision repair default due to MBD4 deficiency.

Inactivating mutations of MBD4 have been reported in subsets of various tumors. A deficiency of this DNA glycosylase, recognizing specifically T:G mismatch resulting from the deamination of methyl-cytosine, results in a hypermutated phenotype due to the accumulation of CpG>TpG transitions. Here, we hypothesize that the difference in DNA metabolism consecutive to MBD4 deficiency may result in specific cytotoxicities in MBD4-deficient tumor cells in a synthetic lethality fashion. After a large-scale drug repurposing screen, we show in two isogenic MBD4 knock-out cell models that the inactivation of MBD4 sensitizes cancer cells to cytidine analogs. We further confirm the exquisite activity of gemcitabine in an MBD4-deficient co-clinical model as (i) it completely prevented the development of an MBD4-deficient uveal melanoma patient-derived xenograft and (ii) treatment in the corresponding patient resulted in an exceptional tumor response. These data suggest that patients harboring MBD4-deficient tumors may be treated efficiently by cytidine analogs.

Tumor Growth Rate as a Predictive Marker for Recurrence and Survival After Liver Resection in Patients with Liver Metastases of Uveal Melanoma.

BACKGROUND: Surgical management of liver metastases of uveal melanoma (LMUM) is associated with the best survival rates, especially for patients with a low tumor burden in the liver. The aim was to determine whether the tumor growth rate (TGR0) before liver resection helps predict survival in patients with resectable LMUM. METHODS: This retrospective study included 99 patients with LMUM treated with liver resection between November 2007 and November 2020. TGR0 was expressed as the percentage change in tumor volume over 1 month according to two pretreatment imaging scans. Multivariate Cox analyses identified independent predictors of disease-free survival (DFS) and overall survival (OS). RESULTS: DFS and OS had a statistically significant positive linear relationship (Spearman correlation r = 0.68, p < 0.001). A disease-free interval (DFI) > 24 months and a TGR0 ≤ 50%/month were independent factors associated with better DFS and OS. The 2-component model including TGR0 and DFI had a mean time-dependent area under the curve (AUC) of 0.81 (95% CI, 0.75-0.86) and 0.77 (95% CI, 0.67-0.87), respectively, for predicting DFS and OS. DFI with TGR0 defined three kinetic risk groups that had distinct DFS and OS outcomes (p < 0.001). Cytogenetic alterations at baseline were partially predictive factors of the kinetic risk score based on TGR0 and DFI. DISCUSSION: The assessment of TGR0 improves prognostic stratification by identifying patients at high risk of recurrence and poor survival after liver resection. TGR0 and DFI, reflecting tumor aggressivity, have the potential to be important markers for systemic adjuvant decisions.

MBD4 deficiency is predictive of response to immune checkpoint inhibitors in metastatic uveal melanoma patients.

BACKGROUND: MBD4 mutations have been reported in uveal melanomas, acute myeloid leukemias, colorectal adenocarcinomas, gliomas, and spiradenocarcinomas and cause a hypermutated phenotype. Although metastatic uveal melanomas (mUM) are usually resistant to immune checkpoint inhibitors (ICI), the first reported MBD4-mutated (MBD4m) patient responded to ICI, suggesting that MBD4 mutation may predict response to ICI. METHODS: Retrospective cohort of mUM patients treated with ICI. MBD4 was sequenced in a subset of these patients. RESULTS: Three hundred mUM patients were included. Median follow-up was 17.3 months. Ten patients with an objective response and 20 cases with stable disease for >12 months were observed, corresponding to an objective response rate of 3.3% and a clinical benefit (i.e., responder patients and stable disease) rate of 10%. Of the 131 tumors sequenced for MBD4, five (3.8%) were mutated. MBD4 mutation was associated with a better objective response rate as three out of five MBD4m versus 4% of MBD4 wild-type patients responded (p < 0.001). Of these five responders, three presented progressive disease at 2.8, 13.9, and 22.3 months. Median PFS was 4.0 months in MBD4 wild-type and 22.3 months in MBD4m patients (HR = 0.22; p = 0.01). Median OS in MBD4def patients was unreached as compared to 16.6 months in MBD4pro (HR = 0.11; 95% CI: 0.02-0.86; log-rank p-test = 0.04; Fig. 2e). CONCLUSIONS: In mUM patients, MBD4 mutation is highly predictive for the response, PFS, and overall survival benefit to ICI. MBD4 could be a tissue-agnostic biomarker and should be sequenced in mUM, and other tumor types where MBD4 mutations are reported.

