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BackgroundAdrenocortical carcinoma (ACC) is a rare malignancy without good treatment options. There are limited data about the use of immunotherapy in ACC. We investigated the efficacy and safety of pembrolizumab in patients with metastatic ACC.MethodsThis is a pre-specified cohort of a single-center, investigator-initiated, phase II clinical trial using pembrolizumab monotherapy in patients with rare malignancies. Patients must have had prior treatment fail in the past 6 months before study enrollment. Patients were enrolled from August 2016 to October 2018. Follow-up data were updated as of March 26, 2019.Patients received 200 mg pembrolizumab intravenously every 3 weeks without concomitant oncologic therapy. The primary endpoint was non-progression rate (NPR) at 27 weeks. Other endpoints included adverse events, tumor responses measured independently by objective radiologic criteria, and select immunological markers.ResultsSixteen patients with ACC (including eight women [50%]) were included in this cohort. Ten patients (63%) had evidence of hormonal overproduction (seven had cortisol-producing ACC). Non-progression rate at 27 weeks was evaluable in 14 patients, one patient was lost to follow-up, and one patient left the study because of an adverse event. Five of 14 patients were alive and progression-free at 27 weeks (non-progression rate at 27 weeks was 36, 95% confidence interval 13–65%). Of the 14 patients evaluable for imaging response by immune-related Response Evaluation Criteria in Solid Tumors, two had a partial response (including one with cortisol-producing ACC), seven had stable disease (including three with cortisol-producing ACC), and five had progressive disease, representing an objective response rate of 14% (95% confidence interval 2–43%). Of those who had stable disease, six had disease stabilization that lasted ≥4 months. Severe treatment-related adverse events (≥grade 3) were seen in 2 of 16 patients (13%) and resulted in one patient discontinuing study participation. All studied tumor specimens (14/14) were negative for programmed cell death ligand-1 expression. Thirteen of 14 tumor specimens (93%) were microsatellite-stable. Eight of 14 patients (57%) had a high tumor-infiltrating lymphocyte score on immunohistochemistry staining.ConclusionsSingle-agent pembrolizumab has modest efficacy as a salvage therapy in ACC regardless of the tumor’s hormonal function, microsatellite instability status, or programmed cell death ligand-1 status. Treatment was well tolerated in most study participants, with a low rate of severe adverse events.Trial registrationClinicalTrials.gov identifier: NCT02721732, Registered March 29, 2016.

This study describes the structures of the IZUMO1 protein, found on sperm, and the JUNO protein, found on eggs, and sheds light on their roles in sperm–egg fusion during fertilization. Structure of the human fertilization complex During fertilization in mammals, the sperm-associated protein IZUMO1 recognizes the receptor JUNO at the egg surface, but the structural details of the interactions were previously unknown. In two papers published in this issue of Nature , Halil Aydin et al . and Umeharu Ohto et al . present the first atomic-resolution structures of human IZUMO1 and JUNO in unbound and bound conformations. Aydin et al . describe a boomerang-shaped structure for IZUMO1, and their data suggest that IZUMO1 undergoes a major conformational change on binding with high affinity to JUNO. Ohto et al . report an elongated rod-shaped structure for IZUMO1, comprising a helical bundle IZUMO domain connected by a β-hairpin region to an immunoglobulin-like domain. Mutational studies of the IZUMO1–JUNO interface by both groups reveal the structural determinants required for binding. These results provide data that can inform the development of novel non-hormonal contraceptives and fertility treatments. Fertilization is an essential biological process in sexual reproduction and comprises a series of molecular interactions between the sperm and egg 1 , 2 . The fusion of the haploid spermatozoon and oocyte is the culminating event in mammalian fertilization, enabling the creation of a new, genetically distinct diploid organism 3 , 4 . The merger of two gametes is achieved through a two-step mechanism in which the sperm protein IZUMO1 on the equatorial segment of the acrosome-reacted sperm recognizes its receptor, JUNO, on the egg surface 4 , 5 , 6 . This recognition is followed by the fusion of the two plasma membranes. IZUMO1 and JUNO proteins are indispensable for fertilization, as constitutive knockdown of either protein results in mice that are healthy but infertile 5 , 6 . Despite their central importance in reproductive medicine, the molecular architectures of these proteins and the details of their functional roles in fertilization are not known. Here we present the crystal structures of human IZUMO1 and JUNO in unbound and bound conformations. The human IZUMO1 structure exhibits a distinct boomerang shape and provides structural insights into the IZUMO family of proteins 7 . Human IZUMO1 forms a high-affinity complex with JUNO and undergoes a major conformational change within its N-terminal domain upon binding to the egg-surface receptor. Our results provide insights into the molecular basis of sperm–egg recognition, cross-species fertilization, and the barrier to polyspermy, thereby promising benefits for the rational development of non-hormonal contraceptives and fertility treatments for humans and other mammals.

