Sensitivity, specificity, and accuracy of molecular profiling on circulating cell-free DNA in refractory or relapsed multiple myeloma patients, results of MM-EP1 study

As a promising alternative to bone marrow aspiration (BMA), mutational profiling on blood-derived circulating cell-free tumor DNA (cfDNA) is a harmless and simple technique to monitor molecular response and treatment resistance of patients with refractory/relapsed multiple myeloma (R/R MM). We evaluated the sensitivity and specificity of cfDNA compared to BMA CD138 positive myeloma plasma cells (PCs) in a series of 45 R/R MM patients using the 29-gene targeted panel (AmpliSeq) NGS. KRAS, NRAS, FAM46C, DIS3, and TP53 were the most frequently mutated genes. The average sensitivity and specificity of cfDNA detection were 65% and 97%, respectively. The concordance per gene between the two samples was good to excellent according to Cohen's κ coefficients interpretation. An increased number of mutations detected in cfDNA were associated with a decreased overall survival. In conclusion, we demonstrated cfDNA NGS analysis feasibility and accuracy in R/R MM patients who may benefit from early phase clinical trial.

Myelodysplastic syndrome following chimeric antigen receptor T-cell therapy treated with allogenic stem cell transplantation

Chimeric antigen receptor (CAR) T-cell therapy is currently approved for the treatment of B-cell non-Hodgkin lymphomas and B-cell acute lymphoblastic leukemia. Prolonged hematological toxicity is an emergent concern following CAR T cells and occurred in 30% of patients with unknown mechanism. Few cases of myelodysplastic syndrome (MDS) following CAR T-cell therapy were reported and attributed to previous chemotherapies in heavily pretreated patients. The authors report the case of a patient with diffuse large B-cell lymphoma treated with axicabtagene ciloleucel who developed prolonged hematological toxicity by day 28. During the follow-up, the diagnosis of MDS was made. The patient underwent allogenic hematological stem cell transplantation. The patient remains in complete remission of his lymphoma and MDS 19 months after hematological stem cell transplantation.

Liquid Biopsies for Circulating Tumor DNA Detection May Reveal Occult Hematologic Malignancies in Patients With Solid Tumors

PURPOSE

High-risk clonal hematopoiesis (CH) is frequently incidentally found in patients with solid tumors undergoing plasma cell-free DNA sequencing. Here, we aimed to determine if the incidental detection of high-risk CH by liquid biopsy may reveal occult hematologic malignancies in patients with solid tumors.

MATERIALS AND METHODS

Adult patients with advanced solid cancers enrolled in the Gustave Roussy Cancer Profiling study (ClinicalTrials.gov identifier: NCT04932525) underwent at least one liquid biopsy (FoundationOne Liquid CDx). Molecular reports were discussed within the Gustave Roussy Molecular Tumor Board (MTB). Potential CH alterations were observed, and patients referred to hematology consultation in the case of pathogenic mutations in JAK2, MPL, or MYD88, irrespective of the variant allele frequency (VAF), or in DNMT3A, TET2, ASXL1, IDH1, IDH2, SF3B1, or U2AF1 with VAF ≥ 10%, while also considering patient cancer-related prognosis. TP53 mutations were discussed case-by-case.

RESULTS

Between March and October 2021, 1,416 patients were included. One hundred ten patients (7.7%) carried at least one high-risk CH mutation: DNMT3A (n = 32), JAK2 (n = 28), TET2 (n = 19), ASXL1 (n = 18), SF3B1 (n = 5), IDH1 (n = 4), IDH2 (n = 3), MPL (n = 3), and U2AF1 (n = 2). The MTB advised for hematologic consultation in 45 patients. Overall, 9 patients of 18 actually addressed had confirmed hematologic malignancies that were occult in six patients: two patients had myelodysplastic syndrome, two essential thrombocythemia, one a marginal lymphoma, and one a Waldenström macroglobulinemia. The other three patients were already followed up in hematology.

CONCLUSION

The incidental findings of high-risk CH through liquid biopsy may trigger diagnostic hematologic tests and reveal an occult hematologic malignancy. Patients should have a multidisciplinary case-by-case evaluation.

Therapy-related Myeloid Neoplasms Following PARP Inhibitors: Real-life Experience

PURPOSE

To provide insights into the diagnosis and management of therapy-related myeloid neoplasms (t-MN) following PARP inhibitors (PARPi).

