Modulation of human thrombopoietin receptor conformations uncouples JAK2 V617F-driven activation from cytokine-induced stimulation.

The thrombopoietin receptor (TpoR) plays a central role in myeloproliferative neoplasms (MPNs). Mutations in JAK2, calreticulin, or TpoR itself drive the constitutive activation of TpoR and uncontrolled proliferation and differentiation of hematopoietic stem cells and progenitors. The JAK2 V617F mutation is responsible for most MPNs, and all driver mutants induce pathologic TpoR activation. Existing therapeutic strategies have focused on JAK2 kinase inhibitors that are unable to differentiate between the mutated MPN clone and healthy cells. Surprisingly, the targeting of TpoR itself has remained poorly explored despite its central role in pathology. Here, we performed a comprehensive characterization of human TpoR activation under physiological and pathological conditions, focusing on the JAK2 V617F mutant. Using a system of controlled dimerization of the transmembrane and cytosolic domains of TpoR, we discovered that human TpoR (hTpoR) adopts different dimeric conformations upon Tpo-induced vs JAK2 V617F-mediated activation. We identified the amino acids and specific dimeric conformation of hTpoR responsible for activation in complex with JAK2 V617F and confirmed our findings in the full-length receptor context in hematopoietic cell lines and primary bone marrow cells. Remarkably, we found that the modulation of hTpoR conformations by point mutations allowed for specific inhibition of JAK2 V617F-driven activation without affecting Tpo-induced signaling. Our results demonstrate that modulation of the hTpoR conformation is a viable therapeutic strategy for JAK2 V617F-positive MPNs and set the path for novel drug development by identifying precise residues of hTpoR involved in JAK2 V617F-specific activation.

CALR mutant protein rescues the response of MPL p.R464G variant associated with CAMT to eltrombopag.

Congenital amegakaryocytic thrombocytopenia (CAMT) is a severe inherited thrombocytopenia due to loss-of-function mutations affecting the thrombopoietin (TPO) receptor, MPL. Here, we report a new homozygous MPL variant responsible for CAMT in 1 consanguineous family. The propositus and her sister presented with severe thrombocytopenia associated with mild anemia. Next-generation sequencing revealed the presence of a homozygous MPLR464G mutation resulting in a weak cell-surface expression of the receptor in platelets. In cell lines, we observed a defect in MPLR464G maturation associated with its retention in the endoplasmic reticulum. The low cell-surface expression of MPLR464G induced very limited signaling with TPO stimulation, leading to survival and reduced proliferation of cells. Overexpression of a myeloproliferative neoplasm-associated calreticulin (CALR) mutant did not rescue trafficking of MPLR464G to the cell surface and did not induce constitutive signaling. However, it unexpectedly restored a normal response to eltrombopag (ELT), but not to TPO. This effect was only partially mimicked by the purified recombinant CALR mutant protein. Finally, the endogenous CALR mutant was able to restore the megakaryocyte differentiation of patient CD34+ cells carrying MPLR464G in response to ELT.

[Iron deficiency and anemia in junior women's competitive sport]. / Carence martiale et anémie dans le sport de compétition junior féminin.

An iron deficient athlete is likely to develop iron deficiency anemia, a pathology that may lead to a decrease in performance. If adult athletes, women and men, are aware of the need for regular monitoring, young people under 18 are not necessarily aware of the risks associated with competitive sports practice in the presence of anemia. Even if the guidelines are well known and described, a lack of regular monitoring is found for the aforementioned age group. In junior female athletes practicing basketball, a significant rate of iron deficiency or even iron deficiency anemia was found during annual analyses. The authors wish to emphasize the importance of regular medical and laboratory follow-up for younger athletes who often no longer have a pediatrician and no attending physician.

