Search

Supplementary Figure from The Polarity and Specificity of Antiviral T Lymphocyte Responses Determine Susceptibility to SARS-CoV-2 Infection in Patients with Cancer and Healthy Individuals

Supplementary Data from The Polarity and Specificity of Antiviral T Lymphocyte Responses Determine Susceptibility to SARS-CoV-2 Infection in Patients with Cancer and Healthy Individuals

Vaccination against coronavirus disease 2019 (COVID-19) relies on the in-depth understanding of protective immune responses to severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2). We characterized the polarity and specificity of memory T cells directed against SARS-CoV-2 viral lysates and peptides to determine correlates with spontaneous, virus-elicited, or vaccine-induced protection against COVID-19 in disease-free and cancer-bearing individuals. A disbalance between type 1 and 2 cytokine release was associated with high susceptibility to COVID-19. Individuals susceptible to infection exhibited a specific deficit in the T helper 1/T cytotoxic 1 (Th1/Tc1) peptide repertoire affecting the receptor binding domain of the spike protein (S1-RBD), a hotspot of viral mutations. Current vaccines triggered Th1/Tc1 responses in only a fraction of all subject categories, more effectively against the original sequence of S1-RBD than that from viral variants. We speculate that the next generation of vaccines should elicit Th1/Tc1 T-cell responses against the S1-RBD domain of emerging viral variants.Significance:This study prospectively analyzed virus-specific T-cell correlates of protection against COVID-19 in healthy and cancer-bearing individuals. A disbalance between Th1/Th2 recall responses conferred susceptibility to COVID-19 in both populations, coinciding with selective defects in Th1 recognition of the receptor binding domain of spike.See related commentary by McGary and Vardhana, p. 892.This article is highlighted in the In This Issue feature, p. 873

Hemangioblasts derived from mesodermal lineage are the earliest precursors of hematopoietic stem cells and endothelial cells. Embryonic stem cells (ESC) and induced pluripotent stem cells (iPSC) are the only experimental systems in which these cells can be assayed and quantified. We show here using CML-derived iPSC and blast-cell colony forming (Bl-CFC) assays that hemangioblasts are highly expanded in CML derived iPSC as compared to human H1-ESC-derived hemangioblasts. BCR-ABL signaling pathway is intact in these cells with evidence of CRK-L phosphorylation which is reduced by the use of Imatinib. Hematopoietic progenitor assays generated using blast-CFC demonstrates also a highly increased hematopoietic progenitor potential of these cells as compared to H1-ESC. The same results were also obtained using hematopoietic progenitor assays via embryoid body formation. In CML iPSC, we have also found a significant reduction of Aryl Hydrocarbon Receptor (AHR) expression. Further inhibition of AHR using StemRegenin (SR1), an AHR antagonist, led to an increase of blast-cell colonies in CML iPSC whereas the use of an AHR agonist inhibited blast cell colonies. Thus, our results show for the first time, the possibility of establishment of a myeloproliferative phenotype using patient-derived iPSC and the presence of a major expansion of the hemangioblast compartment and hemangioblast-derived hematopoietic progenitors in this context. They also suggest that the AHR signaling pathway could represent a novel druggable target in CML.

Coats plus (CP) syndrome is an inherited autosomal recessive condition that results from mutations in the conserved telomere maintenance component 1 gene (CTC1). The CTC1 protein functions as a part of the CST protein complex, a protein heterotrimer consisting of CTC1–STN1–TEN1 which promotes telomere DNA synthesis and inhibits telomerase-mediated telomere elongation. However, it is unclear how CTC1 mutations may have an effect on telomere structure and function. For that purpose, we established the very first induced pluripotent stem cell lines (iPSCs) from a compound heterozygous patient with CP carrying deleterious mutations in both alleles of CTC1. Telomere dysfunction and chromosomal instability were assessed in both circulating lymphocytes and iPSCs from the patient and from healthy controls of similar age. The circulating lymphocytes and iPSCs from the CP patient were characterized by their higher telomere length heterogeneity and telomere aberrations compared to those in control cells from healthy donors. Moreover, in contrast to iPSCs from healthy controls, the high levels of telomerase were associated with activation of the alternative lengthening of telomere (ALT) pathway in CP-iPSCs. This was accompanied by inappropriate activation of the DNA repair proteins γH2AX, 53BP1, and ATM, as well as with accumulation of DNA damage, micronuclei, and anaphase bridges. CP-iPSCs presented features of cellular senescence and increased radiation sensitivity. Clonal dicentric chromosomes were identified only in CP-iPSCs after exposure to radiation, thus mirroring the role of telomere dysfunction in their formation. These data demonstrate that iPSCs derived from CP patients can be used as a model system for molecular studies of the CP syndrome and underscores the complexity of telomere dysfunction associated with the defect of DNA repair machinery in the CP syndrome.