  The dense clustering of glycans creates an unfavorable environment for the interaction of otherwise neutralizing antibodies. [...]critical regions on EBOV GP, such as the receptor-binding site, are hidden under layers of glycan. [...]host BST-2 is incorporated in the membrane of the nascent virion and forms a protein tether to prevent viral release. [...]it may be worthwhile to explore the role of the transmembrane domain of EBOV GP in BST-2 antagonism.

Duplication of ancestral hypoxia-inducible factor (HIF)α coincided with the evolution of vertebrate species. Paralogs HIF1α and HIF2α are the most well-known factors for modulating the cellular transcriptional profile following hypoxia. However, how the processes of natural selection acted upon the coding region of these two genes to optimize the cellular response to hypoxia during evolution remains unclear. A key negative regulator of HIFα is von Hippel-Lindau (VHL) tumour suppressor protein. Here we show that evolutionarily-relevant substitutions can modulate a secondary contact between HIF1α Met561 and VHL Phe91. Notably, HIF1α binds more tightly than HIF2α to VHL due to a conserved Met to Thr substitution observed in the vertebrate lineage. Similarly, substitution of VHL Phe91 with Tyr, as seen in invertebrate species, decreases VHL affinity for both HIF1α and HIF2α. We propose that vertebrate evolution involved a more complex hypoxia response with fine-tuned divergence of VHL affinity for HIF1α and HIF2α. Paralogs HIF1α and HIF2α are important modulators regulating cellular transcriptional profile following hypoxia. Here, the authors investigate evolutionary substitutions that fine tune the interaction between HIFα and their regulator VHL in the vertebrate and invertebrate lineages.

It is definitively established that mutations in transcription factor HIF-2α are causative of both neuroendocrine tumors (class 1 disease) and polycythemia (class 2 disease). However, the molecular mechanism that underlies this emergent genotype–phenotype relationship has remained unclear. Here, we report the structure of HIF-2α peptide bound to pVHL-elongin B-elongin C (VBC) heterotrimeric complex, which shows topographical demarcation of class 1 and 2 mutations affecting residues predicted, and demonstrated via biophysical analyses, to differentially impact HIF-2α-pVHL interaction interface stability. Concordantly, biochemical experiments showed that class 1 mutations disrupt pVHL affinity to HIF-2α more adversely than class 2 mutations directly or indirectly via impeding PHD2-mediated hydroxylation. These findings suggest that neuroendocrine tumor pathogenesis requires a higher HIF-2α dose than polycythemia, which requires only a mild increase in HIF-2α activity. These biophysical data reveal a structural basis that underlies, and can be used to predict de novo, broad genotype-phenotype correlations in HIF-2α-driven disease. Hypoxia inducible factor (HIF)-2α transcription factor is mutated in polycythemia and various neuroendocrine tumors. Here the authors present the crystal structure of a HIF-2α peptide bound to the pVHL-elongin B-elongin C (VBC) heterotrimeric complex and propose a classification scheme for HIF-2α mutations that helps to predict disease phenotype outcome.