EXPERIMENTAL DESIGN

In a French cancer center, we identified and described the profiles of 13 t-MN diagnosed among 37 patients with ovarian cancer referred to hematology consultation for cytopenia under PARPi. Next, we described these 13 t-MN post-PARPi among 37 t-MN post ovarian cancer according to PARPi exposure. Finally, we described 69 t-MN post-PARPi in a national cohort.

RESULTS

From 2016 to 2021, cumulative incidence of t-MN was 3.5% (13/373) among patients with ovarian cancer treated with PARPi. At time of hematologic consultation, patients with t-MN had a longer PARPi exposure (9 vs. 3 months, P = 0.01), lower platelet count (74 vs. 173 G/L, P = 0.0005), and more cytopenias (2 vs. 1, P = 0.0005). Compared with t-MN not exposed to PARPi, patients with t-MN-PARPi had more BRCA1/2 germline mutation (61.5% vs. 0%, P = 0.03) but similar overall survival (OS). In the national cohort, most t-MN post-PARPi had a complex karyotype (61%) associated with a high rate of TP53 mutation (71%). Median OS was 9.6 months (interquartile range, 4-14.6). In multivariate analysis, a longer time between end of PARPi and t-MN (HR, 1.046; P = 0.02), olaparib compared with other PARPi (HR, 5.82; P = 0.003) and acute myeloid leukemia (HR, 2.485; P = 0.01) were associated with shorter OS.

CONCLUSIONS

In a large series, we described a high incidence of t-MN post-PARPi associated with unfavorable cytogenetic and molecular abnormalities leading to poor OS. Early detection is crucial, particularly in cases of delayed cytopenia.

Cell-free DNA sequencing as a potential screening tool for phase I targeted treatment in refractory/relapse diffuse large B cell lymphoma

Not available.

Large deletions in immunoglobulin genes are associated with a sustained absence of DNA Polymerase η

Somatic hypermutation of immunoglobulin genes is a highly mutagenic process that is B cell-specific and occurs during antigen-driven responses leading to antigen specificity and antibody affinity maturation. Mutations at the Ig locus are initiated by Activation-Induced cytidine Deaminase and are equally distributed at G/C and A/T bases. This requires the establishment of error-prone repair pathways involving the activity of several low fidelity DNA polymerases. In the physiological context, the G/C base pair mutations involve multiple error-prone DNA polymerases, while the generation of mutations at A/T base pairs depends exclusively on the activity of DNA polymerase η. Using two large cohorts of individuals with xeroderma pigmentosum variant (XP-V), we report that the pattern of mutations at Ig genes becomes highly enriched with large deletions. This observation is more striking for patients older than 50 years. We propose that the absence of Pol η allows the recruitment of other DNA polymerases that profoundly affect the Ig genomic landscape.

[Burkitt lymphoma, a diagnostic emergency]

Burkitt lymphoma, a diagnostic emergency. Burkitt lymphoma is a highly aggressive B-cell non-Hodgkin lymphoma. This is the first human tumor where a chromosomal translocation that activates an oncogene (c-myc) has been described. The diagnosis and initiation of therapy is an emergency. The main lymphoma localizations are the digestive tract, the central nervous system and the bone marrow in the sporadic form observed in Western countries. Tumor lysis syndrome can be present even before therapy and can necessitate rapid chemotherapy in intensive care unit. Dose-dense chemotherapy regimens, implemented during the last 25 years can cure the majority of patients, especially children, but remains associated with a high toxicity. The adjunction of rituximab to chemotherapy is still investigated in high-risk groups in children and is now part of the treatment in adults.

