Haploidentical transplantation for acute lymphoblastic leukemia in childhood

Efficacy and Reliability of T-Cell-Depleted Haploidentical Stem Cell Transplantation in Hematologic Disorders: A Retrospective Study

BACKGROUND

A promising recent strategy for haploidentical transplantation is the depletion of T lymphocytes based on the selective elimination of T cells by manipulation, which enables a very low incidence of nonrelapse mortality and graft-vs-host disease. It is more expensive than conventional unmanipulated methods and requires dedicated transplant centers and sufficient stem cell processing facilities. This retrospective study aimed to evaluate the relapse, survival, and clinical data of the patients and to analyze the outcomes of the technique.

METHODS

The study included 56 adult patients who underwent haploidentical stem cell transplantation via αβ T-cell depletion.

RESULTS

The median age of the patients at the time of hematopoietic stem cell transplantation was 41.5 years (range, 20-70 years); 22 patients (39.3%) were women. After the transplantation, half of the patients (50.0%) needed immunosuppressive drugs, and 17.9% of the patients experienced a post-transplant relapse. The mortality rate was 55.4%, and nonrelapse mortality was 25.0%. The 100-day mortality rate was 19.6%. The median overall days was 1101 days (142-3813 days), whereas the median progression-free overall was 302.5 days (11-2479 days). Being older (age >40), having hypertension, having acute liver graft-vs-host disease, and having systemic fungal infection were found as risk factors that significantly increased mortality (with 3.5-, 2.8-, 3.7-, and 2.7-fold increases, respectively).

CONCLUSION

To conclude, T-cell-depleted hematopoietic stem cell transplantation is an effective and reliable technique that has the potential to decrease morbidity and improve relapse-free survival, especially for young patients requiring haploidentical donor transplantation for hematologic malignancy.

T-Cell Depleted Haploidentical Transplantation in Children With Hematological Malignancies: A Comparison Between CD3+/CD19+ and TCRαβ+/CD19+ Depletion Platforms

Background

T-cell depleted (TCD) haploidentical transplantation using CD3+/CD19+ and TCRαβ+/CD19+ depletion techniques has been increasingly used in children with hematological malignancies. We present a retrospective study aimed to compare transplant outcomes in children with leukemia receiving a TCD haploidentical transplant using either CD3+/CD19+ or TCRαβ+/CD19+ platforms.

Methods

A total of 159 children with leukemia (ALL=80) (AML=79) that received a TCD haploidentical transplantation using either CD3+/CD19+ (n=79) or TCRαβ+/CD19+ (n=80) platforms between 2005 and 2020 were included. Median age was 9 years in both groups. There were no differences in patient, donor, and transplant characteristics between groups except for donor KIR B genotype more frequent in the TCRαβ+/CD19+ group (91%) than in the CD3+/CD19+ group (76%) (p=0.009) and a high number of NK+ cells and lower CD19+ cells infused in the TCRαβ+/CD19+ group (35.32x106/kg and 0.06 x106/Kg) than in the CD3+/CD19 group (24.6x106/Kg and 0.25 x106/Kg) (p=0.04 and p=0.0001), respectively. Conditioning was based on TBF. Median follow-up for survivors was 11 years (range; 8-16 y) in CD3+/CD19+ group and 5 years (range; 2-9 y) in the TCRαβ+/CD19+ group.

Results

Engraftment kinetics were similar in both groups (13 days for neutrophils and 10 days for platelets). There was no difference in the incidence of acute GvHD II-IV (29 ± 5% in the CD3+/CD19+ group vs 38 ± 5% in the TCRαβ+/CD19+ group) and chronic GvHD (32 ± 5% vs 23 ± 4%, respectively). NRM was 23 ± 5% in the CD3+/CD19+group vs 21 ± 4% in the TCRαβ+/CD19+group. Relapse incidence was also similar, 32 ± 5% vs 34 ± 6%, respectively. DFS and OS were not different (45 ± 5% vs 45 ± 6% and 53 ± 6% vs 58 ± 6% respectively). As there were no differences on transplant outcomes between groups, we further analyzed all patients together for risk factors associated with transplant outcomes. On multivariate analysis, we identified that early disease status at transplant (HR: 0.16; 95%CI (0.07-0.35) (p=0.0001), presence of cGvHD (HR: 0.38; 95%CI (0.20-0.70) (p= 0.002), and donor KIR-B genotype (HR: 0.50; 95%CI (0.32-0.90) (p=0.04) were associated with better DFS.

