Extended induction chemotherapy does not improve the outcome for high-risk neuroblastoma patients: results of the randomized open-label GPOH trial NB2004-HR

BACKGROUND

Long-term survival of high-risk neuroblastoma patients is still below 50% despite intensive multimodal treatment. This trial aimed to address whether the addition of two topotecan-containing chemotherapy courses compared to standard induction therapy improves event-free survival (EFS) of these patients.

PATIENTS AND METHODS

An open-label, multicenter, prospective randomized controlled trial was carried out at 58 hospitals in Germany and Switzerland. Patients aged 1-21 years with stage 4 neuroblastoma and patients aged 6 months to 21 years with MYCN-amplified tumors were eligible. The primary endpoint was EFS. Patients were randomly assigned to standard induction therapy with six chemotherapy courses or to experimental induction chemotherapy starting with two additional courses of topotecan, cyclophosphamide, and etoposide followed by standard induction chemotherapy (eight courses in total). After induction chemotherapy, all patients received high-dose chemotherapy with autologous hematopoietic stem cell rescue and isotretinoin for consolidation. Radiotherapy was applied to patients with active tumors at the end of induction chemotherapy.

RESULTS

Of 536 patients enrolled in the trial, 422 were randomly assigned to the control arm (n = 211) and the experimental arm (n = 211); the median follow-up time was 3.32 years (interquartile range 1.65-5.92). At data lock, the 3-year EFS of experimental and control patients was 34% and 32% [95% confidence Interval (CI) 28% to 40% and 26% to 38%; P = 0.258], respectively. Similarly, the 3-year overall survival of the patients did not differ [54% and 48% (95% CI 46% to 62% and 40% to 56%), respectively; P = 0.558]. The response to induction chemotherapy was not different between the arms. The median number of non-fatal toxicities per patient was higher in the experimental group while the median number of toxicities per chemotherapy course was not different.

CONCLUSION

While the burden for the patients was increased by prolonging the induction chemotherapy and the toxicity, the addition of two topotecan-containing chemotherapy courses did not improve the EFS of high-risk neuroblastoma patients and thus cannot be recommended. CLINICAL TRIALS.

GOV NUMBER

NCT number 03042429.

Bloodstream infection in paediatric cancer centres--leukaemia and relapsed malignancies are independent risk factors

In a prospective multicentre study of bloodstream infection (BSI) from November 01, 2007 to July 31, 2010, seven paediatric cancer centres (PCC) from Germany and one from Switzerland included 770 paediatric cancer patients (58% males; median age 8.3 years, interquartile range (IQR) 3.8-14.8 years) comprising 153,193 individual days of surveillance (in- and outpatient days during intensive treatment). Broviac catheters were used in 63% of all patients and Ports in 20%. One hundred forty-two patients (18%; 95% CI 16 to 21%) experienced at least one BSI (179 BSIs in total; bacteraemia 70%, bacterial sepsis 27%, candidaemia 2%). In 57%, the BSI occurred in inpatients, in 79% after conventional chemotherapy. Only 56 % of the patients showed neutropenia at BSI onset. Eventually, patients with acute lymphoblastic leukaemia (ALL) or acute myeloblastic leukaemia (AML), relapsed malignancy and patients with a Broviac faced an increased risk of BSI in the multivariate analysis. Relapsed malignancy (16%) was an independent risk factor for all BSI and for Gram-positive BSI.

CONCLUSION

This study confirms relapsed malignancy as an independent risk factor for BSIs in paediatric cancer patients. On a unit level, data on BSIs in this high-risk population derived from prospective surveillance are not only mandatory to decide on empiric antimicrobial treatment but also beneficial in planning and evaluating preventive bundles.

WHAT IS KNOWN

• Paediatric cancer patients face an increased risk of nosocomial bloodstream infections (BSIs). • In most cases, these BSIs are associated with the use of a long-term central venous catheter (Broviac, Port), severe and prolonged immunosuppression (e.g. neutropenia) and other chemotherapy-induced alterations of host defence mechanisms (e.g. mucositis). What is New: • This study is the first multicentre study confirming relapsed malignancy as an independent risk factor for BSIs in paediatric cancer patients. • It describes the epidemiology of nosocomial BSI in paediatric cancer patients mainly outside the stem cell transplantation setting during conventional intensive therapy and argues for prospective surveillance programmes to target and evaluate preventive bundle interventions.

Significantly increased CD70 up regulation on TEL-AML positive B cell precursor acute lymphoblastic leukemia cells following CD40 stimulation

BACKGROUND

TEL-AML the most common genetic alteration in childhood precursor B acute lymphoblastic leukemia (BCP-ALL) is associated with a favorable prognosis.

PATIENTS AND METHOD

We studied the expression of nerve growth factor/tumor necrosis factor receptor (NGFR/TNFR)/ligand family members on 108 primary BCP-ALL samples by flow cytometry and compared both their baseline expression and CD40-induced modulation on TEL-AML positive and negative leukemia samples.

RESULTS

Our findings demonstrate that TEL-AML positive patients exhibit a significantly higher percentage of CD40, CD27 and p75NTR positive blasts at diagnosis. This might well contribute to the improved relapse-free survival of these patients assessed in Kaplan Meier analysis as CD27 and p75NTR directly mediate apoptotic signals. Furthermore CD40 ligation enhances antigen presenting and T cell stimulatory capacity via significant up regulation of CD70 while adequate response to physiological maturation signals as indicated by concomitant down regulation of CD27 is retained in TEL-AML positive leukemia.

CONCLUSION

These data provide novel insights in immunological control mechanisms preserved in this leukemia subtype and suggest that not only treatment with chemicals such as HDAC inhibitors but also retained in vivo response to CD40 ligation contributes to improved immune surveillance in these patients which may add to a superior relapse-free survival observed particularly in the presence of other risk factors.

Bloodstream infections in paediatric cancer patients. Prospective comparative study in 2 university hospitals

BACKGROUND

Preventive approaches (including those related to care of long term central venous catheters, CVADs) and the incidence of bloodstream infections (BSI) in 2 German university affiliated paediatric oncology units.

PATIENTS AND METHODS

Non-interventional prospective observational study using the Oncoped surveillance module. Center A included 85 patients in 31 months and Center B 84 patients in 21 months. The populations did not differ in terms of age, gender, malignancy and disease status (first illness vs. relapse). Center A used ports (46 %) and 2 different Broviac catheters (54 %), in Center B nearly all patients with a CVAD had Broviacs (96 %). 30 BSI (24 patients) were diagnosed in Centre A and 28 BSI (22 patients) in Center B. Patients with relapsed malignancy experienced more BSI (51.4 % vs. 20.9 %; p = 0.001). Incidence rates were significantly lower in Center A (3.47 vs. 7.93 BSI/1000 CVAD days; p = 0.037). Poisson regression analysis revealed a significant lower incidence density (BSI/100 inpatient days) for all BSI in Center A (RR 0.47 CI95 0.27-0.81, p = 0.006). Overall, 52 % of all pathogens detected in blood cultures in Center A were Gram-positive (57 % in Center B) and 48 % Gram-negative (43 in Center B). One ALL patient without a CVAD died due to overwhelming sepsis caused by an ESBL-producing E. cloacae isolate.

CONCLUSION

Paediatric cancer treatment centers differ substantially in regard to management of CVADs and in other preventive strategies. The most important use of local surveillance data is longitudinal internal assessment in close cooperation with microbiology and hospital hygiene experts.