Immunophenotypic clustering of myelodysplastic syndromes

Myelodysplastic syndromes (MDSs) are heterogeneous diseases of bone marrow (BM) cell precursors for which immunophenotypic characterization is still considered irrelevant despite the accuracy and sensitivity of flow cytometry techniques. The aim of this study was to determine whether immunophenotypic abnormalities could be defined in MDSs and could correlate with the French-American-British classification and cytogenetics. Analysis was performed on 275 BM samples (207 MDS patients, 68 controls) and 25 control blood samples. Immunophenotyping was based on a primary gating of blast cells, monocytes, and granulocytes according to CD45 antigen expression and side scatter light diffraction. Immunophenotypic hierarchical clustering was performed to analyze the results. The data obtained show that (1) immunophenotypic clustering partly discriminates patients with refractory anemia with excess blasts/refractory anemia with excess blasts in transformation (RAEB/RAEB-T), chronic myelomonocytic leukemia (CMML), and refractory anemia/refractory anemia with ring sideroblasts (RA/RARS) for CD45(lo) blast cells and patients with RA/CMML, RARS, and RAEB/RAEB-T for CD45(hi)/side scatter(hi) (SS(hi)) granulocytes; (2) the most discriminating markers were CD16, CD34, CD36, CD38, CD71, and HLA-DR for blast cells and CD11b, CD13, CD33, CD36, CD38, CD71, and HLA-DR for CD45(hi)/SS(hi) granulocytes; (3) clusters related to CD34 expression were associated with high levels of blast cells on BM smear; (4) clusters related to high levels of CD36 expression on CD45(lo) blast cells and CD45(hi)/SS(hi) granulocytes were associated with a poor International Prognosis Scoring System score; and (5) high levels of CD71 expression on CD45(hi)/SS(hi) granulocytes were associated with the RARS category. These results show a close relationship between immunophenotypic abnormalities and BM dysplasia and suggest that flow cytometry could be a future tool for the characterization of MDSs.

In vitro production of dendritic cells from human blood monocytes for therapeutic use

Dendritic cells (DC) are professional antigen-presenting cells that are promising adjuvants for clinical immunotherapy. Methods to generate in vitro large numbers of functional human DC using either peripheral blood monocytes or CD34(+) pluripotent hematopoietic progenitor cells have been now developed. For this purpose, their in vitro production for further clinical use need to fit good manufacturing practice (GMP) conditions. In the present review, we give our experience of such a procedure: it includes collection of mononuclear cells by apheresis, separation of monocytes by elutriation, and culture of monocytes with GM-CSF + IL-13 + human serum (autologous patient's serum or AB serum) or in a serum-free medium (AIM V). The characteristics of monocyte-derived DC grown in these various conditions varied mainly regarding their phenotype and their morphology in confocal microscopy, whereas no significant differences were found in their capacity to phagocytize latex particles and to stimulate allogeneic (MLR) or autologous lymphocytes (antigen-presentation tests). The DC were also cryopreserved in bags (either by putting the bags directly in a -80 degrees C mechanical freezer or using a classical liquid nitrogen controlled-rate freezer at -1 degrees C/min) in a solution containing 10% dimethyl sulfoxide (Me(2)SO) and 2% human albumin in doses of DC available for several infusions. The mean recoveries after freezing and thawing were not statistically different (around 70%). The immunophenotype of DC, as well as the T lymphocyte-stimulating capacity, were not modified by the freezing--thawing procedure. The results obtained demonstrate that the experimental conditions we set up are easily applicable in clinical trials and lead to large numbers of well-defined DC. Clinical trials using DC already published will be discussed.

In vitro generation of dendritic cells from human blood monocytes in experimental conditions compatible for in vivo cell therapy

DC are professional APC that are promising adjuvants for clinical immunotherapy. Methods to generate in vitro large numbers of functional human DC using either peripheral blood monocytes or CD34+ pluripotent HPC have been developed recently. However, the various steps of their in vitro production for further clinical use need to fit good manufacturing practice (GMP) conditions. Our study focused on setting up such a full procedure, including collection of mononuclear cells (MNC) by apheresis, separation of monocytes by elutriation, and culture of monocytes with GM-CSF + IL-13 + autologous serum (SAuto) in sterile Teflon bags. The procedure was first developed with apheresis products from 7 healthy donors. Its clinical feasibility was then tested on 7 patients with breast cancer. The characteristics of monocyte-derived DC grown with SAuto (or in some instances with a pooled AB serum) were compared with those obtained in the presence of FBS by evaluation of their phenotype, their morphology in confocal microscopy, and their capacity to phagocytize latex particles and to stimulate allogeneic (MLR) or autologous lymphocytes (antigen-presentation tests). The results obtained demonstrate that the experimental conditions we set up are easily applicable in clinical trials and lead to large numbers of well-defined SAuto-derived DC as efficient as those derived with FBS.

Fas-mediated apoptosis of mouse embryo stem cells: its role during embryonic development

PROBLEM

Fas antigen (APO-1/CD95) can regulate the activity of various cells during adulthood. This study aimed at determining whether Fas may also be involved in the regulation of very early events such as the embryo preimplantation stage.