Un sportif carencé en fer risque de développer une anémie ferriprive qui peut être à l'origine d'une diminution des performances. Les sportifs adultes, femmes et hommes, ont conscience de la nécessité d'un suivi régulier mais cette connaissance des risques liés à l'anémie dans la pratique sportive n'est pas forcément présente chez les jeunes de moins de 18 ans. Même si les lignes de conduite sont décrites et connues, on observe un manque de suivi régulier dans la tranche d'âge précitée. Chez les basketteuses féminines juniors, un taux de carence martiale significatif, voire une anémie ferriprive, a été retrouvé lors des analyses annuelles. Les auteurs souhaitent mettre ce problème en évidence et souligner l'importance d'un suivi médical et biologique régulier pour les sportifs en devenir qui n'ont souvent plus de médecin pédiatre et pas encore de médecin traitant.

MPL mutations in essential thrombocythemia uncover a common path of activation with eltrombopag dependent on W491.

Mutations in the MPL gene encoding the human thrombopoietin receptor (TpoR) drive sporadic and familial essential thrombocythemias (ETs). We identified 2 ET patients harboring double mutations in cis in MPL, namely, L498W-H499C and H499Y-S505N. Using biochemical and signaling assays along with partial saturation mutagenesis, we showed that L498W is an activating mutation potentiated by H499C and that H499C and H499Y enhance the activity of the canonical S505N mutation. L498W and H499C can activate a truncated TpoR mutant, which lacks the extracellular domain, indicating these mutations act on the transmembrane (TM) cytosolic domain. Using a protein complementation assay, we showed that L498W and H499C strongly drive dimerization of TpoR. Activation by tryptophan substitution is exquisitely specific for position 498. Using structure-guided mutagenesis, we identified upstream amino acid W491 as a key residue required for activation by L498W or canonical activating mutations such as S505N and W515K, as well as by eltrombopag. Structural data point to a common dimerization and activation path for TpoR via its TM domain that is shared between the small-molecule agonist eltrombopag and canonical and novel activating TpoR mutations that all depend on W491, a potentially accessible extracellular residue that could become a target for therapeutic intervention.

Lithium treatment reverses irradiation-induced changes in rodent neural progenitors and rescues cognition.

Cranial radiotherapy in children has detrimental effects on cognition, mood, and social competence in young cancer survivors. Treatments harnessing hippocampal neurogenesis are currently of great relevance in this context. Lithium, a well-known mood stabilizer, has both neuroprotective, pro-neurogenic as well as antitumor effects, and in the current study we introduced lithium treatment 4 weeks after irradiation. Female mice received a single 4 Gy whole-brain radiation dose on postnatal day (PND) 21 and were randomized to 0.24% Li2CO3 chow or normal chow from PND 49 to 77. Hippocampal neurogenesis was assessed on PND 77, 91, and 105. We found that lithium treatment had a pro-proliferative effect on neural progenitors, but neuronal integration occurred only after it was discontinued. Also, the treatment ameliorated deficits in spatial learning and memory retention observed in irradiated mice. Gene expression profiling and DNA methylation analysis identified two novel factors related to the observed effects, Tppp, associated with microtubule stabilization, and GAD2/65, associated with neuronal signaling. Our results show that lithium treatment reverses irradiation-induced loss of hippocampal neurogenesis and cognitive impairment even when introduced long after the injury. We propose that lithium treatment should be intermittent in order to first make neural progenitors proliferate and then, upon discontinuation, allow them to differentiate. Our findings suggest that pharmacological treatment of cognitive so-called late effects in childhood cancer survivors is possible.

Prospective phase II study of children affected by bilateral intraocular retinoblastoma with macular involvement of both eyes or in the only preserved eye. Macular tumor control, eye preservation rate, and visual outcome.