L1CAM and laminin vascular network: Association with the high-risk replacement histopathologic growth pattern in uveal melanoma liver metastases.

The replacement histopathologic growth pattern (rHGP) in melanoma liver metastases connotes an aggressive phenotype (vascular co-option; angiotropic extravascular migratory spread) and adverse prognosis. Herein, replacement and desmoplastic HGP (dHGP) were studied in uveal melanoma liver metastases (MUM). In particular, L1CAM and a "laminin vascular network" were detected at the advancing front of 14/20 cases (p = 0.014) and 16/20 cases (p = 6.4e-05) rHGPs, respectively, but both were absent in the dHGP (8/8 cases) (p = 0.014, and p = 6.3e-05, respectively). L1CAM highlighted progressive extension of angiotropic melanoma cells along sinusoidal vessels in a pericytic location (pericytic mimicry) into the hepatic parenchyma. An inverse relationship between L1CAM expression and melanin index (p = 0.012) suggested differentiation toward an amelanotic embryonic migratory phenotype in rHGP. Laminin labeled the basement membrane zone interposed between sinusoidal vascular channels and angiotropic melanoma cells at the advancing front. Other new findings: any percentage of rHGP and pure rHGP had a significant adverse effect on metastasis-specific overall survival (p = 0.038; p = 0.0064), as well as predominant rHGP (p = 0.0058). Pure rHGP also was associated with diminished metastasis-free survival relative to dHGP (p = 0.040), possibly having important implications for mechanisms of tumor spread. In conclusion, we report for the first time that L1CAM and a laminin vascular network are directly involved in this high-risk replacement phenotype. Further, this study provides more detailed information about the adverse prognostic effect of the rHGP in MUM.

EPHA2, EPHA4, and EPHA6 Expression in Uveal Melanomas: Searching for the Culprits of Neoplasia.

Uveal melanomas (UMs) comprise the most common primary intraocular malignancies in adults, with the eye representing the second most common site for melanoma, following the skin. Prognosis remains poor, with approximately half of the cases presenting with metastatic disease at the time of diagnosis. Erythropoietin-producing human hepatocellular receptors (EPHs) comprise the largest known family of tyrosine receptors, in which, along with their ligands, ephrins, play an important role in a plethora of processes in human physiology, and are implicated in key steps of carcinogenesis. In the present study, EPHA2, EPHA4, and EPHA6 immunohistochemical expressions were investigated in UM tissues and further correlated to a multitude of clinicopathological parameters, including disease stage and patients' overall survival (OS). High levels of EPHA2 expression were significantly associated with increased tumor vertical thickness (p = 0.03) and the presence of intrascleral involvement (p = 0.05), whereas high EPHA6 nuclear expression was associated with older age at diagnosis (p = 0.03) and absence of retinal detachment (p = 0.05). In a multivariate survival analysis, increased EPHA4 expression was associated with shortened OS along with the presence of metastasis (p < 0.001) and monosomy 3 (p = 0.02). In a separate model, the concurrent overexpression of at least two of the investigated EPHs (HR = 14.7, p = 0.03) also proved to be an independent poor prognostic factor. In conclusion, our results implicate these specific members of the EPHA group as potential biomarkers for disease prognosis as well as possible targets for the development of novel therapeutic interventions.

Tumour growth rate improves tumour assessment and first-line systemic treatment decision-making for immunotherapy in patients with liver metastatic uveal melanoma.