METHOD OF STUDY

We used mouse embryo stem (ES) cell line as a model for testing the effect of Fas crosslinking upon anti-Fas monoclonal antibody (MoAb) treatment. In addition, this treatment was also applied to in-vitro mouse-embryo culture.

RESULTS

Flow-cytometry analysis of cultured ES cells demonstrated an increase in Fas expression. unchanged in the presence of mouse interleukin-2, while greatly upregulated in the presence of lipopolysaccharide (LPS). As determined by various means, ES cells may undergo a Fas-mediated apoptosis, slightly but significantly intensified by the addition of LPS to cell cultures. We also report that anti-Fas MoAb directly inhibited two-cell stage mouse-embryo (preimplantation) development in in-vitro culture conditions.

CONCLUSION

These data suggest a novel mechanism controlling the regulation of physiological cell turnover as well as blastocyst implantation in early embryo development.

Presence of primitive lymphoid progenitors with NK or B potential in ex vivo expanded bone marrow cell cultures

OBJECTIVE

In previous work, we showed that CD34+ bone marrow cells can be successfully expanded along the myeloid pathway in stroma- and serum-free conditions in the presence of SCF+IL-3+IL-6+Flt3-l+G-CSF+MGDF. Due to the lack of phenotypically detectable lymphoid cells, it was necessary to address the question of the lymphoid potential of the expanded populations under these conditions.

MATERIALS AND METHODS

The present report describes a long-term culture system that supports human B- and NK-cell differentiation from the day 14 fraction without further selection of the more primitive cells. In NK proliferation assays, the cells were maintained over stroma cells in the presence of IL-2 for 4-5 weeks. NK initiating cells (NK-IC) were determined by a limiting dilution assay. In B-cell cultures, the expanded cells were maintained over MS5 in the presence of Flt3-l for 4-8 weeks.

RESULTS

NK cells rose from 0.2%+/-0.04% at culture initiation to 71%+/-6% at week 5. These cells displayed cytolytic activity. NK-IC evaluation showed a mean 18-fold expansion in the day 14 expanded fraction as compared to the initial day 0 fraction. Similarly, CD19+ cells rose from 0.1% at culture initiation to 30%+/-1% at week 6. Cells produced under these B-LTC conditions were CD34-CD19+CD10+. We also demonstrated that the CD34+/Lin- sorted cells from the day 14 fraction gave rise to NK and B cells.

CONCLUSION

This culture system permits the revelation of a population that, although poorly represented in terms of phenotypically detectable cells, nevertheless retains high levels of lymphoid NK and B potential after 14 days expansion. Such data suggest the persistence, or expansion, of lymphoid progenitors and, hence, the multipotentiality of the expanded progenitor/stem cells.

MAP kinase inactivation is required only for G2-M phase transition in early embryogenesis cell cycles of the starfishes Marthasterias glacialis and Astropecten aranciacus

Downregulation of MAP kinase is a universal consequence of fertilization in the animal kingdom. Here we show that oocytes of the starfishes Astropecten aranciacus and Marthasterias glacialis complete meiotic maturation and form a pronucleus when treated with 1-methyladenine and then complete DNA replication and arrest at G2 if not fertilized. Release of G2 by fertilization or a variety of parthenogenetic treatments is associated with inactivation of MAP kinase. Prevention of MAP kinase inactivation by microinjection of Ste11-DeltaN, a constitutively active budding yeast MAP kinase kinase kinase, arrests fertilized eggs at G2 in either the first or the second mitotic cell cycle, in a dose-dependent manner. G1 arrest is never observed. Conversely, inactivation of MAP kinase by microinjection of the MAP kinase-specific phosphatase Pyst-1 releases mature starfish oocytes from G2 arrest. The role of MAP kinase in arresting cell cycle at various stages in oocytes of different animal species is discussed.

