Long-term use of everolimus for refractory arrhythmia in a child with tuberous sclerosis complex.

Tuberous sclerosis complex is associated with the occurrence of cardiac rhabdomyomas that may result in life-threatening arrhythmia unresponsive to standard antiarrhythmic therapy. We report the case of an infant with multiple cardiac rhabdomyomas who developed severe refractory supraventricular tachycardia (SVT) that was successfully treated with everolimus. Pharmacological mTOR inhibition rapidly improved arrhythmia within few weeks after treatment initiation and correlated with a reduction in tumor size. Intermediate attempts to discontinue everolimus resulted in rhabdomyoma size rebound and recurrence of arrhythmic episodes, which resolved on resumption of therapy. While everolimus treatment led to successful control of arrhythmia in the first years of life, episodes of SVT reoccurred at the age of 6 years. Electrophysiologic testing confirmed an accessory pathway that was successfully ablated, resulting in freedom of arrhythmic events. In summary we present an in-depth evaluation of the long-term use of everolimus in a child with TSC-associated SVT, including the correlation between drug use and arrhythmia outcome. This case report provides important information on the safety and efficacy of an mTOR inhibitor for the treatment of a potentially life-threatening cardiac disease manifestation in TSC for which the optimal treatment strategy is still not well established.

Histology-based classifier to distinguish early mycosis fungoides from atopic dermatitis.

BACKGROUND: Histopathological differentiation of early mycosis fungoides (MF) from benign chronic inflammatory dermatoses remains difficult and often impossible, despite the inclusion of all available diagnostic parameters. OBJECTIVE: To identify the most impactful histological criteria for a predictive diagnostic model to discriminate MF from atopic dermatitis (AD). METHODS: In this multicentre study, two cohorts of patients with either unequivocal AD or MF were evaluated by two independent dermatopathologists. Based on 32 histological attributes, a hypothesis-free prediction model was developed and validated on an independent patient's cohort. RESULTS: A reduced set of two histological features (presence of atypical lymphocytes in either epidermis or dermis) was trained. In an independent validation cohort, this model showed high predictive power (95% sensitivity and 100% specificity) to differentiate MF from AD and robustness against inter-individual investigator differences. LIMITATIONS: The study investigated a limited number of cases and the classifier is based on subjectively evaluated histological criteria. CONCLUSION: Aiming at distinguishing early MF from AD, the proposed binary classifier performed well in an independent cohort and across observers. Combining this histological classifier with immunohistochemical and/or molecular techniques (such as clonality analysis or molecular classifiers) could further promote differentiation of early MF and AD.

Degradable Hydrogel for Sustained Localized Delivery of Anti-Tumor Drugs.

Disadvantages of systemically administered immunomodulatory anti-tumor therapies include poor efficacy and high toxicity. Direct intratumoral injection of a drug is often associated with rapid efflux from the site of administration, thus reducing local exposure and therapeutic efficacy, while potentially increasing systemic adverse events. To address this, a sustained release prodrug technology was developed using a transient conjugation (TransConTM) technology to provide long-term high local drug exposure after injection in the tumor while minimizing systemic exposure. TransCon technology for systemic delivery is clinically validated, with multiple compounds in late-stage clinical development and approval of a once-weekly growth hormone for pediatric growth hormone deficiency. As a further application of this technology, this report describes the design, preparation, and functional characterization of hydrogel microspheres as insoluble, yet degradable carrier system. Microspheres were obtained after reaction of PEG-based polyamine dendrimers and bifunctional crosslinkers. Resiquimod, a TLR7/8 agonist, and axitinib, a vascular endothelial growth factor tyrosine kinase inhibitor, were chosen as anti-cancer drugs. The drugs were covalently attached to the carrier by linkers, which released the drugs under physiological conditions. Essentially all resiquimod or axitinib was released over weeks before physical degradation of the hydrogel microsphere was observed. In summary, TransCon Hydrogel technology allows localized sustained-release drug delivery for cancer therapy enabling high local drug concentrations while at the same time ensuring low systemic drug exposure over weeks with a single injection, which may improve the therapeutic index and improve efficacy, while minimizing systemic adverse events. A hydrogel prodrug of resiquimod, TransCon TLR7/8 agonist, is currently being investigated in clinical trials of patients with solid tumors (NCT04799054).