BACKGROUND: Conservative treatments of intraocular retinoblastoma often consist of chemotherapy and focal treatments. The protocols vary and currently may combine two or three drugs, with different number of cycles, associated to the ocular treatments. In case of macular/paramacular involvement, tumor location and retinal scars induced by focal treatments often have a major negative impact on final visual outcome. METHODS: This study aimed to include children affected by bilateral intraocular macular/paramacular retinoblastoma in a prospective phase II study. The protocol consisted of six cycles of a three-drug combination (vincristine, etoposide, carboplatin), and the addition of macula-sparing transpupillary thermotherapy (TTT) to the third cycle. The primary endpoint was the local control rate without external beam radiotherapy (EBR) and/or enucleation. RESULTS: Nineteen patients (26 eyes) were included from July 2004 to November 2009. Thirteen eyes belonged to group V of the Reese-Ellsworth classification and 10 to group D of the International Intraocular Retinoblastoma Classification. Macular/paramacular tumors were treated with chemotherapy alone in nine eyes, and with chemotherapy associated with macula-sparing TTT in 17 eyes. Four eyes experienced macular relapse. At a median follow up of 77 months, 23 eyes (88.5%) were saved without EBR, two were enucleated and one received EBR. The median visual acuity of the 24 saved eyes was 20/50. No severe adverse effect was observed. CONCLUSION: Six cycles of a three-drug combination associated with macula-sparing TTT achieved good tumor control, improved eye preservation rates without EBR, and decreased macular damage, often providing satisfactory visual results with long-term follow up.

[Hallux Rigidus: first metatarsophalangeal arthrosis Symptoms and current treatments]. / Hallux rigidus : arthrose métatarsophalangienne du premier rayon - Symptômes et traitements actuels.

Metatarsophalangeal arthritis of the first ray of the foot, also known as hallux rigidus, is an invalidating cause of walking that is still underestimated. It is associated to a local deformation of the first ray with a limitation of the dorsal mobilization of the joint, affecting thus the propulsion of the foot. Several stages of the disease exist, and symptoms as well as the treatment will depend on the moment of the consultation. In this paper, we present the different clinical pictures and adapted treatments according to the stage of the disease, and we share our results of a new modality of surgery that conserves the articular mobility of the joint.

L'arthrose métatarsophalangienne du premier rayon du pied, connue également sous le nom de « hallux rigidus ¼, est une pathologie invalidante de la marche encore sous-estimée. Elle est associée à une déformation localisée du premier rayon et à une limitation de la flexion dorsale au niveau de l'articulation, affectant ainsi la propulsion. Plusieurs stades de cette maladie existent, et les symptômes ainsi que leurs traitements dépendront du moment de consultation. Dans cet article, nous présentons les différents symptômes et traitements de cette arthrose, adaptés selon le stade en partageant notre expérience avec les nouveautés technologiques conservatrices du mouvement articulaire et leur résultat à moyen terme.

TREATMENT OF EXUDATIVE CIRCUMSCRIBED CHOROIDAL HEMANGIOMA: Efficacy of Fractionated Proton Therapy (20 Gray Relative Biological Effectiveness in 8 Fractions).

PURPOSE: To evaluate treatment of circumscribed choroidal hemangioma by hyperfractionated proton beam therapy protocol (20 gray relative biological effectiveness in 8 fractions) on tumor control, attachment of retina and visual function. METHODS: Retrospective review of patients treated between January 2010 and April 2015 with at least 6 months of follow-up. RESULTS: Forty-three patients with exudative and symptomatic circumscribed choroidal hemangioma were included. Before treatment, 41 (95%) presented an exudative retinal detachment, median visual acuity was 20/63 and median tumor thickness was 3.3 mm. Mean follow-up was 26 months (7-62). At last follow-up, all patients presented regression of ultrasound tumor thickness and 23/43 (53.5%) a totally flat scar. The mean time to achieve a flat scar was 20 months. Retina was reattached in all patients except one with 9 months of follow-up. Visual acuity was improved or stabilized in 37 patients (86%) and final median visual acuity was 20/25. No patient presented radiation maculopathy or papillopathy. CONCLUSION: Proton beam therapy with a dose of 20 gray relative biological effectiveness delivered in 8 fractions provides excellent anatomical and functional results and are comparable with those obtained with the same dose delivered in 4 fractions. Longer follow-up is required to determine the long-term radiation sequelae.

