Alternative genetic alterations of MYC, BCL2, and/or BCL6 in high-grade B-cell lymphoma (HGBL) and diffuse large B-cell lymphoma (DLBCL): Can we identify different prognostic subgroups?

High-grade B-cell lymphoma (HGBL)/diffuse large B-cell lymphoma (DLBCL) with rearrangements (R) in MYC and BCL2 and/or BCL6 are correlated with poor prognosis. Little is known about the impact of other genetic alterations (gain (G) or amplification (A)) of these genes. The aim of the study was to investigate whether we can identify new prognostic subgroups. Fluorescence in situ hybridization (FISH) results from 169 HGBL/DLBCL were retrospectively categorized into: (1) concurrent MYC-R and BCL2-R and/or BCL6-R-samples with MYC-R and BCL2-R (+/- BCL6-R); n = 21, and HGBL/DLBCL with MYC-R and BCL6-R; n = 11; (2) concurrent R and G/A in MYC and BCL2 and/or BCL6 called "alternative HGBL/DLBCL"-samples with (n = 16) or without (n = 6) BCL2 involvement; (3) BCL2 and/or BCL6 alterations without MYC involvement (n = 35); (4) concurrent G/A in MYC and BCL2 and/or BCL6 without R (n = 25); and (5) "No alterations" (n = 55). Patients with HGBL/DLBCL-MYC/BCL2 and "alternative" HGBL/DLBCL (with BCL2 involvement) had significantly worse survival rates compared to the "no alterations" group. G/A of these genes in the absence of rearrangements did not show any prognostic significance. HGBL/DLBCL with MYC-R and BCL6-R without BCL2 involvement showed a better survival rate compared to HGBL/DLBCL-MYC/BCL2. According to immunohistochemistry, "double/triple" expression (DEL/TEL) did not show a significantly worse outcome compared to absent DEL/TEL. This study highlights the continued value of FISH assessment of MYC, BCL2, and BCL6 in the initial evaluation of HGBL/DLBCL with different survival rates between several genetic subgroups.

Epidemiological characteristics and outcome of viral respiratory tract infections in the first year after allogeneic hematopoietic cell transplantation.

Adverse outcomes of viral respiratory tract infections (RTI) have been reported in recipients of allogeneic hematopoietic cell transplantation. Using a laboratory-developed multiparameter PCR in a consecutive series of 242 patients, we found the highest incidence of viral RTI in the pre-engraftment phase. The occurrence of multiple episodes of viral RTI or viral pneumonia was significantly associated with a higher hazard of non-relapse mortality in the first year after transplantation. We observed a 90-day mortality of 19.7% after viral RTI, which was significantly different between patient groups stratified according to the ISI score.

Obinutuzumab plus lenalidomide in advanced, previously untreated follicular lymphoma in need of systemic therapy: a LYSA study.

Obinutuzumab and lenalidomide (referred to as the GALEN combination) is an active immunomodulatory combination with a manageable safety profile in multiple types of lymphoma. We report efficacy and safety results for the phase 2 GALEN study in previously untreated patients with advanced follicular lymphoma (FL). Eligible patients aged ≥18 years had an Eastern Cooperative Oncology Group performance status ≤2 and high-tumor burden, grade 1 to 3a FL. Induction treatment was obinutuzumab (1000 mg IV, days 8, 15, and 22, cycle 1; day 1, cycles 2-6) plus lenalidomide (20 mg/d, days 1-21, cycle 1; days 2-22, cycles 2-6) for six 28-day cycles. Maintenance included obinutuzumab (1000 mg every 2 cycles) plus lenalidomide (10 mg, days 2-22) for ≤12 cycles (year 1) followed by obinutuzumab (1000 mg every 56 days) for 6 cycles (year 2). The primary end point was complete response rate (CRR) after induction per the 1999 International Working Group criteria. From October 2015 to February 2017, a total of 100 patients were enrolled. CRR after induction was 47%, and the overall response rate (ORR) was 92%. Post hoc analyses per the 2014 Lugano classification, including patients with missing bone marrow assessments, identified an additional 13 patients fulfilling CRR criteria, resulting in a complete metabolic response of 80% and an ORR of 94%. At a median follow-up of 3.7 years, 3-year progression-free survival and overall survival were 82% and 94%, respectively. The most common adverse event was neutropenia (48% any grade; 47% grade ≥3). Only 2% of patients presented with febrile neutropenia; others were mainly grade ≤2. No other specific grade ≥3 toxicity occurred at a frequency >3%. Overall, these results showed promising clinical efficacy for the chemotherapy-free GALEN backbone in previously untreated patients with high tumor burden FL. Except for neutropenia, the safety profile of the combination is remarkable. The study was registered at clinicaltrials.gov as #NCT01582776.