BACKGROUND: The RECIST-based response variably matches the clinical benefit of systemic therapies for liver metastatic uveal melanoma (LMUM). The aims were to determine whether the tumour growth rate (TGR) can help predict the survival in patients with LMUM and to provide information for the management of first-line systemic treatment. METHODS: This retrospective study included 147 (training: n = 110, validation: n = 37) patients with LMUM treated with first-line systemic treatment between 2010 and 2021. Two TGR-derived parameters were calculated, TGR0 and TGR3m. Multivariate Cox analyses identified independent predictors of progression-free survival (PFS) and overall survival (OS). RESULTS: TGR3m was a strong independent prognostic factor of PFS and OS (p < 0.001). The RECIST-based response was no longer significant in the OS analyses. Only immunotherapy regimens correlated with higher OS (HR = 0.2; 95% CI, 0.1-0.5; p < 0.001) in the low-TGR3m (≤50%/m) subgroup. These findings were confirmed in the validation cohort. TGR0, disease-free interval (DFI), and the sum of target lesions at baseline were predictive factors of low TGR3m. DISCUSSION: The use of TGR3m would improve tumour assessment by identifying patients who would benefit from first-line immunotherapy regimens despite PD. TGR0, DFI and the sum of target lesions were correlated with TGR3m, which can support first-line treatment decision-making for immunotherapy.

Histone Deacetylase (HDAC)-1, -2, -4, and -6 in Uveal Melanomas: Associations with Clinicopathological Parameters and Patients' Survival.

BACKGROUND: Uveal melanoma (UM) represents the most common primary intraocular malignancy in adults, exerting high metastatic potential and poor prognosis. Histone deacetylases (HDACs) play a key role in carcinogenesis, and HDAC inhibitors (HDACIs) are currently being explored as anti-cancer agents in clinical settings. The aim of this study was to evaluate the clinical significance of HDAC-1, -2, -4, and -6 expression in UM. METHODS: HDAC-1, -2, -4, and -6 expression was examined immunohistochemically in 75 UM tissue specimens and was correlated with tumors' clinicopathological characteristics, the presence of tumor-infiltrating lymphocytes (TILS), as well as with our patients' overall survival (OS). RESULTS: HDAC-2 was the most frequently expressed isoform (66%), whereas we confirmed in addition to the expected nuclear expression the presence of cytoplasmic expression of class I HDAC isoforms, namely HDAC-1 (33%) and HDAC-2 (9.5%). HDAC-4 and -6 expression was cytoplasmic. HDAC-1 nuclear expression was associated with increased tumor size (p = 0.03), HDAC-6 with higher mitotic index (p = 0.03), and nuclear HDAC-2 with epithelioid cell morphology (p = 0.03) and presence of tumor-infiltrating lymphocytes (p = 0.04). The association with the remaining parameters including Monosomy 3 was not significant. Moreover, the presence as well as the nuclear expression pattern of HDAC-2 were correlated with patients' improved OS and remained significant in multivariate survival analysis. CONCLUSIONS: These findings provide evidence for a potential role of HDACs and especially HDAC-2 in the biological mechanisms governing UM evolution and progression.

Definition of Biologically Distinct Groups of Conjunctival Melanomas According to Etiological Factors and Implications for Precision Medicine.

Conjunctival melanoma (ConjMel) is a potentially deadly ocular melanoma, originating from partially sunlight-exposed mucosa. We explored the mutational landscape of ConjMel and studied the correlation with etiological factors. We collected 47 primary ConjMel samples and performed next-generation sequencing of 400 genes. Hotspot mutations in BRAF, NRAS, HRAS, and KIT were observed in 16 (34%), 5 (11%), 2, and 2 cases, respectively. Patients with BRAF and CDKN2A-mutated ConjMel tended to be younger while the NF1-mutated one tended to be older. The eight tumors arising from nevi were enriched in CTNNB1 mutations (63% vs. 8%; Fisher's exact p-test = 0.001) compared to non-nevi ConjMel and five were devoid of BRAF, RAS, NF1, or KIT mutations, suggesting a specific oncogenic process in these tumors. The two KIT-mutated cases carried SF3B1 mutations and were located on sun-protected mucosa, a genotype shared with genital and anorectal mucosal melanomas. Targetable mutations were observed in ERBB2, IDH1, MET, and MAP2K1 (one occurrence each). Mutational landscape of ConjMel characterizes distinct molecular subtypes with oncogenic drivers common with mucosal and skin melanomas. CTNNB1 mutations were associated with nevus-derived ConjMel. Concomitant KIT/SF3B1 mutations in sun-protected cases suggest a common tumorigenic process with genital and anorectal mucosal melanomas.