MHC class II deficiency cured by unrelated mismatched umbilical cord blood transplantation: case report and review of 68 cases in the literature

MHC class II deficiency is a rare and fatal form of primary combined immunodeficiency caused by a lack of T-cell-dependent humoral and cellular immune response to foreign antigens, which can only be cured by allogenic stem cell transplantation. In the literature search, we identified 68 cases of HSCT in MHC class II deficiency in the last 14 yr. Pre- and post-transplant MHC class II deficiency is complicated by overwhelming viral infections, a high incidence of GvHD, and graft failure with a poor overall survival rate below 50%. We report an eight-month-old boy presenting with severe respiratory infections and chronic diarrhea, whose sister died at the age of four yr from septicemia. MHC II deficiency was caused by an RFXANK-mutation and treated successfully by 4/6 mismatched unrelated CBT after a myeloablative conditioning regimen based on anti-thymocyte globulin, busulfane, fludarabine, and cyclophosphamide. At present, our patient is well with full immune reconstitution 3(4/12) yr after CBT. CB may represent an alternative source of stem cells for children with MHC class II deficiency without a suitable donor.

Prospective, comprehensive, and effective viral monitoring in children undergoing allogeneic hematopoietic stem cell transplantation

Major advances in the monitoring and treatment of viral infections after hematopoietic stem cell transplantation (HSCT) have been achieved over the last decade. The appropriate extent of viral monitoring and antiviral therapy remains controversial, and reports in pediatric patients receiving allogeneic unmanipulated hematopoietic stem cells (HSCs) are sparse. A total of 40 pediatric patients who underwent HSCT with either peripheral blood stem cells (PBSCs, n = 30) or bone marrow (BM; n = 10) were prospectively monitored every week for viral DNAemia (VDNA) by simultaneous detection of cytomegalovirus (CMV), Epstein-Barr virus (EBV), human herpesvirus 6 (HHV6), human adenovirus (ADV), and polyoma BK virus (BKV) using real-time TaqMan polymerase chain reaction (PCR). All patients received prophylactic acyclovir and preemptive ganciclovir (GCV) when 500 copies/microg DNA (EBV/HHV6) or >1 copy/microg DNA (CMV) were detected on 2 consecutive measurements. VDNA occurred in 25 of 40 recipients (CMV, 11/40 patients [28%]; EBV, 19/40 [48%]; HHV6, 2/40 [5%]; ADV/BKV, 1/40) and was found exclusively after neutrophil engraftment and in most cases up to day +100. Recurrent VDNA (P = .028) and (readily treatable) viral disease (P = .003) were observed predominantly in patients suffering from nonmalignant diseases, a cohort characterized by delayed lymphocyte engraftment. VDNA occurred more frequently in HLA-mismatched HSCT and in the 24 of 40 patients receiving antithymocyte globulin (ATG). The incidence of EBV, but not that of CMV, was increased in the ATG group. Yet, in these patients, viral loads of both EBV and CMV were higher, but with prompt initiation of preemptive GCV, no posttransplantation lymphoproliferative disorder or other life-threatening morbidities occurred. HHV6 was typically detected at low viral loads (<10(2) copies/microg DNA), with only 5% of HSC recipients fulfilling our HHV6 criteria for triggering GCV treatment. In multivariate analysis, ATG treatment, HLA mismatch, recipient CMV seropositivity, and stem cell source, but not severe acute graft-versus-host disease were identified as independent risk factors for VDNA. This comprehensive viral monitoring program with defined thresholds for initiation of preemptive GCV effectively prevents the development of critical viral disease, even in high-risk patients receiving ATG.

Allogeneic stem cell transplantation for pediatric and adolescent patients with CML: results from the prospective trial CML-paed I

PURPOSE

Stem cell transplantation (SCT) can definitely cure chronic myeloid leukemia (CML), a rare disease in childhood. We prospectively evaluated the results of early SCT in pediatric CML after standardized pretreatment with hydroxyurea+/-interferon.

PATIENTS AND METHODS

Between 1995 and 2004, 200 children (median age: 12.4 years) were enrolled and stratified: given the availability of an HLA-matched related donor (MRD), SCT was scheduled within 6 months and otherwise from an unrelated donor (UD) within 12 months following diagnosis.

RESULTS

176 patients underwent SCT; from MRD within median 4 months and from UD within median 11 months after diagnosis. At SCT, 158 patients were in chronic phase (CP1 or CP2), 9 patients were in accelerated phase and 9 patients were in blast crisis (BC). The conditioning regimen - total body irradiation or busulfan - exerted no different impact on overall survival (OS). Probability of OS at 5 years was 87+/-11% if grafted from a sibling (n=41), 52+/-9% from matched UD (MUD, n=71), and 45+/-16% from mismatched donors (MMD, n=55), respectively. A trend for better OS in CP1 was observed if SCT was performed within 6 months (n=49; 74+/-9%), compared to 7-12 months (n=52; 62+/-15%), and >12 months (n=43; 62+/-17%) after diagnosis, respectively (p=0.157). Probability of relapse at 5 years was 20+/-12%. Transplant-related mortality and graft-versus-host disease mainly contributed to the inferior outcome in UD and HLA-mismatched SCT.

CONCLUSION

These data from the first prospective trial on CML restricted to children and adolescents might be considered for decision making when balancing the risks of SCT against the increasing use of imatinib as upfront treatment for CML.

Treosulfan-based high-dose chemotherapy with autologous stem cell transplantation in high-risk Ewing sarcoma

10546

Background: High-dose chemotherapy (HDC) is widely used in consolidation treatment of Ewing sarcoma patients with primary disseminated or recurrent disease. Standard busulfan-based regimens are not compatible with radiotherapy to central axis sites. Treosulfan is a newly-developed bifunctional alkylating agent that has been shown to be safe in current trials of the German Society for Pediatric Hematology and Oncology (GPOH) even in heavily pre-treated patients including axial radiation. Methods: Event-free survival (EFS) and overall survival (OS) for 21 patients with primary disseminated disease (PDD) and survival after relapse for 11 relapse patients recruited from the EURO-E.W.I.N.G.99 trial 1998–2007 were analyzed. PDD-patients had received VIDE induction prior to treosulfan-based HDC (treosulfan: 36g/m2; melphalan: 140mg/m2) followed by autologous stem cell transplantation. Median follow up was 1.72 yrs. Relapse patients had received appropriate second line chemotherapy regimens prior to treosulfan-based HDC. Median follow up after relapse was 2.26 yrs. Results: Seventeen of 21 (81%) PDD-patients had a central axis site of the primary tumor, 8 patients (38%) presented with a pelvic tumor. Metastatic sites were: bone (76%), bone marrow (22%), CNS (10%), liver (15%), lymphnode (29%), other (16%), and additionally lung metastases in 57%. 1y-EFS was 0.70 (SE=.10), 2y-EFS was 0.27 (SE=0.10), and 3y-EFS was 0.16 (SE=.09). 1y-OS was 0.84 (SE=.08), 2y-OS was 0.46 (SE=.13), and 3y-OS was 0.32 (SE=.12). In the cohort of 11 relapse patients two patients (18%) had a local relapse, 3 (27%) a combined relapse, and 6 (55%) a systemic relapse. Six of 11 (55%) relapse patients had a late relapse >2 yrs from diagnosis. Survival after relapse at 3yrs was 0.70 (SE=.15). Conclusions: Treosulfan-based HDC is an alternative approach in high-risk Ewing tumor patients especially after relapse to consolidate a second remission. Further investigation and comparison to other standard HDC regimens is needed.