Direct cloning of astrocytes from primary culture without previous immortalization

In primary cultures, much evidence shows the existence of different subtypes of astrocytes that are not all identified. One methodology for studying these subtypes can be their cloning. The present investigation shows a method for a direct cloning of astrocytes without previous immortalization. Astrocytes from the cerebral cortex of newborn rats were cultured, purified by shaking, and harvested by trypsinization. One single astrocyte was plated in a small volume of a homemade cloning medium. After getting a colony, successive platings were made using larger and larger vessels, up to 60-mm-diameter petri dishes. Then, subcultures were made. The yield of the cloning was similar to that of common eukaryotic cell clonings. All along the cloning procedure, the cells were positively immunostained with anti-glial fibrillary acidic protein antibodies. Cloned cells from some batches were spindle-shaped, looking like fibroblasts. Nevertheless, they were immunostained with anti-glial fibrillary acidic protein antibodies, unlike true fibroblasts. These spindle-shaped astrocytes were compared to cells from an astrocytoma cell line that had the same shape. The growth pattern of the astrocytoma cells was different from that of the astrocytes cloned from the primary cultures. All the types of studied cells contained glycogen. On the basis of the criteria of morphology, of glial fibrillary acidic protein immunolabeling, and of glycogen synthesis, the cloned cells kept the characteristics of astrocytes. This study shows that it is perfectly possible to get clones of astrocytes from one astrocyte without previous immortalization, giving thus a convenient material for the study of astrocyte biology.

Isolation of carbohydrate metabolic clones from cultured astrocytes

Astrocytes are the principal sites of glycogen synthesis in the nervous tissue. Growing evidence shows that there are many types of astrocytes. The aim of the present investigation was to isolate different types of astrocytes that display different carbohydrate anabolism. Astrocytes from newborn rat brain were directly cloned from primary cultures without a previous transformation. Many clones were obtained, and they were termed CP clones. Another series of clones, termed SV clones, were obtained after the transfection of the primary cultures by the SV40 T antigen. The effectiveness of the transfection was verified by the rate of DNA synthesis using flow cytometry and by the presence of plasmid DNA in the genomic DNA of the astrocytes using the Southern blot method. After the transfection, the growth velocity increased greatly. The size and shape of the astrocytes were the same for each cell in a given clone, regardless of the cloning method utilized. However, these sizes and shapes could be different from one clone to another in CP clones, whereas all the astrocytes of all the SV clones looked like each other. All the clones obtained stained positively with anti-glial fibrillary acidic protein antibodies. Glycogen stained in the clones using concanavalin A-horseradish peroxidase. The glycogen content was also measured using biochemical analysis. Concordant results obtained using two methods showed that some clones contained an important quantity of glycogen while other clones contained a small amount, in the CP series as well as in the SV series. This property was the same for the intracellular glucose concentrations. The activity of the gluconeogenic enzyme fructose-1, 6-bisphosphatase was measured in each clone using spectrophotometry. This activity was also significantly different from one clone to another. The clones containing large amounts of glycogen had important fructose-1,6-bisphosphatase activity. The present results show that it is possible to clone astrocytes either directly from primary cultures without immortalization or after their transformation. When analyzing these clones, it appears that carbohydrate anabolism can be significantly different from one astrocyte to another. This difference may also exist in vivo.

Regulation of fructose-1,6-bisphosphatase activity in primary cultured astrocytes

In the gluconeogenic pathway, fructose-1,6-bisphosphatase (EC 3. 1. 3. 11) is the last key-enzyme before the synthesis of glucose-6-phosphate. The extreme diversity of cells present in the whole brain does not facilitate in vivo study of this enzyme and makes it difficult to understand the regulatory mechanisms of the related carbohydrate metabolism. It is for instance difficult to grasp the actual effect of ions like potassium, magnesium and manganese on the metabolic process just as it is difficult to grasp the effect of different pH values and the influence of glycogenic compounds such as methionine sulfoximine. The present investigation attempts to study the expression and regulation of fructose-1,6-bisphosphatase in cultured astrocytes. Cerebral cortex of new-born rats was dissociated into single cells that were then plated. The cultured cells were flat and roughly polygonal and were positively immunostained by anti-glial fibrillary acidic protein antibodies. Cultured astrocytes are able to display the activity of fructose-1,6-bisphosphatase. This activity was much higher than that in brain tissue in vivo. Fructose-1,6-bisphosphatase in cultured astrocytes did not require magnesium ions for its activity. The initial velocity observed when the activity was measured in standard conditions was largely increased when the enzyme was incubated with Mn2+. This increase was however followed by a decrease in absorbance resulting in the induction, by the manganese ions, of a singular kinetics in the enzyme activity. Potassium ions also stimulated fructose-1,6-bisphosphatase activity.(ABSTRACT TRUNCATED AT 250 WORDS)