High total metabolic tumor volume at baseline predicts survival independent of response to therapy.

Early identification of ultra-risk diffuse large B-cell lymphoma (DLBCL) patients is needed to aid stratification to innovative treatment. Previous studies suggested high baseline total metabolic tumor volume (TMTV) negatively impacts survival of DLBCL patients. We analyzed the prognostic impact of TMTV and prognostic indices in DLBCL patients, aged 60 to 80 years, from the phase 3 REMARC study that randomized responding patients to R-CHOP (rituximab plus cyclophosphamide, doxorubicin, vincristine, and prednisone) into maintenance lenalidomide or placebo. TMTV was computed on baseline positron emission tomography/computed tomography using the 41% maximum standardized uptake value method; the optimal TMTV cutoff for progression-free (PFS) and overall survival (OS) was determined and confirmed by a training validation method. There were 301 out of 650 evaluable patients, including 192 patients classified as germinal center B-cell-like (GCB)/non-GCB and MYC/BCL2 expressor. Median baseline TMTV was 238 cm3; optimal TMTV cutoff was 220 cm3. Patients with high vs low TMTV showed worse/higher Eastern Cooperative Oncology Group performance status (ECOG PS) ≥2, stage III or IV disease, >1 extranodal site, elevated lactate dehydrogenase, International Prognostic Index (IPI) 3-5, and age-adjusted IPI 2-3. High vs low TMTV significantly impacted PFS and OS, independent of maintenance treatment. Although the GCB/non-GCB profile and MYC expression did not correlate with TMTV/survival, BCL2 >70% impacted PFS and could be stratified by TMTV. Multivariate analysis identified baseline TMTV and ECOG PS as independently associated with PFS and OS. Even in responding patients, after R-CHOP, high baseline TMTV was a strong prognosticator of inferior PFS and OS. Moreover, TMTV combined with ECOG PS may identify an ultra-risk DLBCL population. This trial was registered at www.clinicaltrials.gov as #NCT01122472.

Lenalidomide maintenance for diffuse large B-cell lymphoma patients responding to R-CHOP: quality of life, dosing, and safety results from the randomised controlled REMARC study.

Lenalidomide maintenance therapy prolonged progression-free survival (PFS) versus placebo in elderly patients with diffuse large B-cell lymphoma (DLBCL) responding to induction chemotherapy in the phase 3 REMARC study. This subpopulation analysis assessed the impact of lenalidomide maintenance and treatment-emergent adverse events (TEAEs) on health-related quality of life (HRQOL). Global health status (GHS), and physical functioning and fatigue subscales were evaluated in patients who completed the European Organisation for Research and Treatment of Cancer quality-of-life questionnaire-C30 v3.0. The impact of TEAEs classified post hoc as subjective (patients can feel) or observable (only measurable by physicians) on dose reductions and discontinuations was assessed. Among 457 patients (lenalidomide, n = 229; placebo, n = 228), mean (standard deviation) GHS was similar between treatment arms [68·2 (20·7) Versus 72·0 (17·8)] at randomisation and remained similar during maintenance. Patients receiving lenalidomide experienced no meaningful changes in GHS, physical functioning, or fatigue. Observable TEAEs were more common (81·1% Versus 66·3%) and more likely to lead to dose reductions, than subjective TEAEs in both arms. PFS was superior in the lenalidomide arm regardless of dose reduction. Lenalidomide maintenance prolonged PFS and did not negatively impact HRQOL in patients with DLBCL despite TEAEs being more common, when compared with placebo.