Conclusions

Our data suggest that there are no advantages in transplant outcomes between TCD platforms. Risk factors for survival are dependent on disease characteristic, donor KIR genotype, and chronic GvHD rather than the TCD platform used.

Comparison of clinical outcomes between unrelated single umbilical cord blood and "ex-vivo" T-cell depleted haploidentical transplantation in children with hematological malignancies

BACKGROUND

Over the last two decades, umbilical cord blood (UCB) and haploidentical transplantation (HaploHSCT) have emerged as alternative sources of hematopoietic stem cell for allogeneic transplantation. There are few retrospective studies and no prospective studies comparing both types of alternative transplantation in pediatric patients.

RESULTS

We analyzed the data of 134 children with hematological malignancies who received a hematopoietic stem cell transplantation from a single umbilical cord blood (UCB) (n = 42) or an "ex-vivo" T-cell depleted transplant from a haploidentical-related donor (HaploHSCT) (n = 92) between 1996 and 2014. Hematological recovery was faster after HaploHSCT than the UCB transplant group (median times to neutrophil and platelet recovery: 13 vs. 16 days, 10 vs. 57 days, respectively) (P < 0.001). The HaploHSCT group had a significantly early immune reconstitution based on NK and CD8 + T cells compared with the UCB group. However, after the first year post-transplantation, HaploHSCT had a lower number of CD4 + T and B lymphocytes compared with the UCB transplant recipients. The cumulative incidence of TRM was 29±8% in the HaploHSCT group versus 40±5% in the UCB group. Relapse incidence was 21±7% in the HaploHSCT group and 19±8% in the UCB group. Probability of DFS was 58±8% in the HaploHSCT group versus 40±9% in the UCB group (P = 0.051).

CONCLUSIONS

TCD haploidentical transplant is associated with advantages in terms of engraftment and early immune reconstitution kinetics. TCD haploidentical transplant was associated with lower incidence of infectious and non-infectious complications, especially in the early phases of the transplant compared with UCB transplant recipients. However, there are no advantages in transplant outcomes compared with UCB transplant.

CD3/CD19 Depletion for T-cell Reduction of Allogeneic Transplants: Mostly Efficient, but not Robust

Aggressive T-cell depletion, in vitro or in vivo, is a prerequisite for survival of haplo-identical stem cell transplantation. The classical T-cell-depleted transplant, immunomagnetically enriched CD34+ cells, is very safe with respect to graft-versus-host reactivity, but associated with very high transplant-related and relapse mortality with an overall probability of survival of only 20%. Protocols for T- and B-cell depletion were therefore developed, reasoning that transplantation of the majority of Natural Killer (NK) cells and the substantial dose of residual T-cells might improve survival, which was, in principle, confirmed. Anecdotal reports of frequent failure to achieve adequate T-cell depletion prompted review of the aggregate data for transplant quality at our center. The first observation is the relative paucity of combined CD3/CD19 depletion processes as PTCy protocols have made inroads, 13 depletions in 8 years. Median T- and B-cell log-depletion were -3.89 and -1.92, respectively; instead of, CD34+ cell recovery was generally high (median 92%), as was NK-cell recovery (median 52%). However, the process failed to yield satisfactory T- and B-cell depletion in two out of 13 preparations, of which one product could be rescued by a second round of depletion, at the expense of CD34+ cell recovery. In our hands, the process is thus insufficiently robust for routine clinical use. Assuming similar observations in other centers, this may explain implementation of alternative protocols, such as TCRαβ/CD19 depletion or transplantation of unmanipulated grafts with subsequent in vivo depletion.

Depletion of CD45RA+ T cells: Advantages and disadvantages of different purification methods

BACKGROUND

Recently, new advances were made regarding the depletion of CD45RA⁺ naïve T cells from haploidentical grafts as they are suspected to be the most alloreactive.

METHODS

Within this project we investigated CD45RA-depletion from G-CSF mobilized PBSC by two different purification strategies according to GMP, specifically direct depletion of CD45RA⁺ cells (one-step approach), or CD34-positive selection followed by CD45RA-depletion (two-step approach).