International audience

Patients with cancer are presumed to be at increased risk of severe COVID-19 outcomes due to underlying malignancy and treatment-induced immunosuppression. Of the first 178 patients managed for COVID-19 at the Gustave Roussy Cancer Centre, 125 (70.2%) were hospitalized, 47 (26.4%) developed clinical worsening and 31 (17.4%) died. An age of over 70 years, smoking status, metastatic disease, cytotoxic chemotherapy and an Eastern Cooperative Oncology Group score of ≥2 at the last visit were the strongest determinants of increased risk of death. In multivariable analysis, the Eastern Cooperative Oncology Group score remained the only predictor of death. In contrast, immunotherapy, hormone therapy and targeted therapy did not increase clinical worsening or death risk. Biomarker studies found that C-reactive protein and lactate dehydrogenase levels were significantly associated with an increased risk of clinical worsening, while C-reactive protein and D-dimer levels were associated with an increased risk of death. COVID-19 management impacted the oncological treatment strategy, inducing a median 20 d delay in 41% of patients and adaptation of the therapeutic strategy in 30% of patients. Barlesi and colleagues describe the determinants of severe COVID-19 outcomes in patients with cancer managed at the Gustave Roussy Cancer Centre.

Vaccination against coronavirus disease 2019 (COVID-19) relies on the in-depth understanding of protective immune responses to severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2). We characterized the polarity and specificity of memory T cells directed against SARS-CoV-2 viral lysates and peptides to determine correlates with spontaneous, virus-elicited, or vaccine-induced protection against COVID-19 in disease-free and cancer-bearing individuals. A disbalance between type 1 and 2 cytokine release was associated with high susceptibility to COVID-19. Individuals susceptible to infection exhibited a specific deficit in the T helper 1/T cytotoxic 1 (Th1/Tc1) peptide repertoire affecting the receptor binding domain of the spike protein (S1-RBD), a hotspot of viral mutations. Current vaccines triggered Th1/Tc1 responses in only a fraction of all subject categories, more effectively against the original sequence of S1-RBD than that from viral variants. We speculate that the next generation of vaccines should elicit Th1/Tc1 T-cell responses against the S1-RBD domain of emerging viral variants. Significance: This study prospectively analyzed virus-specific T-cell correlates of protection against COVID-19 in healthy and cancer-bearing individuals. A disbalance between Th1/Th2 recall responses conferred susceptibility to COVID-19 in both populations, coinciding with selective defects in Th1 recognition of the receptor binding domain of spike. See related commentary by McGary and Vardhana, p. 892. This article is highlighted in the In This Issue feature, p. 873

Background The worldwide pandemic caused by the SARS-CoV-2 virus is characterized by significant and unpredictable heterogeneity in symptoms that remains poorly understood. Methods Transcriptome and single cell transcriptome of COVID19 lung were integrated with deeplearning analysis of MHC class I immunopeptidome against SARS-COV2 proteome. Results An analysis of the transcriptomes of lung samples from COVID-19 patients revealed that activation of MHC class I antigen presentation in these tissues was correlated with the amount of SARS-CoV-2 RNA present. Similarly, a positive relationship was detected in these samples between the level of SARS-CoV-2 and the expression of a genomic cluster located in the 6p21.32 region (40 kb long, inside the MHC-II cluster) that encodes constituents of the immunoproteasome. An analysis of single-cell transcriptomes of bronchoalveolar cells highlighted the activation of the immunoproteasome in CD68 + M1 macrophages of COVID-19 patients in addition to a PSMB8-based trajectory in these cells that featured an activation of defense response during mild cases of the disease, and an impairment of alveolar clearance mechanisms during severe COVID-19. By examining the binding affinity of the SARS-CoV-2 immunopeptidome with the most common HLA-A, -B, and -C alleles worldwide, we found higher numbers of stronger presenters in type A alleles and in Asian populations, which could shed light on why this disease is now less widespread in this part of the world. Conclusions HLA-dependent heterogeneity in macrophage immunoproteasome activation during lung COVID-19 disease could have implications for efforts to predict the response to HLA-dependent SARS-CoV-2 vaccines in the global population.

Optimal vaccination and immunotherapy against coronavirus disease COVID-19 relies on the in-depth comprehension of immune responses determining the individual susceptibility to be infected by SARS-CoV-2 and to develop severe disease. We characterized the polarity and specificity of circulating SARS-CoV-2-specific T cell responses against whole virus lysates or 186 unique peptides derived from the SARS-CoV-2 or SARS-CoV-1 ORFeome on 296 cancer-bearing and 86 cancer-free individuals who were either from the pre-COVID-19 era (67 individuals) or contemporary COVID-19-free (237 individuals) or who developed COVID-19 (78 individuals) in 2020/21. The ratio between the prototypic T helper 1 (TH1) cytokine, interleukin-2, and the prototypic T helper 2 (TH2) cytokine, interleukin-5 (IL-5), released from SARS-CoV-2-specific memory T cells measured in early 2020, among SARS-CoV-2-negative persons, was associated with the susceptibility of these individuals to develop PCR-detectable SARS-CoV-2 infection in late 2020 or 2021. Of note, T cells from individuals who recovered after SARS-CoV-2 re-infection spontaneously produced elevated levels of IL-5 and secreted the immunosuppressive TH2 cytokine interleukin-10 in response to SARS-CoV-2 lysate, suggesting that TH2 responses to SARS-CoV-2 are inadequate. Moreover, individuals susceptible to SARS-CoV-2 infection exhibited a deficit in the TH1 peptide repertoire affecting the highly mutated receptor binding domain (RBD) amino acids (331-525) of the spike protein. Finally, current vaccines successfully triggered anti-RBD specific TH1 responses in 88% healthy subjects that were negative prior to immunization. These findings indicate that COVID-19 protection relies on TH1 cell immunity against SARS-CoV-2 S1-RBD which in turn likely drives the phylogenetic escape of the virus. The next generation of COVID-19 vaccines should elicit high-avidity TH1 (rather than TH2)-like T cell responses against the RBD domain of current and emerging viral variants.