TARP is an immunotherapeutic target in acute myeloid leukemia expressed in the leukemic stem cell compartment.

Immunotherapeutic strategies targeting the rare leukemic stem cell compartment might provide salvage to the high relapse rates currently observed in acute myeloid leukemia (AML). We applied gene expression profiling for comparison of leukemic blasts and leukemic stem cells with their normal counterparts. Here, we show that the T-cell receptor γ chain alternate reading frame protein (TARP) is over-expressed in de novo pediatric (n=13) and adult (n=17) AML sorted leukemic stem cells and blasts compared to hematopoietic stem cells and normal myeloblasts (15 healthy controls). Moreover, TARP expression was significantly associated with a fms-like tyrosine kinase receptor-3 internal tandem duplication in pediatric AML. TARP overexpression was confirmed in AML cell lines (n=9), and was found to be absent in B-cell acute lymphocytic leukemia (n=5) and chronic myeloid leukemia (n=1). Sequencing revealed that both a classical TARP transcript, as described in breast and prostate adenocarcinoma, and an AML-specific alternative TARP transcript, were present. Protein expression levels mostly matched transcript levels. TARP was shown to reside in the cytoplasmic compartment and showed sporadic endoplasmic reticulum co-localization. TARP-T-cell receptor engineered cytotoxic T-cells in vitro killed AML cell lines and patient leukemic cells co-expressing TARP and HLA-A*0201. In conclusion, TARP qualifies as a relevant target for immunotherapeutic T-cell therapy in AML.

Oral azacitidine compared with standard therapy in patients with relapsed or refractory follicular helper T-cell lymphoma (ORACLE): an open-label randomised, phase 3 study.

BACKGROUND: Follicular helper T-cell lymphomas (TFHL) harbour frequent alterations in genes that regulate DNA methylation. Preliminary reports suggest that treatment with 5-azacitidine has clinical activity in patients with relapsed or refractory TFHL. We aimed to compare the oral form of azacitidine with investigator's choice standard therapy (ICT; ie, gemcitabine, bendamustine, or romidepsin) in patients with relapsed or refractory TFHL. METHODS: Patients older than 18 years with relapsed or refractory TFHL (angioimmunoblastic T-cell lymphoma, follicular lymphoma, or nodal T-cell lymphoma with phenotype, ie, positive with two or more markers among CD10, BCL6, CXCL13, PD1, or ICOS) based on the 2017 WHO classification of haematological neoplasms, with an Eastern Cooperative Oncology Group performance status score of 0-3, were recruited in university hospitals from five European countries and from Japan. Patients were randomly assigned 1:1 to treatment with either azacitidine given at a dose of 300 mg once a day (200 mg in Japanese patients) for 14 days in a 28-day cycle or gemcitabine, bendamustine, or romidepsin according to the investigator's choice. Random assignment was stratified by the number of previous lines of therapy and by the presence of previous or concomitant myeloid malignancy. The primary endpoint was investigator-assessed progression-free survival, presented in the intention-to-treat population. This Article is the final analysis of this trial, registered at ClinicalTrials.gov (Europe NCT03593018 and Japan NCT03703375). FINDINGS: 86 patients (median age 69 years [IQR 62-76], 50 patients were male, 36 were female) were enrolled between Nov 9, 2018, to Feb 22, 2021; 42 in the azacitidine group and 44 in the ICT group. With a median follow-up of 27·4 months (IQR 20·2-32·9), the median progression-free survival was 5·6 months (95% CI 2·7 -8·1) in the azacitidine group versus 2·8 months (1·9-4·8) in the ICT group (hazard ratio of 0·63 (95% CI 0·38-1·07); 1-sided p=0·042). Grade 3-4 adverse events were reported in 32 (76%) of 42 patients in the azacitidine group versus 42 (98%) of 43 patients in the ICT group. The most adverse grade 3 or worse adverse events were haematological (28 [67%] of 42 patients vs 40 [93%] of 43 patients), infection (8 [19%] and 14 [33%]), and gastrointestinal (5 [12%] vs 1 [2%] for azacitidine and ICT, respectively). There were two treatment-related deaths in the azacitidine group (one endocarditis and one candidiasis) and three in the ICT group (one heart failure, one COVID-19, and one cause unknown). INTERPRETATION: Although the pre-specified primary outcome of the trial was not met, the favourable safety profile suggests that azacitidine could add to the treatment options in these difficult to treat diseases especially in combination with other drugs. Trials with combination are in preparation in a platform trial. FUNDING: Bristol-Myers Squibb. TRANSLATION: For the French translation of the abstract see Supplementary Materials section.

