Donor specific anti-HLA antibodies in hematopoietic stem cell transplantation. Single Center prospective evaluation and desensitization strategies employed

BACKGROUND

In the setting of mismatched-hematopoietic stem cells transplantation, the detection of antibodies directed against donor-specific HLA allele(s) or antigen(s) (DSA) represents a barrier for engraftment. It is thus necessary to plan an immunosuppressive strategy, or to select an alternative donor. This prospective study aimed at evaluating the efficacy of our strategy for testing DSAs and the efficacy of the desensitization strategy (DS) employed between November 2017 and November 2020.

MATERIALS AND METHODS

The anti-HLA antibody search was performed using the Luminex bead assays (Lifecode ID and LSA I/II-Immucor) and expressed as mean fluorescence intensity (MFI >1,000 positive). If the patient had DSAs and no alternative donors, a DS was employed with rituximab (day -15), 2 single volume plasmaphereses (PP; days -9 and -8), intravenous immunoglobulins (day -7) and infusion of HLA selected platelets, if persistent DSAs were directed against class I HLA. DS was scheduled with or without PP, according to the DSA MFI (>1,000 or <5,000) and FCXM (flow cytometry crossmatch).

RESULTS

Twenty-two out of 126 patients (17.46%) showed anti-HLA antibodies, 5 of them DSAs (3.97% of total); 3 patients underwent DS obtaining engraftment. Female gender (p=0.033) and a history of previous pregnancies or miscarriages (p=0.009) showed a statistically significant impact on alloimmunization. Factors associated with a delayed neutrophil engraftment were patient's female gender (p=0.039), stem cell source (p=0.025), and a high HSCT-specific comorbidity index (p=0.028). None of the analyzed variables, including the DSA detection, influenced engraftment.

CONCLUSIONS

Our study confirms the importance to test DSAs in mismatched-hematopoietic stem cells transplantation The DS used proved successful in removing DSAs. Prospective multicenter studies are needed to better define and validate consensus strategies on DSA management in HSCT.

Peripherally inserted central venous catheter for pediatric acute leukemia: A retrospective 11-year single-center experience

BACKGROUND

Peripherally inserted central catheters (PICCs) are successfully increasingly used in children in onco-hematologic setting. PICC insertion, especially in oncologic patients, can be associated with adverse events (thrombosis, mechanical complications, and infections). Data regarding the use of PICC, as long-term access in pediatric patients with severe hematologic diseases, are still limited.

METHODS

We retrospectively evaluated the safety and efficacy of 196 PICC, inserted in 129 pediatric patients with acute leukemia diagnosed and treated at Pediatric Hematology Unit, Sapienza University of Rome.

RESULTS

The 196 PICC analyzed were in situ for a median dwell time of 190 days (range 12-898). In 42 children, PICC was inserted twice and in 10, three times or more due to hematopoietic stem cell transplant, disease recurrence, or PICC-related complications. The overall complication rate was 34%: catheter-related bloodstream infections (CRBSI) occurred in 22% of cases after a median time of 97 days; a catheter-related thrombosis (CRT) in 3.5% and mechanical complications in 9% of cases. Premature removal for complications occurred in 30% of PICC. One death from CRBSI was observed.

CONCLUSIONS

To our knowledge, this study represents the largest cohort of pediatric patients who have inserted the PICC for acute leukemia. In our experience, PICC was a cheap, safe, and reliable device for long-term intravenous access in children with acute leukemia. This has been possible with the help of dedicated PICC team.

Case Report: Severe cutaneous adverse event associated with checkpoint inhibition in the setting of CAR T-cell therapy: beyond CRS

Anti-CD19 chimeric antigen receptor (CAR) T cell therapy actually represents the standard of care for multiple relapsed or refractory primary mediastinal B-cell lymphoma (r/r PMBCL). Checkpoint inhibitors, such as pembrolizumab, appear to be a safe and effective treatment strategy for patients who are ineligible for or resistant to autologous stem cell transplantation. Although preclinical studies suggested that checkpoint inhibitors may enhance the vitality and anti-tumor activity of CAR T cells, there are no substantial/robust clinical data about the immune-mediated toxicity of their association. We describe a case of a severe cutaneous adverse event arising immediately after Cytokine Release Syndrome (CRS) on day +6 from CAR T cells infusion in a young r/r PMBCL patient who previously received pembrolizumab. These skin lesions were interpreted as an immune mediated adverse event, considering their prompt improvement and fully recovering achieved with the addition of immunoglobulin infusion to systemic steroid therapy. This case of life-threatening cutaneous adverse event calls for further investigations about off-target immune-related adverse events deriving from the combination of CAR T cell therapy and checkpoint inhibition, whose synergic therapeutic effect is promising.