A novel EWS-CREB3L3 gene fusion in a mesenteric sclerosing epithelioid fibrosarcoma.

Sclerosing epithelioid fibrosarcoma (SEF) is a rare, malignant fibroblastic neoplasm, morphologically composed of cords, nests or sheets of monotonous epithelioid cells within a collagenous matrix. It has been recently characterized by recurrent pathogenic EWS-CREB3L1/2 or FUS-CREB3L2 fusions and common MUC4 protein expression by immunohistochemistry. Typically SEF occur in middle-aged adults and rarely have been reported within the abdominal cavity. Here we report an 18-year-old man with intraabdominal tumor and multiple disseminated liver metastases, presenting pure SEF histologic and immunophenotypic features. Fluorescence in situ hybridization analysis showed unbalanced rearrangement of Ewing sarcoma breakpoint region 1 (EWSR1) gene. Genomic profiling by array CGH, followed by RT-PCR and sequencing analysis, revealed a previously not reported EWSR1 translocation partner, cAMP-responsive element-binding protein 3-like 3 (CREB3L3). The novel EWSR1-CREB3L3 fusion further extends the range of fusion types involving EWSR1 that are characteristic for SEF.

Necrotizing enterocolitis as an adverse effect of recombinant interleukin-2 and Ch14.18 in maintenance therapy for high-risk neuroblastoma.

Recombinant interleukin-2 is used with ch14.18/CHO to improve the cytotoxic activity of NK lymphocytes against neoplastic cells. The efficacy of this treatment is limited by its potential side effects. We report an unusual case of necrotizing enterocolitis associated with the administration of interleukin-2 and ch14.18/CHO in maintenance therapy for localized NMyc amplified neuroblastoma (NBL). This case highlights the potentially significant toxicity of this immunotherapy that is currently being tested in the high-risk NBL-1.5 protocol. Further, short-term, medium-term, and long-term follow-up in this patient population will be warranted to judge the potential benefit of this treatment versus the short-term, medium-term, and long-term side effects in a patient population with an outcome that is better than that of stage 4 NBL patients.

Choroidal melanoma: does endoresection prevent neovascular glaucoma in patient treated with proton beam irradiation?

PURPOSE: To evaluate the efficacy of endoresection after proton beam radiotherapy to prevent neovascular glaucoma (NVG) in patients treated for choroidal melanoma. METHODS: From a series of 4,867 patients treated for choroidal melanoma were prospectively recorded in the database (Macro Infermed 3.075). One hundred and seventy-one patients presenting a tumor diameter >10 mm and thickness >5 mm treated with proton beam (PB) radiotherapy were selected. One group of 63 patients was treated with PB therapy followed by endoresection (PE) of the scar. This group was compared with 2 historical matched controlled groups: 57 patients treated with PB therapy alone (P) and 51 patients treated with PB therapy followed by transpupillary thermotherapy of the scar (PTTT). Main outcome measures are as follows: age, gender, tumor diameter, tumor thickness, pre- and posttreatment visual acuity, NVG rate, secondary enucleation rate, and 5-year survival. Statistical analysis was performed using R version 2.5.1 software. RESULTS: Correlations between the 3 groups were P = 0.29 for age, P = 4.7×10 for tumor diameter, and P = 6.44×10 for tumor thickness. Comparison between the 3 groups showed that 2-year survival without secondary enucleation was 96.2% for PE, 88.8% for P, and 98% for PTTT (P = 0.203) (95% confidence interval). Two-year survival without NVG (95% confidence interval) was 92.7% (85.1-1.00) for PE, 54.6% for P, and 62.1% for PTTT (P = 0.0001). The difference between the endoresection (PE) group and the PB radiotherapy (P) and PB radiotherapy + TTT (PTTT) groups in terms of reduction of the NVG rate was statistically significant. Relative risk of developing NVG was calculated with the P group as reference, relative risk = 1. The relative risk of the PTTT group was 0.79 (20% reduction of the risk), and the relative risk of the PE group was 0.18 (82% reduction of the risk of developing NVG). CONCLUSION: This study shows that endoresection of the necrotic scar after PB radiotherapy reduces the risk of NVG and secondary enucleation for selected choroidal melanoma patients.