Infectious diarrhea after allogeneic hematopoietic cell transplantation assessed by a multiplex polymerase chain reaction assay.

OBJECTIVES: To determine the incidence of infectious diarrhea after allogeneic hematopoietic cell transplantation (HCT) using a multiplex polymerase chain reaction assay and assess risk factors for developing infectious diarrhea. METHODS: This was a single-center retrospective study of 140 consecutive allogeneic HCT recipients. Infectious diarrhea was assessed using a laboratory-developed multiplex polymerase chain reaction the first year after transplantation. RESULTS: The incidence rate of infectious diarrhea episodes was 47 per 100 person-years, with the highest rate observed in the pre-engraftment phase. Most episodes were seen as nosocomial infections (38%) and most affected patients (82%) had only one episode of infectious diarrhea. The cumulative incidence of at least one episode of infectious diarrhea was 32% after 1 year. Nonrelapse mortality was higher in transplant recipients with at least one episode of infectious diarrhea (hazard ratio (HR) 2.02, 95% CI = 1.07-3.80). The most frequently observed pathogens were Clostridium difficile, adenovirus, Enteropathogenic Escherichia coli, and Campylobacter jejuni. Patients with acute lower gastrointestinal graft-vs-host disease stage 3 or 4 (HR 3.68, 95% CI = 1.57-8.63) conferred a higher risk for a first infectious diarrhea episode. CONCLUSION: Infectious diarrhea after allogeneic HCT was seen in about one-third of the patients, mostly as nosocomial infection in the pre-engraftment phase.

Breast implant associated EBV-positive Diffuse Large B-cell lymphoma: an underrecognized entity?

Breast-implant associated (BIA) lymphoma is an infrequent type of cancer occurring in the fluid and fibrous capsule around a textured breast implant. Recently, both the 2022 WHO 5th edition classification of Haematological tumours (WHO HAEM5) and 2022 International Consensus Classification of Mature Lymphoid Neoplasms (22ICC), recognized breast implant-associated Anaplastic Large Cell Lymphoma (BIA-ALCL) as a definitive entity, defined as a mature CD30-positive T-cell lymphoma, confined by a fibrous capsule, in a breast implant setting. Only few B-cell lymphomas have been reported in the literature to be associated with breast implants. Here we report two EBV-positive Diffuse Large B-cell lymphomas (EBV + DLBCL) in relation to a breast implant, both expressing CD30 as well as EBV latency type 3. Both lesions were considered as DLBCL associated with chronic inflammation (CI-DLBCL), but one presented as a 7 cm solid mass, while the other presented as a fibrin-associated DLBCL (FA-DLBCL) in an HIV patient. Clinically, both are in complete remission 6 months or longer after capsulectomy and graft removal, without additional chemotherapy.Such cases, characterized by large CD30-positive cells, can easily be misdiagnosed as BIA-ALCL if the cell of origin is not further established. Therefore, a diagnostic panel including lineage-specific B-and T-cell markers and EBER in situ hybridization is essential to recognize this rare entity, to understand lymphomagenesis, to predict outcome and to define clinical approach.

RHAMM/HMMR (CD168) is not an ideal target antigen for immunotherapy of acute myeloid leukemia.