Patients with cancer are at higher risk of severe coronavirus infectious disease 2019 (COVID-19), but the mechanisms underlying virus-host interactions during cancer therapies remain elusive. When comparing nasopharyngeal swabs from cancer and non-cancer patients for RT-qPCR cycle thresholds measuring acute respiratory syndrome coronavirus-2 (SARS-CoV-2) in 1063 patients (58% with cancer, 89% COVID-19+), we found that malignant disease favors the magnitude and duration of viral RNA shedding concomitant with prolonged serum elevations of type 1 IFN that anticorrelated with anti-RBD IgG antibodies. Chronic viral RNA carriers exhibited the typical immunopathology of severe COVID-19 at the early phase of infection including circulation of immature neutrophils, depletion of non-conventional monocytes and a general lymphopenia that, however, was accompanied by a rise in plasmablasts, activated follicular T helper cells, and non-naive Granzyme B+ FasL+, EomehighTCF-1high, PD-1+CD8+ Tc1 cells. Virus-induced lymphopenia worsened cancer-associated lymphocyte loss, and low lymphocyte counts correlated with chronic SARS-CoV-2 RNA shedding, COVID-19 severity and a higher risk of cancer-related death in the first and second surge of the pandemic. Lymphocyte loss correlated with significant changes in metabolites from the polyamine and biliary salt pathways as well as increased blood DNA from Enterobacteriaceae and Micrococcaceae gut family members in long term viral carriers. We surmise that cancer therapies may exacerbate the paradoxical association between lymphopenia and COVID-19-related immunopathology, and that the prevention of COVID-19-induced lymphocyte loss may reduce cancer-associated death.

The circulating metabolome provides a snapshot of the physiological state of the organism responding to pathogenic challenges. Here we report alterations in the plasma metabolome reflecting the clinical presentation of COVID-19 patients with mild (ambulatory) diseases, moderate disease (radiologically confirmed pneumonitis, hospitalization and oxygen therapy), and critical disease (in intensive care). This analysis revealed major disease- and stage-associated shifts in the metabolome, meaning that at least 77 metabolites including amino acids, lipids, polyamines and sugars, as well as their derivatives, were altered in critical COVID-19 patient’s plasma as compared to mild COVID-19 patients. Among a uniformly moderate cohort of patients who received tocilizumab, only 10 metabolites were different among individuals with a favorable evolution as compared to those who required transfer into the intensive care unit. The elevation of one single metabolite, anthranilic acid, had a poor prognostic value, correlating with the maintenance of high interleukin-10 and -18 levels. Given that products of the kynurenine pathway including anthranilic acid have immunosuppressive properties, we speculate on the therapeutic utility to inhibit the rate-limiting enzymes of this pathway including indoleamine 2,3-dioxygenase and tryptophan 2,3-dioxygenase.

BackgroundIn mammalians, hematopoietic stem cells (HSC) arise in the dorsal aorta from the hemogenic endothelium, followed by their migration to fetal liver and to bone marrow. In zebrafish, kidney is the site of primary hematopoiesis. In humans, the presence of HSC in the fetal or adult kidney has not been established.MethodsWe analyzed the presence of HSC markers in human fetal kidneys by analysis of single-cell datasets. We then analyzed in kidney organoids derived from iPSC, the presence of hematopoietic markers using transcriptome analyses.Results12 clusters were identified of stromal, endothelial, and nephron cell type-specific markers in the two fetal stage (17 weeks) kidney datasets. Among these, expression of hematopoietic cells in Cluster 9 showed expression of primitive markers. Moreover, whole transcriptome analysis of our iPSC-derived kidney organoids revealed induction of the primitive hematopoietic transcription factor RUNX1 as found in the human fetal kidney cortex.ConclusionsThese finding support the presence of cells expressing HSC transcriptome in human kidney. The mechanisms of the appearance of the cells with the same transcriptional features during iPSC-derived kidney organoid generation requires further investigation.