Optical Density Ratio of Subretinal Fluid in Choroidal Melanomas Versus Choroidal Naevi Assessed by Optical Coherence Tomography.

Purpose: The purpose of this study was to determine whether optical density ratio (ODR) of subretinal fluid (SRF) on optical coherence tomography (OCT) differs between choroidal naevi and melanomas. Methods: One hundred ninety-nine patients (one eye per patient) presenting choroidal melanoma or choroidal naevus with SRF on OCT, evaluated between February and June 2019, were retrospectively included. Other retinal conditions, opaque media, and low-quality OCT were excluded. Mean pixel intensity of SRF (range = 0-255) was quantified using a semi-automated procedure by a masked observer on standard horizontal OCT sections. Mean vitreous intensity served as the reference for ODR. Results: One hundred twenty-eight patients with choroidal melanoma and 71 patients with choroidal naevus were included in this study. ODR (mean ± SD) was higher in melanomas (181 ± 64) than in naevi (78 ± 48, P < 0.0001). ODR was correlated to lesion thickness (P < 0.0001, r = 0.27), largest basal diameter (P = 0.028, r = 0.16) and, among naevi, to the number of risk factors for growth into melanoma (P = 0.032, r = 0.22). Among 110 patients with naevi or melanoma who underwent fluorescein angiography, ODR was 120.7 ± 550.1 in eyes presenting angiographic pinpoints versus 14.19 ± 26.0 in eyes that did not (P = 0.06). Fourteen eyes with naevi that transformed into melanoma over 3 years had a mean baseline ODR of 94.7 ± 243.5 compared to 4.01 ± 9.74 in 28 matched naevi eyes of similar size that did not transform (P = 0.027). Conclusions: SRF ODR is higher in choroidal melanoma compared to choroidal naevi. This OCT-derived imaging marker is also higher in choroidal naevi with the potential to transform into melanoma, compared to stationary naevi.

Constitutive activation and oncogenicity are mediated by loss of helical structure at the cytosolic boundary of thrombopoietin receptor mutant dimers.

Dimerization of the thrombopoietin receptor (TpoR) is necessary for receptor activation and downstream signaling through activated Janus kinase 2. We have shown previously that different orientations of the transmembrane (TM) helices within a receptor dimer can lead to different signaling outputs. Here we addressed the structural basis of activation for receptor mutations S505N and W515K that induce myeloproliferative neoplasms. We show using in vivo bone marrow reconstitution experiments that ligand-independent activation of TpoR by TM asparagine (Asn) substitutions is proportional to the proximity of the Asn mutation to the intracellular membrane surface. Solid-state NMR experiments on TM peptides indicate a progressive loss of helical structure in the juxtamembrane (JM) R/KWQFP motif with proximity of Asn substitutions to the cytosolic boundary. Mutational studies in the TpoR cytosolic JM region show that loss of the helical structure in the JM motif by itself can induce activation, but only when localized to a maximum of six amino acids downstream of W515, the helicity of the remaining region until Box 1 being required for receptor function. The constitutive activation of TpoR mutants S505N and W515K can be inhibited by rotation of TM helices within the TpoR dimer, which also restores helicity around W515. Together, these data allow us to develop a general model for activation of TpoR and explain the critical role of the JM W515 residue in the regulation of the activity of the receptor.

JAK inhibitors and COVID-19.

