The treatment of leukemia/lymphoma by chimeric antigen receptor (CAR) redirected T cells with specificity for CD19 induced complete remissions in the majority of patients with a realistic hope for cure. However, recent follow-up data revealed a substantial risk of relapse through leukemic cells which lack the CAR targeted antigen. In this situation a bispecific CAR with binding domains for CD19 and CD20 is aimed at recognizing also leukemic cells with only one cognate antigen. The anti-CD20-CD19 bispecific CAR induced a full T cell response upon engagement of CD19 or CD20 on target cells showing a true “OR” gate recognition in redirecting T cell activation. T cells with the anti-CD20-CD19 CAR efficiently killed patient’s chronic lymphocytic leukemia (CLL) cells in vitro. The bispecific CAR T cells cleared pediatric acute lymphocytic leukemia (ALL) with a mixed CD19+CD20+/CD20- phenotype from blood and bone marrow of transplanted mice while anti-CD20 CAR T cells left CD20- leukemic cells behind without cure from disease. Data indicate the superior anti-leukemic activity in the control of leukemia implying that the anti-CD20-CD19 bispecific CAR T cells may reduce the risk of relapse through antigen-loss leukemic cells in the long-term.

Although immortalized cell lines have been extensively used to optimize treatment strategies in cancer, the usefulness of such in vitro systems to recapitulate primary disease is limited. Therefore, the design of in vivo models ideally utilizing patient‐derived material is of critical importance. In this regard, NOD.Cg‐Prkdc^scidIL2rg^tmWjl/Sz (NSG) mice have been reported to provide superior engraftment rates. However, limited data exist on the validity of such a model to constitute a surrogate marker for clinical parameters. We studied primary and serial engraftment on more than 200 NSG mice with 54 primary pediatric B cell precursor acute lymphatic leukemia (B‐ALL), myeloid leukemia (AML) and T cell leukemia (T‐ALL) samples, characterized the leukemogenic profile and correlated engraftment kinetics with clinical outcome. Median time to engraftment was 7–10 weeks and 90% of the mice engrafted. Male recipients conferred significantly higher engraftment levels than female recipients (p ≤ 0.004). PCR‐based minimal residual disease marker expression and fluorescence in situ hybridization confirmed the presence of patient‐specific genetic aberrations in mice. Transcriptome cluster analysis of genes known to be important in the leukemogenesis of all three diseases revealed that well‐known tumor‐regulating genes were expressed to a comparable extent in mice and men. The extent of engraftment and overall survival of NSG mice highly correlated with the individual prognosis of B‐ALL, AML and T‐ALL patients. Thus, we propose an in vivo model that provides a valuable preclinical tool to explore the heterogeneity of leukemic disease and exploit patient‐tailored leukemia‐targeting strategies within multivariate analyses.

Fascinating earlier evidence suggests an intrinsic capacity of human natural killer (NK) cells to acquire adaptive immune features in the context of cytomegalovirus (CMV) infection or pro-inflammatory cytokine stimulation. Since the role of memory NK cells in cancer has so far remained elusive and adoptive NK cell transfer in relapsing pediatric acute B cell precursor leukemia (BCP-ALL) patients awaits improvement, we asked the question whether tumor-priming could promote the generation of memory NK cells with enhanced graft-vs.-leukemia (GvL) reactivity. Here, we provide substantial evidence that priming of naive human NK cells with pediatric acute B cell leukemia or acute myeloid leukemia specimens induces a functional conversion to tumor-induced memory-like (TIML)-NK cells displaying a heightened tumor-specific cytotoxicity and enhanced perforin synthesis. Cell cycles analyses reveal that tumor-priming sustainably alters the balance between NK cell activation and apoptosis in favor of survival. In addition, gene expression patterns differ between TIML- and cytokine-induced memory-like (CIML)-NK cells with the magnitude of regulated genes being distinctly higher in TIML-NK cells. As such, the tumor-induced conversion of NK cells triggers the emergence of a so far unacknowledged NK cell differentiation stage that might promote GvL effects in the context of adoptive cell transfer.

Key Points Both mature KIR+ and immature KIR− NK cells exert antileukemic activity toward pediatric BCP-ALL in vivo. In vivo treatment with low-dose 5-aza-cytidine enhances immature and mature NK-cell counts and promotes antitumor response.

Septic diseases are characterized by an initial systemic, proinflammatory phase, followed by a period of anti-inflammation. In the context of the latter, monocytes have been described to display altered functions, including reduced TNF secretion and T cell-stimulating capacities in response to recall antigens. This hyporesponsiveness is supposed to be detrimental for coping with secondary infections. We here characterize bacterially reprogrammed PBMC-derived monocytes with special focus on their phagocytic activity. Hence, we have implemented a surrogate model of the early, postinflammatory period by exposing PBMCs to Escherichia coli on d0 and rechallenging them with bacteria on d2. This induced the emergence of a distinct monocytic phenotype with profound phagocytic impairments but a preserved ability for naïve T cell stimulation. The compromising effects on phagocytosis required the presence of bacteria and were not mimicked by TLR4 ligation or exposure to isolated cytokines alone. Moreover, the impairments were specific for the engulfment of bacteria and were coupled to a selective down-regulation of FcγR and SR expression. Intriguingly, this monocytic phenotype contributed to the stimulation of a T_H17-polarized adaptive immune response in the context of secondary infection. Our findings extend the current knowledge of monocytic reprogramming and identify the phagocytic capacity of monocytes as a putative sepsis biomarker.

OBJECTIVES: Extracorporeal membrane oxygenation (ECMO) is recommended in adults with drowning-associated hypothermia and out-of-hospital cardiac arrest (OHCA). Our experience of managing a drowned 2-year-old girl with hypothermia (23°C) and cardiac arrest (58 min) prompted this summary using the CAse REport (CARE) guideline to address the question of optimal rewarming procedure in such patients. DESIGN/PATIENTS: Following the CARE guideline, we identified 24 reports in the “PubMed database” describing children less than or equal to 6 years old with a temperature less than or equal to 28°C who had been rewarmed using conventional intensive care ± ECMO. Adding our patient, we were able to analyze a total of 57 cases. MAIN RESULTS: The two groups (ECMO vs non-ECMO) differed with respect to submersion time, pH and potassium but not age, temperature or duration of cardiac arrest. However, 44 of 44 in the ECMO group were pulseless on arrival versus eight of 13 in the non-ECMO group. Regarding survival, 12 of 13 children (92%) undergoing conventional rewarming survived compared with 18 of 44 children (41%) undergoing ECMO. Among survivors, 11 of 12 children (91%) in the conventional group and 14 of 18 (77%) in the ECMO group had favorable outcome. We failed to identify any correlation between “rewarming rate” and “outcome.” CONCLUSIONS: In this summary analysis, we conclude that conventional therapy should be initiated for drowned children with OHCA. However, if this therapy does not result in return of spontaneous circulation, a discussion of withdrawal of intensive care might be prudent when core temperature has reached 34°C. We suggest further work is needed using an international registry.