Pediatric Autologous Hematopoietic Stem Cell Transplantation: Safety, Efficacy, and Patient Outcomes. Literature Review

Autologous stem cell transplantation (auto-HSCT) is a part of the therapeutic strategy for various oncohematological diseases. The auto-HSCT procedure enables hematological recovery after high-dose chemotherapy, otherwise not tolerable, by the infusion of autologous hematopoietic stem cells. Unlike allogeneic transplant (allo-HSCT), auto-HSCT has the advantage of lacking acute-graft-versus-host disease (GVHD) and prolonged immunosuppression, however, these advantages are counterbalanced by the absence of graft-versus-leukemia. Moreover, in hematological malignancies, the autologous hematopoietic stem cell source may be contaminated by neoplastic cells, leading to disease reappearance. In recent years, allogeneic transplant-related mortality (TRM) has progressively decreased, almost approaching auto-TRM, and many alternative donor sources are available for the majority of patients eligible for transplant procedures. In adults, the role of auto-HSCT compared to conventional chemotherapy (CT) in hematological malignancies has been well defined in many extended randomized trials; however, such trials are lacking in pediatric cohorts. Therefore, the role of auto-HSCT in pediatric oncohematology is limited, in both first- and second-line therapies and still remains to be defined. Nowadays, the accurate stratification in risk groups, according to the biological characteristics of the tumors and therapy response, and the introduction of new biological therapies, have to be taken into account in order to assign auto-HSCT a precise role in the therapeutic strategies, also considering that in the developmental age, auto-HSCT has a clear advantage over allo-HSCT, in terms of late sequelae, such as organ damage and second neoplasms. The purpose of this review is to report the results obtained with auto-HSCT in the different pediatric oncohematological diseases, focusing on the most significant literature data in the context of the various diseases and discussing this data in the light of the current therapeutic landscape.

Benefits and Safety of Empiric Antibiotic Treatment Active Against KPC-K. pneumoniae in Febrile Neutropenic Patients with Acute Leukemia Who are Colonized with KPC-K. pneumoniae. A 7-Years Retrospective Observational Cohort Study

Purpose

To evaluate the benefits and safety of the empiric antibiotic treatment (EAT) active against KPC-K. pneumoniae in febrile neutropenic patients with acute leukaemia (AL) who are colonised by KPC-K. pneumoniae.

Patients and Methods

A 7-year (2013-2019) retrospective observational cohort study was conducted at the Haematology, Sapienza Rome University (Italy) on 94 febrile neutropenia episodes (FNE) in AL patients KPC-K. pneumoniae carriers treated with active EAT.

Results

Eighty-two (87%) FNE were empirically treated with antibiotic combinations [38 colistin-based and 44 ceftazidime-avibactam (CAZAVI)-based], 12 with CAZAVI monotherapy. Successful outcomes were observed in 88/94 (94%) FNE, 46/49 (94%) microbiologically documented infections, and 24/27 (89%) gram-negative bloodstream infections (GNB-BSI). Mortality due to infective causes was 4.2% (2.1% within 1 week). KPC-K. pneumoniae infections caused 28/94 FNE (30%) and KPC-K. pneumoniae-BSI was documented in 22 FNE (23.4%) (85% of GNB-BSI), in all cases patients received active EAT, and 21 survived. KPC-K.pneumoniae-BSI mortality rate was 4.5%. CAZAVI-based EAT showed better results than colistin-based EAT (55/56 vs 33/38, p = 0.037), overall and without EAT modification (41/56 vs 20/38, p = 0.02). Empirical combinations including CAZAVI were successful in 98% of cases (43/44 vs 33/38 for colistin-based EAT, p = 0.01), without modifications in 82% (36/44 vs 20/28, p = 0.02). All deaths occurred in patients treated with colistin-based EAT (4/38 vs 0/56, p = 0.02). CAZAVI-containing EAT was the only independent factor for an overall successful response (HR 0.058, CI 0.013-1.072, p = 0.058). Nephrotoxicity occurred in 3(8%) patients undergoing colistin-based EAT (none in those undergoing CAZAVI-based EAT, p = 0.02).