BACKGROUND: Criteria for good candidate antigens for immunotherapy of acute myeloid leukemia are high expression on leukemic stem cells in the majority of patients with acute myeloid leukemia and low or no expression in vital tissues. It was shown in vaccination trials that Receptor for Hyaluronic Acid Mediated Motility (RHAMM/HMMR) generates cellular immune responses in patients with acute myeloid leukemia and that these responses correlate with clinical benefit. It is not clear however whether this response actually targets the leukemic stem cell, especially since it was reported that RHAMM is expressed maximally during the G2/M phase of the cell cycle. In addition, tumor specificity of RHAMM expression remains relatively unexplored. DESIGN AND METHODS: Blood, leukapheresis and bone marrow samples were collected from both acute myeloid leukemia patients and healthy controls. RHAMM expression was assessed at protein and mRNA levels on various sorted populations, either fresh or after manipulation. RESULTS: High levels of RHAMM were expressed by CD34(+)CD38(+) and CD34(-) acute myeloid leukemia blasts. However, only baseline expression of RHAMM was measured in CD34(+)CD38(-) leukemic stem cells, and was not different from that in CD34(+)CD38(-) hematopoietic stem cells from healthy controls. RHAMM was significantly up-regulated in CD34(+) cells from healthy donors during in vitro expansion and during in vivo engraftment. Finally, we demonstrated an explicit increase in the expression level of RHAMM after in vitro activation of T cells. CONCLUSIONS: RHAMM does not fulfill the criteria of an ideal target antigen for immunotherapy of acute myeloid leukemia. RHAMM expression in leukemic stem cells does not differ significantly from the expression in hematopoietic stem cells from healthy controls. RHAMM expression in proliferating CD34+ cells of healthy donors and activated T cells further compromises RHAMM-specific T-cell-mediated immunotherapy.

Effectiveness and Safety of Ibrutinib for Chronic Lymphocytic Leukemia in Routine Clinical Practice: 3-Year Follow-up of the Belgian Ibrutinib Real-World Data (BiRD) Study.

The multicenter observational BiRD study investigated the real-world effectiveness and safety of ibrutinib in patients with chronic lymphocytic leukemia (CLL), mantle cell lymphoma (MCL) and Waldenström's macroglobulinemia (WM) in Belgium. This interim analysis reports results for patients with CLL, with a median follow-up of 34 months. Overall, patients had predominantly relapsed/refractory disease (73%) and were elderly (median age 72 years) with high-risk features such as del17p and/or TP53 mutations (59%). Patients were included either prospectively or retrospectively, and the total patient population effectiveness results were adjusted with left truncation. In the effectiveness population (N = 221: prospective, n = 71; retrospective, n = 150), the overall response rate was 90.0%. Median progression-free survival was 38.3 months (prospective, not estimable; retrospective, 51.5 months) and median overall survival was not yet estimable in the total, prospective and retrospective groups. Treatment-emergent adverse events (TEAEs) for the prospective and retrospective groups are reported separately. Any-grade TEAEs of interest in the prospective/retrospective groups included infections (67.1%/60.1%), diarrhea (20.5%/10.5%), hypertension (16.4%/9.8%) and atrial fibrillation (12.3%/7.2%). Major bleeding was reported in 5.5%/3.3% of prospective/retrospective patients, with little difference observed between those receiving versus not receiving antithrombotic treatment. Discontinuations due to toxicity were reported in 10.5% of patients. Results from this interim analysis show treatment with ibrutinib to be effective and tolerable, with no new safety signals observed. Future analyses will report on longer-term follow-up.

Obinutuzumab combined with lenalidomide for relapsed or refractory follicular B-cell lymphoma (GALEN): a multicentre, single-arm, phase 2 study.