Intratumoral delivery of TransCon™ TLR7/8 Agonist promotes sustained anti-tumor activity and local immune cell activation while minimizing systemic cytokine induction.

BACKGROUND: Intratumoral (IT) delivery of toll-like receptor (TLR) agonists has shown encouraging anti-tumor benefit in preclinical and early clinical studies. However, IT delivery of TLR agonists may lead to rapid effusion from the tumor microenvironment (TME), potentially limiting the duration of local inflammation and increasing the risk of systemic adverse events. METHODS: To address these limitations, TransCon™ TLR7/8 Agonist-an investigational sustained-release prodrug of resiquimod that uses a TransCon linker and hydrogel technology to achieve sustained and predictable IT release of resiquimod-was developed. TransCon TLR7/8 Agonist was characterized for resiquimod release in vitro and in vivo, in mice and rats, and was assessed for anti-tumor efficacy and pharmacodynamic activity in mice. RESULTS: Following a single IT dose, TransCon TLR7/8 Agonist mediated potent tumor growth inhibition which was associated with sustained resiquimod release over several weeks with minimal induction of systemic cytokines. TransCon TLR7/8 Agonist monotherapy promoted activation of antigen-presenting cells in the TME and tumor-draining lymph nodes, with evidence of activation and expansion of CD8+ T cells in the tumor-draining lymph node and TME. Combination of TransCon TLR7/8 Agonist with systemic immunotherapy further promoted anti-tumor activity in TransCon TLR7/8 Agonist-treated tumors. In a bilateral tumor setting, combination of TransCon TLR7/8 Agonist with systemic IL-2 potentiated tumor growth inhibition in both injected and non-injected tumors and conferred protection against tumor rechallenge following complete regressions. CONCLUSIONS: Our findings show that a single dose of TransCon TLR7/8 Agonist can mediate sustained local release of resiquimod in the TME and promote potent anti-tumor effects as monotherapy and in combination with systemic immunotherapy, supporting TransCon TLR7/8 Agonist as a novel intratumoral TLR agonist for cancer therapy. A clinical trial to evaluate the safety and efficacy of TransCon TLR7/8 Agonist, as monotherapy and in combination with pembrolizumab, in cancer patients is currently ongoing (transcendIT-101; NCT04799054).

The Pediatric Precision Oncology INFORM Registry: Clinical Outcome and Benefit for Patients with Very High-Evidence Targets.

INFORM is a prospective, multinational registry gathering clinical and molecular data of relapsed, progressive, or high-risk pediatric patients with cancer. This report describes long-term follow-up of 519 patients in whom molecular alterations were evaluated according to a predefined seven-scale target prioritization algorithm. Mean turnaround time from sample receipt to report was 25.4 days. The highest target priority level was observed in 42 patients (8.1%). Of these, 20 patients received matched targeted treatment with a median progression-free survival of 204 days [95% confidence interval (CI), 99-not applicable], compared with 117 days (95% CI, 106-143; P = 0.011) in all other patients. The respective molecular targets were shown to be predictive for matched treatment response and not prognostic surrogates for improved outcome. Hereditary cancer predisposition syndromes were identified in 7.5% of patients, half of which were newly identified through the study. Integrated molecular analyses resulted in a change or refinement of diagnoses in 8.2% of cases. SIGNIFICANCE: The pediatric precision oncology INFORM registry prospectively tested a target prioritization algorithm in a real-world, multinational setting and identified subgroups of patients benefiting from matched targeted treatment with improved progression-free survival, refinement of diagnosis, and identification of hereditary cancer predisposition syndromes.See related commentary by Eggermont et al., p. 2677.This article is highlighted in the In This Issue feature, p. 2659.

