COGNITION: a prospective precision oncology trial for patients with early breast cancer at high risk following neoadjuvant chemotherapy.

BACKGROUND: COGNITION (Comprehensive assessment of clinical features, genomics and further molecular markers to identify patients with early breast cancer for enrolment on marker driven trials) is a diagnostic registry trial that employs genomic and transcriptomic profiling to identify biomarkers in patients with early breast cancer with a high risk for relapse after standard neoadjuvant chemotherapy (NACT) to guide genomics-driven targeted post-neoadjuvant therapy. PATIENTS AND METHODS: At National Center for Tumor Diseases Heidelberg patients were biopsied before starting NACT, and for patients with residual tumors after NACT additional biopsy material was collected. Whole-genome/exome and transcriptome sequencing were applied on tumor and corresponding blood samples. RESULTS: In the pilot phase 255 patients were enrolled, among which 213 were assessable: thereof 48.8% were identified to be at a high risk for relapse following NACT; 86.4% of 81 patients discussed in the molecular tumor board were eligible for a targeted therapy within the interventional multiarm phase II trial COGNITION-GUIDE (Genomics-guided targeted post neoadjuvant therapy in patients with early breast cancer) starting enrolment in Q4/2022. An in-depth longitudinal analysis at baseline and in residual tumor tissue of 16 patients revealed some cases with clonal evolution but largely stable genetic alterations, suggesting restricted selective pressure of broad-acting cytotoxic neoadjuvant chemotherapies. CONCLUSIONS: While most precision oncology initiatives focus on metastatic disease, the presented concept offers the opportunity to empower novel therapy options for patients with high-risk early breast cancer in the post-neoadjuvant setting within a biomarker-driven trial and provides the basis to test the value of precision oncology in a curative setting with the overarching goal to increase cure rates.

Camera-based photoplethysmography in critical care patients.

BACKGROUND: Camera-based photoplethysmography (cbPPG) is an optical measurement technique that reveals pulsatile blood flow in cutaneous microcirculation from a distance. cbPPG has been shown to reflect pivotal haemodynamic events like cardiac ejection in healthy subjects. In addition, it provides valuable insight into intrinsic microcirculatory regulation as it yields dynamic, two-dimensional perfusion maps. In this study, we evaluate the feasibility of a clinical cbPPG application in critical care patients. METHODS: A mobile camera set-up to record faces of patients at the bed site was constructed. Videos were made during the immediate recovery after cardiac surgery under standard critical care conditions and were processed offline. Major motion artefacts were detected using an optical flow technique and suitable facial regions were manually annotated. cbPPG signals were highpass filtered and Fourier spectra out of consecutive 10s signal segments calculated for heart rate detection. Signal-to-noise ratios (SNR) of the Fourier spectra were derived as a quality measure. Reference data of vital parameters were synchronously acquired from the bed site monitoring system. RESULTS: Seventy patient videos of an average time of 28.6±2.8 min were analysed. Heart rate (HR) was detected within a±5 bpm range compared to reference in 83% of total recording time. Low SNR and HR detection failure were mostly, but not exclusively, attributed to non-physiological events like patient motion, interventions or sudden changes of illumination. SNR was reduced by low arterial blood pressure, whereas no impact of other perioperative or disease-related parameters was identified. CONCLUSION: Cardiac ejection is detectable by cbPPG under pathophysiologic conditions of cardiovascular disease and perioperative medicine. cbPPG measurements can be seamlessly integrated into the clinical work flow of critical care patients.

CD95 promotes metastatic spread via Sck in pancreatic ductal adenocarcinoma.

Cancer stem cells (CSCs) have been implicated in the initiation and maintenance of tumour growth as well as metastasis. Recent reports link stemness to epithelial-mesenchymal transition (EMT) in cancer. However, there is still little knowledge about the molecular markers of those events. In silico analysis of RNA profiles of 36 pancreatic ductal adenocarcinomas (PDAC) reveals an association of the expression of CD95 with EMT and stemness that was validated in CSCs isolated from PDAC surgical specimens. CD95 expression was also higher in metastatic pancreatic cells than in primary PDAC. Pharmacological inhibition of CD95 activity reduced PDAC growth and metastasis in CSC-derived xenografts and in a murine syngeneic model. On the mechanistic level, Sck was identified as a novel molecule indispensable for CD95's induction of cell cycle progression. This study uncovers CD95 as a marker of EMT and stemness in PDAC. It also addresses the molecular mechanism by which CD95 drives tumour growth and opens tantalizing therapeutic possibilities in PDAC.