During SARS-CoV-2 infection, the innate immune response can be inhibited or delayed, and the subsequent persistent viral replication can induce emergency signals that may culminate in a cytokine storm contributing to the severe evolution of COVID-19. Cytokines are key regulators of the immune response and virus clearance, and, as such, are linked to the-possibly altered-response to the SARS-CoV-2. They act via a family of more than 40 transmembrane receptors that are coupled to one or several of the 4 Janus kinases (JAKs) coded by the human genome, namely JAK1, JAK2, JAK3, and TYK2. Once activated, JAKs act on pathways for either survival, proliferation, differentiation, immune regulation or, in the case of type I interferons, antiviral and antiproliferative effects. Studies of graft-versus-host and systemic rheumatic diseases indicated that JAK inhibitors (JAKi) exert immunosuppressive effects that are non-redundant with those of corticotherapy. Therefore, they hold the potential to cut-off pathological reactions in COVID-19. Significant clinical experience already exists with several JAKi in COVID-19, such as baricitinib, ruxolitinib, tofacitinib, and nezulcitinib, which were suggested by a meta-analysis (Patoulias et al.) to exert a benefit in terms of risk reduction concerning major outcomes when added to standard of care in patients with COVID-19. Yet, only baricitinib is recommended in first line for severe COVID-19 treatment by the WHO, as it is the only JAKi that has proven efficient to reduce mortality in individual randomized clinical trials (RCT), especially the Adaptive COVID-19 Treatment Trial (ACTT-2) and COV-BARRIER phase 3 trials. As for secondary effects of JAKi treatment, the main caution with baricitinib consists in the induced immunosuppression as long-term side effects should not be an issue in patients treated for COVID-19.We discuss whether a class effect of JAKi may be emerging in COVID-19 treatment, although at the moment the convincing data are for baricitinib only. Given the key role of JAK1 in both type I IFN action and signaling by cytokines involved in pathogenic effects, establishing the precise timing of treatment will be very important in future trials, along with the control of viral replication by associating antiviral molecules.

Targets in MPNs and potential therapeutics.

Philadelphia-negative classical Myeloproliferative Neoplasms (MPNs), including Polycythemia Vera (PV), Essential Thrombocythemia (ET) and Primary Myelofibrosis (PMF), are clonal hemopathies that emerge in the hematopoietic stem cell (HSC) compartment. MPN driver mutations are restricted to specific exons (14 and 12) of Janus kinase 2 (JAK2), thrombopoietin receptor (MPL/TPOR) and calreticulin (CALR) genes, are involved directly in clonal myeloproliferation and generate the MPN phenotype. As a result, an increased number of fully functional erythrocytes, platelets and leukocytes is observed in the peripheral blood. Nevertheless, the complexity and heterogeneity of MPN clinical phenotypes cannot be solely explained by the type of driver mutation. Other factors, such as additional somatic mutations affecting epigenetic regulators or spliceosomes components, mutant allele burdens and modifiers of signaling by driver mutants, clonal architecture and the order of mutation acquisition, signaling events that occur downstream of a driver mutation, the presence of specific germ-line variants, the interaction of the neoplastic clone with bone marrow microenvironment and chronic inflammation, all can modulate the disease phenotype, influence the MPN clinical course and therefore, might be useful therapeutic targets.

Immunoglobulin Heavy Chain High-Throughput Sequencing in Pediatric B-Precursor Acute Lymphoblastic Leukemia: Is the Clonality of the Disease at Diagnosis Related to Its Prognosis?

High-throughput sequencing (HTS) of the immunoglobulin heavy chain (IgH) locus is a recent very efficient technique to monitor minimal residual disease of B-cell precursor acute lymphoblastic leukemia (BCP-ALL). It also reveals the sequences of clonal rearrangements, therefore, the multiclonal structure, of BCP-ALL. In this study, we performed IgH HTS on the diagnostic bone marrow of 105 children treated between 2004 and 2008 in Belgium for BCP-ALL in the European Organization for Research and Treatment of Cancer (EORTC)-58951 clinical trial. Patients were included irrespectively of their outcome. We described the patterns of clonal complexity at diagnosis and investigated its association with patients' characteristics. Two indicators of clonal complexity were used, namely, the number of foster clones, described as clones with similar D-N2-J rearrangements but other V-rearrangement and N1-joining, and the maximum across all foster clones of the number of evolved clones from one foster clone. The maximum number of evolved clones was significantly higher in patients with t(12;21)/ETV6:RUNX1. A lower number of foster clones was associated with a higher risk group after prephase and t(12;21)/ETV6:RUNX1 genetic type. This study observes that clonal complexity as accessed by IgH HTS is linked to prognostic factors in childhood BCP-ALL, suggesting that it may be a useful diagnostic tool for BCP-ALL status and prognosis.