No significant financial relationships to disclose.

Relapse, not regimen-related toxicity, was the major cause of treatment failure in 11 children with Down syndrome undergoing haematopoietic stem cell transplantation for acute leukaemia

We report a retrospective analysis of 11 children with Down syndrome (DS) treated by SCT in eight German/Austrian SCT centres. Indications for transplantation were acute lymphoblastic leukaemia (N=8) and acute myeloid leukaemia (N=3). A reduced intensity conditioning (RIC) containing 2 Gy TBI was given to two patients, another five received a myeloablative regimen with 12 Gy TBI. Treosulphan or busulphan was used in the remaining four children. Four of eleven (36%) patients are alive. All of them were treated with a myeloablative regimen. One of the four surviving children relapsed 9 months after SCT and is currently receiving palliative outpatient treatment. The main cause of death was relapse (5/11). Two children died of regimen-related toxicity (RRT), one from severe exfoliative dermatitis and multiorgan failure after a treosulphan-containing regimen, the other from GvHD-related infections after RIC. Acute GvHD of the skin was observed in 10 of 10 evaluable patients, and chronic GvHD in 4 of 8. Our data show that DS patients can tolerate commonly used, fully myeloablative preparative regimens. The major cause of death is relapse rather than RRT resulting in an event-free survival of 18% and over all survival of 36%.

Trends in infections in children with malignant disease in 2000: comparison of data of 1980/81

Children with cancer have an overall chance of survival of 70-80%. Despite significant advances in supportive care during the last years, infections remain a major cause of therapy-associated morbidity and death. Between January and December 2000, oncology patients (ONC) treated on a pediatric oncology ward after chemotherapy (n = 109), loco-regional thermochemotherapy (n = 13), or hematopoietic stem cell (HSCT) transplantation (n = 35) suffered a total of 249 febrile infectious complications (HSCT 40/ONC 209). These episodes were analyzed retrospectively and compared with 125 ONC patients with 133 febrile infections in 1980/81. The relative incidence of fever of unknown origin (FUO) decreased from 1980/81 to 2000 (p <.001). The frequency of bloodstream infections (BSI) in febrile episodes was comparable in both periods with 37% (50/135) in 1980 and 29% (72/249) in 2000. In both periods, gram-positive bacteria were the most frequent organisms, whereas gram-negative organisms were detected in approximately 20% of BSI. In 1980/81 microbiologically (MDI) or clinically documented infections (CDI) were not detected, whereas in 2000 27% of all infectious were MDI/CDI. During the last 20 years, improved diagnostic tools have resulted in an increased detection rate of infectious agents causing febrile episodes in pediatric cancer patients. The comparison of the two observation periods did not reveal a change in the microbiologic spectrum. Despite the fact that in 2000 more patients were treated with intensified chemotherapy because of relapse, infection-related mortality was unchanged compared to 1980/81. This observation may indicate a sufficient preemptive antibacterial therapy followed by better diagnostic tools and goal-oriented treatment.

Role of Survivin Splice Variants in Pediatric Acute Precursor B Lymphoblastic Leukemia

BACKGROUND

Survivin, a member of the inhibitor of apoptosis protein (IAP) family is transiently expressed at low levels during normal hematopoesis but profoundly overexpressed in adult leukemia potentially contributing to leukemogenesis due to deregulated apoptosis and defective cell cycle control. Alternative splicing results in four different mRNA variants survivin, survivin2B, survivin-DeltaExon3 and survivin-3B, with distinct cellular localization patterns and anti-apoptotic potential. Due to co-localization of survivin and survivin-2B in the cytoplasm survivin-2B may permit interactive fine-tuning of survivin actions and moreover play an attenuating role in its anti-apoptotic function. Lack of survivin-2B is associated with disease progression of malignomas suggesting a differential role of these isoforms in tumorigenesis.

PATIENTS AND METHODS

We therefore determined the expression of the functional survivin splice variants performing RT- and real-time PCR in a purely pediatric cohort of 20 patients suffering from precursor B-ALL (BCP-ALL).

RESULTS

Here, we demonstrate for the first time in pediatric patients with precursor B-ALL an association between lower survivin-2B expression and affiliation to the high risk group.

CONCLUSION

The idea that survivin-2B may act as natural antagonist of survivin could potentially be used in novel approaches of anti-cancer treatment by influencing the proportional expression of the different splice variants.

Immunotherapy in children: report from the Reisensburg-Symposium October 20-22, 2004 and recent advances

Immunotherapy of childhood malignancies has a magic aura of promising an easy way to cure. It is not only the public, but also the medical community, which has caused this hope. Therefore, it was worthwhile to bring together a panel of experts working in the field of immunotherapy in order to discuss ongoing projects, and to show hopes and disappointments. The result was a fascinating symposium sponsored by The Kind Philipp Leukemia Foundation (Mönchengladbach, Germany). The symposium took place in the Reissensburg near Ulm (Germany) which gives the ideal location for such an event.

Evaluation of different protocols for gene transfer into non-obese diabetes/severe combined immunodeficiency disease mouse repopulating cells

PURPOSE

Although gene transfer with retroviral vectors has shown distinct clinical success in defined settings, efficient genetic manipulation of hematopoietic progenitor cells remains a challenge. To address this issue we have evaluated different transduction protocols and retroviral constructs in the non-obese diabetes (NOD)/severe combined immunodeficiency disease (SCID) xenograft model.

METHODS

An extended transduction protocol requiring 144 h of in vitro manipulation was compared to a more conventional protocol requiring 96 h only.

RESULT

While pretransplantation analysis of cells transduced with a retroviral vector, expressing the enhanced green fluorescent protein (EGFP) marker gene, demonstrated significantly higher overall transduction rates for the extended protocol (33.6 +/- 2.3 vs. 22.1 +/- 3.8%), EGFP expression in CD34+ cells before transplantation (4.0 +/- 0.9 vs. 11.6 +/- 2.5%), engraftment of human cells in NOD/SCID bone marrow 4 weeks after transplantation (4.5 +/- 1.7 vs. 36.5 +/- 9.4%) and EGFP expression in these cells (0 +/- 0 vs. 11.3 +/- 2.8%) were significantly impaired. When the 96 h protocol was used in combination with the spleen focus forming virus (SFFV)/murine embryonic stem cell (MESV) hybrid vector SFbeta11-EGFP, high transduction rates for CD45+ (41.0 +/- 5.3%) and CD34+ (38.5 +/- 3.7%) cells prior to transplantation, as well as efficient human cell engraftment in NOD/SCID mice 4 weeks after transplantation (32.4 +/- 3.5%), was detected. Transgene expression was observed in B-lymphoid (15.9 +/- 2.0%), myeloid (36.5 +/- 3.5%) and CD34+ cells (10.1 +/- 1.5%).

CONCLUSION

Our data show that CD34+ cells maintained in cytokines for multiple days may differentiate and loose their capacity to contribute to the haematological reconstitution of NOD/SCID mice. In addition, the SFFV/MESV hybrid vector SFbeta11-EGFP allows efficient transduction of and gene expression in haematopoietic progenitor cells.