RESULTS

With log -3.9 and - 3.8 the depletion quality of CD45RA⁺ T cells was equally for both approaches together with a close to complete CD19⁺ B cell depletion. However, due to a high expression of CD45RA the majority of NK cells were lost within both CD45RA depletion strategies. Stem cell recovery after one-step CD45RA-depletion was at median 52.0% (range: 49.7-67.2%), which was comparable to previously published recovery data received from direct CD34 positive selection. Memory T cell recovery including CD4⁺ and CD8⁺ memory T cell subsets was statistically not differing between both purification approaches. The recovery of CD4⁺ and CD8⁺ T cells was as well similar, but overall a higher amount of cytotoxic than T-helper cells were lost as indicated by an increase of the CD4/CD8 ratio.

CONCLUSIONS

CD45RA-depletion from G-CSF mobilized PBSC is feasible as one- and two-step approach and results in sufficient reduction of CD45RA⁺ T cells as well as B cells, but also to a co-depletion of NK cells. However, by gaining two independent cell products, the two-step approach enables the highest clinical flexibility in regard to individual graft composition with precise dosage of stem cells and T cells.

A New Conditioning Regimen Can Significantly Promote Post-Transplant Immune Reconstitution and Improve the Outcome of Umbilical Cord Blood Transplantation for Patients

This study included data from 81 consecutively enrolled patients with hematological diseases who had been treated with unrelated umbilical cord blood transplantation (UCBT) between September 2014 and April 2019. All patients received intense conditioning regimens with combined fludarabine and high-dose cyclophosphamide (FC) before undergoing UCBT. Sixty-seven patients received a single UCBT, and 14 patients received a double UCBT. Fifty patients were pretreated with the fludarabine, busulfan, and cyclophosphamide (FBC) protocol, while 31 patients were treated with FC before transplantation. Graft-versus-host disease (GVHD) was prevented with cyclosporine A and mycophenolate mofetil administration. According to low-resolution, human leukocyte antigen (HLA) donor-recipient matching at six sites, 53 patients had 5-6 matches, while 28 patients had 4 matches. Seventy-eight patients (96.3%) achieved complete engraftment in this study. Thirty-six patients developed acute GVHD (aGVHD). The cumulative incidence of grade I-II aGVHD at day 100 posthematopoietic stem cell transplantation was 29.6%, and the cumulative incidence of grade III-IV aGVHD was 14.8%. At the end of the follow-up, 12 patients died due to treatment-related complications, and 4 died of disease relapse after transplantation. The transplant-related deaths were due to transplant-related infection (8 of 81), GVHD (2 of 81), and organ toxicity (2 of 81). The probability of overall survival (OS) was 80.2%. A higher dose of cyclophosphamide combined with fludarabine conditioning in UCBT was an effective curative method for treatment of hematologic disorders and could enhance the engraftment of umbilical cord blood stem cells, promote post-transplant immune reconstitution, and improve OS.

Review of Haploidentical Hematopoietic Cell Transplantation

Use of haploidentical (haplo) donors for hematopoietic cell transplantation (HCT) has significantly increased in the last decade. The major advantage with this strategy is universal availability and faster acquisition of the donor, along with affordability and provision of immunotherapy in post-transplantation period. Historically, haplo-HCT was associated with compromised outcomes because of high rates of graft-versus-host disease and graft failure, but after the development of a post-transplantation high-dose cyclophosphamide strategy, which results in selective T-cell depletion, these issues have been addressed to a large extent. Nevertheless, graft failure, high treatment-related mortality due to graft-versus-host disease, infections, delayed immune reconstitution, and disease relapse remain significant concerns. As the experience with haplo-HCTs grows, the clinical outcomes are becoming more at par with those seen with fully matched unrelated donor allogeneic HCTs.

[What is established in cell therapies? : Possibilities and limits in immuno-oncology]

Cell and gene therapy as part of immuno-oncology has reached an important milestone in medicine. After decades of experience stem cell transplantation is well established with worldwide >1 million transplantations to date. Due to the improved success of the last years using chimeric antigen receptor (CAR) T cells for CD19 positive leukemia and lymphomas, the interest in cellular therapies is continuously increasing. The current review also gives a short overview about donor lymphocytes, antigen-specific T cells, regulatory T cells, natural killer (NK) cells, mesenchymal stromal cells and induced pluripotent stem (iPS) cells in immuno-oncology.

