Meinolf Siepermann

The CD70/CD27 Pathway Is Critical for Stimulation of an Effective Cytotoxic T Cell Response against B Cell Precursor Acute Lymphoblastic Leukemia

For effective immunotherapy, maintaining the frequency and cytotoxic potential of effector cells is critical. In this context costimulation via the CD70/CD27 pathway has been proven essential. CD70 has been reported to be expressed to varying degrees on malignant B cells. However, in B cell precursor acute lymphboblastic leukemia, the most common childhood malignancy, the role of CD70 in stimulation of antileukemic T cell responses has so far not been delineated. Herein we demonstrate that in B cell precursor acute lymphboblastic leukemia expression of CD70 is low but can be induced upon blast activation via CD40. Both CD70 and CD80/CD86 up-regulated on CD40-stimulated blasts contribute to primary stimulation of T cell proliferation and cytokine production in an additive manner. These two signals also cooperate in the prevention of T cell anergy. In contrast to blockade of CD70 during the effector phase, inhibition of CD70-mediated costimulation during generation of antileukemic T cells prevents effector cell proliferation and reduces their cytotoxic capacity. Modulation of the CD70/CD27 pathway may thus represent a novel therapeutic approach for augmenting magnitude and quality of the antileukemic response in B cell precursor acute lymphboblastic leukemia.

Immunotherapy with the trifunctional anti‐CD20 x anti‐CD3 antibody FBTA05 (Lymphomun) in paediatric high‐risk patients with recurrent CD20‐positive B cell malignancies

Children with B cell malignancies refractory to standard therapy are known to have a poor prognosis and very limited treatment options. Here, we report on the treatment and follow‐up of ten patients diagnosed with relapsed or refractory mature B‐cell Non Hodgkin Lymphoma (B‐NHL), Burkitt leukaemia (B‐AL) or pre B‐acute lymphoblastic leukaemia (pre B‐ALL). All children were treated with FBTA05 (now designated Lymphomun), an anti‐CD3 x anti‐CD20 trifunctional bispecific antibody (trAb) in compassionate use. Within individual treatment schedules, Lymphomun was applied (a) after allogeneic stem cell transplantation (allo‐SCT, n = 6) to induce sustained long‐term remission, or (b) stand alone prior to subsequent chemotherapy to eradicate residual disease before allo‐SCT (n = 4). Nine of ten children displayed a clinical response: three stable diseases (SD), one partial remission (PR) and five induced or sustained complete remissions (CR). Five of these nine responders died during follow‐up. The other patients still maintain CR with a current overall survival of 874–1424 days (median: 1150 days). In conclusion, despite the dismal clinical prognosis of children refractory to standard therapy, immunotherapy with Lymphomun resulted in a favourable clinical outcome in this cohort of refractory paediatric patients.

De novo PIK3R1 gain-of-function with recurrent sinopulmonary infections, long-lasting chronic CMV-lymphadenitis and microcephaly.

PIK3R1 (phosphoinositide-3-kinase, regulatory subunit 1) gain-of-function has recently been described in patients with recurrent sinopulmonary infections, chronic CMV-/EBV-infections, lymphoproliferation, and hypogammaglobulinemia. Here we report a 15-year-old boy with treatment refractory CMV lymphadenitis, severe combined immunodeficiency, microcephaly and a severe developmental defect of Th17 cells. To avoid poor outcome, hematopoietic stem cell transplantation (HSCT) was performed. Subsequently, whole exome sequencing revealed a de novo heterozygous G-to-C mutation (chr5: 5:67,589,663: G>C) at the splice donor site of the PIK3R1 gene. Our data suggest that PIK3R1 gain-of-function leads to developmental defects in helper and regulatory T-cell subsets, the latter expanding the immunological features of PIK3R1 gain-of-function. T-cell subsets play a critical role in the regulation of immune response against infectious agents and of autoimmunity and thus may be particularly accountable for the clinical phenotype of affected patients.

