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Background: MICA and MICB are tightly regulated stress-induced proteins that trigger the immune system by binding to the activating receptor NKG2D on cytotoxic lymphocytes. MICA and MICB are highly polymorphic molecules with prevalent expression on several types of solid tumors and limited expression in normal/healthy tissues, making them attractive targets for therapeutic intervention. Methods: We have generated a series of anti-MICA and MICB cross-reactive antibodies with the unique feature of binding to the most prevalent isoforms of both these molecules. Results: The anti-MICA and MICB antibody MICAB1, a human IgG1 Fc-engineered monoclonal antibody (mAb), displayed potent antibody-dependent cellular cytotoxicity (ADCC) and antibody-dependent cellular phagocytosis (ADCP) of MICA/B-expressing tumor cells in vitro. However, it showed insufficient efficiency against solid tumors in vivo, which prompted the development of antibody-drug conjugates (ADC). Indeed, optimal tumor control was achieved with MICAB1-ADC format in several solid tumor models, including patient-derived xenografts (PDX) and carcinogen-induced tumors in immunocompetent MICAgen transgenic mice. Conclusions: These data indicate that MICA and MICB are promising targets for cytotoxic immunotherapy.

International audience; Knowledge of the BRAF mutational status has become essential for melanoma therapeutic management. B-Raf inhibitors are associated with significant overall survival in patients with BRAFV600-mutated metastatic melanoma. Although the BRAF mutation appears to be an early and driver mutation, some authors hypothesized that its expression was not stable during melanoma progression, suggesting a molecular heterogeneity. This argument is often used to explain discrepancy in molecular status among patients with melanoma, discrepancies that we occasionally met during our practice. We retrospectively compared BRAF mutational status on matched melanoma samples (primary & metastatic lesions), thus 150 samples from 56 patients were analysed through immunohistochemistry anti-BRAF, PCR-HRM and Sanger sequencing, Next Generation Sequencing (NGS) and digital PCR. Seven cases presented an apparent tumor heterogeneity. The analysis of these discrepancies by a technique of increasing sensitivity made it possible to identify 1 false-negative result for the immunohistochemistry, 1 false-negative result for the NGS sequencing and 5 (3%) false-negative results by PCR-HRM SANGER. Our results are consistent with the most recent data, demonstrating the stability of the BRAF mutation during the course of melanoma. Immunohistochemistry shows excellent sensitivity for detecting the main BRAF mutation. In our study, the mutational heterogeneity was actually misleading, a result of imperfect sensitivity of some older molecular approaches.; La connaissance du statut mutationnel du gène BRAF est devenue essentielle dans la prise en charge du mélanome. Les inhibiteurs de B-Raf sont à l’origine d’une nette amélioration de la survie globale chez les patients présentant un mélanome métastatique muté BRAF V600. Bien que la mutation BRAF soit considérée comme un événement précoce et conducteur (driver), certains travaux ont émis l’hypothèse qu’elle n’était pas stable lors de l’évolution d’un mélanome, impliquant une hétérogénéité moléculaire. Cet argument est souvent utilisé pour expliquer les discordances de statut moléculaire observées chez certains patients atteints de mélanome, discordances occasionnellement rencontrées au cours de notre pratique. Nous avons rétrospectivement comparé le statut mutationnel du gène BRAF sur plusieurs prélèvements appariés de mélanome (primitif & localisations secondaires), soit 150 prélèvements pour 56 patients, en utilisant l’immunohistochimie anti-BRAF, la PCR-HRM et séquençage Sanger, le séquençage massivement parallèle (NGS) et la PCR digitale. Sept cas présentaient une apparente hétérogénéité tumorale. L’analyse de ces discordances par une technique de sensibilité croissante a permis d’identifier 1 résultat faux-négatif pour l’immunohistochimie, 1 résultat faux-négatif pour le séquençage NGS et 5 (3 %) résultats faux-négatifs par technique PCR-HRM SANGER. Nos résultats sont cohérents avec les données les plus récentes, témoignant de la stabilité de la mutation BRAF au cours de l’évolution d’un mélanome. L’immunohistochimie présente une sensibilité excellente pour détecter la mutation majoritaire de BRAF. Dans notre étude, l’hétérogénéité mutationnelle était en réalité factice, conséquence d’une sensibilité imparfaite de certaines approches moléculaires plus anciennes.