Conclusion

KPC-K. pneumoniae infections are frequent in colonised AL patients with FNE. EAT with active antibiotics, mainly CAZAVI-based combinations, was effective, safe, and associated with low overall and KPC-K. pneumoniae-BSI-related mortality.

Reduced mortality from KPC-K.pneumoniae bloodstream infection in high-risk patients with hematological malignancies colonized by KPC-K.pneumoniae

BACKGROUND

KPC-K.pneumoniae bloodstream infection (KPC-KpBSI) mortality rate in patients with hematological malignancies is reported about 60%. The initial treatment active against KPC-K.pneumoniae is crucial for survival and KPC-K.pneumoniae rectal colonization usually precedes KPC-KpBSI. We evaluated the impact on KPC-KpBSI mortality of the preemptive use of antibiotics active against KPC-K.pneumoniae, as opposed to inactive or standard empiric antibiotics, for the empiric treatment of febrile neutropenia episodes in patients with hematological malignancy identified as KPC-K.pneumoniae intestinal carriers.

METHODS

We compared the outcomes of KPC-KpBSIs occurring in high-risk hematological patients known to be colonized with KPC-K.pneumoniae, during two time periods: March2012-December2013 (Period 1, initial approach to KPC-K.pneumoniae spread) and January2017-October2018 (Period 2, full application of the preemptive strategy). The relative importance of the various prognostic factors that could influence death rates were assessed by forward stepwise logistic regression models.

RESULTS

KPC-KpBSI-related mortality in hematological patients identified as KPC-K.pneumoniae carriers dropped from 50% in Period 1 to 6% in Period 2 (p < 0.01), from 58 to 9% in acute myeloid leukemia carriers(p < 0.01). KPC-KpBSIs developed in patients identified as KPC-K.pneumoniae carriers were initially treated with active therapy in 56% and 100% of cases in Period 1 and Period 2, respectively (p < 0.01), in particular with an active antibiotic combination in 39 and 94% of cases, respectively(p < 0.01). The 61% of KPC-KpBSI observed in Period 1 developed during inactive systemic antibiotic treatment (none in Period 2, p < 0.01), fatal in the 73% of cases. Overall, KPC-KpBSI-related mortality was 88% with no initial active treatment, 11.5% with at least one initial active antibiotic (p < 0.01), 9% with initial active combination. Only the initial active treatment resulted independently associated with survival.

CONCLUSIONS

In high-risk hematological patients colonized by KPC-K.pneumoniae, the empiric treatment of febrile neutropenia active against KPC-K.pneumoniae reduced KPC-KpBSI-related mortality to 6% and prevented fatal KPC-KpBSI occurrence during inactive systemic antibiotic treatment.

Photo-Biomodulation as a Prevention Modality of Oral Mucositis in Patients Undergoing Allogeneic Hematopoietic Stem Cell Transplantation

The aim of the study was to observe the effectiveness of a photo-biomodulation (PBM) protocol for the prevention of oral mucositis (OM) in patients undergoing allogeneic hematopoietic stem cell transplantation (aHSCT). A case-control study was conducted on 40 patients undergoing aHSCT. The patients were divided into two groups; the preventive group (PG) included 20 patients (7 females and 13 males) who were subjected to intra-oral PBM for five sessions a week, starting one day before the conditioning regimen and continuing until the 10th day after transplantation (D+10). In each session, ten points on the at-risk mucosal surfaces were irradiated using a double diode laser that emits two wavelengths simultaneously at 650 nm and at 904–910 nm with the following parameters at each point: energy of 4 J, and power of 88.9 mW. The control group (CG) included 20 patients (10 females and 10 males) who were not subjected to laser therapy and were selected retrospectively to compare the obtained results. For all patients, OM was assessed by the World Health Organization (WHO) grading scale. Eight patients in the PG did not experience OM during their hospitalization period (with grade 0). Severe OM was observed in 40% of the patients in the PG, while in the CG, severe OM was shown in 85% of the patients. The mean duration of OM in the PG was significantly lower than that of CG (4.7 days in the PG and 15 days in the CG) (p < 0.001). The study demonstrated that the preventive PBM protocol reduced the severity and duration of OM in patients undergoing aHSCT.

Voriconazole treatment in adults and children with hematological diseases: can it be used without measurement of plasma concentration?