Oral low-dose chemotherapy: successful treatment of an alveolar rhabdomyosarcoma during pregnancy.

We report for the first time the impact of neoadjuvant oral low‐dose chemotherapy consisting of oral trofosfamide, idarubicin, and etoposide (O‐TIE) in the case of alveolar rhabdomyosarcoma (RMS) in the lower jaw of an 18‐year‐old woman at 27 weeks of gestation, without fetal complications and a highly efficient anti‐tumor response. Our study suggests the possible application of O‐TIE treatment in a neoadjuvant setting during pregnancy and recommends a schedule that can be considered for the treatment of patients with high‐risk sarcomas who cannot be treated with intensive chemotherapy for various reasons. Pediatr Blood Cancer 2012; 58: 104–106.

Epidemiology and clinical characteristics of pandemic (H1N1) 2009 influenza infection in pediatric hemato‐oncology and hematopoietic stem cell transplantation patients

For children with hemato‐oncologic diseases, especially after hematopoietic stem cell transplantation (HSCT), the risk for developing complications related to pandemic influenza A (H1N1) 2009 (pH1N1) infection is largely unknown.

Invasive aspergillosis in pediatric oncology patients: a rare event with poor prognosis--case analysis to plan better targeted prophylactic or therapeutic measurement.

Despite the implementation of new antifungal drugs, invasive aspergillosis (IA) still remains a considerable challenge in pediatric oncology with a severe mortality. Prophylactic and therapeutic measurement have to be evaluated in these rare but poor prognostic patients. Therefore the entire group of patients at risk of developing IA has to be defined before cooperative prospective trials. In a retrospective analysis including all our patients with malignancies we looked for patients with proven/probable IA. Cases of the period from 2003 to 2008 were analyzed in detail.In the period between 2003 to 2008 24 of 755 patients were affected by proven/ probable IA. Compared to former studies incidence increased from 1.3%in 1980 to 3.4% in 2008. AML patients with or without allogeneic/haploidentical stem cell transplantation were at highest risk (24% and 25% respectively, in comparison to 1% in ALL-patients). Survival after 2 years was 50% for patients with AML and IA. In patients with high risk to develop IA the effect of intensified, intravenous antimycotic prophylaxis has to be proven prospectively in a cooperative and randomized setting.

Reduced Expression and Defective Modulation of TNF Receptor/Ligand Family Molecules on proB-ALL Blasts

BACKGROUND There is a subgroup of pediatric patients with an immature immunophenotype of proB-ALL that still poses a therapeutic challenge, even if the overall prognosis in B cell precursor acute lymphoblasic leukemia (BCP-ALL) is very good. Due to impaired treatment response these patients are prone to suffer relapse and are thus by definition stratified into the clinically defined high risk group receiving intensified chemotherapy. Besides response to chemotherapy long term prognosis is also influenced by immunological control mechanisms. Thus, high expression of the TNF receptor CD40 has been shown to prevent particularly late relapse in BCP-ALL suggesting a pivotal role of this regulatory molecule for maintenance of the remission status. PATIENTS AND METHODS We therefore determined the baseline expression and CD40-mediated modulation of TNF receptor and costimulatory molecules in 5 patients with proB-ALL, 8 with preB-ALL and 22 with c-ALL performing FACS analysis. We particularly compared the TNF receptor status on proB-ALL blasts to the expression on more mature preB- and c-ALL blasts. RESULTS Here, we demonstrate for the first time a significantly lower baseline expression and CD40-induced modulation capacity of TNF receptor and costimulatory molecules in pediatric proB-ALL compared to more mature precursor B-ALL blasts. CONCLUSION The lower expression and defective capacity of proB-ALL blasts to respond to CD40 ligand stimulation might resemble the immature feature of these blasts and besides increased chemoresistance contribute to the impaired prognosis of these patients due to escape from apoptosis and immunological control mechanisms.