Sarcoma classification by DNA methylation profiling.

Sarcomas are malignant soft tissue and bone tumours affecting adults, adolescents and children. They represent a morphologically heterogeneous class of tumours and some entities lack defining histopathological features. Therefore, the diagnosis of sarcomas is burdened with a high inter-observer variability and misclassification rate. Here, we demonstrate classification of soft tissue and bone tumours using a machine learning classifier algorithm based on array-generated DNA methylation data. This sarcoma classifier is trained using a dataset of 1077 methylation profiles from comprehensively pre-characterized cases comprising 62 tumour methylation classes constituting a broad range of soft tissue and bone sarcoma subtypes across the entire age spectrum. The performance is validated in a cohort of 428 sarcomatous tumours, of which 322 cases were classified by the sarcoma classifier. Our results demonstrate the potential of the DNA methylation-based sarcoma classification for research and future diagnostic applications.

Brainstem biopsy in pediatric diffuse intrinsic pontine glioma in the era of precision medicine: the INFORM study experience.

PURPOSE: Diffuse intrinsic pontine glioma (DIPG) is a highly aggressive paediatric brain tumour with fatal outcome. The Individualised Therapy For Relapsed Malignancies In Childhood (INFORM) registry study offers comprehensive molecular profiling of high-risk tumours to identify target alterations for potential precision therapy. We analysed molecular characteristics and clinical data after brainstem biopsy of all enrolled newly diagnosed DIPGs. PATIENTS AND METHODS: From -February 2015 to February 2018, 21 subsequent primary DIPG cases were enrolled in the nation-wide multicentre INFORM registry study after brainstem biopsy. Whole-genome, whole-exome sequencing and DNA methylation analysis were performed, and RNA-sequencing was added in case of sufficient material. Clinical data were obtained from standardised questionnaires and the INFORM clinical data bank. RESULTS: Tumour material obtained from brainstem biopsy was sufficient for DNA analysis in all cases and RNA analysis in 16 of 21 cases. In 16 of 21 cases (76%), potential targetable alterations were identified including highly relevant MET and NTRK1 fusions as well as an EZH2 alteration not previously described in DIPG. In 5 of 21 cases, molecular information was used for initiation of targeted treatment. The majority of patients (19/21) presented with neurological deficits at diagnosis. Newly arising or worsening of neurological deficits post-biopsy occurred in nine patients. Symptoms were reversible or improved notably in eight cases. CONCLUSION: In this multicentre study setting, brainstem biopsy of DIPG was feasible and yielded sufficient material for comprehensive molecular profiling. Relevant molecular targets were identified impacting clinical management in a substantial subset. Death or severe bleeding occurred in none of the cases. One of 20 patients experienced unilateral paraesthesia possibly related to biopsy.

Opposing Tumor-Promoting and -Suppressive Functions of Rictor/mTORC2 Signaling in Adult Glioma and Pediatric SHH Medulloblastoma.

Most human cancers arise from stem and progenitor cells by the sequential accumulation of genetic and epigenetic alterations, while cancer modeling typically requires simultaneous multiple oncogenic events. Here, we show that a single p53 mutation, despite causing no defect in the mouse brain, promoted neural stem and progenitor cells to spontaneously accumulate oncogenic alterations, including loss of multiple chromosomal (chr) regions syntenic to human chr10 containing Pten, forming malignant gliomas with PI3K/Akt activation. Rictor/mTORC2 loss inhibited Akt signaling, greatly delaying and reducing glioma formation by suppressing glioma precursors within the subventricular zone stem cell niche. Rictor/mTORC2 loss delayed timely differentiation of granule cell precursors (GCPs) during cerebellar development, promoting sustained GCP proliferation and medulloblastoma formation, which recapitulated critical features of TP53 mutant sonic hedgehog (SHH) medulloblastomas with GLI2 and/or N-MYC amplification. Our study demonstrates that Rictor/mTORC2 has opposing functions in neural stem cells and GCPs in the adult and the developing brain, promoting malignant gliomas and suppressing SHH-medulloblastoma formation, respectively.