Indication and timing of trough plasma-voriconazole (VCZ)-concentration (t-PVC) measurement during VCZ treatment is a debated issue. Patterns of t-PVC were prospectively evaluated in pediatric (50 courses) and adult (95 courses) hematologic patients. Efficacy patterns were defined: adequate, t-PVC always ≥1 mcg/ml; borderline, at least one t-PVC measurement <1 mcg/ml but median value of the measurements ≥1 mcg/ml; inadequate, median value of the measurements <1 mcg/ml. Toxicity patterns were defined: favorable, t-PVC always ≤5 mcg/ml; borderline, one or more t-PVC measurements >5 mcg/ml but median value of the measurements ≤5 mcg/ml; unfavorable, median value of the measurements >5 mcg/ml. In children and adults the mean t-PVCs were higher during intravenous treatments. The t-PVC efficacy pattern was adequate, borderline and inadequate in 48%, 12%, and 40% of courses, respectively, in children, and in 66.3%, 16.8%, and 16.8% of courses, respectively, in adults. Adequate efficacy pattern was more frequent in children with body weight above the median (≥25 kg) (OR 4.8; P = .011) and in adults with active hematological disease receiving intravenous therapy (OR 3.93; P = .006). Favorable toxicity pattern was more frequent in children receiving VCZ daily dosage below the median (<14 mg/kg) (OR 4.18; P = .027) and in adults with body weight below the median (<68 kg) (OR 0.22; P = .004). T-PVC measurement is generally needed, however, a non t-PVC guided approach may be considered in heavier adults receiving intravenous VCZ. The risk of supratherapeutic levels does not seem an absolute indication for t-PVC monitoring.

Enterovirus D68-Associated Acute Flaccid Myelitis in Immunocompromised Woman, Italy

In Italy in 2016, acute flaccid myelitis developed in a woman who had received a hematopoietic stem cell transplant. Enterovirus D68 viral genome was detected in respiratory and cerebrospinal fluid samples, and the viral protein 1 sequence clustered with lineage B3. Immunocompromised adults may be at risk for enterovirus D68-associated neurologic complications.

Reappraising the timing of transplant for indolent non-Hodgkin lymphomas

INTRODUCTION

Indolent non-Hodgkin lymphomas (iNHL) remain incurable with standard approaches. The timing of autologous stem cell transplant (ASCT) is changing following the introduction of new drugs that can potentially defer the transplant, improved reduced intensity conditioning (RIC) and haploidentical allogeneic SCT (allo-SCT).

AREAS COVERED

The most relevant aspects concerning the role of hematopoietic stem cell transplantation in the management of iNHL are discussed. Literature search methodology included examination of PubMed index and meeting presentations. Expert commentary: ASCT is not currently employed as consolidation in first-line, being reserved to patients with refractory/relapsed disease. The curative potential of graft-versus-lymphoma (GVL) after RIC allo-SCT could be particularly beneficial in patients with iNHL relapsing after ASCT. This scenario could be modified in the near future by better definition of high-risk patients at diagnosis, by the improvement of minimal residual disease (MRD) evaluation and by the introduction of new drugs in the therapeutic algorithm.

Can chronic myeloid leukaemia in children and adolescents be successfully treated without haematopoietic stem cell transplant? A single centre experience

We analysed the long-term outcome of 35 children and adolescents (<20 years at diagnosis) with chronic myeloid leukaemia (CML) in chronic phase: 20 patients had received interferon-alpha and/or tyrosine kinase inhibitors (TKIs), and 15 underwent a haematopoietic stem cell transplant. The 10-year survival probabilities were similar in transplanted and non-transplanted patients (73·3% vs. 72·1%, respectively), whereas the survival probability was significantly lower in patients diagnosed before 1999 compared to those diagnosed afterwards (62·1% vs. 100%, P = 0·0384). The availability of TKIs and the standardized molecular monitoring have significantly improved treatment, management and outcome in children and adolescents with CML.

Catheter-associated bloodstream infections and thrombotic risk in hematologic patients with peripherally inserted central catheters (PICC)

PURPOSE

The use of peripherally inserted central catheters (PICC) as an alternative to other central venous access devices (CVAD) is becoming very frequent in cancer patients. To evaluate the impact of complications associated to these devices in patients with hematologic malignancies, we revised the catheter-related bloodstream infections (CRBSI) and the catheter-related thrombotic complications (CRTC) observed at our institute between January 2009 and December 2012.