Prognostic Implications of MRI Melanin Quantification and Cytogenetic Abnormalities in Liver Metastases of Uveal Melanoma.

To evaluate the prognostic implications of melanin quantification assessed by magnetic resonance imaging (MRI) with respect to the clinical, pathological, and genetic features of liver metastases of uveal melanoma (LMUM). This single-center retrospective cohort study included 63 patients eligible for margin-free resection of LMUM between 2007 and 2018. Comparative genomic hybridization of resected liver metastases on microarrays was performed for genetic risk classification. Metastases exhibiting monosomy 3 with any type of gain of chromosome 8 (M3/8g) were considered high-genetic-risk. MRI melanin quantification using the mean T1 signal (mT1s) in liver metastases was assessed quantitatively on preoperative imaging examination and compared to that of gross pathological evaluation. The association between MRI melanin quantification and overall survival (OS) was assessed by multivariate analysis using the Cox proportional hazards model. Gross pathological assessment of melanin content and MRI melanin quantification were strongly correlated (r = 0.8, p < 0.001). Independent prognostic factors associated with OS were disease-free interval ≤ 24 months (HR = 3.1; 95% CI, 1.6-6.0; p < 0.001), high-genetic-risk (HR = 2.2; 95% CI, 1.1-4.8; p = 0.04), mT1s > 1.1 (HR = 2.3; 95% CI, 1.2-4.7; p = 0.019), and complete hepatic resection (HR = 0.3; 95% CI, 0.2-0.7; p = 0.004). In patients with high-genetic-risk, mT1s showed a significant association with OS (HR = 3.7; 95% CI, 1.5-9.3; p = 0.006). The median OS was 17.5 months vs. 27 months for >1.1 and ≤1.1 mT1s tumors, respectively (p = 0.003). We showed that the level of pigmentation in M3/8g LMUM identified two subsets that were correlated with distinct clinical outcomes.

Association of TRF2 expression and myeloid-derived suppressor cells infiltration with clinical outcome of patients with cutaneous melanoma.

The outcome of patients with cutaneous melanoma has been strongly modified by recent advances obtained with Immune Checkpoint Inhibitors (ICIs). However, despite this breakthrough, durable response to ICIs is limited to a subset of patients. We investigated whether the expression of TRF2, which preserves telomere integrity, and have an effect on tumor immunosurveillance notably by directly recruiting and activating myeloid-derived suppressor cells (MDSCs), could be a prognostic biomarker in patients with relapsed or metastatic melanoma based on different treatment regimens. We evaluated retrospectively the association of TRF2 expressed in melanoma cells in combination with intratumoral CD33+ CD15+ CD14- MDSCs, as detected by immunohistochemistry and quantified by digital analysis, to clinicopathological features and overall survival (OS) among 48 patients treated with ICIs and 77 patients treated with other treatment options. The densities/mm2 of TRF2+ cells (P=.003) and CD33+ cells (P=.004) were individually significantly related to poor OS. In addition, only the combined expression of CD33+/CD15+/CD14- cells/mm2 was significantly correlated to poor OS (P=.017) in the whole study population as well as in patients treated by ICIs (P=.023). There was no significant difference in OS when analyzing the other markers individually or in combination according to the treatment regimen. The pre-treatment assessment of TRF2 expression and CD33+ cells/mm2 along with the density of CD33+/CD15+/CD14- cells/mm2 could assess OS and better predict clinical response of patients with melanoma treated by ICIs.