International audience; YAP1-NUTM1 fusion transcripts have been recently reported in poroma and porocarcinoma. NUTM1 translocation can be screened by nuclear protein in testis (NUT) immunohistochemistry in various malignancies, but its diagnostic performance has not been thoroughly validated on a large cohort of cutaneous epithelial neoplasms. We have evaluated NUT immunohistochemical expression in a large cohort encompassing 835 cases of various cutaneous epidermal or adnexal epithelial neoplasms. NUT expression was specific to eccrine poromas and porocarcinoma, with 32% of cases showing NUT expression. All other cutaneous tumors tested lacked NUT expression, including mimickers such as seborrheic keratosis, Bowen disease, basal cell carcinoma, squamous cell carcinoma, Merkel cell carcinoma, nodular hidradenoma, and all other adnexal tumors tested. Remarkably, NUT expression was more frequent in a distinct morphologic subgroup. Indeed, 93% of poroid hidradenoma (dermal/subcutaneous nodular poroma, 13/14) and 80% of poroid hidradenocarcinoma cases (malignant poroid hidradenoma, 4/5) showed NUT expression, in contrast to 17% and 11% of classic poroma (4/23) and porocarcinoma cases (4/35), respectively. RNA sequencing of 12 NUT-positive neoplasms further confirmed the presence of a YAP1-NUTM1 fusion transcript in all cases, and also an EMC7-NUTM1 gene fusion in a single case. In the setting of a cutaneous adnexal neoplasm, nuclear expression of NUT accurately and specifically diagnosed a specific subgroup of benign and malignant poroid tumors, all associated with a NUTM1 fusion, which frequently harbored a poroid hidradenoma morphology.

The use of videoconferencing had increased significantly during lockdown. During this period, videoconferencing has been used in the pathological department of pathology (Timone university hospital, Marseille, France) for academic, diagnosis and referral. We provide our point of view regarding the use of this tool. As discussing slides through videoconferencing is a new and specific activity, we have also summarised specific recommendations for practical remote histopathology meetings., Le confinement et la distanciation sociale ont généralisé l’usage de la visioconférence, tant dans la sphère privée que professionnelle. Ainsi, l’utilisation de la visioconférence a considérablement augmenté durant la période du confinement et cette technologie a été utilisée dans le service d’anatomie pathologique du centre hospitalo-universitaire Timone, à Marseille, à visée universitaire, hospitalière et de recours. Nous apportons notre point de vue concernant l’utilisation de cet outil informatique. La discussion de lames par visioconférence est un exercice nouveau et particulier ; plusieurs recommandations sont émises pour un bon déroulement de ces réunions d’histopathologie à distance.

Knowledge of the BRAF mutational status has become essential for melanoma therapeutic management. B-Raf inhibitors are associated with significant overall survival in patients with BRAFV600-mutated metastatic melanoma. Although the BRAF mutation appears to be an early and driver mutation, some authors hypothesized that its expression was not stable during melanoma progression, suggesting a molecular heterogeneity. This argument is often used to explain discrepancy in molecular status among patients with melanoma, discrepancies that we occasionally met during our practice. We retrospectively compared BRAF mutational status on matched melanoma samples (primarymetastatic lesions), thus 150 samples from 56 patients were analysed through immunohistochemistry anti-BRAF, PCR-HRM and Sanger sequencing, Next Generation Sequencing (NGS) and digital PCR. Seven cases presented an apparent tumor heterogeneity. The analysis of these discrepancies by a technique of increasing sensitivity made it possible to identify 1 false-negative result for the immunohistochemistry, 1 false-negative result for the NGS sequencing and 5 (3%) false-negative results by PCR-HRM SANGER. Our results are consistent with the most recent data, demonstrating the stability of the BRAF mutation during the course of melanoma. Immunohistochemistry shows excellent sensitivity for detecting the main BRAF mutation. In our study, the mutational heterogeneity was actually misleading, a result of imperfect sensitivity of some older molecular approaches.