METHODS

A total of 612 PICCs were inserted into 483 patients at diagnosis or in subsequent phases of their hematologic disease. PICCs were successfully inserted in all cases. The median duration of in situ PICC placement was 101 days (interquartile range, 48-184 days).

RESULTS

A CRBSI occurred in 47 cases (7.7 %), with a rate of 0.59 per 1000 PICC days. A CRTC was recorded in 16 cases (2.6 %), with a rate of 0.20 per 1000 PICC days. No serious complication was associated to these events. Cox regression analyses of variables associated to CRBSIs and to CRTCs showed that only the type of disease (acute leukemia compared to other diseases) was significantly associated to a higher incidence of CRBSIs, while no feature was predictive for a higher risk of CRTCs.

CONCLUSIONS

PICCs represent a useful and safe alternative to conventional CVAD for the management of patients with hematologic malignancies.

Proven Epstein-Barr encephalitis with negative EBV-DNA load in cerebrospinal fluid after allogeneic hematopoietic stem cell transplantation in a child with acute lymphoblastic leukemia

We report a case of EBV encephalitis in a seven-yr-old child with Ph+ ALL. Two months after an allogeneic HSCT from his HLA mismatched mother, the patient showed an altered sensorium, generalized seizures, and a left hemiparesis. Brain MRI demonstrated multiple lesions highly suggestive for viral encephalitis. Blood and CSF PCR analyses were negative for the most common viruses involved in immunocompromised patients including EBV. A cerebral biopsy was performed, which showed intense gliosis and perivascular lymphocytic cuffing. PCR analysis performed on brain tissue was positive only for the EBV genome, while extensive investigations for other viral infections were negative. The patient's neurological symptoms rapidly worsened and he died two months later. This case report suggests that in patients presenting neurological and radiological signs of encephalitis after an HSCT, an EBV involvement should be considered, even in the absence of CSF and blood PCR virus detection.

Selective splenic artery embolization for the treatment of thrombocytopenia and hypersplenism in paroxysmal nocturnal hemoglobinuria

Background

PNH is associated with abdominal vein thrombosis, which can cause splenomegaly and hypersplenism. The combination of thrombosis, splenomegaly, and thrombocytopenia (TST) is challenging because anticoagulants are indicated but thrombocytopenia may increase the bleeding risk. Splenectomy could alleviate thrombocytopenia and reduce portal pressure, but it can cause post-operative thromboses and opportunistic infections. We therefore sought to determine whether selective splenic artery embolization (SSAE) is a safe and effective alternative to splenectomy for TST in patients with PNH.

Methods

Four patients with PNH and TST received successive rounds of SSAE. By targeting distal vessels for occlusion, we aimed to infarct approximately 1/3 of the spleen with each procedure.

Results

Three of 4 patients had an improvement in their platelet count, and 3 of 3 had major improvement in abdominal pain/discomfort. The one patient whose platelet count did not respond had developed marrow failure, and she did well with an allo-SCT. Post-procedure pain and fever were common and manageable; only one patient developed a loculated pleural effusion requiring drainage. One patient, who had had only a partial response to eculizumab, responded to SSAE not only with an improved platelet count, but also with an increase in hemoglobin level and decreased transfusion requirement.

Conclusions

These data indicate that SSAE can decrease spleen size and reverse hypersplenism, without exposing the patient to the complications of splenectomy. In addition, SSAE probably reduces the uptake of opsonised red cells in patients who have had a limited response to eculizumab, resulting in an improved quality of life for selected patients.

Recognition of adult and pediatric acute lymphoblastic leukemia blasts by natural killer cells

In this study, we aimed to investigate the pathways of recognition of acute lymphoblastic leukemia blasts by natural killer cells and to verify whether differences in natural killer cell activating receptor ligand expression among groups defined by age of patients, or presence of cytogenetic/molecular aberrations correlate with the susceptibility to recognition and killing. We analyzed 103 newly diagnosed acute lymphoblastic leukemia patients: 46 adults and 57 children. Pediatric blasts showed a significantly higher expression of Nec-2 (P=0.03), ULBP-1 (P=0.01) and ULBP-3 (P=0.04) compared to adult cells. The differential expression of these ligands between adults and children was confined to B-lineage acute lymphoblastic leukemia with no known molecular alterations. Within molecularly defined subgroups of patients, a high surface expression of NKG2D and DNAM1 ligands was found on BCR-ABL(+) blasts, regardless of patient age. Accordingly, BCR-ABL(+) blasts proved to be significantly more susceptible to natural killer-dependent lysis than B-lineage blasts without molecular aberrations (P=0.03). Cytotoxic tests performed in the presence of neutralizing antibodies indicated a pathway of acute lymphoblastic leukemia cell recognition in the setting of the Nec-2/DNAM-1 interaction. These data provide a biological explanation of the different roles played by alloreactive natural killer cells in pediatric versus adult acute lymphoblastic leukemia and suggest that new natural killer-based strategies targeting specific subgroups of patients, particularly those BCR-ABL(+), are worth pursuing further.