Therapy of chronic myeloid leukaemia can benefit from the activation of stem cells: simulation studies of different treatment combinations.

BACKGROUND: Newly diagnosed patients with chronic myeloid leukaemia (CML) are currently treated with tyrosine kinase inhibitors (TKIs) such as imatinib, nilotinib or dasatinib. However, incomplete eradication of residual disease is a general problem of long-term TKI therapy. Activation of mouse haematopoietic stem cells by interferon-α (IFNα) stimulated the discussion of whether a combination treatment leads to accelerated eradication of the CML clone. METHODS: We base our simulation approach on a mathematical model describing human CML as a competition phenomenon between normal and malignant cells. We amend this model to incorporate the description of IFNα activity and simulate different scenarios for potential treatment combinations. RESULTS: We demonstrate that the overall sensitivity of CML stem cells to IFNα activation is a crucial determinant for the benefit of a potential combination therapy. We furthermore show that pulsed IFNα together with continuous TKI administration is the most promising strategy for a combination treatment in which the therapeutic benefit prevails adverse side effects. CONCLUSION: Our modelling approach is a highly beneficial tool to quantitatively address the competition between normal and leukaemic haematopoiesis in treated CML patients. We derive testable predictions for different experimental settings that are suggested before the clinical implementation of the combination treatment.

Leukemic spleen cells are more potent than bone marrow-derived cells in a transgenic mouse model of CML.

Spleen size ranks among the most important risk factors in chronic myeloid leukemia (CML), but the pathogenic mechanisms of splenic hematopoiesis in CML remain poorly defined. Here, we studied the biology of Bcr-Abl positive leukemia-initiating cells in the spleen, using an inducible transgenic mouse model of CML. Disease kinetics showed greater increases of immature leukemic cells in spleen vs bone marrow (BM). To assess how Bcr-Abl alters the behavior of spleen-derived CML cells, we transplanted these cells either before ('pre-uninduced') or 44 days after ('pre-induced') expression of the oncogene. Mice transplanted with pre-induced spleen cells showed significantly increased neutrophilia and splenomegaly compared with mice receiving pre-uninduced spleen cells, suggesting that Bcr-Abl expression in the donors had increased splenic tumor burden. However, pre-induction also altered the biology of these cells, as shown by a striking increase in erythropoietic potential. These results differ from those of BM-derived CML stem cells where pre-induction of Bcr-Abl had previously been shown to decrease disease transplantability. Moreover, splenic cells were less sensitive to imatinib than BM cells. In conclusion, Bcr-Abl alters the biology of splenic leukemic stem cells by a cell-autonomous mechanism, but the disease phenotype is also influenced by the microenvironment of these cells.

Genome-wide mapping of Myc binding and gene regulation in serum-stimulated fibroblasts.

The transition from quiescence to proliferation is a key regulatory step that can be induced by serum stimulation in cultured fibroblasts. The transcription factor Myc is directly induced by serum mitogens and drives a secondary gene expression program that remains largely unknown. Using mRNA profiling, we identify close to 300 Myc-dependent serum response (MDSR) genes, which are induced by serum in a Myc-dependent manner in mouse fibroblasts. Mapping of genomic Myc-binding sites by ChIP-seq technology revealed that most MDSR genes were directly targeted by Myc, but represented a minor fraction (5.5%) of all Myc-bound promoters (which were 22.4% of all promoters). Other target loci were either induced by serum in a Myc-independent manner, were not significantly regulated or were negatively regulated. MDSR gene products were involved in a variety of processes, including nucleotide biosynthesis, ribosome biogenesis, DNA replication and RNA control. Of the 29 MDSR genes targeted by RNA interference, three showed a requirement for cell-cycle entry upon serum stimulation and 11 for long-term proliferation and/or survival. Hence, proper coordination of key regulatory and biosynthetic pathways following mitogenic stimulation relies upon the concerted regulation of multiple Myc-dependent genes.

Lineage- and stage-restricted lentiviral vectors for the gene therapy of chronic granulomatous disease.