Three cases of renal relapse after allogeneic hematopoietic stem cell transplantation for childhood acute lymphoblastic leukemia

Isolated renal relapse after allogeneic hematopoietic stem cell transplantation (alloHSCT) in children with acute lymphoblastic leukemia (ALL) is a rare condition. Generally, in ALL, the sites most frequently affected by extramedullary relapse are the central nervous system (CNS) and the testicles. Here we report on three young boys with relapsed B-precursor ALL, who underwent alloHSCT from HLA-identical siblings and suffered a histopathologically proven isolated unilateral renal relapse (two patients) or a combined renal and testicular relapse (one patient) 6, 10 and 12 months post alloHSCT. In all patients at the time of relapse bone marrow showed complete remission with complete donor hematopoiesis. They all received total body irradiation with partial shielding of the kidneys as part of their conditioning therapy, such that renal shielding could be an explanation for the observed accumulation of renal relapses. Moreover, during the past few years so called immune privilege has been postulated for frequent relapse sites such as the CNS, the testicles and the anterior chamber of the eye. Impaired accessability of these organs by cytotoxic T-cells (CTLs) with a reduced graft-versus-leukemia (GvL) effect after alloHSCT is based on a number of different molecular and cellular mechanisms. Similar mechanisms have been shown to be effective in the tubulointerstitial space of the kidney, rendering the kidney a potentially immune privileged site. Due to these observations we advocate sufficient treatment of the kidneys during conditioning therapy.

Herpes simplex virus type-1 amplicon vectors for vaccine generation in acute lymphoblastic leukemia

For leukemia vaccine generation, high-efficiency gene transfer is required to express immunomodulatory molecules that stimulate potent antileukemic immune responses. In this context, herpes simplex virus type-1 (HSV-1)-derived vectors have proven to be a promising tool for genetic modification of lymphoblastic leukemia cells. Yet, vector-associated viral protein expression might inadvertently modulate vaccine efficacy facilitating both immune evasion and immune stimulation. To explore the issue of immune-stimulation versus immune-suppression in immature lymphoblastic leukemia cells, two types of HSV-1 amplicon vectors, helper virus-dependent and helper virus-free that express the immunomodulatory molecules CD70 and IL-2, were compared with regard to their vector-associated immunomodulatory potential. We first established that lymphoblastic cell lines and primary acute lymphoblastic leukemia (ALL) cells express HSV receptor genes. Lymphoblastic cell lines were transduced with high efficiency, and in primary ALL cells high gene transfer rates of 47+/-15 and 42+/-14% were obtained with helper virus-dependent and -free HSV-1 amplicon vectors, respectively. The efficacy of the two amplicon vectors to induce antineoplastic responses was assessed in a vaccine setting in mice with pre-existing highly malignant lymphoblastic disease. Treatment of mice with vaccine cells transgenically expressing CD70+IL2 significantly suppressed lymphoblastic cell proliferation and improved survival. Of note, when helper virus-dependent HSV-1 amplicon vectors were used for vaccine preparation, the high immunogenic potential of the vector itself, in the absence of transgenic CD70+IL2 expression, seemed to be sufficient to mediate protection comparable to the antineoplastic response achieved by expression of immunomodulatory molecules. Thus for vaccine generation in B lymphoblastic leukemia, the immunogenic potential of HSV-1 helper virus-dependent amplicon vectors does provide additional benefit to the high transduction efficiency of HSV-1-derived vectors.

Surveillance of nosocomial infections in paediatric recipients of bone marrow or peripheral blood stem cell transplantation during neutropenia, compared with adult recipients

The aim of this prospective study was to analyse the incidence of nosocomial infections (NIs) during neutropenia after haematopoietic stem cell transplantation (HSCT) in paediatric and adult patients. Diagnosis of NI followed the modified surveillance protocol of the German National Reference Centre for Surveillance of NIs. During the 24-month study period, 38 and 39 transplantations were performed in paediatric and adult patients, respectively. Eighty percent and 92% of the paediatric and adult patients, respectively, underwent allogenic HSCT. In total, 1156 neutropenic days were documented. The incidence of NI during neutropenia in all recorded cases was 38.9 NI per 1000 days, without significant difference between the groups. No difference was found in the incidence rates of pneumonia, while there was a trend towards a higher incidence of bloodstream infection in adult patients. Significantly more episodes of fever of unknown origin were found in paediatric than adult patients. Pathogens were isolated in 19 of 45 cases of NI. Of the clinically documented infections, Gram-positive organisms were isolated in 79%, Gram-negative organisms were isolated in 16% and fungi were isolated in 5%. Surveillance of NI is an effective instrument to control the quality of health care. It should focus on device-associated infections or specific high-risk targets such as nosocomial pneumonia.

Immunotherapy in allogeneic hematopoietic stem cell transplantation--not just a case for effector cells

The concept that in allogeneic hematopoietic stem cell transplantation (alloHSCT) the immune system plays a prominent role in the control of leukemic disease is supported by the clinical observation that immunological effector mechanisms contribute to the elimination of leukemic blasts. The failure to induce prolonged remission after alloHSCT has led to resurgent interest in complementing concepts of immune modulation to improve the antileukemic reponse. While the general focus has been placed on manipulation of cytotoxic effector cell populations, we will explore the dual role of leukemia cells as both antigen-presenting and target cells and describe various vaccination strategies to facilitate a protective antileukemic immune response in this setting. In addition, we will introduce mesenchymal stem cells (MSC) as another cell population recently recognized for their immunomodulatory properties. The potential benefits and hazards of MSC-cotransplantation in alloHSCT with regard to the graft versus leukemia (GvL) and the graft versus host (GvH) response will be discussed.

Donor leukocyte infusion after hematopoietic stem cell transplantation in patients with juvenile myelomonocytic leukemia

Juvenile myelomonocytic leukemia (JMML) is a clonal myeloproliferative disorder of early childhood. In all, 21 patients with JMML who received donor leukocyte infusion (DLI) after allogeneic hematopoietic stem cell transplantation (HSCT) for either mixed chimerism (MC, n=7) or relapse (n=14) were studied. Six patients had been transplanted from an HLA-matched sibling and 15 from other donors. Six of the 21 patients (MC: 3/7 patients; relapse: 3/14 patients) responded to DLI. Response rate was significantly higher in patients receiving a higher total T-cell dose (> or =1 x 10(7)/kg) and in patients with an abnormal karyotype. None of the six patients receiving DLI from a matched sibling responded. Response was observed in five of six patients who did and in one of 15 children who did not develop acute graft-versus-host disease following DLI (P=0.01). The overall outcome was poor even for the responders. Only one of the responders is alive in remission, two relapsed, and three died of complications. In conclusion, this study shows that some cases of JMML may be sensitive to DLI, this providing evidence for a graft-versus-leukemia effect in JMML. Infusion of a high number of T cells, strategies to reduce toxicity, and cytoreduction prior to DLI may improve the results.

Similar Survival Following HLA-Identical Sibling Transplantation for Standard Indication in Children with Haematologic Malignancies: A Single Center Comparison of Mobilized Peripheral Blood Stem Cell with Bone Marrow Transplantation

BACKGROUND

Peripheral blood stem cell (PBSC) grafts are increasingly used for autologous and allogeneic haematopoietic stem cell transplantation (alloHSCT) with the aim to hasten neutrophil and platelet engraftment and thereby to reduce transplant-related complications due to infections, bleeding and graft failure. Based on the paucity of data on PBSC transplantation in children we performed a retrospective single-center analysis comparing the outcome of children receiving mobilized PBSC from human leukocyte antigen (HLA)-identical sibling donors to bone marrow (BM) transplant recipients.