Molecular analysis of Fanconi anemia: the experience of the Bone Marrow Failure Study Group of the Italian Association of Pediatric Onco-Hematology

Fanconi anemia is an inherited disease characterized by congenital malformations, pancytopenia, cancer predisposition, and sensitivity to cross-linking agents. The molecular diagnosis of Fanconi anemia is relatively complex for several aspects including genetic heterogeneity with mutations in at least 16 different genes. In this paper, we report the mutations identified in 100 unrelated probands enrolled into the National Network of the Italian Association of Pediatric Hematoly and Oncology. In approximately half of these cases, mutational screening was carried out after retroviral complementation analyses or protein analysis. In the other half, the analysis was performed on the most frequently mutated genes or using a next generation sequencing approach. We identified 108 distinct variants of the FANCA, FANCG, FANCC, FANCD2, and FANCB genes in 85, 9, 3, 2, and 1 families, respectively. Despite the relatively high number of private mutations, 45 of which are novel Fanconi anemia alleles, 26% of the FANCA alleles are due to 5 distinct mutations. Most of the mutations are large genomic deletions and nonsense or frameshift mutations, although we identified a series of missense mutations, whose pathogenetic role was not always certain. The molecular diagnosis of Fanconi anemia is still a tiered procedure that requires identifying candidate genes to avoid useless sequencing. Introduction of next generation sequencing strategies will greatly improve the diagnostic process, allowing a rapid analysis of all the genes.

Outcome of patients activating an unrelated donor search for severe acquired aplastic anemia

Patients with severe aplastic anemia (SAA) without a sibling donor receive immunosuppressive treatment (IST) with anti-thymocyte globulin (ATG). In the case of no response to IST, a voluntary unrelated donor (VUD) search is usually started. This study analyzes the outcome of ATG-refractory SAA patients activating a VUD search. Of 179 patients, 68 had at least one HLA-A, -B, and -DR matched donor identified and underwent HSCT while 50 also with a donor were not transplanted because of early death (8), late response to IST (34), transplant refusal (1), or other (7). Conversely, 61 had no matched donor, 13 of those ultimately received a mismatched HSCT. All but one received marrow stem cells. Among patients aged <17 years, those with at least one matched donor had a significant higher 4-year survival as compared to others (79% ± 6% versus 53% ± 10%, P = 0.01). There was also a survival advantage independent of recipient age when the donor search was initiated in the recent 2000-2005 study-period (74% ± 6% versus 47% ± 10%, P < 0.05). In multivariate analysis, the identification of a matched VUD tended to impact favourably on survival in patients with a recent donor search (P = 0.07). This study provides evidence for the use of unrelated donor HSCT in children and adults with IST-refractory SAA.

Concurrent search for unrelated cord and volunteer donor in high-risk acute lymphoblastic leukemia

To assess the effectiveness of the search for an unrelated donor on the outcome of patients with high-risk acute lymphoblastic leukemia, we analyzed prospectively 136 patients who underwent a search for cord blood (CB) and an unrelated volunteer donor (UD) at the same time. The probability of finding a donor was 58.2%, 70.3%, and 75.7% at 3, 6, and 12 months, respectively. The median time to find a donor was 1.8 months for CB and 3.5 months for UD. Of the 99 patients with a donor, 38.4% failed to undergo the transplant because of a relapse observed at a median of 4 months from the start of the search. In univariate analysis, absence of relapse during the search (p < 0.0001) and transplant (p = 0.004) showed a positive impact on long-term survival. In multivariate analysis, relapse during the search remained the key factor affecting survival (p < 0.0001). Since an extension of the search beyond 3 months enables only a slight increase in the probability of finding a donor compared to the increased risk of relapse, the time of the search should not exceed the 3-month time point. The simultaneous search for CB and UD increases the likelihood of performing a timely transplant.

