Leucine-rich a-2-glycoprotein 1 (LRG1) is a candidate therapeutic target for treating the neovascular form of age-related macular degeneration (nvAMD). In this study we examined the expression of LRG1 in eyes of nvAMD patients. Choroidal neovascular membranes (CNVMs) from patients who underwent submacular surgery for retinal pigment epithelium–choroid graft transplantation were collected from 5 nvAMD patients without any prior intravitreal anti-VEGF injection, and from six patients who received intravitreal anti-VEGF injections before surgery. As controls free of nvAMD, retina sections were obtained from the eyes resected from a patient with lacrimal sac tumor and from a patient with neuroblastoma. CNVMs were immunostained for CD34, LRG1, and α-smooth muscle actin (α-SMA). Aqueous humor samples were collected from 58 untreated-naïve nvAMD patients prior to the intravitreal injection of anti-VEGF and 51 age-matched cataract control patients, and LRG1 concentration was measured by ELISA. The level of LRG1 immunostaining is frequently high in both the endothelial cells of the blood vessels, and myofibroblasts in the surrounding tissue of CNVMs of treatment-naïve nvAMD patients. Furthermore, the average concentration of LRG1 was significantly higher in the aqueous humor of nvAMD patients than in controls. These observations provide a strong experimental basis and scientific rationale for the progression of a therapeutic anti-LRG1 monoclonal antibody into clinical trials with patients with nvAMD.

Maria Chiara Siciliano, Dr, Giorgio Bertolazzi, Selina Glaser, Massimo Granai, Cosimo Lori, Roberto Boccacci, Dr, Srujana V. Yellapragada, Margherita Vannu

Background: Complex cases of retinoblastoma (RB) often require integrative molecular approaches to define tumor etiology and guide clinical management. Purpose: Our aim was to evaluate the usefulness of combining aqueous humor (AH)/plasma cell-free DNA next-generation sequencing (cfDNA-NGS) and long-read–whole-genome sequencing (LR-WGS) to resolve diagnostically challenging RB cases. Case Description: We report the case of a 3-year-old Caucasian girl, conceived by heterologous assisted reproductive technology (ART), presenting with unilateral, widely infiltrative RB in the right eye. She exhibited limited verbal communication, a glabellar angioma extending to the nasal bridge and philtrum, and mild hypertelorism. Standard blood testing revealed no pathogenic SNVs, CNVs, or methylation abnormalities in the RB1 gene. Targeted cfDNA analysis using the Illumina TruSight Oncology 500 (TSO500) panel on AH and plasma identified a somatic RB1 splice-site variant (c.1498+2T>C) with a variant allele frequency (VAF) of 98.5%, consistent with biallelic inactivation. Additional gains (fold change > 1.5) were found in AH and confirmed in plasma, suggesting a germline 13q duplication. Third-generation LR-WGS, performed with Oxford Nanopore Technology (ONT), on blood confirmed a 24.6 Mb duplication on chromosome 13, compatible with the rare 13q duplication syndrome characterized by psychomotor delay, craniofacial dysmorphism, and hemangiomas. AH-cfDNA revealed additional somatic copy-number alterations, including amplifications (i.e., MDM4 and ALK) and deletions (i.e., BRCA2), indicating progressive clonal tumor evolution. Conclusions: This experience tells us that a combined approach with TSO500 Illumina NGS on cfDNA, along with LR-WGS, is able to help solve complex cases and define the appropriate treatment and surveillance strategy.

Background/Objectives: B-cell receptor (BCR) signalling is implicated in Burkitt lymphoma (BL) lymphomagenesis, although its activation may differ across biological and epidemiological settings. While surface IgM is the predominant immunoglobulin isotype of BCR in BL, cases expressing IgA transcripts or lacking detectable surface immunoglobulin (sIg) expression have been reported, suggesting a more complex pattern of sIg expression than previously recognized. This study aimed to evaluate sIg heavy-chain expression by immunohistochemistry in a relatively large series of BL cases from endemic and sporadic settings and to investigate the mutational landscape of surface immunoglobulin-undetectable (sIg-UND) cases. Methods: sIg heavy-chain expression was assessed by immunohistochemistry in 55 formalin-fixed paraffin-embedded BL samples. Targeted next-generation sequencing was performed on four sIg-UND cases using an Illumina capture-based custom panel covering 74 lymphoma-related genes. KRAS and NRAS hotspot mutations were additionally assessed by real-time PCR. Results: Overall, 41/55 cases showed IgM expression, including 31 IgM-positive and 10 IgM+/UND cases, whereas 8/55 cases showed IgA expression (IgA+/UND). IgA-expressing cases were significantly enriched at mucosal sites, particularly the oral cavity and gastrointestinal tract, consistent with the relevance of these anatomical sites to mucosal IgA production. Six cases lacked detectable sIg expression, showing negativity for all tested immunoglobulin heavy chains in more than 90% of neoplastic cells. Four sIg-UND cases were available for sequencing. These cases harbored mutations affecting genes commonly altered in BL, together with alterations in genes less commonly represented in recurrent BL series, such as MEF2B, CREBBP, PRDM1, PIM1, ARID3A, HIST1H1B, and HIST1H1C. Conclusions: Our study provides a systematic immunohistochemical characterization of surface immunoglobulin heavy-chain expression in a relatively large series of endemic and sporadic BL. We identified a subset of IgA-expressing BL cases enriched at mucosal sites, whereas rarer cases lacked detectable surface immunoglobulin expression. The mutational profile of sIg-UND cases highlights alterations affecting genes involved in epigenetic regulation, chromatin organization, and B-cell differentiation, which may contribute to the biological heterogeneity of these cases. No KRAS or NRAS hotspot mutations were detected in the four sequenced sIg-UND cases, as assessed by targeted NGS and real-time PCR. Further functional studies are needed to clarify the biological and clinical significance of sIg-UND BL cases and to determine the functional relevance of the identified alterations.