PATIENTS AND METHODS

Between 1996 and 2004, 16 children with haematologic malignancies and standard indication for alloHSCT underwent PBSC transplantation from HLA-identical sibling donors. The outcome of these children was compared to a historic control group of 19 bone marrow (BM) transplant recipients. Time to neutrophil engraftment, incidence of acute and chronic graft-versus-host disease (GvHD), relapse rate, transplant-related mortality, event-free and overall survival were analyzed.

RESULTS

Neutrophil engraftment was achieved significantly faster after PBSC compared to BM transplantation with a median time to neutrophil engraftment of 11 (range: 8-21) and 19 (16-44) days for the PBSC and BM cohort, respectively (p < 0.001). Two of 19 (11 %) BM recipients did not achieve primary neutrophil engraftment and both patients died due to infectious complications. The rate of clinically significant acute GvHD > or = grade II was higher in the PBSC compared to the BM group (75 vs. 39 %; p = 0.045). Incidences of chronic GvHD (PBSC vs. BM: 60 vs. 44 %), death of disease (13 vs. 21 %) and death of complication (13 vs. 16 %) were comparable between both groups (p = ns). With a median follow up of 4.7 years (PBSC) and 10.2 years (BM) overall survival (PBSC vs. BM: 68.6 +/- 13.5 vs. 63.2 +/- 11.1 %; p = 0.65) and event-free survival (67.0 +/- 12.1 vs. 63.2 +/- 11.1 %; p = 0.80) is without demonstrable difference in both groups.

CONCLUSIONS

Transplantation of PBSC compared to BM is associated with faster neutrophil engraftment and a higher rate of > or = grade II acute GvHD. As overall survival and event-free survival is similar when using PBSC and BM, PBSC is an alternative stem cell source for HLA-identical sibling transplantation. Further prospective analyses with higher number of patients stratified according to well established risk factors are required to define the precise role of both stem cell sources for children with haematologic malignancies.

Transplantation of Haematopoietic Stem Cells Derived from Cord Blood, Bone Marrow or Peripheral Blood: A Single Centre Matched-Pair Analysis in a Heterogeneous Risk Population

BACKGROUND

Beside the transplantation of haematopoietic stem cells derived from bone marrow (BMT) and peripheral blood (PBSCT) in the absence of a well-matched donor, transplantation of cord blood (CBT) has been shown to be a valid alternative. To validate the efficacy of CBT in comparison to BMT and PBSCT we performed a single-centre based matched-pair analysis.

PATIENTS AND METHODS

Between 1996 and 2003, 15 paediatric patients with non-malignant and malignant diseases of heterogenous risk underwent CBT. 198 paediatric patients undergoing BMT or PBSCT during the same time and at the same centre were available for selection as appropriate controls for matched-pair analysis. Matching criteria in descending hierarchy were disease, risk status, type of donor, age at HSCT, gender and year of transplantation. 47 % of CB grafts were < or = 4/6 HLA-matched whereas close to 90 % of grafts in the BMT and PBSCT cohorts were completely matched.

RESULTS

Neutrophil engraftment was comparable in CB and BM recipients (p = 0.529) while engraftment following PBSCT occurs significantly earlier (p < 0.01). Median time to neutrophil recovery was 20 (range: 13-36), 19 (14-28) and 14 (9-24) days for the CBT, BMT and PBSCT cohort respectively. Of note contrary to the expectation, with regard to a reduced risk of Graft-versus-Host-Disease (GvHD) there was no clear advantage in the CBT cohort with a similar overall GvHD rate in all 3 groups. This observation can be attributed to the fact that in the CBT cohort the proportion of patients with an HLA-mismatched donor was higher than in the other cohorts. Rate of death of complications (DOC) was high in CB recipients (40 %), but not statistically different from BM (27 %) and PBSC recipients (13 %). In contrast to the CBT and BMT cohort with only 1 patient dead of disease (DOD), 4 PBSC recipients (31 %) died suffering from a relapse. 2-year event-free survival (EFS) in patients with malignant disease was 38.5 %, 69.2 % and 33.0 % for the CBT, BMT and PBSCT cohort respectively. 5-year overall survival (OS) was 53.3 % in the CBT, 66.4 % in the BMT and 50.9 % in the PBSCT cohort. There was no statistical difference between the cohorts transplanted with CB and BM or PBSC regarding EFS and OS (EFS: p = 0.24 and p = 0.72; OS: p = 0.53 and p = 0.64).

CONCLUSIONS

Transplantation of < or = 4/6 HLA-matched CB grafts seems to be associated with a higher risk of GvHD, graft rejection and lethal opportunistic infection. With an overall survival of 53 % in our 15 patients this analysis documents that even in high risk patients, CB may be a valid alternate HSC source in children who lack a well-matched donor. This is especially true, if a > 4/6 HLA-matched CB with > 2.0 x 10 (7) total nucleated cells/kg bodyweight is available. Thus, parallel to the search for a BM or PBSC donor, searching for an adequate CB unit should be initiated.

Defibrotide in the treatment of children with veno-occlusive disease (VOD): a retrospective multicentre study demonstrates therapeutic efficacy upon early intervention

Veno-occlusive disease (VOD) of the liver is a complication observed particularly in patients undergoing hematopoietic stem cell transplantation (HSCT). Defibrotide (DF) is a polydeoxyribonucleotide with aptameric activity on endothelium. We evaluated in a retrospective analysis the efficacy of DF in pediatric patients developing hepatic VOD after HSCT.A total of 45 patients between 0.2 and 20 years (median age: 8.2 years) with hepatic VOD were treated with DF: 22 patients (49%) met risk criteria for severe or progressive disease and 23 (51%) for moderately severe and mild disease. The median duration of DF treatment was 17 days. In all, 34 patients (76%) achieved complete response (CR) with a survival rate of 64% at day 100. CR rate in patients with severe disease was 50% with long-term survival of 36%. The average DF dose in the CR group was 45 mg/kg/day and in the no responder (NR) group 27 mg/kg/day. The use of additional drugs besides DF to treat VOD made no difference in the outcome compared to DF alone. The average interval from diagnosis to start of DF was 1 day in the CR and 5.5 days in NR group. In multivariate analysis, early intervention remained the only significant factor for a CR.

Increasing mixed chimerism defines a high-risk group of childhood acute myelogenous leukemia patients after allogeneic stem cell transplantation where pre-emptive immunotherapy may be effective

Children with leukemias and increasing mixed chimerism (increasing MC) after allogeneic stem cell transplantation have the highest risk to relapse. Early immunological intervention was found to be effective in these cases. To substantiate this on a defined group of pediatric acute myelogenous leukemia (AML) patients, we performed serial analysis of post transplant chimerism and pre-emptive immunotherapy in patients with increasing MC. In total, 81 children were monitored, 62 patients revealed complete chimerism (CC), low-level MC or decreasing MC. Increasing MC was detected in 19 cases. Despite early immunological intervention relapse was still significantly more frequent in patients with increasing MC (9/19) than in patients with CC, low-level or decreasing MC (8/62, P<0.005). The probability of 3-year event-free survival (EFS) was 52% for all patients (n=81), 59% for patients with CC, low-level MC, 60% for patients with decreasing MC (n=62), and 28% for patients with increasing MC (n=19, P<0.005). Patients with increasing MC who received early immunological intervention showed a significantly enhanced probability for event-free survival (pEFS 36%, n=15) compared to patients with increasing MC without intervention (pEFS 0%, n=4, P<0.05). These results prove that pediatric AML patients with increasing MC are at highest risk for relapse and that early immunological intervention can prevent relapse in these patients.