Summary Blood myeloid cells are known to be dysregulated in the coronavirus disease 2019 (COVID-19) caused by SARS-CoV-2. It is unknown whether the innate myeloid response differs with disease severity, and whether markers of innate immunity discriminate high risk patients. Thus, we performed high dimensional flow cytometry and single cell RNA sequencing of COVID-19 patient peripheral blood cells and detected the disappearance of non-classical CD14LowCD16High monocytes, the accumulation of HLA-DRLow classical monocytes, and the release of massive amounts of calprotectin (S100A8/S100A9) in severe cases. Immature CD10LowCD101-CXCR4+/- neutrophils with an immuno-suppressive profile accumulated as well in blood and lungs, suggesting emergency myelopoiesis. We finally showed that calprotectin plasma level and a routine flow cytometry assay detecting decreased frequencies of non-classical monocytes could discriminate patients who develop a severe COVID-19 form, suggesting a predictive value that deserves prospective evaluation., Highlights • Severe patients accumulate HLA-DRLow monocytes and immature neutrophils in blood/lung. • Calprotectin level positively correlates with neutrophil count and disease severity. • Loss of non-classical monocytes could identify high risk of severe COVID-19.

Background: The SARS-CoV-2 outbreak significantly affected Gustave Roussy cancer center Here, we report the Gustave Roussy experience on older patients (OP) with cancer during the SARS-CoV-2 outbreak Methods: Cancer pts with suspected SARS-CoV-2 infection were admitted at Gustave Roussy starting March, 12th Screening indications have been adapted over time All the COVID-19 pts positively tested and managed at Gustave Roussy between March 14th and April 15th have been included in a redcap database Pts and underlying oncological and COVID-19 diseases characteristics have been collected Cancer and COVID-19 managements, and outcomes have been assessed The primary endpoint of this analysis was the clinical deterioration, defined as the need for O2 supplementation of 6l/min or more, or death of any cause Results: Among the first 137 cancer pts diagnosed with SARS-CoV-2, 36 patients were aged 70 years old or over (26%) Most of them were female (61%) with a median age of 75 5 years old Most frequent underlying cancers were solid tumors (92%) including GI (19%), lung (17%), GYN (14%) and head and neck (14%) Most OP (36%) were ECOG Performans status 2 versus 24% in younger patients (YP) The diagnosis of SARS-CoV-2 infection was made by RT-PCR or thoracic CT scan alone in 97% and 3% of the cases, respectively in OP and in 92% and 8% in YP Most OP experienced symptoms prior to testing (92%) compared to YP (80%) Symptoms differed according to age with more cough with sputum production in OP (14% versus 5%), dyspnea (39% versus 31%), diarrhea (17% versus 9%), shivers (8% versus 0%), sore throat (8% versus 4%) and no anosmia nor agueusia The majority of OP was hospitalized (81%) compared to 72% of YP and treated with HCQ/AZI (15;52%) compared to 25 (35%) YP with inclusion in the ONCOVID trial (EudraCT: 2020-01250-21) They did not receive any IL-6 inhibitor Only one OP was admitted in the ICU (3%) Clinical deterioration occurred in 10 OP (29%) There was no impact of age on clinical worsening (HR=1 157;95%CI 0 55-2 42;p=0 7) However age was associated with worse overall survival (OS) (HR=2 45 95%CI 1 02-5 92;p=0 0463) Results will be updated at the meeting Conclusions: OP with cancer had a different disease presentation, same rate of clinical worsening but worse OS in SARS-CoV-2 infection Legal entity responsible for the study: The authors Funding: Has not received any funding Disclosure: All authors have declared no conflicts of interest

We successfully converted hepatocytes isolated from adult mice into expandable and stable leucine-rich repeat-containing G-protein-coupled receptor 5 (LGR5)-positive endodermal progenitor cells (EndoPCs). This was accomplishedin vitrothrough transient exposure to four transcriptional factors (OCT3/4, SOX2, KLF4, and cMYC) and STAT3 activators. EndoPCs were generated by a process that involved an epithelial-mesenchymal transition (EMT) without the use of any components of the canonical WNT/β-catenin or LGR5/R-spondin signaling pathways. We showed that the proliferation and capacity for self-renewal of EndoPCs in 2D long-term culture were controlled by three interrelated signaling pathways: gp130/JAK/STAT3, LGR5/R-spondin, and WNT/β-catenin. After long-term maintenance in two- and three-dimensional culture systems, EndoPCs were able to differentiate into liver-restricted lineages such as hepatocyte-like cells and bile duct-like structuresin vitroandin vivo. After intra-muscular injection, EndoPCs generated macroscopically visible and well-vascularized liver-like tissue, which contained Alb+liver parenchyma-like structures and substantial, KRT7/KRT19+bile duct-like cell organizations.ConclusionWe have developed an efficient method for producing LGR5+adult endodermal stem cells. These cells will be useful for thein vitrostudy of the molecular mechanisms of liver development and have important potential for therapeutic strategies, including approaches based on bioengineered liver tissue. These cells also open up new avenues for experiments focused on disease modeling, toxicology studies, and regenerative medicine applications.