Insertional mutagenesis represents a serious adverse effect of gene therapy with integrating vectors. However, although uncontrolled activation of growth-promoting genes in stem cells can predictably lead to oncological processes, this is far less likely if vector transcriptional activity can be restricted to fully differentiated cells. Diseases requiring phenotypic correction only in mature cells offer such an opportunity, provided that lineage/stage-restricted systems can be properly tailored. In this study, we followed this reasoning to design lentiviral vectors for the gene therapy of chronic granulomatous disease (CGD), an immune deficiency due a loss of nicotinamide adenine dinucleotide phosphate (NADPH) oxidase in phagocytes, most often secondary to mutations in gp91(phox). Using self-inactivating HIV1-derived vectors as background, we first expressed enhanced green fluorescent protein (eGFP) from a minimal gp91(phox) promoter, adding various natural or synthetic transcriptional regulatory elements to foster both specificity and potency. The resulting vectors were assessed either by transplantation or by lentiviral transgenesis, searching for combinations conferring strong and specific expression into mature phagocytic cells. The most promising vector was modified to express gp91(phox) and used to treat CGD mice. High-level restoration of NADPH activity was documented in granulocytes from the treated animals. We propose that this lineage-specific lentiviral vector is a suitable candidate for the gene therapy of CGD.

c-Myc and activated Ras during skin tumorigenesis: cooperation at the cancer stem cell level?

Mutations leading to overexpression and activation of the oncogenes Myc and Ras are among the most frequent lesions known to occur in human and murine cancers. These genes are also the pioneering example for oncogene cooperation during tumorigenesis, whereby the anticancer effects of Myc deregulation (apoptosis) and oncogenic Ras (senescence) are antagonized and therefore canceled out by each other. Here I review the role of endogenous and overexpressed c-Myc in murine skin, focusing primarily on epidermal stem cells. In addition, recent data suggesting an essential role for the endogenous c-Myc-p21(CIP1) pathway in Ras-driven skin tumorigenesis are discussed.

Conditional mutation of Rb causes cell cycle defects without apoptosis in the central nervous system.

Targeted disruption of the retinoblastoma gene in mice leads to embryonic lethality in midgestation accompanied by defective erythropoiesis. Rb(-/-) embryos also exhibit inappropriate cell cycle activity and apoptosis in the central nervous system (CNS), peripheral nervous system (PNS), and ocular lens. Loss of p53 can prevent the apoptosis in the CNS and lens; however, the specific signals leading to p53 activation have not been determined. Here we test the hypothesis that hypoxia caused by defective erythropoiesis in Rb-null embryos contributes to p53-dependent apoptosis. We show evidence of hypoxia in CNS tissue from Rb(-/-) embryos. The Cre-loxP system was then used to generate embryos in which Rb was deleted in the CNS, PNS and lens, in the presence of normal erythropoiesis. In contrast to the massive CNS apoptosis in Rb-null embryos at embryonic day 13.5 (E13.5), conditional mutants did not have elevated apoptosis in this tissue. There was still significant apoptosis in the PNS and lens, however. Rb(-/-) cells in the CNS, PNS, and lens underwent inappropriate S-phase entry in the conditional mutants at E13.5. By E18.5, conditional mutants had increased brain size and weight as well as defects in skeletal muscle development. These data support a model in which hypoxia is a necessary cofactor in the death of CNS neurons in the developing Rb mutant embryo.

c-Myc regulates mammalian body size by controlling cell number but not cell size.

Overexpression of the proto-oncogene c-myc has been implicated in the genesis of diverse human tumours. c-Myc seems to regulate diverse biological processes, but its role in tumorigenesis and normal physiology remains enigmatic. Here we report the generation of an allelic series of mice in which c-myc expression is incrementally reduced to zero. Fibroblasts from these mice show reduced proliferation and after complete loss of c-Myc function they exit the cell cycle. We show that Myc activity is not needed for cellular growth but does determine the percentage of activated T cells that re-enter the cell cycle. In vivo, reduction of c-Myc levels results in reduced body mass owing to multiorgan hypoplasia, in contrast to Drosophila c-myc mutants, which are smaller as a result of hypotrophy. We find that c-myc substitutes for c-myc in fibroblasts, indicating they have similar biological activities. This suggests there may be fundamental differences in the mechanisms by which mammals and insects control body size. We propose that in mammals c-Myc controls the decision to divide or not to divide and thereby functions as a crucial mediator of signals that determine organ and body size.

Negative regulation of neural stem/progenitor cell proliferation by the Pten tumor suppressor gene in vivo.

The mechanisms controlling neural stem cell proliferation are poorly understood. Here we demonstrate that the PTEN tumor suppressor plays an important role in regulating neural stem/progenitor cells in vivo and in vitro. Mice lacking PTEN exhibited enlarged, histoarchitecturally abnormal brains, which resulted from increased cell proliferation, decreased cell death, and enlarged cell size. Neurosphere cultures revealed a greater proliferation capacity for tripotent Pten-/- central nervous system stem/progenitor cells, which can be attributed, at least in part, to a shortened cell cycle. However, cell fate commitments of the progenitors were largely undisturbed. Our results suggest that PTEN negatively regulates neural stem cell proliferation.