AlloHSCT in paediatric ALL and AML in complete remission: improvement over time impacted by accreditation?

Allogeneic hematopoietic stem cell transplantation (alloHSCT) has become a well-established treatment option for many patients suffering from malignant and non-malignant diseases. In the past decade, high-resolution HLA-typing, remission surveillance, pre-emptive immune intervention, and standardisation in supportive care measures have substantially improved transplant outcomes. This retrospective study evaluated transplant procedures in 162 paediatric patients with acute lymphoblastic leukaemia (n = 124) or acute myeloid leukaemia (n = 38) who received their first alloHSCT in our institution over an 11-year period. We observed a significant reduction in risk of non-relapse mortality (NRM) over time (HR = 0.34, 95% CI 0.12-0.98; P = 0.05), the 4-year NRM estimate decreased from 20% in 2005-2008 to 7% in 2012-2016 (P = 0.02) and an increase in survival after relapse. There was no significant difference in patients who received a graft from a sibling, haplo, or an unrelated donor with regard to their overall survival (P = 0.45), event-free survival (P = 0.61), and non-relapse mortality (P = 0.19). Our data suggest that a specific transplant infrastructure with a highly experienced team in an accredited transplant centre likely contributes to better transplant outcomes for acute leukaemia patients in complete remission regardless of donor type.

Joint Modeling of Immune Reconstitution Post Haploidentical Stem Cell Transplantation in Pediatric Patients With Acute Leukemia Comparing CD34+-Selected to CD3/CD19-Depleted Grafts in a Retrospective Multicenter Study

Rapid immune reconstitution (IR) following stem cell transplantation (SCT) is essential for a favorable outcome. The optimization of graft composition should not only enable a sufficient IR but also improve graft vs. leukemia/tumor effects, overcome infectious complications and, finally, improve patient survival. Especially in haploidentical SCT, the optimization of graft composition is controversial. Therefore, we analyzed the influence of graft manipulation on IR in 40 patients with acute leukemia in remission. We examined the cell recovery post haploidentical SCT in patients receiving a CD34⁺-selected or CD3/CD19-depleted graft, considering the applied conditioning regimen. We used joint model analysis for overall survival (OS) and analyzed the dynamics of age-adjusted leukocytes; lymphocytes; monocytes; CD3⁺, CD3⁺CD4⁺, and CD3⁺CD8⁺ T cells; natural killer (NK) cells; and B cells over the course of time after SCT. Lymphocytes, NK cells, and B cells expanded more rapidly after SCT with CD34⁺-selected grafts (P = 0.036, P = 0.002, and P < 0.001, respectively). Contrarily, CD3⁺CD4⁺ helper T cells recovered delayer in the CD34 selected group (P = 0.026). Furthermore, reduced intensity conditioning facilitated faster immune recovery of lymphocytes and T cells and their subsets (P < 0.001). However, the immune recovery for NK cells and B cells was comparable for patients who received reduced-intensity or full preparative regimens. Dynamics of all cell types had a significant influence on OS, which did not differ between patients receiving CD34⁺-selected and those receiving CD3/CD19-depleted grafts. In conclusion, cell reconstitution dynamics showed complex diversity with regard to the graft manufacturing procedure and conditioning regimen.

Ewing sarcoma partial regression without GvHD by chondromodulin-I/HLA-A*02:01-specific allorestricted T cell receptor transgenic T cells