International audience

Objective. To evaluate the vascular occlusion and midterm tissue toxicity properties of a combination of ethylene-vinyl alcohol (EVOH) (Squid 18®) (75%) and alcohol (25%)—Alco-Squid 18—in a swine model. Materials and Methods. Alco-Squid 18 (75% Squid 18® mixed with 25% alcohol) (AS18) was compared to embolization with 96% alcohol alone and to embolization with Squid 18® (S18®) alone. An arteriovenous malformation (AVM) model was created in group 1 (n = 2). Each AVM model was then embolized with AS18 or S18® alone with evaluation of a ratio between the volume of embolic agent divided by the volume of the AVM (evaluated by CT). For group 2 (n = 5), each agent was tested on three different kidneys (upper pole kidney artery). Pre- and postinterventional CTs, angiographies, blood alcohol content dosages, and histological studies (3 months postintervention) were performed. Results. AS18 has better distal distribution than S18® alone, both in the kidneys (mean capsule-S18® distance: 3.9 mm (±0.23) and mean capsule-AS18 distance: 2.3 mm (±0.11) ( p = 0.029 ) and in the AVM model. Histological exploration found a higher rate of tubular necrosis with AS18 compared with S18® alone and alcohol alone (3.78 ± 0.44 compared to 2.33 ± 1.22 p = 0 . 012 and 1.22 ± 0.67 p < 0 . 0001 ). The blood alcohol content was negligible in all cases. Conclusion. AS18 can suggest a better distal sclerotic and embolic character as compared with S18® alone without systemic toxicity.

International audience; Pediatric neoplasms with a myofibroblastic differentiation are frequent in children, in particular myofibroma. Recently, a novel deep soft tissue myofibroblastic neoplasm has been described with high cellularity, a smooth muscle phenotype and SRF-RELA fusion. We report the case of a 15-year-old boy who presented with a tumor of the deep soft tissue of the arm, with overlapping histological features with the recently described SRF-RELA group of myofibromas but differing by the presence of calcifications, a novel SRF-STAT6 fusion transcript and nuclear expression of STAT6. No local recurrence nor distant metastasis was detected at the current follow-up of 29 months. The clinical relevance of this novel fusion requires further investigations.

Background: MICA and MICB are tightly regulated stress-induced proteins that trigger the immune system by binding to the activating receptor NKG2D on cytotoxic lymphocytes. MICA and MICB are highly polymorphic molecules with prevalent expression on several types of solid tumors and limited expression in normal/healthy tissues, making them attractive targets for therapeutic intervention. Methods: We have generated a series of anti-MICA and MICB cross-reactive antibodies with the unique feature of binding to the most prevalent isoforms of both these molecules. Results: The anti-MICA and MICB antibody MICAB1, a human IgG1 Fc-engineered monoclonal antibody (mAb), displayed potent antibody-dependent cellular cytotoxicity (ADCC) and antibody-dependent cellular phagocytosis (ADCP) of MICA/B-expressing tumor cells in vitro. However, it showed insufficient efficiency against solid tumors in vivo, which prompted the development of antibody-drug conjugates (ADC). Indeed, optimal tumor control was achieved with MICAB1-ADC format in several solid tumor models, including patient-derived xenografts (PDX) and carcinogen-induced tumors in immunocompetent MICAgen transgenic mice. Conclusions: These data indicate that MICA and MICB are promising targets for cytotoxic immunotherapy.