Total orbital exenteration with temporalis muscle transfer and secondary healing.

OBJECTIVE: To evaluate the outcomes of orbital exenteration with temporalis muscle flap repair of the socket and secondary healing of the anterior surface of the flap in ocular, conjunctival, and eyelid malignancies. DESIGN: Retrospective single-centre study. PARTICIPANTS: Consecutive patients who underwent total exenteration for malignancy with temporal muscle flap repair of the socket between December 2009 and January 2016. METHODS: We report the outcomes of this surgical technique in terms of healing without fistula formation and time to epithelialization. RESULTS: Twenty-nine patients underwent surgery using this technique. Diagnoses consisted of 18 conjunctival melanomas, 2 choroidal melanomas, 6 squamous cell carcinomas, 2 sebaceous cell carcinomas, and 1 basal cell carcinoma. Mean age at surgery was 70.7 years and mean follow-up was 27.4 months. On histological analysis, tumour excision was complete in 25 patients, of whom 3 had an orbital recurrence after exenteration (3 conjunctival melanomas). Four patients had incomplete tumour excision, of whom 3 underwent postoperative orbital radiotherapy with no subsequent orbital recurrences. Complete epithelialization of the socket occurred in mean 7.9 weeks (range 2-16 weeks). Flap necrosis occurred in 1 patient after postoperative radiotherapy (with sino-nasal fistula formation); 2 other patients developed sino-orbital fistulas. CONCLUSION: After orbital exenteration, spontaneous epithelialization of the socket may take up to several months. Use of a temporalis muscle flap can reduce the duration of socket healing postoperatively, even if left to heal by secondary intention. This may facilitate early postoperative radiotherapy when indicated. Aesthetic results are acceptable and local surgical complications are rare.

Functional Consequences of Mutations in Myeloproliferative Neoplasms.

Driver mutations occur in Janus kinase 2 (JAK2), thrombopoietin receptor (MPL), and calreticulin (CALR) in BCR-ABL1 negative myeloproliferative neoplasms (MPNs). From mutations leading to one amino acid substitution in JAK2 or MPL, to frameshift mutations in CALR resulting in a protein with a different C-terminus, all the mutated proteins lead to pathologic and persistent JAK2-STAT5 activation. The most prevalent mutation, JAK2 V617F, is associated with the 3 entities polycythemia vera (PV), essential thrombocythemia (ET), and myelofibrosis (MF), while CALR and MPL mutations are associated only with ET and MF. Triple negative ET and MF patients may harbor noncanonical mutations in JAK2 or MPL. One major fundamental question is whether the conformations of JAK2 V617F, MPL W515K/L/A, or CALR mutants differ from those of their wild type counterparts so that a specific treatment could target the clone carrying the mutated driver and spare physiological hematopoiesis. Of great interest, a set of epigenetic mutations can co-exist with the phenotypic driver mutations in 35%-40% of MPNs. These epigenetic mutations, such as TET2, EZH2, ASXL1, or DNMT3A mutations, promote clonal hematopoiesis and increased fitness of aged hematopoietic stem cells in both clonal hematopoiesis of indeterminate potential (CHIP) and MPNs. Importantly, the main MPN driver mutation JAK2 V617F is also associated with CHIP. Accumulation of several epigenetic and splicing mutations favors progression of MPNs to secondary acute myeloid leukemia. Another major fundamental question is how epigenetic rewiring due to these mutations interacts with persistent JAK2-STAT5 signaling. Answers to these questions are required for better therapeutic interventions aimed at preventing progression of ET and PV to MF, and transformation of these MPNs in secondary acute myeloid leukemia.