BACKGROUND: Lenalidomide plus rituximab is approved to treat patients with relapsed or refractory follicular lymphoma. Obinutuzumab has been shown to enhance antibody-dependent cellular cytotoxicity, phagocytosis, and direct B-cell killing better than rituximab. Our aim was to determine the activity and safety of lenalidomide plus obinutuzumab in previously treated patients with relapsed or refractory follicular lymphoma. METHODS: In this multicentre, single-arm, phase 2 study, patients were enrolled from 24 Lymphoma Academic Research Organisation centres in France. Eligible patients (age ≥18 years) had histologically confirmed CD20-positive relapsed or refractory follicular lymphoma of WHO grade 1, 2, or 3a; an ECOG performance status of 0-2; and received at least one previous rituximab-containing therapy. Patients received oral lenalidomide (20 mg) plus intravenously infused obinutuzumab as induction therapy (1000 mg; six 28-day cycles), 1-year maintenance with lenalidomide (10 mg; 12 28-day cycles; days 2-22) plus obinutuzumab (1000 mg; alternate cycles), and 1-year maintenance with obinutuzumab (1000 mg; six 56-day cycles; day 1). The primary endpoint was the proportion of patients who achieved an overall response at induction end as per investigator assessment using the 1999 international working group criteria. The secondary endpoints were event-free survival, progression-free survival, overall survival, and safety. Analyses were per-protocol; the efficacy population included all patients who received at least one dose of both obinutuzumab and lenalidomide, and the safety population included all patients who received one dose of either investigational drug. The study is registered with ClinicalTrials.gov, number NCT01582776, and is ongoing but closed to accrual. FINDINGS: Between June 11, 2014, and Dec 18, 2015, 89 patients were recruited and 86 patients were evaluable for efficacy and 88 for safety. Median follow-up was 2·6 years (IQR 2·2-2·8). 68 (79%) of 86 evaluable patients (95% CI 69-87) achieved an overall response at induction end, meeting the prespecified primary endpoint. At 2 years, event-free survival was 62% (95% CI 51-72), progression-free survival 65% (95% CI 54-74), duration of response 70% (95% CI 57-79), and overall survival 87% (95% CI 78-93). Complete response was achieved by 33 (38%, 95% CI 28-50) of 86 patients at induction end, and the proportion of patients achieving a best overall response was 70 (81%, 95% CI 72-89) and 72 (84%, 74-91) of 86 patients during induction and treatment, respectively. The most common adverse events were asthenia (n=54, 61%), neutropenia (n=38, 43%), bronchitis (n=36, 41%), diarrhoea (n=35, 40%), and muscle spasms (n=34, 39%). Neutropenia was the most common toxicity of grade 3 or more; four (5%) patients had febrile neutropenia. 57 serious adverse events were reported in 30 (34%) of 88 patients. The most common serious adverse events were basal cell carcinoma (n=5, 6%), febrile neutropenia (n=4, 5%), and infusion-related reaction (n=3, 3%). One patient died due to treatment-related febrile neutropenia. INTERPRETATION: Our data shows that lenalidomide plus obinutuzumab is active in previously treated patients with relapsed or refractory follicular lymphoma, including those with early relapse, and has a manageable safety profile. Randomised trials of new immunomodulatory regimens, such as GALEN or using GALEN as a backbone, versus lenalidomide plus rituximab, are warranted. FUNDING: Lymphoma Academic Research Organisation, and Celgene and Roche.

A new transcript in the TCRB locus unveils the human ortholog of the mouse pre-Dß1 promoter.

INTRODUCTION: While most transcripts arising from the human T Cell Receptor locus reflect fully rearranged genes, several germline transcripts have been identified. We describe a new germline transcript arising from the human TCRB locus. METHODS: cDNA sequencing, promoter, and gene expression analyses were used to characterize the new transcript. RESULTS: The new germline transcript encoded by the human TCRB locus consists of a new exon of 103 bp, which we named TRBX1 (X1), spliced with the first exon of gene segments Cß1 or Cß2. X1 is located upstream of gene segment Dß1 and is therefore deleted from a V-DJ rearranged TCRB locus. The X1-Cß transcripts do not appear to code for a protein. We define their transcription start and minimal promoter. These transcripts are found in populations of mature T lymphocytes from blood or tissues and in T cell clones with a monoallelic TCRB rearrangement. In immature thymocytes, they are already detectable in CD1a- CD34+ CD4- CD8- cells, therefore before completion of the TCRB rearrangements. CONCLUSIONS: The X1 promoter appears to be the ortholog of the mouse pre-Dß1 promoter (PDß1). Like PDß1, its activation is regulated by Eß in T cells and might facilitate the TCRB rearrangement process by contributing to the accessibility of the Dß1 locus.

Humanized Mice to Study Human T Cell Development.