Discovery of 8-Membered Ring Sulfonamides as Inhibitors of Oncogenic Mutant Isocitrate Dehydrogenase 1.

Evidence suggests that specific mutations of isocitrate dehydrogenases 1 and 2 (IDH1/2) are critical for the initiation and maintenance of certain tumor types and that inhibiting these mutant enzymes with small molecules may be therapeutically beneficial. In order to discover mutant allele-selective IDH1 inhibitors with chemical features distinct from existing probes, we screened a collection of small molecules derived from diversity-oriented synthesis. The assay identified compounds that inhibit the IDH1-R132H mutant allele commonly found in glioma. Here, we report the discovery of a potent (IC50 = 50 nM) series of IDH1-R132H inhibitors having 8-membered ring sulfonamides as exemplified by the compound BRD2879. The inhibitors suppress (R)-2-hydroxyglutarate production in cells without apparent toxicity. Although the solubility and pharmacokinetic properties of the specific inhibitor BRD2879 prevent its use in vivo, the scaffold presents a validated starting point for the synthesis of future IDH1-R132H inhibitors having improved pharmacological properties.

Enhancer hijacking activates GFI1 family oncogenes in medulloblastoma.

Medulloblastoma is a highly malignant paediatric brain tumour currently treated with a combination of surgery, radiation and chemotherapy, posing a considerable burden of toxicity to the developing child. Genomics has illuminated the extensive intertumoral heterogeneity of medulloblastoma, identifying four distinct molecular subgroups. Group 3 and group 4 subgroup medulloblastomas account for most paediatric cases; yet, oncogenic drivers for these subtypes remain largely unidentified. Here we describe a series of prevalent, highly disparate genomic structural variants, restricted to groups 3 and 4, resulting in specific and mutually exclusive activation of the growth factor independent 1 family proto-oncogenes, GFI1 and GFI1B. Somatic structural variants juxtapose GFI1 or GFI1B coding sequences proximal to active enhancer elements, including super-enhancers, instigating oncogenic activity. Our results, supported by evidence from mouse models, identify GFI1 and GFI1B as prominent medulloblastoma oncogenes and implicate 'enhancer hijacking' as an efficient mechanism driving oncogene activation in a childhood cancer.

Genomic and transcriptomic analyses match medulloblastoma mouse models to their human counterparts.

Medulloblastoma is a malignant embryonal brain tumor with highly variable outcome. In order to study the biology of this tumor and to perform preclinical treatment studies, a lot of effort has been put into the generation of appropriate mouse models. The usage of these models, however, has become debatable with the advances in human medulloblastoma subgrouping. This study brings together multiple relevant mouse models and matches genetic alterations and gene expression data of 140 murine tumors with 423 human medulloblastomas in a global way. Using AGDEX analysis and k-means clustering, we show that the Blbp-cre::Ctnnb1(ex3)(Fl/+)Trp53 (Fl/Fl) mouse model fits well to human WNT medulloblastoma, and that, among various Myc- or Mycn-based mouse medulloblastomas, tumors in Glt1-tTA::TRE-MYCN/Luc mice proved to be most specific for human group 3 medulloblastoma. None of the analyzed models displayed a significant match to group 4 tumors. Intriguingly, mice with Ptch1 or Smo mutations selectively modeled SHH medulloblastomas of adulthood, although such mutations occur in all human age groups. We therefore suggest that the infantile or adult gene expression pattern of SHH MBs are not solely determined by specific mutations. This is supported by the observation that human medulloblastomas with PTCH1 mutations displayed more similarities to PTCH1 wild-type tumors of the same age group than to PTCH1-mutated tumors of the other age group. Together, we provide novel insights into previously unrecognized specificity of distinct models and suggest these findings as a solid basis to choose the appropriate model for preclinical studies on medulloblastoma.

Genome sequencing of SHH medulloblastoma predicts genotype-related response to smoothened inhibition.