Background: Chondromodulin-I (CHM1) sustains malignancy in Ewing sarcoma (ES). Refractory ES carries a dismal prognosis and patients with bone marrow (BM) metastases do not survive irrespective of therapy. We assessed HLA-A*02:01/CHM1-specific allorestricted T cell receptor (TCR) wild-type and transgenic cytotoxic (CD8⁺) T cells against ES. Patients and Methods: Three refractory HLA-A2⁺ ES patients were treated with HLA-A*02:01/peptide-specific allorepertoire-derived (i.e., allorestricted) CD8⁺ T cells. Patient #1 received up to 4.8 × 10⁵/kg body weight HLA-A*02:01^- allorestricted donor-derived wild-type CD8⁺ T cells. Patient #2 received up to 8.2 × 10⁶/kg HLA-A*02:01^- donor-derived and patient #3 up to 6 × 10⁶/kg autologous allorestricted TCR transgenic CD8⁺ T cells. All patients were treated with the same TCR complementary determining region 3 allorecognition sequence for CHM1 peptide 319 (CHM1³¹⁹). Results: HLA-A*02:01/CHM1³¹⁹-specific allorestricted CD8⁺ T cells showed specific in vitro lysis of all patient-derived ES cell lines. Therapy was well tolerated and did not cause graft versus host disease (GvHD). Patients #1 and #3 showed slow progression, whereas patient #2, while having BM involvement, showed partial metastatic regression associated with T cell homing to involved lesions. CHM1³¹⁹ TCR transgenic T cells could be tracked in his BM for weeks. Conclusions: CHM1³¹⁹-TCR transgenic T cells home to affected BM and may cause partial disease regression. HLA-A*02:01/antigen-specific allorestricted T cells proliferate in vivo without causing GvHD.

In-vitro influence of mycophenolate mofetil (MMF) and Ciclosporin A (CsA) on cytokine induced killer (CIK) cell immunotherapy

Background

Cytokine-induced-killer (CIK) cells are a promising immunotherapeutic approach for impending relapse following hematopoietic stem cell transplantation (HSCT). However, there is a high risk for treatment failure associated with severe graft versus host disease (GvHD) necessitating pharmaceutical intervention post-transplant. Whether immunosuppression with mycophenolate mofetil (MMF) or Ciclosporin A (CsA) influences the cytotoxic effect of CIK cell immunotherapy is still an open issue.

Methods

CIK cells were generated from PBMC as previously described followed by co-incubation with mycophenolic acid (MPA) or CsA. Proliferation, cytotoxicity and receptor expression were investigated following short- (24 h), intermediate- (3 days) and long-term (7 days) MPA incubation with the intention to simulate the in vivo situation when CIK cells were given to a patient with relevant MPA/CsA plasma levels.

Results

Short-term MPA treatment led to unchanged proliferation capacity and barely had any effect on viability and cytotoxic capability in vitro. The composition of CIK cells with respect to T-, NK-like T- and NK cells remained stable. Intermediate MPA treatment lacked effects on NKG2D, FasL and TRAIL receptor expression, while an influence on proliferation and viability was detectable. Furthermore, long-term treatment significantly impaired proliferation, restricted viability and drastically reduced migration-relevant receptors accompanied by an alteration in the CD4/CD8 ratio. CD3⁺CD56⁺ cells upregulated receptors relevant for CIK cell killing and migration, whereas T cells showed the most interference through significant reductions in receptor expression. Interestingly, CsA treatment had no significant influence on CIK cell viability and the cytotoxic potential against K562.

Conclusions

Our data indicate that if immunosuppressant therapy is indispensable, efficacy of CIK cells is maintained at least short-term, although more frequent dosing might be necessary.

Electronic supplementary material

The online version of this article (doi:10.1186/s12967-016-1024-4) contains supplementary material, which is available to authorized users.

Novel treatment of severe combined immunodeficiency utilizing ex-vivo T-cell depleted haploidentical hematopoietic stem cell transplantation and CD45RA+ depleted donor lymphocyte infusions

BACKGROUND

Allogeneic hematopoietic stem cell transplantation (HSCT) is the only curative treatment available for severe combined immunodeficiency (SCID); although, there is a high incidence of severe infections and an increased risk of graft-versus host-disease (GvHD) with HSCT. Early intervention is a crucial prognostic factor and a HLA-haploidentical parental donor is often available. Haploidentical HSCT protocols utilizing extensively ex vivo T-cell depleted grafts (CliniMACs system) have proven efficient in preventing GvHD, but cause a delay in early T-cell recovery that increases the risk of viral infections. Here, we present a novel approach for treating SCID that combines selective depletion of GvHD-inducing alpha/beta (α/β) T-cells from the haploidentical HSCT graft with a subsequent donor lymphocyte infusion (DLI) enriched for CD45RO+ memory T-cells.