The immune reconstitution after an allogeneic stem cell transplant correlates with the risk of graft-versus-host disease and cytomegalovirus infection

Aim of the study was to correlate the clinical outcome of eighteen patients who have undergone an allogeneic stem cell transplant (SCT) with the concentration in the peripheral blood (PB) of lymphocyte subpopulations evaluated at 1 year from transplant. The occurrence of acute GVHD and CMV infection correlated with the concentration of Tregs in the PB; CMV infection also correlated with the content of NK cells. The obtained results document that the concentration of Tregs in the PB after an allogeneic SCT may protect from GVHD and from CMV infection; the potential anti-viral role of NK cells is confirmed.

Clofarabine, cyclophosphamide and etoposide as single-course re-induction therapy for children with refractory/multiple relapsed acute lymphoblastic leukaemia

The safety and efficacy of the combination clofarabine/cyclophosphamide/etoposide were evaluated in children with advanced acute lymphoblastic leukaemia (ALL). The study enrolled 25 paediatric patients (median age 12.5 years) with either refractory (n = 17; 68%) or multiple relapsed (n = 8; 32%) ALL to receive clofarabine 40 mg/m(2), cyclophosphamide 400 mg/m(2) and etoposide 150 mg/m(2), daily for 5 consecutive days. No patient died from treatment-related complications. The most common adverse events were febrile neutropenia, mucositis and reversible liver toxicity; no case of liver veno-occlusive disease was reported. The overall remission rate was 56%: 13 patients (52%) achieved complete remission (CR) and one (4%) CR without platelet recovery (CRp). In seven of the 13 (54%) patients achieving CR, remissions were of sufficient duration to allow patients to receive allogeneic haematopoietic stem cell transplantation. The probability of CR/CRp was greater in the 17 patients with B cell precursor ALL than in the eight with T-ALL (76% vs. 12%, respectively, P < 0.01). The 18-month overall survival probability was 39% and 0% in patients who did or did not respond to the treatment, respectively (P < 0.01). These data suggest that the clofarabine/cyclophosphamide/etoposide regimen is well tolerated and can induce clinical response in a relevant proportion of children with refractory/multiple relapsed ALL.

Human mesenchymal stem cells inhibit antibody production induced in vitro by allostimulation

BACKGROUND

Antibodies directed against alloantigens are implicated in the pathogenesis of several immune reactions complicating transplantation, including humoral rejection after solid organ transplantation. Mesenchymal stem cells (MSCs) have immunomodulatory capacity, since in vivo they may prolong skin graft survival in the animal model and can rescue patients with life-threatening graft-versus-host disease.

METHODS

To investigate whether MSCs exert an inhibitory effect on antibody production during allostimulation, we stimulated peripheral blood mononuclear cells, obtained from healthy controls or sensitized patients undergoing dialysis for end-stage renal failure, in mixed lymphocyte culture (MLC), and evaluated immunoglobulin production either in the absence or in the presence of third-party allogeneic MSCs. We also evaluated the effect of MSCs on B-cell allostimulation performed adding to MLC a polyclonal stimulus delivered by an agonist anti-CD40 monoclonal antibody.

RESULTS

We found that the addition of MSCs at the beginning of MLC considerably inhibited immunoglobulin production in standard MLC, irrespective of the MSC dose employed. Conversely, immunoglobulin secretion induced by direct CD40-CD40L binding was not significantly inhibited. Furthermore, we demonstrated, in one sensitized patient, that secretion of donor-specific anti-HLA class I antibodies detected both in baseline serum and in the supernatant of control MLC was inhibited by the addition of MSCs. Mechanistically, the addition of MSCs induced a striking decrease of IL-5 production in the cultures.

CONCLUSIONS

Our findings suggest that third-party MSC are able to suppress allo-specific antibody production in vitro, and may therefore help overcome a positive cross-match in sensitized transplant recipients.

Unrelated cord blood transplant in children with high-risk acute lymphoblastic leukemia: a long-term follow-up

BACKGROUND AND OBJECTIVES

The aim of this single center study was to assess the impact of pre-transplant factors on long-term follow-up in young patients affected by high-risk acute lymphoblastic leukemia (ALL) who underwent an unrelated cord blood transplant (CBT). The conditioning regimens, graft-versus-host disease (GVHD) prophylaxis and supportive policies were uniform for all patients.