Cancer is maintained by the activity of a rare population of self-renewing “cancer stem cells” (CSCs), which are resistant to conventional therapies. CSCs share several antigenic determinants with pluripotent stem cells (PSCs). We show here that PSCs, combined with a histone deacetylase inhibitor (HDACi), are able to elicit major anti-tumor responses in a model of highly aggressive breast cancer. This immunotherapy strategy was effective in preventing tumor establishment and efficiently targeted CSCs by inducing extensive modifications of the tumor microenvironment. The anti-tumor effect was correlated with a reduction in regulatory T and myeloid-derived suppressor cell populations and an increase in cytotoxic CD8+T cells within the tumor and the spleen along with a drastic reduction in metastatic dissemination and an improvement in the survival rate. These results demonstrate for the first time the possibility of using PSCs and HDACi as an allogeneic anticancer vaccine, in future universal immunotherapy strategies.

Patients with cancer are presumed to be at increased risk of severe COVID-19 outcomes due to underlying malignancy and treatment-induced immunosuppression. Of the first 178 patients managed for COVID-19 at the Gustave Roussy Cancer Centre, 125 (70.2%) were hospitalized, 47 (26.4%) developed clinical worsening and 31 (17.4%) died. An age of over 70 years, smoking status, metastatic disease, cytotoxic chemotherapy and an Eastern Cooperative Oncology Group score of ≥2 at the last visit were the strongest determinants of increased risk of death. In multivariable analysis, the Eastern Cooperative Oncology Group score remained the only predictor of death. In contrast, immunotherapy, hormone therapy and targeted therapy did not increase clinical worsening or death risk. Biomarker studies found that C-reactive protein and lactate dehydrogenase levels were significantly associated with an increased risk of clinical worsening, while C-reactive protein and D-dimer levels were associated with an increased risk of death. COVID-19 management impacted the oncological treatment strategy, inducing a median 20 d delay in 41% of patients and adaptation of the therapeutic strategy in 30% of patients.

International audience; Recent experimental data suggest that the heterogeneity of chronic myeloid leukemia (CML) stem cells may be the result of the development of unique molecular events generating functional consequences in terms of the resistance and persistence of leukemic stem cells. To explore this phenomenon, we designed a single-cell transcriptome assay evaluating simultaneously the expression of 87 genes. Highly purified CD34+ cells from three CML patients at diagnosis were immobilized in microfluidic chips, and the expression of 87 genes was evaluated in each cell. This analysis identified a group of 13 highly connected genes including NANOG, POU5F1, LIN28A, and SOX2, representing on average 8.59% of the cell population analyzed. Bioinformatics analysis with the corrected matrix and t-distributed stochastic neighbor embedding (tSNE) algorithm identified four distinct clusters, and the pseudotime analysis confirmed the presence of seven stem cell states in the four clusters identified. ALOX5 expression was associated with the group of cells expressing the pluripotency markers. In in vitro analyses , two genes that were predicted to undergo similar regulation using pseudotime analysis (ALOX5 and FGFR) were found to be similarly inhibited by ponatinib, an FGFR inhibitor. Finally, in an independent cohort of CML patients, we found that pluripotency gene expression is a common feature of CD34+ CML cells at diagnosis. Overall, these experiments allowed identification of individual CD34+ cells expressing high levels of pluripotency genes at diagnosis , in which a continuum of transitional states were identified using pseudotime analysis. These results suggest that leukemic stem cell persistence in CML needs to be targeted simultaneously rather than using a single pathway. Chronic myeloid leukemia (CML) is a clonal hematopoietic malignancy, characterized by acquisition of the t(9;22) translo-cation leading to Ph1 chromosome and its counterpart BCR-ABL oncogene, in a very primitive hematopoietic stem cell [1]. CML is a model of targeted therapies as the proof of concept of the feasibility of targeting the tyrosine kinase (TK) activity BCR-ABL using TK inhibitors (TKIs) has been found to lead to major responses and remissions [2]. The use of ima-tinib and, later, second-generation [3,4] and third-generation [5] TKI therapies has changed the natural history of the disease and prolonged overall survival [6]. Moreover, recent results from CML registries indicate that the overall survival of CML patients responding to TKI therapies could equal that of the general population of the same age and sex [7]. However, the Offprint requests to: Ali G. Turhan

Heterozygous non-synonymous (p.S142F) mutation in HNF1A leads to maturity-onset diabetes of the young (MODY) type 3, which is a subtype of dominant inherited young-onset non-autoimmune diabetes due to the defect of insulin secretion from pancreatic beta cells. We generated induced pluripotent stem cells (iPSCs) from a patient with HNF1A p.S142F mutation. Cells from this patient, which were reprogrammed by non-integrative viral transduction had normal karyotype, harboured the HNF1A p.S142F mutation, expressed pluripotency hallmarks.