BACKGROUNDPancreatic ductal adenocarcinoma (PDAC) is one of the most lethal malignancies, with unpredictable responses to chemotherapy. Approaches to assay patient tumors before treatment and identify effective treatment regimens based on tumor sensitivities are lacking. We developed an organoid-based platform (OBP) to visually quantify patient-derived organoid (PDO) responses to drug treatments and associated tumor-stroma modulation for personalized PDAC therapy.METHODSWe retrospectively quantified apoptotic responses and tumor-stroma cell proportions in PDOs via 3D immunofluorescence imaging through annexin A5, α-smooth muscle actin (α-SMA), and cytokeratin 19 (CK-19) levels. Simultaneously, an ex vivo organoid drug sensitivity assay (ODSA) was used to measure responses to standard-of-care regimens. Differences between ODSA results and patient tumor responses were assessed by exact McNemar's test.RESULTSImmunofluorescence signals, organoid growth curves, and Ki-67 levels were measured and authenticated through the OBP for up to 14 days. ODSA drug responses were not different from patient tumor responses, as reflected by CA19-9 reductions following neoadjuvant chemotherapy (P = 0.99). PDOs demonstrated unique apoptotic and tumor-stroma modulation profiles (P < 0.0001). α-SMA/CK-19 ratio levels of more than 1.0 were associated with improved outcomes (P = 0.0179) and longer parental patient survival by Kaplan-Meier analysis (P = 0.0046).CONCLUSIONHeterogenous apoptotic drug responses and tumor-stroma modulation are present in PDOs after standard-of-care chemotherapy. Ratios of α-SMA and CK-19 levels in PDOs are associated with patient survival, and the OBP could aid in the selection of personalized therapies to improve the efficacy of systemic therapy in patients with PDAC.FUNDINGNIH/National Cancer Institute grants (K08CA218690, P01 CA117969, R50 CA243707-01A1, U54CA224065), the Skip Viragh Foundation, the Bettie Willerson Driver Cancer Research Fund, and a Cancer Center Support Grant for the Flow Cytometry and Cellular Imaging Core Facility (P30CA16672).

Ebola virus (EBOV) entry requires the surface glycoprotein (GP) to initiate attachment and fusion of viral and host membranes. Here we report the crystal structure of EBOV GP in its trimeric, pre-fusion conformation (GP1+GP2) bound to a neutralizing antibody, KZ52, derived from a human survivor of the 1995 Kikwit outbreak. Three GP1 viral attachment subunits assemble to form a chalice, cradled by the GP2 fusion subunits, while a novel glycan cap and projected mucin-like domain restrict access to the conserved receptor-binding site sequestered in the chalice bowl. The glycocalyx surrounding GP is likely central to immune evasion and may explain why survivors have insignificant neutralizing antibody titres. KZ52 recognizes a protein epitope at the chalice base where it clamps several regions of the pre-fusion GP2 to the amino terminus of GP1. This structure provides a template for unravelling the mechanism of EBOV GP-mediated fusion and for future immunotherapeutic development. Ebola virus structure: Trimeric surface protein bound to a human survivor antibody The Ebola virus, one of the most feared of pathogens, causes a severe haemorrhagic fever with up to 90% human mortality. Since 1994, outbreaks of the virus have increased fourfold. Although initial vaccine trials in primates have shown promise, no vaccines or post-exposure treatments are yet available. And it is still not clear why the virus is so pathogenic or why the immune response is so weak in fatal cases. A team from The Scripps Research Institute has now determined the crystal structure of the trimeric Ebola virus glycoprotein bound to a neutralizing antibody isolated from a human survivor. The structure reveals a putative receptor-binding site sequestered in a bowl of a chalice formed by three GP1 viral attachment subunits (in shades blue in the molecular surface model on the cover), cradled by three GP2 fusion subunits (coloured white). Access to the site is restricted by a glycan cap and a protruding mucin-like domain. The antibody (in yellow) bridges the GP1 and GP2 subunits and is specific for the prefusion, viral surface conformation of GP2. Cover graphics by Christina Corbaci & Michael Pique. The crystal structure of Ebola virus glycoprotein is shown in complex with a neutralizing antibody. The structure suggests that the antibody prevents infection by preventing conformational changes of GP2 required for fusion.