DESIGN AND METHODS

We analyzed the results of CBT performed in 30 patients, aged <18 years, affected by high risk ALL. As conditioning regimen, all patients received 12 Gy fractionated total body irradiation, etoposide, cyclophosphamide and horse anti-lymphocyte globulin. GVHD prophylaxis consisted of 6-methylprednisolone and cyclosporine A. RESULTS The cumulative incidence of engraftment was 93% (95% CI:0.85-0.93). The cumulative incidence of grade III-IV acute and chronic GVHD was 7% (95% CI:0.01-0.19) and 33% (95% CI: 0.17-0.64), respectively. The 9-year cumulative incidence of transplant-related mortality and relapse was 34% (95% CI:0.13-0.45) and 31% (95% CI:0.16-0.61), respectively. The 9-year overall survival, leukemia-free survival and event-free survival were 42% (95% CI:0.52-0.93), 47% (95% CI:0.25-0.61) and 46% (95% CI:0.33-0.61), respectively. A number of CFU-GM <1 x 10(4)/Kg of recipient body weight was the only factor that negatively affected all outcome parameters both in univariate and multivariate analyses.

INTERPRETATION AND CONCLUSIONS

The infused cell dose expressed as in vitro progenitor cell growth represents the most important pre-transplant factor affecting the long-term outcome after an unrelated CBT in young patients with high risk ALL. The number of CFU-GM should thus be considered in the selection process of cord blood units for transplant.

CODOX-M/IVAC (NCI 89-C-41) in children and adolescents with Burkitt's leukemia/lymphoma and large B-cell lymphomas: a 15-year monocentric experience

During the last 15 years, we have used the National Cancer Institute (NCI) 89-C-41 protocol in patients aged younger than 21 years with Burkitt's leukemia/lymphoma (BLL) and diffuse large B-cell lymphoma (DLBCL). According to the Magrath staging system, patients were classified as low and high risk. Low-risk received three cycles of the CODOX-M regimen; high-risk patients received four alternating cycles with the CODOX-M and IVAC regimens. Thirty-five patients entered the study: 32 (91%) achieved complete remission (CR); three were non-responders and died and one patient died in CR. Two responders relapsed after 2 months and one presented early B acute lymphoblastic leukemia 33 months from the end of therapy. The 5-year overall survival and event free-survival are 83% and 80%, respectively. No late toxicity was registered. In our experience with a median follow-up of 11 years, the NCI 89-C-41 protocol has confirmed its high cure rate in BLL and DLBCL children and adolescents.

Preemptive therapy of EBV-related lymphoproliferative disease after pediatric haploidentical stem cell transplantation

The treatment of Epstein-Barr virus (EBV)-related post-transplant lymphoproliferative disease (PTLD) after hematopoietic stem cell transplantation (HSCT) is still unsatisfactory. We conducted a prospective trial to evaluate the impact of routine EBV surveillance and preemptive treatment with the anti-CD20 monoclonal antibody rituximab on the development of PTLD in pediatric recipients of extensively T-cell depleted HSCT from an HLA-haploidentical relative. Twenty-seven patients were included in the surveillance program, 12 developed EBV DNA positivity, with 8 of 12 presenting with sustained viral DNA levels requiring treatment with rituximab. Treatment was well tolerated, and induced clearance of EBV DNA in all patients. However, 4/8 patients showed a new increase in EBV load, coincident with the emergence of CD20(-)/CD19(+) B cells in peripheral blood, accompanied by overt PTLD in 3 patients. The latter cleared PTLD after receiving donor EBV-specific cytotoxic T-lymphocytes (CTLs), and persist in remission at a median 30-month follow-up. EBV-specific T-cell frequency, undetectable at time of EBV DNA positivity, was restored by T-cell therapy to levels comparable with controls. We conclude that preemptive therapy with rituximab is safe, but only partly effective in haplo-HSCT recipients. Patients who progress to PTLD under rituximab treatment can be rescued permanently by infusion of EBV-specific CTLs.

Breakthrough Candida krusei fungemia during fluconazole prophylaxis followed by breakthrough zygomycosis during caspofungin therapy in a patient with severe aplastic anemia who underwent stem cell transplantation

We report a case of breakthrough invasive zygomycosis in a stem cell transplant recipient who was receiving caspofungin for treatment of a breakthrough Candida krusei fungemia that occurred during fluconazole prophylaxis. Also, patients receiving the echinocandin caspofungin remain at risk for pathogens, such as zygomycetes, that are intrinsically resistant to this agent.