Smoothened (SMO) inhibitors recently entered clinical trials for sonic-hedgehog-driven medulloblastoma (SHH-MB). Clinical response is highly variable. To understand the mechanism(s) of primary resistance and identify pathways cooperating with aberrant SHH signaling, we sequenced and profiled a large cohort of SHH-MBs (n = 133). SHH pathway mutations involved PTCH1 (across all age groups), SUFU (infants, including germline), and SMO (adults). Children >3 years old harbored an excess of downstream MYCN and GLI2 amplifications and frequent TP53 mutations, often in the germline, all of which were rare in infants and adults. Functional assays in different SHH-MB xenograft models demonstrated that SHH-MBs harboring a PTCH1 mutation were responsive to SMO inhibition, whereas tumors harboring an SUFU mutation or MYCN amplification were primarily resistant.

Reduced H3K27me3 and DNA hypomethylation are major drivers of gene expression in K27M mutant pediatric high-grade gliomas.

Two recurrent mutations, K27M and G34R/V, within histone variant H3.3 were recently identified in ∼50% of pHGGs. Both mutations define clinically and biologically distinct subgroups of pHGGs. Here, we provide further insight about the dominant-negative effect of K27M mutant H3.3, leading to a global reduction of the repressive histone mark H3K27me3. We demonstrate that this is caused by aberrant recruitment of the PRC2 complex to K27M mutant H3.3 and enzymatic inhibition of the H3K27me3-establishing methyltransferase EZH2. By performing chromatin immunoprecipitation followed by next-generation sequencing and whole-genome bisulfite sequencing in primary pHGGs, we show that reduced H3K27me3 levels and DNA hypomethylation act in concert to activate gene expression in K27M mutant pHGGs.

Recurrent somatic alterations of FGFR1 and NTRK2 in pilocytic astrocytoma.

Pilocytic astrocytoma, the most common childhood brain tumor, is typically associated with mitogen-activated protein kinase (MAPK) pathway alterations. Surgically inaccessible midline tumors are therapeutically challenging, showing sustained tendency for progression and often becoming a chronic disease with substantial morbidities. Here we describe whole-genome sequencing of 96 pilocytic astrocytomas, with matched RNA sequencing (n = 73), conducted by the International Cancer Genome Consortium (ICGC) PedBrain Tumor Project. We identified recurrent activating mutations in FGFR1 and PTPN11 and new NTRK2 fusion genes in non-cerebellar tumors. New BRAF-activating changes were also observed. MAPK pathway alterations affected all tumors analyzed, with no other significant mutations identified, indicating that pilocytic astrocytoma is predominantly a single-pathway disease. Notably, we identified the same FGFR1 mutations in a subset of H3F3A-mutated pediatric glioblastoma with additional alterations in the NF1 gene. Our findings thus identify new potential therapeutic targets in distinct subsets of pilocytic astrocytoma and childhood glioblastoma.

The multicomponent approach to N-methyl peptides: total synthesis of antibacterial (-)-viridic acid and analogues.

Two syntheses of natural viridic acid, an unusual triply N-methylated peptide with two anthranilate units, are presented. The first one is based on peptide-coupling strategies and affords the optically active natural product in 20% overall yield over six steps. A more economical approach with only four steps leads to the similarly active racemate by utilizing a Ugi four-component reaction (Ugi-4CR) as the key transformation. A small library of viridic acid analogues is readily available to provide first SAR insight. The biological activities of the natural product and its derivatives against the Gram-negative bacterium Aliivibrio fischeri were evaluated.

Alkylidene branched lupane derivatives: synthesis and antitumor activity.

Several novel alkylidene branched lupane derivatives have been prepared. Many of these compounds showed a significant cytotoxicity. The most active compound, 2-methylene-betulonic acid, showed IC(50) values between 0.2 and 0.6 µM for 15 different human cancer cell lines. Cytotoxicity can be improved by encapsulation in liposomes. These compounds act by triggering apoptotic cell death as shown by DNA-laddering experiments and acridine orange/ethidium bromide staining.