DNA hypomethylation perturbs the function and survival of CNS neurons in postnatal animals.

DNA methyltransferase I (Dnmt1), the maintenance enzyme for DNA cytosine methylation, is expressed at high levels in the CNS during embryogenesis and after birth. Because embryos deficient for Dnmt1 die at gastrulation, the role of Dnmt1 in the development and function of the nervous system could not be studied by using this mutation. We therefore used the cre/loxP system to produce conditional mutants that lack Dnmt1 in neuroblasts of embryonic day 12 embryos or in postmitotic neurons of the postnatal animal. Conditional deletion of the Dnmt1 gene resulted in rapid depletion of Dnmt1 proteins, indicating that the enzyme in postmitotic neurons turns over quickly. Dnmt1 deficiency in postmitotic neurons neither affected levels of global DNA methylation nor influenced cell survival during postnatal life. In contrast, Dnmt1 deficiency in mitotic CNS precursor cells resulted in DNA hypomethylation in daughter cells. Whereas mutant embryos carrying 95% hypomethylated cells in the brain died immediately after birth because of respiratory distress, mosaic animals with 30% hypomethylated CNS cells were viable into adulthood. However, these mutant cells were eliminated quickly from the brain within 3 weeks of postnatal life. Thus, hypomethylated CNS neurons were impaired functionally and were selected against at postnatal stages.

Inducible chromosomal translocation of AML1 and ETO genes through Cre/loxP-mediated recombination in the mouse.

Transgenic mice have been used to explore the role of chromosomal translocations in the genesis of tumors. But none of these efforts has actually involved induction of a translocation in vivo. Here we report the use of Cre recombinase to replicate in vivo the t(8;21) translocation found in human acute myeloid leukemia (AML). As in the human tumors, the murine translocation fuses the genes AML1 and ETO. We used homologous recombination to place loxP sites at loci that were syntenic with the break points for the human translocation. Cre activity was provided in mice by a transgene under the control of the Nestin promoter, or in cultured B cells by infecting with a retroviral vector encoding Cre. In both instances, Cre activity mediated interchromosomal translocations that fused the AML1 and ETO genes. Thus, reciprocal chromosomal translocations that closely resemble rearrangements found in human cancers can be achieved in mice.

Cre-mediated gene inactivation demonstrates that FGF8 is required for cell survival and patterning of the first branchial arch.

In mammals, the first branchial arch (BA1) develops into a number of craniofacial skeletal elements including the jaws and teeth. Outgrowth and patterning of BA1 during early embryogenesis is thought to be controlled by signals from its covering ectoderm. Here we used Cre/loxP technology to inactivate the mouse Fgf8 gene in this ectoderm and have obtained genetic evidence that FGF8 has a dual function in BA1: it promotes mesenchymal cell survival and induces a developmental program required for BA1 morphogenesis. Newborn mutants lack most BA1-derived structures except those that develop from the distal-most region of BA1, including lower incisors. The data suggest that the BA1 primordium is specified into a large proximal region that is controlled by FGF8, and a small distal region that depends on other signaling molecules for its outgrowth and patterning. Because the mutant mice resemble humans with first arch syndromes that include agnathia, our results raise the possibility that some of these syndromes are caused by mutations that affect FGF8 signaling in BA1 ectoderm.

The chicken limb deformity gene encodes nuclear proteins expressed in specific cell types during morphogenesis.

The chicken limb deformity (ld) mutation affects morphogenesis of both limbs and kidneys and is one of few murine mutations for which the affected gene has been isolated. Analysis of the chicken homolog reveals evolutionary conservation of large parts of the encoded ld gene products. This is the first study of these proteins, their intracellular localization, and their temporal and spatial distribution during embryogenesis. A major 180-kD protein is expressed in chicken embryos and certain adult tissues. The proteins are localized in the nuclei of different embryonic cell types in a characteristic punctate pattern. In the developing chicken limb bud, they are expressed in the newly differentiated apical ectodermal ridge and the mesenchymal compartment, where an unequal distribution along the anteroposterior and, subsequently, the dorsoventral axes, is observed. During kidney morphogenesis, expression is initially restricted to the epithelial compartment of the pronephros and mesonephros. These results correlate well with the previous analysis of the murine ld phenotype and imply determinative roles for ld gene products during the morphogenesis of limbs and kidneys. Unexpected expression in the notochord, floor plate, and ventral horns suggests an involvement of the ld gene products in establishment of the dorsoventral polarity of the neural tube.