Characterization of CD34+ Progenitor-Derived Dendritic Cells Pulsed with Tumor Cell Lysate for a Vaccination Strategy in Children with Malignant Solid Tumors and a Poor Prognosis

BACKGROUND

Children and adolescents with primary multifocal, refractory or relapsed malignant extracranial solid tumors still have a poor prognosis inspite of intensive standard radio-/chemotherapy. Here complementary immunomodulatory treatment modalities may prove beneficial as consolidation therapy following cytoreduction. Neuroblastoma, Ewing tumor and soft tissue sarcoma cells have principally been shown to be susceptible towards both cytotoxic and humoral effector mechanisms. Yet in vivo they are not capable of inducing an effective antitumor response which has been attributed to low level MHC expression and lack of costimulatory surface molecules. Professional antigen - presenting cells such as dendritic cells (DCs) in contrast are capable of activating unprimed T cells and are therefore ideal tools for vaccine generation.

RESULTS

Here we demonstrate that DCs may be generated from CD34+ progenitor cells to clinical scale in a three to four week cell culture process including an initial expansion and subsequent differentiation and maturation steps. DCs derived from CD34+ progenitors express the expected marker profile and are highly effective in stimulating allogeneic T cell effectors. We also demonstrate that they effectively take up fluorescence-labelled tumor cell lysate.

DISCUSSION

Having established a cell culture process for clinical scale DC production utilizing CD34+ progenitors as the cellular source we discuss the role of CD34+ derived DCs in clinical vaccination protocols. The rationale for a phase I/II DC dose escalation study for high risk pediatric patients with extracranial solid tumors assessing safety, immunological and clinical efficacy of serial combined intranodal and subcutaneous injections of tumor cell lysate-pulsed autologous DCs is delineated.

Long-Time Survival after Unrelated Bone Marrow Transplantation in Children and Adolescents and Targeted Therapy with CD25 Blockade to Prevent GVHD

To evaluate longtime survival after matched unrelated donor (MUD) transplantation a group of patients (n = 10) with intensified GVHD prophylaxis were compared to patients receiving matched sibling (MSD) transplantation (n = 10); all transplantations were done between 1989 and 1995 in the same institution. A murine monoclonal antibody against CD25 was assessed in addition to standard GVHD prophylaxis for reducing GVHD in children with advanced leukemia after MUD BMT (group I). We compared the incidence of GVHD, relapse and survival under prophylaxis with either anti-CD25 (group I, n = 10) or MSD BMT without anti-CD25 (group II, n = 10) with respect to known risk factors of transplant related morbidity, mortality and outcome. 3/10 leukemia patients in both groups were in CR3 or in relapse at time of transplant. Whereas incidence of acute GVHD grade III and IV was significantly higher in group I compared to group II (0.4 vs. 0.0), no differences in engraftment, or chronic GVHD were seen between both groups. In addition, overall (0.5 vs. 0.6) and leukemia free survival (0.5 vs. 0.6) was not different after 8 respectively 10 years from transplant. Murine anti-CD25 therapy may have contributed to matching outcome of MUD vs. MSD marrow transplants in children with advanced leukemia. In conclusion, the use of anti-CD25 in modulation of CD25+ regulatory and effector T cells in allo- and leukemia recognition merrits further exploration of its potential to improve both tolerance and leukemia control. Since the outcome of children with leukemia that received intensified GVHD prophylaxis in MUD BMT was similar to children with MSD transplants, MUD BMT has to be considered as an equivalent therapeutic option for patients, who have no HLA-identical sibling donor.

Osteosarcoma after allogeneic bone marrow transplantation. A report of four cases from the Cooperative Osteosarcoma Study Group (COSS)

Osteosarcoma, one of the most frequent secondary malignancies after the treatment of young patients with cancer, has only very rarely been observed in association with hematopoietic stem cell transplantation (HSCT). We report four patients who were identified by searching the database of the Cooperative Osteosarcoma Study Group (COSS) for patients whose osteosarcoma arose following HSCT. Transplant indications had been acute lymphoblastic leukemia (3). and sickle cell disease (1). and the stem cell source was bone marrow in all cases (three allogeneic, one syngeneic). All four had received chemotherapy with alkylators as part of their conditioning regimen and/or first line therapy. The conditioning regimen included total body irradiation in three patients. The osteosarcomas arose at the age (adolescence) and sites (around the knee) typical for the disease. All four patients received chemotherapy as part of multimodal osteosarcoma treatment, and all four are currently alive, three in continuous remission at 5 7/12, 2 11/12, and 0 6/12 years and one with relapsed osteosarcoma at 4 1/12 years. One of the osteosarcoma-free survivors suffered a third malignancy, myelodysplastic syndrome. Osteosarcoma should be included among the secondary malignancies that can arise following HSCT. Multi-modal therapy according to guidelines for de novo osteosarcoma can lead to long-term survival in selected patients.

Serial evaluation of the oncological pediatric risk of mortality (O-PRISM) score following allogeneic bone marrow transplantation in children

The O-PRISM score was introduced for risk assessment in children transferred to intensive care following BMT. The aim of this study is to determine the prognostic value of a serial evaluation of the O-PRISM score. Ninety-three children, 58 allogeneic-related and 35 unrelated BMT, were evaluated. At weekly intervals, the O-PRISM was calculated based on the standard PRISM score and the three additional variables CRP, GVHD and hemorrhage. Overall survival was 0.51 +/- 0.05 (48/93 patients). Seventeen children died of recurrent disease and 28 of BMT-related complications. High O-PRISM scores significantly correlated with adverse outcome. The relative risks of DOC of patients with scores > or =10 compared to patients with lower scores were: day 0: 3.9 (95% confidence-interval: 1.1-13.7, P = 0.02), day 7: 2.0 (0.7-6.2, P = 0.20), day 14: 5.2 (1.9-14.0, P = 0.001), day 21: 5.6 (1.9-16.5, P = 0.001), day 28: 11.5 (3.8-100.9, P < 0.001), day 35: 7.3 (1.9-27.7, P = 0.001). As early as day 0, children with scores > or =10 points showed a higher cumulative incidence of DOC than patients with lower scores (0.69 +/- 0.15 vs 0.27 +/- 0.05, P = 0.02). The O-PRISM score represents a useful clinical parameter for serial risk assessment following BMT. As it indicates fatal events early, it may be helpful for parent information and even more for the early establishment of intensified supportive treatment. The O-PRISM score may therefore be a valuable parameter for the evaluation of different strategies for BMT and supportive treatment.

Tumor vaccines--application to childhood cancer

Currently, several clinical studies explore the therapeutic potential of tumor vaccines which are genetically modified to produce immunostimulatory molecules as a complementary approach for conventional cancer therapy. In this review the immunological basis and the preclinical design of such vaccine strategies are described with particular emphasis to acute leukemia and neuroblastoma. The role of cytokines, chemokines and costimulatory surface molecules for generation of tumor vaccines is summarized, and the advantages and disadvantages of autologous, allogenic and dendritic cell vaccines are discussed. Finally, combination-immunogens are introduced as a potent means of enhancing the anti-tumor response.