Summary: MEN2A is a hereditary cancer-predisposing syndrome that affects patients with germline RET mutations. The effects of this oncogenic tyrosine kinase in the context of primitive stem cells are not known. In order to study these events, we generated a MEN2A induced Pluripotent Stem Cell (iPSC) line from a patient with RET mutation and an isogenic counterpart by CRISPR-Cas9 correction of the mutation. Whole exome sequencing of iPSC before and after CRISPR-Cas9 genome edition revealed no major exonic off target effect of the CRISPR correction. However, an integrative differential gene expression analysis of iPSC with oncogenic RETC634Y and its gene-corrected iPSC with RETY634C as well as RETwt iPSCs revealed activation of the Early Growth Response 1 (EGR1) transcriptional program in RET-mutated iPSC, a pathway shown to be involved in RET-induced oncogenesis. These data constitute the first proof of concept of the feasibility of the use of an iPSC and its genome-corrected counterpart to unravel the molecular mechanisms underlying the development of the hereditary MEN2A cancer predisposing syndrome.

Background: Outcomes and risk factors associated with COVID-19 worsening among cancer patients have previously been reported. However, the actual impact of SARs-Co-V2 infection on the cancer treatment strategy remains unknown. Here, we report the Gustave Roussy (GR) experience, one year after the onset of the pandemic focusing on the impact of COVID-19 in patients with ongoing management of oncohematological disease. Methods: All patients positively tested for SARS-CoV-2 and managed at GR between Mar 14th 2020 and Feb 15th 2021 (data cut-off) have been included. Patients underlying oncohematological disease and COVID19 characteristics have been collected. Cancer and COVID-19 management and outcomes have been assessed. Primary endpoint was the overall impact of COVID-19 on oncological and hematological treatment strategy assessed at 1, 3, 6 and 12 months. Results: At the time of the analysis, 423 patients (median age: 62 years) were found positive for SARS-CoV-2 and managed at GR with a median follow up of 5.6 months (0-13 months). Among them, 284 (67%) were admitted due to COVID-19. Clinical deterioration occurred in 87 patients (21%), 43 patients (10%) were transferred in intensive care unit and 123 (29%) patients died, among which 47 (11%) died from COVID-19. Overall, 329 (78%) patients were on active treatment for underlying oncohematological disease at time of COVID diagnosis. Impact of COVID-19 on cancer treatment strategy in those patients is presented in the Table. The majority (N=268, 81%) had no change in oncological strategy. For those who experienced a delay, median delay in treatment was 21 days (N=99, [1-77]), 30 days (N=15, [15-56]), 7 days (N=8,[3-35]) for systemic treatment, surgery and radiotherapy respectively. [Formula presented] Conclusions: COVID-19 outbreak is associated with a significant mortality in patients with cancer. However, for patients who did not die from COVID-19, we provide the first report supporting that ongoing treatment was maintained or could be resumed in the majority of cases in a timely manner. Legal entity responsible for the study: Gustave Roussy. Funding: Has not received any funding. Disclosure: All authors have declared no conflicts of interest.

BRCA1 germline mutation confers hereditary predisposition for breast and ovarian cancer. To understand the physiopathology of mammary and ovarian epithelial cancer transformation, and to identify early driver molecular events, we have generated an iPSC line from a patient carrying a germline exon 17 deletion in BRCA1 gene (BRAC1Ex17 iPSC) in a high-risk family context. Blood cells were reprogrammed used non-integrative virus of Sendai. The BRCA1-deleted iPSC had normal karyotype, harboured a deletion in the exon 17 of the BRCA1 gene, expressed pluripotent hallmarks and had the differentiation capacity into the three germ layers.

We report here the first use of whole-genome sequencing (WGS) to examine the initial clonal dynamics in an unusual patient with chronic myeloid leukemia (CML), who presented in chronic phase (CP) with doubly marked BCR-ABL1+/JAK2V617F-mutant cells and, over a 9-year period, progressed into an accelerated phase (AP) and then terminal blast phase (BP). WGS revealed that the diagnostic cells also contained mutations in ASXL1, SEC23B, MAD1L1, and RREB1 as well as 12,000 additional uncommon DNA variants. WGS of endothelial cells generated from circulating precursors revealed many of these were shared with the CML clone. Surprisingly, WGS of induced pluripotent stem cells (iPSCs) derived from the AP cells revealed only six additional coding somatic mutations, despite retention by the hematopoietic progeny of the parental AP cell levels of BCR-ABL1 expression and sensitivity to imatinib and pimozide. Limited analysis of BP cells revealed independent subclonal progression to homozygosity of the MAD1L1 and RREB1 variants. MAD1L1 and SEC23B mutations were also identified in 2 of 101 cases of myeloproliferative neoplasms, but not in 42 healthy subjects. These findings challenge historic concepts of clonal evolution in CML.