While in vitro models exist to study human T cell development, they still lack the precise environmental stimuli, such as the exact combination and levels of cytokines and chemokines, that are present in vivo. Moreover, studying the homing of hematopoietic stem (HSC) and progenitor (HPC) cells to the thymus can only be done using in vivo models. Although species-specific differences exist, "humanized" models are generated to circumvent these issues. In this chapter, we focus on the humanized mouse models that can be used to study early T cell development. Models that study solely mature T cells, such as the SCID-PBL (Tary-Lehmann et al., Immunol Today 16:529-533) are therefore not discussed here, but have recently been reviewed (Shultz et al., Nat Rev Immunol 12:786-798).

Colistin and neurotoxicity: recommendations for optimal use in cystic fibrosis patients.

Case description The use of i.v. colistin reappeared recently for the treatment of multidrug-resistant Gram negative organisms in the intensive care and cystic fibrosis (CF) setting. According to the latest pharmacokinetic data, a loading dose and high antibiotic doses are given. Two cases of adverse events (paraesthesias, bad taste) were observed immediately after the start of infusion of a high dose of i.v. colistin in adult CF patients at the Ghent University Hospital. Conclusion Recommendations for optimal administration of i.v. colistin in adult CF patients are scarce. This article highlights the importance of mode of administration to avoid toxicity and relates it to recent pharmacokinetic/-dynamic literature.

Can immunotherapy specifically target acute myeloid leukemic stem cells?

Accumulating evidence supports the role of leukemic stem cells (LSCs) in the high relapse rate of acute myeloid leukemia (AML) patients. The clinical relevance of LSCs, which were originally characterized in xenograft models, has recently been confirmed by the finding that stem cell-like gene expression signatures can predict the clinical outcome of AML patients. The targeted elimination of LSCs might hence constitute an efficient therapeutic approach to AML. Here, we review immunotherapeutic strategies that target LSC-associated antigens, including T cell-mediated and monoclonal antibody-based regimens. Attention is given to the issue of antigen specificity because this is relevant to the therapeutic window and determines the superiority of LSC-targeting immunotherapy.

Specific Notch receptor-ligand interactions control human TCR-αß/γδ development by inducing differential Notch signal strength.

In humans, high Notch activation promotes γδ T cell development, whereas lower levels promote αß-lineage differentiation. How these different Notch signals are generated has remained unclear. We show that differential Notch receptor-ligand interactions mediate this process. Whereas Delta-like 4 supports both TCR-αß and -γδ development, Jagged1 induces mainly αß-lineage differentiation. In contrast, Jagged2-mediated Notch activation primarily results in γδ T cell development and represses αß-lineage differentiation by inhibiting TCR-ß formation. Consistently, TCR-αß T cell development is rescued through transduction of a TCR-ß transgene. Jagged2 induces the strongest Notch signal through interactions with both Notch1 and Notch3, whereas Delta-like 4 primarily binds Notch1. In agreement, Notch3 is a stronger Notch activator and only supports γδ T cell development, whereas Notch1 is a weaker activator supporting both TCR-αß and -γδ development. Fetal thymus organ cultures in JAG2-deficient thymic lobes or with Notch3-blocking antibodies confirm the importance of Jagged2/Notch3 signaling in human TCR-γδ differentiation. Our findings reveal that differential Notch receptor-ligand interactions mediate human TCR-αß and -γδ T cell differentiation and provide a mechanistic insight into the high Notch dependency of human γδ T cell development.

In vitro generation of immune cells from pluripotent stem cells.

Stem cell transplant recipients and acquired or inherited immune-deficiency patients could benefit from the infusion of B, T and/or NK cells. These lymphoid cells can be generated in vitro from bone marrow derived CD34+CD45+ hematopoietic stem cells (HSC). The number of cells that can be obtained in this way is limited especially in the adult. An alternative source may therefore constitute human pluripotent stem cells (PSC) such as embryonic (hESC) or induced pluripotent stem cells (hiPSC). Here, we focus on present knowledge on the generation of lymphoid cells from hESC. The two main obstacles for the generation of clinically relevant immune cells are the failure to generate from hESC long-term repopulating HSC which could be kept in culture for prolonged time; and insufficient knowledge of the selection process which generates mature T cells from CD4 CD8 double positive (DP) precursors in vitro.