Autoimmune disease induced by dendritic cell immunization against leukemia

Induction of an optimal immune response will likely be a prerequisite for successful immunotherapy of human leukemias and other malignancies. Dendritic cells are highly effective at inducing an immune response to antigens to which the host is unresponsive, while transgenic expression of the costimulator molecule CD40 ligand (gp39/CD154) and the T cell growth factor interleukin 2 (IL2) are also able to augment immune responsiveness. We therefore investigated whether a combination of these two distinctive approaches to immunostimulation could safely increase the anti-tumor immune response compared to each stimulus alone. We injected BALB/CBYJ mice with syngeneic dendritic cells (DC) exposed to A20 lymphoblastic leukemia cell-derived peptides and proteins which had been acid-eluted from the cell surface. In additional mice, the pulsed DC were mixed with genetically modified syngeneic fibroblasts that were expressing CD40 ligand or secreting interleukin 2 (IL2). Three days after their third, weekly, vaccination, they were challenged with parental A20 cells. Tumor growth was suppressed by responses to pulsed DC alone (P < 0.02). This suppression was further enhanced when pulsed DC were coinjected with fibroblasts expressing CD40 ligand and IL2 (P < 0.0005 compared to DC alone) even though CD40 ligand and IL2-expressing fibroblasts alone offered no significant protection in this model. Mice receiving the full complement of immunostimulants either failed to develop visible tumors or developed small tumors which quickly necrosed and regressed, allowing the mice to become long term tumor-free survivors. Antibody mediated depletion of either CD4+ or CD8+ T-cell subset significantly reduced the level of protection afforded by the vaccination. However, it became evident that this intensive stimulation of the immune system lead not only to tumor eradication but also to destruction of cells bearing normal self antigens. Hence, 60 days after challenge with A20 cells all mice in the DC/IL2/CD40 ligand group developed a severe, systemic autoimmune disorder that resembled graft versus host disease and manifest itself by significant peripheral blood cytotoxicity against autologous fibroblasts, blood dyscrasias, gross hepatosplenomegaly, cachexia and fur loss. This phenomenon depended on CD8+ cytotoxic T lymphocytes. Our results therefore suggest that the most effective strategies of immunotherapy against leukemia may also exceed the threshold of anergic cells, leading to a loss of self tolerance to normal self-antigens and the induction of an CD8+ anti-self effector response.

Increased transduction efficiency of primary hematopoietic cells by physical colocalization of retrovirus and target cells

Efficient gene transfer into hematopoietic stem cells offers a number of potential therapeutic applications. However, the relatively low titer of retroviral supernatants and the requirement for cell division to ensure integration have meant that transduction efficiency has been low. We have modified a flowthrough approach to cell transduction and have been able consistently to increase gene transfer efficiency into human hematopoietic progenitor cells. We transduced CD34 cells with retroviral vectors encoding a truncated nerve growth factor receptor (NGFR) or neo. Retroviral supernatant was pulled through 0.2-micron polycarbonated membranes, followed by placement of cells on the filter. In the absence of cytokines, the transduction efficiency of CD34 cells with a NGFR vector was increased 3-11-fold over that obtained at an identical MOI in liquid culture to produce 11%-44% transduction. Furthermore, both Thy1+ and Thy1- subsets in a total CD34 population were transduced with similar efficiency, and transduction with a neo vector, as measured by G418 resistance in clonogenic assays, increased 1.5-5-fold. The mechanism by which gene transfer is improved may reflect colocalization of cells and retrovirus. Costaining of cells transduced on the filter with an NGFR retrovirus with both an NGFR antibody and a gp70 antibody that recognizes viral coat protein revealed high-level coexpression. The levels of in vitro gene transfer we obtain are equivalent to those observed when CD34 cells are cocultured in liquid culture with cytokines. However, culture with cytokines may commit CD34 cells to differentiation and has produced disappointingly low levels of subsequent in vivo gene transfer. Gene marking studies using distinguishable retroviral vectors will provide a means of learning whether the effects of flowthrough transduction genuinely enhance the efficiency of gene transfer to human marrow-repopulating cells.

CD40 ligand induces an antileukemia immune response in vivo

Leukemia cells may express tumor specific antigens in association with Class I and II major histocompatability complex (MHC) molecules. However, lack of expression of conventional costimulator molecules means that these cells tend to induce specific T-cell anergy rather than activation. CD40 ligand (CD40L) is a costimulator molecule that directly activates T cells and may promote antigen presentation by CD40-expressing cells, which include professional antigen presenting cells and B-acute lymphoblastic leukemia (ALL) cells from many patients. We determined whether transgenic expression of CD40L could enhance an antileukemia immune response using a CD40+ murine lymphoblastic (A20) leukemia and a CD40- myeloblastic (WEHI-3) leukemia in a tumor treatment model. Injection of otherwise nonimmunogenic A20 cells in the presence of CD40L induced an immune response active against preexisting A20 tumor at a distant site. Moreover, concomitant local secretion of transgenic interleukin-2 (IL-2) further amplified the antileukemic response induced and increased protection against preexisting tumor. In ex vivo studies, CD40 activation of A20 cells enhances the antigen presenting potential of A20 cells by upregulating expression of B7.1 (CD80), Class I and II MHC molecules, and increases expression of fas antigens. The importance of CD40 activation to the resulting antitumor response is further emphasized by the failure of transgenic CD40L to protect against the CD40- WEHI myeloblastic leukemia. Depletion studies showed the protective effects against A20 cells to be mediated by a combination of CD4+ and CD8+ T lymphocytes and by natural killer (NK) cells. These results suggest a means by which CD40+ leukemia cells may be rendered immunogenic in vivo.

A novel herpes vector for the high-efficiency transduction of normal and malignant human hematopoietic cells

Herpes simplex viruses (HSVs) would offer numerous advantages as vectors for gene transfer, but as yet they have not proved capable of transducing hematopoietic cells. Using a genetically inactivated form of HSV that is restricted to a single cycle of replication (disabled single-cycle virus, [DISC-HSV]), we have transduced normal human hematopoietic progenitor cells and primary leukemia blasts with efficiencies ranging from 80% to 100%, in the absence of growth factors or stromal support. Toxicity was low, with 70% to 100% of cells surviving the transduction process. Peak expression of transferred genes occurred at 24 to 48 hours after transduction with the DISC-HSV vector, declining to near background levels by 14 days. Despite this limitation, sufficient protein is produced by the inserted gene to permit consideration of the vector for applications in which transient expression is adequate. One example is the transfer of immunostimulatory genes, to generate leukemia immunogens. Thus, murine A20 leukemia cells transduced with a DISC-HSV vector encoding granulocyte-macrophage colony-stimulating factor were able to stimulate a potent antitumor response in mice, even against pre-existing leukemia. The exceptional transducing ability of the DISC-HSV vector should therefore facilitate genetic manipulation of normal and malignant human hematopoietic cells for biological and clinical investigation.