Mitochondrial DNA (mtDNA) copy number in peripheral blood has been suggested as risk modifier in various types of cancer. However, its influence on melanoma risk is unclear. We evaluated the association between mtDNA copy number in peripheral blood and melanoma risk in 500 melanoma cases and 500 healthy controls from an ongoing melanoma study. The mtDNA copy number was measured using real-time polymerase chain reaction. Overall, mean mtDNA copy number was significantly higher in cases than in controls (1.15 vs 0.99, P<0.001). Increased mtDNA copy number was associated with a 1.45-fold increased risk of melanoma (95% confidence interval: 1.12-1.97). Significant joint effects between mtDNA copy number and variables related to pigmentation and history of sunlight exposure were observed. This study supports an association between increased mtDNA copy number and melanoma risk that is independent on the known melanoma risk factors (pigmentation and history of sunlight exposure).

The human APOBEC3 family of DNA cytosine deaminases serves as a front-line intrinsic immune response to inhibit the replication of diverse retroviruses. APOBEC3F and APOBEC3G are the most potent factors against HIV-1. As a countermeasure, HIV-1 viral infectivity factor (Vif) targets APOBEC3s for proteasomal degradation. Here we report the crystal structure of the Vif-binding domain in APOBEC3F and a novel assay to assess Vif-APOBEC3 binding. Our results point to an amphipathic surface that is conserved in APOBEC3s as critical for Vif susceptibility in APOBEC3F. Electrostatic interactions likely mediate Vif binding. Moreover, structure-guided mutagenesis reveals a straight ssDNA-binding groove distinct from the Vif-binding site, and an ‘aromatic switch’ is proposed to explain DNA substrate specificities across the APOBEC3 family. This study opens new lines of inquiry that will further our understanding of APOBEC3-mediated retroviral restriction and provides an accurate template for structure-guided development of inhibitors targeting the APOBEC3-Vif axis. APOBEC3F is a DNA cytosine deaminase involved in restriction of HIV-1, but its activity can be suppressed by the viral protein Vif. Here, the authors provide insights into the interaction between these two proteins by determining the structure of the APOBEC3F Vif-binding domain.

Background The purpose of this study was to evaluate a single-institution experience with delivery of preoperative therapy to patients with pancreatic ductal adenocarcinoma (PDAC) prior to pancreatoduodenectomy (PD). Methods Consecutive patients (622) with PDAC who underwent PD following chemotherapy and/or chemoradiation between 1990 and 2014 were retrospectively reviewed. Preoperative treatment regimens, clinicopathologic characteristics, operative details, and long-term outcomes in four successive time periods (1990–1999, 2000–2004, 2005–2009, 2010–2014) were evaluated and compared. Results The average number of patients per year who underwent PD following preoperative therapy as well as the proportion of operations performed for borderline resectable and locally advanced (BR/LA) tumors increased over time. The use of induction systemic chemotherapy, as well as postoperative adjuvant chemotherapy, also increased over time. Throughout the study period, the mean EBL decreased while R0 margin rates and vascular resection rates increased overall. Despite the increase in BR/LA resections, locoregional recurrence (LR) rates remained similar over time, and overall survival (OS) improved significantly (median 24.1, 28.1, 37.3, 43.4 months, respectively, p < 0.0001). Conclusions Despite increases in case complexity, relatively low rates of LR have been maintained while significant improvements in OS have been observed. Further improvements in patient outcomes will likely require disruptive advances in systemic therapy.