Background Current experimental models using either human or mouse cell lines, are not representative of the complex features of GBM. In particular, there is no model to study patient-derived iPSCs to generate a GBM model. Overexpression of c-met gene is one of the molecular features of GBM leading to increased signaling via STAT3 phosphorylation. We generated an iPSC line from a patient with c-met mutation and we asked whether we could use it to generate neuronal-like organoids mimicking features of GBM. Methods We have generated iPSC-aggregates differentiating towards organoids. We analyzed them by gene expression profiling, immunostaining and transmission electronic microscopy analyses (TEM). Results Herein we describe that c-met-mutated iPSC aggregates spontaneously differentiate into dopaminergic neurons more rapidly than control iPSC aggregates in culture. Gene expression profiling of c-met-mutated iPSC aggregates at day +90 showed neuronal- and GBM-related genes, reproducing a genomic network described in primary human GBM. Comparative TEM analyses confirmed the enrichment of these structures in intermediate filaments and abnormal cilia, a feature described in human GBM. The c-met-mutated iPSC-derived organoids, as compared to controls expressed high levels of glial fibrillary acidic protein (GFAP), which is a typical marker of human GBM, as well as high levels of phospho-MET and phospho-STAT3. The use of temozolomide (TMZ) showed a preferential cytotoxicity of this drug in c-met-mutated neuronal-like organoids. General significance This study shows the feasibility of generating “off-the shelf” neuronal-like organoid model mimicking GBM using c-met-mutated iPSC aggregates and its potential future use in research.

Hereditary cancers with cancer-predisposing mutations represent unique models of human oncogenesis, as a driving oncogenic event is present in germline. Currently, there are no satisfactory models to study these malignancies. We report the generation of IPSC from the somatic cells of a patient with hereditary c-met-mutated papillary renal cell carcinoma (PRCC). From these cells we have generated spontaneous aggregates organizing in structures which expressed kidney markers such as PODXL and Six2. These structures expressed PRCC markers both in vitro and in vivo in NSG mice. Gene-expression profiling showed striking molecular similarities with signatures found in a large cohort of PRCC tumor samples. This analysis, applied to primary cancers with and without c-met mutation, showed overexpression of the BHLHE40 and KDM4C only in the c-met-mutated PRCC tumors, as predicted by c-met-mutated embryoid bodies transcriptome. These data therefore represent the first proof of concept of “hereditary renal cancer in a dish” model using c-met-mutated iPSC-derived embryoid bodies, opening new perspectives for discovery of novel predictive progression markers and for drug-screening for future precision-medicine strategies.

International audience; Although human pluripotent stem cells (hPSCs) can theoretically differentiate into any cell type, their ability to produce hematopoietic cells is highly variable from one cell line to another. The underlying mechanisms of this heterogeneity are not clearly understood. Here, using a whole miRNome analysis approach in hPSCs, we discovered that their hematopoietic competency was associated with the expression of several miRNAs and conversely correlated to that of miR-206 specifically. Lentiviral-based miR-206 ectopic expression in H1 hematopoietic competent embryonic stem (ES) cells markedly impaired their differentiation toward the blood lineage. Integrative bioinformatics identified a potential miR-206 target gene network which included hematopoietic master regulators RUNX1 and TAL1. This work sheds light on the critical role of miR-206 in the generation of blood cells off hPSCs. Our results pave the way for future genetic manipulation of hPSCs aimed at increasing their blood regenerative potential and designing better protocols for the generation of bona fide hPSC-derived hematopoietic stem cells. © 2019 by the authors. Licensee MDPI, Basel, Switzerland.

Over the last decade, the possibility of reprogramming malignant cells to a pluripotent state has been achieved in several hematological malignancies, including myeloproliferative neoplasms, myelodysplastic syndromes, and chronic myeloid leukemia (CML). It has been shown that it is readily possible to generate induced pluripotent stem cells (iPSCs) from several types of primary CML cells and to generate progenitors and differentiated cells with variable efficiency. Although these experiments have brought some new insights in the understanding of CML pathophysiology, the ultimate goal of generating induced leukemic stem cells (LSCs) with long-term multilineage potential has not yet been demonstrated. Experiments under way will determine whether additional signaling events are required to induce the emergence of bona fide LSCs. However, iPSC modeling offers the unique possibility to generate pluripotent cells harboring cancer-predisposing mutations using patient-derived noncancerous cells, as has been shown in Li–Fraumeni syndrome, BRCA-1 associated breast carcinomas, or RET-mutated medullary thyroid carcinomas. In these conditions, mutated iPSCs can then be used to study the mutational history that precedes the appearance of the malignant transformation and to develop novel drug-screening strategies. The ability to induce a successful differentiation program toward the tissue in which a given cancer develops or to generate tissue-specific cancer organoids in which the full oncogenic potential can be revealed remains a major challenge in the field. Similarly, in hematological malignancies, a significant hurdle remains due to the lack of adequate technology to induce the emergence of leukemic cells that resemble LSCs, which hinders our ability to study the mechanisms of therapy resistance.