RESULTS

Our patient was diagnosed with SCID (T-B + NK+ phenotype). At 9 months of age, he received a T cell receptor(TCR)α/β-cell depleted graft from his haploidentical mother, following a reduced intensity conditioning regimen with no additional GvHD prophylaxis. Engraftment was rapid with complete donor chimerism and no signs of GvHD. However, at 12 weeks post HSCT, the patient was still T-cell lymphopenic with clinical symptoms of multiple severe viral infections. Consequently, therapeutic DLIs were initiated for enhanced anti-viral immunity. The patient was treated with CD45RA+ depleted haploidentical maternal donor lymphocytes enriched from unmobilized whole blood, and a total T-cell dose of no more than 25 x10(3) CD3+ cells/kg with >99.9% purity of CD3 + CD45RO+ memory T-cells was transferred. Following the DLI, a prompt increase in CD3 + CD4+ and CD3 + CD8+ counts was observed with a subsequent clearance of viral infections. No acute or chronic GvHD was observed.

CONCLUSIONS

Automated depletion of CD45RA+ naïve T-cells from unmobilized whole blood is a simple and rapid strategy to provide unmanipulated DLIs, with a potentially broad repertoire of pathogen specific memory T-cells. In the haploidentical setting, CD45RA+ depleted DLIs can be safely administered at low T-cell doses for efficient enhancement of viral immunity and limited risk of GvHD. We demonstrate the successful use of this approach following TCR-α/β-cell depleted HSCT for the treatment of SCID.

Haploidentical stem cell transplantation augmented by CD45RA negative lymphocytes provides rapid engraftment and excellent tolerability

BACKGROUND

Haploidentical donors are being increasingly used for allogeneic hematopoietic cell transplantation (HCT). However, the requisite T-cell depletion results in a profound and often long-lasting immunocompromised state, and donor lymphocyte infusions bring a risk of graft-versus-host disease (GVHD). Naïve T-cells are believed to be among the most alloreactive T-cell subset and can be identified by CD45RA expression. Allogeneic HCT using CD45RA depletion has not been previously described for haploidentical donors.

PROCEDURE

Eight children with relapsed or refractory solid tumors were transplanted following myeloablative conditioning. Each patient received two cell products, one created by CD3 depletion and the other through CD45RA depletion.

RESULTS

Median CD34 recovery was 59.2% with CD45RA depletion, compared to 82.4% using CD3 depletion. Median CD3+ T-cell dose after CD45RA reduction was 99.2 × 10(6)  cells/kg, yet depletion of CD3+ CD45RA+ cells exceeded 4.5 log. CD45RA depletion also resulted in substantial depletion of B-cells (median 2.45 log). All eight patients engrafted within 14 days and rapidly achieved 100% donor chimerism. No acute GVHD or secondary graft failure was observed.

CONCLUSIONS

CD45RA depletion is a novel approach to haploidentical HCT that offers rapid engraftment with minimal risk of GVHD.

Dendritic cell reconstitution is associated with relapse-free survival and acute GVHD severity in children after allogeneic stem cell transplantation

DCs are potent APCs and key regulators of innate and adaptive immunity. After allo-SCT, their reconstitution in the peripheral blood (PB) to levels similar to those in healthy individuals tends to be slow. We investigate the age- and sex-dependant immune reconstitution of myeloid (mDC) and plasmacytoid DC (pDC) in the PB of 45 children with leukaemia or myelodysplastic syndrome (aged 1-17 years, median 10) after allo-SCT with regard to relapse, acute GVHD (aGVHD) and relapse-free survival. Low pDC/μL PB up to day 60 post SCT are associated with higher incidence of moderate or severe aGVHD (P=0.035), whereas high pDC/μL PB up to day 60 are associated with higher risk of relapse (P<0.001). The time-trend of DCs/μL PB for days 0-200 is a significant predictor of relapse-free survival for both mDCs (P<0.001) and pDCs (P=0.020). Jointly modelling DC reconstitution and complications improves on these simple criteria. Compared with BM, PBSC transplants tend to show slower mDC/pDC reconstitution (P=0.001, 0.031, respectively), but have no direct effect on relapse-free survival. These results suggest an important role for both mDCs and pDCs in the reconstituting immune system. The inclusion of mDCs and pDCs may improve existing models for complication prediction following allo-SCT.