The multiple multicomponent approach to natural product mimics: tubugis, N-substituted anticancer peptides with picomolar activity.

The synthesis of a new generation of highly cytotoxic tubulysin analogues (i.e., tubugis) is described. In the key step, the rare, unstable, and synthetically difficult to introduce tertiary amide-N,O-acetal moiety required for high potency in natural tubulysins is replaced by a dipeptoid element formed in an Ugi four-component reaction. Two of the four components required are themselves produced by other multicomponent reactions (MCRs). Thus, the tubugis represent the first examples of the synthesis of natural-product-inspired compounds using three intertwined isonitrile MCRs.

CD48 stimulation by 2B4 (CD244)-expressing targets activates human NK cells.

Human NK cells can be activated by a variety of different cell surface receptors. Members of the SLAM-related receptors (SRR) are important modulators of NK cell activity. One interesting feature of the SRR is their homophilic interaction, combining receptor and ligand in the same molecule. Therefore, SRR cannot only function as activating NK cell receptors, but also as activating NK cell ligands. 2B4 (CD244) is the only SRR that does not show homophilic interaction. Instead, 2B4 is activated by binding to CD48, a GPI-anchored surface molecule that is widely expressed in the hemopoietic system. In this study, we show that 2B4 also can function as an activating NK cell ligand. 2B4-expressing target cells can efficiently stimulate NK cell cytotoxicity and IFN-gamma production. Using soluble receptor fusion proteins and SRR-transfected cells, we show that 2B4 does not bind to any other SRR expressed on NK cells, but only interacts with CD48. Lysis of 2B4-expressing target cells can be blocked by anti-CD48 Abs and triggering of CD48 in a redirected lysis assay can stimulate NK cell cytotoxicity. This demonstrates that 2B4 can stimulate NK cell cytotoxicity and cytokine production by interacting with NK cell expressed CD48 and adds CD48 to the growing number of activating NK cell receptors.

2B4 (CD244), NTB-A and CRACC (CS1) stimulate cytotoxicity but no proliferation in human NK cells.

The recently described family of SLAM-related receptors plays an important role in the modulation of lymphocyte activity. The members of this family expressed on human NK cells are 2B4 (CD244), NTB-A and CRACC (CS1). The ligands of these surface receptors are also present on all human NK cells, suggesting that 2B4, NTB-A and CRACC are engaged during the contact of neighboring NK cells. Here we investigate the functional consequence of this interaction. We show that blocking the engagement of 2B4, NTB-A and CRACC has no effect on the proliferation or the development of the cytotoxic potential of human NK cells. However, triggering of 2B4, NTB-A or CRACC by their physiological ligands on MHC class I-negative target cells induces potent NK cell cytotoxicity. This suggests that the engagement of inhibitory receptors by MHC class I on neighboring NK cells blocks 2B4-, NTB-A- and CRACC-induced NK cell cytotoxicity, thereby ensuring that NK cells do not kill each other. In support of this, limiting inhibitory receptor engagement by antibodies leads to the autologous killing of NK cells in a 2B4-, NTB-A- and CRACC-dependent manner.

The use of trimeric isoleucine-zipper fusion proteins to study surface-receptor-ligand interactions in natural killer cells.

The ligands for several activating natural killer (NK) cell receptors have not been identified to date. Soluble receptor fusion proteins can be used to stain target cells for the presence of these unidentified ligands. Here, we describe the generation and use of soluble type I NK cell receptor isoleucine-zipper (ILZ) fusion proteins of the immunoglobulin (Ig) superfamily. ILZ-fusion proteins are easy to produce and purify. They form trimeric complexes in solution and display a higher binding avidity than classical immunoglobulin-fusion proteins. ILZ-fusion proteins do not interact with Fc-receptors and can therefore be used to block receptor-ligand interactions in cellular assays. This makes ILZ-fusion proteins a valuable tool to study receptor-ligand interactions in NK cells and other cellular systems.