Secondary orbital exenteration for conjunctival melanoma: A study of 25 cases.

INTRODUCTION: The treatment of conjunctival melanoma is most often conservative, but exenteration is sometimes necessary in order to achieve local control of the disease. It can be performed as a primary procedure in cases of locally advanced disease or as a secondary procedure after one or more recurrences. No benefit to secondary exenteration on patient survival has been demonstrated to date for conjunctival melanoma, and it is generally considered a palliative procedure. PATIENTS AND METHODS: Single-center retrospective study performed in the ocular oncology department of the Institut Curie (Paris, France). We included all patients who underwent secondary orbital exenteration for conjunctival melanoma between January 2008 and January 2016. RESULTS: Twenty-five patients underwent secondary exenteration for conjunctival melanoma. The maximum number of local recurrences prior to exenteration was six. Metastases occurred in 11 patients after exenteration and were more common when there was a greater tumor thickness on histology, if the tumor had not been treated initially in an ocular oncology center, or if there had been a greater number of local recurrences before the secondary exenteration was performed. Seventy-five percent of patients developed metastases when the exenteration was performed after 5 or 6 local recurrences. CONCLUSION: This study suggests that early secondary exenteration (i.e. after a number of local recurrences less than or equal to 4) may reduce the occurrence of metastases (and therefore improve patient survival) in conjunctival melanoma. Thus, secondary exenteration might be a curative surgery in some patients with recurrent disease.

Selective Ophthalmic Artery Chemotherapy with Melphalan in the Management of Unilateral Retinoblastoma: A Prospective Study.

PURPOSE: To determine prospectively the efficacy and to assess potential side effects of melphalan selective ophthalmic artery chemotherapy (SOAC) as first-line treatment for unilateral retinoblastoma. DESIGN: Phase 2 nonrandomized, prospective study. PARTICIPANTS: Patients with unilateral retinoblastoma group B, C, or D of the International Classification for Intraocular Retinoblastoma (IRC). Group D eyes with massive vitreous seeding were not eligible. METHODS: Melphalan SOAC associated with diode laser thermotherapy, cryotherapy, or both at 4-week intervals (3-6 cycles). For persistent vitreous seeding, intravitreal melphalan chemotherapy also was used. MAIN OUTCOME MEASURES: The primary outcome was globe preservation rate. Secondary outcomes were tumor relapse rate, occurrence of ocular or systemic adverse events, and measurement of the dose area product (DAP). RESULTS: Between 2012 and 2017, 39 patients (39 eyes) with unilateral retinoblastoma were included prospectively. Three included patients did not receive SOAC (2 catheterization failures and 1 case of viral syndrome) and were considered failures. At diagnosis, IRC groups for the 36 treated patients were: B, n = 4 (11%); C, n = 13 (36%); and D, n = 19 (53%); median age was 21.5 months (range, 3.2-61.6 months). Median number of SOAC cycles was 3.9 (range, 1-6 cycles), and median melphalan dose was 4.9 mg/procedure. The median DAP was 1.24 Gy.cm2/procedure. Median follow-up was 63 months (range, 34-93 months). SOAC was associated with local treatments for 31 patients (86%): diode laser thermotherapy for all of them and cryotherapy or intravitreal chemotherapy for 10 (32%) and 9 patients (25%), respectively. SOAC treatment was interrupted in 5 patients because of severe ophthalmic (ptosis, n = 2; retinal ischemia, n = 2) or systemic (hypotension, n = 1) adverse events. At the cutoff date analysis, all patients were alive without metastasis. The 18-month eye preservation rate was 80% (range, 68.6%-94.6%). After a follow-up of at least 30 months, the ocular preservation rate was 69% (n = 24 preservations). CONCLUSIONS: This first prospective trial demonstrated that SOAC with melphalan alone as first-line treatment for retinoblastoma is efficient and well tolerated with no metastatic events, although ocular ischemic complications were observed.