SUMMARYHereditary cancers with cancer-predisposing mutations represent unique models of human oncogenesis as a driving oncogenic event is present in germline, exposing the healthy member of a family to the occurrence of cancer. The study of the secondary events in a tissue-specific manner is now possible by the induced pluripotent stem cell (iPSC) technology offering the possibility to generate an unlimited source of cells that can be induced to differentiate towards a tissue at risk of malignant transformation. We report here for the first time, the generation of a c-met-mutated iPSC lines from the somatic cells of a patient with type 1 papillary renal cell carcinoma (PRCC). We demonstrate the feasibility of kidney differentiation with iPSC-derived organoids expressing markers of kidney progenitors with presence of tight junctions and brush borders in tubular structures at transmission electron microscopy. Importantly, c-met-mutated kidney organoids expressed PRCC markers both in vitro and in vivo in NSG mice. Gene expression profiling of c-met-mutated iPSC-derived organoid structures showed striking molecular similarities with signatures found in a large cohort of PRCC patient samples and identified 11 common genes. Among these, BHLHE40 and KDM4C, well-known factors involved in PRCC pathogenesis, were expressed in c-met-mutated kidney organoids. This analysis applied to primary cancers with and without c-met mutation showed overexpression of the BHLHE40 and KDM4C only in the c-met-mutated PRCC tumors, as predicted by c-met-mutated organoid transcriptome. These data represent therefore the first proof of concept of the generation of “renal carcinoma in a dish” model using c-met-mutated iPSC-derived organoids, opening new perspectives for discovery of novel potentially predictive disease markers and novel drugs for future precision medicine strategies.

Tumor progression begins when cancer cells recruit tumor-associated stromal cells to produce a vascular niche, ultimately resulting in uncontrolled growth, invasion, and metastasis. It is poorly understood, though, how this process might be affected by deletions or mutations in the breast cancer type 1 susceptibility (BRCA1) gene in patients with a lifetime risk of developing breast and/or ovarian cancer. To model the BRCA1-deleted stroma, we first generated induced pluripotent stem cells (iPSCs) from patients carrying a germline deletion of exon 17 of the BRCA1 gene (BRCA1+/&minus, who, based on their family histories, were at a high risk for cancer. Using peripheral blood mononuclear cells (PBMCs) of these two affected family members and two normal (BRCA1+/+) individuals, we established a number of iPSC clones via non-integrating Sendai virus-based delivery of the four OCT4, SOX2, KLF4, and c-MYC factors. Induced mesenchymal stem cells (iMSCs) were generated and used as normal and pathological stromal cells. In transcriptome analyses, BRCA1+/&minus, iMSCs exhibited a unique pro-angiogenic signature: compared to non-mutated iMSCs, they expressed high levels of HIF-1&alpha, angiogenic factors belonging to the VEGF, PDGF, and ANGPT subfamilies showing high angiogenic potential. This was confirmed in vitro through the increased capacity to generate tube-like structures compared to BRCA1+/+ iMSCs and in vivo by a matrigel plug angiogenesis assay where the BRCA1+/&minus, iMSCs promoted the development of an extended and organized vessel network. We also reported a highly increased migration capacity of BRCA1+/&minus, iMSCs through an in vitro wound healing assay that correlated with the upregulation of the periostin (POSTN). Finally, we assessed the ability of both iMSCs to facilitate the engraftment of murine breast cancer cells using a xenogenic 4T1 transplant model. The co-injection of BRCA1+/&minus, iMSCs and 4T1 breast cancer cells into mouse mammary fat pads gave rise to highly aggressive tumor growth (2-fold increase in tumor volume compared to 4T1 alone, p = 0.01283) and a higher prevalence of spontaneous metastatic spread to the lungs. Here, we report for the first time a major effect of BRCA1 haploinsufficiency on tumor-associated stroma in the context of BRCA1-associated cancers. The unique iMSC model used here was generated using patient-specific iPSCs, which opens new therapeutic avenues for the prevention and personalized treatment of BRCA1-associated hereditary breast cancer.

Chronic myeloid leukemia (CML) is a clonal malignancy initiated by the occurrence of a t (9;22) translocation, generating Ph1 chromosome and BCR-ABL oncogene in a primitive hematopoietic stem cell (HSC). The resistance of HSC to targeted therapies using tyrosine kinase inhibitors remains a major obstacle towards the cure. We have generated an iPSC line from a patient with CML using leukemic CD34+ cells cryopreserved at diagnosis. Ph1+ CML cells were reprogrammed by non-integrative viral transduction. These iPSCs harboured Ph1 chromosome and expressed pluripotency hallmarks as well as BCR-ABL. Teratoma assays revealed normal differentiation after injection in immunodeficient mice.

MEN2A is a hereditary cancer-predisposing syndrome that affects patients with germline RET mutations. The effects of this oncogenic tyrosine kinase in the context of primitive stem cells are not known. In order to study these events, we generated a MEN2A induced Pluripotent Stem Cell (iPSC) line from a patient with RET mutation and an isogenic counterpart by CRISPR-Cas9 correction of the mutation. Whole exome sequencing of iPSC before and after CRISPR-Cas9 genome edition revealed no major exonic off target effect of the CRISPR correction. However, an integrative differential gene expression analysis of iPSC with oncogenic RET