Splicing Patterns in SF3B1-Mutated Uveal Melanoma Generate Shared Immunogenic Tumor-Specific Neoepitopes.

Disruption of splicing patterns due to mutations of genes coding splicing factors in tumors represents a potential source of tumor neoantigens, which would be both public (shared between patients) and tumor-specific (not expressed in normal tissues). In this study, we show that mutations of the splicing factor SF3B1 in uveal melanoma generate such immunogenic neoantigens. Memory CD8+ T cells specific for these neoantigens are preferentially found in 20% of patients with uveal melanoma bearing SF3B1-mutated tumors. Single-cell analyses of neoepitope-specific T cells from the blood identified large clonal T-cell expansions, with distinct effector transcription patterns. Some of these expanded T-cell receptors are also present in the corresponding tumors. CD8+ T-cell clones specific for the neoepitopes specifically recognize and kill SF3B1-mutated tumor cells, supporting the use of this new family of neoantigens as therapeutic targets. SIGNIFICANCE: Mutations of the splicing factor SF3B1 in uveal melanoma generate shared neoantigens that are uniquely expressed by tumor cells, leading to recognition and killing by specific CD8 T cells. Mutations in splicing factors can be sources of new therapeutic strategies applicable to diverse tumors.This article is highlighted in the In This Issue feature, p. 1861.

The Prognostic Values of PARP-1 Expression in Uveal Melanoma.

BACKGROUND: Uveal melanoma is the most common primary intraocular malignancy in adults. In advanced cases, the prognosis is very poor. Thus far, no effective methods of pharmacotherapy of this cancer have been found. The aim of the study was to evaluate the expression of PARP-1, the best-known member of the family of poly(ADP-ribose) polymerases, in uveal melanoma and its associations with clinicopathological parameters, overall survival, and disease-free survival. METHODS: The study included 91 patients who underwent enucleation due to uveal melanoma. PARP-1 expression was assessed by immunohistochemistry. RESULTS: High PARP-1 expression was associated with more frequent chromosome 3 loss, higher histopathological grade, bigger tumor size, and absence of intrascleral extension. High PARP-1 expression was associated with shorter overall survival time and disease-free survival time. CONCLUSIONS: The above findings indicate that high expression of PARP-1 can be considered as an unfavorable prognostic factor in uveal melanoma.

Germline MBD4 Mutations and Predisposition to Uveal Melanoma.

BACKGROUND: Uveal melanoma (UM) arises from malignant transformation of melanocytes in the uveal tract of the eye. This rare tumor has a poor outcome with frequent chemo-resistant liver metastases. BAP1 is the only known predisposing gene for UM. UMs are generally characterized by low tumor mutation burden, but some UMs display a high level of CpG>TpG mutations associated with MBD4 inactivation. Here, we explored the incidence of germline MBD4 variants in a consecutive series of 1093 primary UM case patients and a series of 192 UM tumors with monosomy 3 (M3). METHODS: We performed MBD4 targeted sequencing on pooled germline (n = 1093) and tumor (n = 192) DNA samples of UM patients. MBD4 variants (n = 28) were validated by Sanger sequencing. We performed whole-exome sequencing on available tumor samples harboring MBD4 variants (n = 9). Variants of unknown pathogenicity were further functionally assessed. RESULTS: We identified 8 deleterious MBD4 mutations in the consecutive UM series, a 9.15-fold (95% confidence interval = 4.24-fold to 19.73-fold) increased incidence compared with the general population (Fisher exact test, P = 2.00 × 10-5, 2-sided), and 4 additional deleterious MBD4 mutations in the M3 cohort, including 3 germline and 1 somatic mutations. Tumors carrying deleterious MBD4 mutations were all associated with high tumor mutation burden and a CpG>TpG hypermutator phenotype. CONCLUSIONS: We demonstrate that MBD4 is a new predisposing gene for UM associated with hypermutated M3 tumors. The tumor spectrum of this predisposing condition will likely expand with the addition of MBD4 to diagnostic panels. Tumors arising in such a context should be recognized because they may respond to immunotherapy.