Combined chemokine and cytokine gene transfer enhances antitumor immunity

The probability of producing a specific antitumor response should be increased by multiplying the number of T lymphocytes that encounter the malignant cells. We tested this prediction in a murine model, using a recently discovered T-cell chemokine, lymphotactin (Lptn). This chemokine increased tumor cell infiltration with CD4+ lymphocytes but generated little antitumor activity. Coexpression of the T-cell growth factor interleukin-2, however, greatly expanded the T lymphocytes attracted by Lptn, affording protection from the growth of established tumor in a CD4+ and CD8+ T cell-dependent manner. Lesser synergy was seen with GM-CSF. Hence coexpression of a T-cell chemokine and T-cell growth factor potentiates antitumor responses in vivo, suggesting a general strategy to improve cancer immunotherapy.

Gene marking and gene therapy for transplantation medicine

The classic application for gene therapy is in the correction of single gene defects, although this has been complicated by the low efficiency of gene transfer into hematopoietic cells. Gene therapy, however, has potential for the modulation of tumor cell growth, drug sensitivity, and antitumor immune responses. In addition, gene marking can be used, in spite of this limited transfer efficiency, to provide information on hematopoiesis, sources of cancer relapse after stem cell transplant, and the relative efficacy of graft manipulation techniques. This article reviews the applications of gene therapy and gene marking in transplantation medicine.

Colocalization of retrovirus and target cells on specific fibronectin fragments increases genetic transduction of mammalian cells

Hematopoietic cells are important targets for genetic modification with retroviral vectors. Attempts at human gene therapy of stem cells have achieved limited success partly because of low gene transfer efficiency. Chymotryptic fragments of the extracellular matrix molecule fibronectin used during infection have been shown to increase transduction of human hematopoietic progenitor cells. Here, we demonstrate that this enhanced gene transfer into mammalian target cells is due to direct binding of retroviral particles to sequences within the fibronectin molecule. Transduction of mammalian cells, including murine long-term repopulating hematopoietic cells, is greatly enhanced when cells are adherent to chimeric fragments containing these retroviral binding sequences. In addition, colocalization of retrovirus and target cells on fibronectin peptides allows targeted transduction of specific cell types by exploiting unique ligand/receptor interactions.

High-efficiency transduction of freshly isolated human tumor cells using adenoviral interleukin-2 vectors

Tumor cells genetically modified to express immunostimulatory molecules can produce high levels of antitumor immunity in rodent models. Although a number of clinical trials are currently in progress to assess the value of the approach in human disease, almost all require ex vivo transduction of cultured tumor cells with retroviral vectors. This process is not feasible for many human malignancies, hampering clinical evaluation of the approach. We have used an E1a,1b/E3 deletion mutant of adenovirus containing either the lacZ or the human interleukin-2 (IL-2) gene to transduce human neuroblastoma cells. This vector transduces fresh neuroblastoma cells and neuroblastoma cell lines with an efficiency of 80-90%, compared to an efficiency of 0-14% obtained with retroviral vectors. Cells transduced with the IL-2 adenovector produce up to 12,000 pg of IL-2/10(6) cells/24 hr. IL-2 adenovector-transduced neuroblasts are immunostimulatory; when they are cultured with patient lymphocytes, they increase the proportion of DR+ T cells and generate major histocompatibility complex (MHC) unrestricted cytotoxic effector cells active against parental (nontransduced) tumor cells. We conclude that IL-2 adenovector can be used to transduce freshly isolated human tumor cells efficiently, which will then produce immunomodulatory quantities of the cytokine. The use of adenoviral rather than retroviral vectors facilitates preparation of human tumor "vaccines" and these vectors are now being used in our clinical study of neuroblastoma patients.

Differential production of interleukin-3 in human T lymphocytes following either CD3 or CD2 receptor activation

Interleukin-3 (IL-3) is expressed in T lymphocytes and stimulates the growth of multipotent hematopoietic progenitors. Little is known, however, about the stimuli that lead to IL-3 protein release. We examined IL-3 and granulocyte-macrophage colony-stimulating factor (GM-CSF) mRNA expression and protein secretion in human T lymphocytes following activation via the TCR/CD3 complex, the CD2 receptor, and the IL-2 receptor. GM-CSF mRNA expression and protein release were found in CD3 and CD2 activated T cells with maximum GM-CSF release following stimulation with IL-2. IL-3 protein release is regulated via the CD2 receptor with virtually no IL-3 release after T cell stimulation via CD3. In contrast, IL-3 mRNA accumulation is more pronounced after CD3 activation than after CD2 activation. This suggests that upregulation of IL-3 protein release following T cell stimulation via CD-2 occurs largely at the translational or posttranslational level. These data also indicate that differential control of cytokine production can occur in response to activation of the alternative T cell receptor. Interaction of the T cell CD2-receptor with its natural ligand LFA-3 expressed on stromal cells might represent a regulatory mechanism for rapid release of IL-3, facilitating proliferation of multipotent hematopoietic cells.

Time course of interferon-gamma production deficiency after autologous and allogeneic stem cell transplantation for malignancies

While success of autologous bone marrow transplantation (BMT) for malignancies largely depends on the cytotoxicity of the ablative regimen, achievement of relapse-free survival after allogeneic BMT is thought to be enhanced by immunologic effects. We therefore investigated in vivo and in vitro production of interferon-gamma (IFN-gamma), soluble interleukin-2 (IL-2) receptor alpha-chain (sCD25), tumor necrosis factor-alpha (TNF-alpha), and granulocyte-macrophage colony-stimulating factor (GM-CSF) in patients before and during various time periods up to 2 years after autologous and allogeneic BMT. Cytokine levels were assessed in patient plasma and in supernatants of patient-derived peripheral blood mononuclear cells (PBMNC) cultured for 3 days in the presence of T cell-specific stimulation via CD3 plus IL-2. Our studies show that IFN-gamma plasma levels are decreased in autologous graft recipients before and during the first 30 days posttransplant. In allogeneic graft recipients, IFN-gamma plasma levels are also decreased during the first 30 days posttransplant, but otherwise are comparable to normal control (NC) values. In vitro stimulated PBMNC from autologous graft recipients also exhibit an IFN-gamma production defect before and during the first 30 days posttransplant. In contrast, before and up to 30 days after allogeneic BMT, stimulated IFN-gamma production is comparable to NC values but then gradually decreases, reaching its trough levels at between 61 and 180 days post-BMT. The IFN-gamma production defects in both patient groups seem to be specific, as sCD25, TNF-alpha, and GM-CSF production in stimulated PBMNC is normal or even enhanced at any time after autologous or allogeneic BMT. Deficient IFN-gamma production in patient-derived PBMNC does not correlate with variation in monocyte, T cell, or natural killer (NK) cell numbers during the posttransplantation course.

Bone marrow fibroblasts from children with aplastic anemia exhibit reduced interleukin-6 production in response to cytokines and viral challenge

Defects of the bone marrow microenvironment have been implicated in the pathogenesis of aplastic anemia (AA). We examined granulocyte/macrophage colony-stimulating factor (GM-CSF) and IL-6 production in bone marrow fibroblasts from five children with AA in response to cytokines and viral challenge with cytomegalovirus (CMV). Cytokine-stimulated IL-6 production in patients' fibroblasts was significantly reduced, whereas GM-CSF production was found to be comparable to normal controls. Also, CMV-mediated stimulation of IL-6 production was significantly lower in bone marrow fibroblasts from patients with AA. During the late phase of CMV-infection, IL-6 production was suppressed in CMV-infected fibroblasts from patients with AA with 90% inhibition of IL-6 protein production and marked reduction in IL-6 mRNA accumulation. Defective IL-6 production in bone marrow fibroblasts might contribute to hematopoietic suppression in some patients with AA.