Pediatric posttransplant relapsed/refractory B-precursor acute lymphoblastic leukemia shows durable remission by therapy with the T-cell engaging bispecific antibody blinatumomab

We report on posttransplant relapsed pediatric patients with B-precursor acute lymphoblastic leukemia with no further standard of care therapy who were treated with the T-cell engaging CD19/CD3-bispecific single-chain antibody construct blinatumomab on a compassionate use basis. Blast load was assessed prior to, during and after blinatumomab cycle using flow cytometry to detect minimal residual disease, quantitative polymerase chain reaction for rearrangements of the immunoglobulin or T-cell receptor genes, and bcr/abl mutation detection in one patient with Philadelphia chromosome-positive acute lymphoblastic leukemia. Blinatumomab was administered as a 4-week continuous intravenous infusion at a dosage of 5 or 15 μg/m(2)/day. Nine patients received a total of 18 cycles. Four patients achieved complete remission after the first cycle of treatment; 2 patients showed a complete remission from the second cycle after previous reduction of blast load by chemotherapy. Three patients did not respond, of whom one patient proceeded to a second cycle without additional chemotherapy and again did not respond. Four patients were successfully retransplanted in molecular remission from haploidentical donors. After a median follow up of 398 days, the probability of hematologic event-free survival is 30%. Major toxicities were grade 3 seizures in one patient and grade 3 cytokine release syndrome in 2 patients. Blinatumomab can induce molecular remission in pediatric patients with posttransplant relapsed B-precursor acute lymphoblastic leukemia and facilitate subsequent allogeneic hematopoietic stem cell transplantation from haploidentical donor with subsequent long-term leukemia-free survival.

Optimal stem cell source for allogeneic stem cell transplantation for hematological malignancies

Hematopoietic stem cell transplant (HSCT) is a standard treatment for many hematological malignancies. Three different sources of stem cells, namely bone marrow (BM), peripheral blood stem cells (PBSC) and cord blood (CB) can be used for HSCT, and each has its own advantages and disadvantages. Randomized controlled trials (RCTs) suggest that there is no significant survival advantage of PBSC over BM in Human Leukocyte Antigen-matched sibling transplant for adult patients with hematological malignancies. PBSC transplant probably results in lower risk of relapse and hence better disease-free survival, especially in patients with high risk disease at the expense of higher risks of both severe acute and chronic graft-versus-host disease (GVHD). In the unrelated donor setting, the only RCT available suggests that PBSC and BM result in comparable overall and disease-free survivals in patients with hematological malignancies; and PBSC transplant results in lower risk of graft failure and higher risk of chronic GVHD. High level evidence is not available for CB in comparison to BM or PBSC. The risks and benefits of different sources of stem cells likely change with different conditioning regimen, strategies for prophylaxis and treatment of GVHD and manipulation of grafts. The recent success and rapid advance of double CB transplant and haploidentical BM and PBSC transplants further complicate the selection of stem cell source. Optimal selection requires careful weighing of the risks and benefits of different stem cell source for each individual recipient and donor. Detailed counseling of patient and donor regarding risks and benefits in the specific context of the patient and transplant method is essential for informed decision making.

Use of V(D)J recombination excision circles to identify T- and B-cell defects and to monitor the treatment in primary and acquired immunodeficiencies

T-cell receptor excision circles (TRECs) and kappa-deleting recombination excision circles (KRECs) are circular DNA segments generated in T and B cells during their maturation in the thymus and bone marrow. These circularized DNA elements persist in the cells, are unable to replicate, and are diluted as a result of cell division, thus are considered markers of new lymphocyte output. The quantification of TRECs and KRECs, which can be reliably performed using singleplex or duplex real-time quantitative PCR, provides novel information in the management of T- and B-cell immunity-related diseases. In primary immunodeficiencies, when combined with flow cytometric analysis of T- and B-cell subpopulations, the measure of TRECs and KRECs has contributed to an improved characterization of the diseases, to the identification of patients’ subgroups, and to the monitoring of stem cell transplantation and enzyme replacement therapy. For the same diseases, the TREC and KREC assays, introduced in the newborn screening program, allow early disease identification and may lead to discovery of new genetic defects. TREC and KREC levels can also been used as a surrogate marker of lymphocyte output in acquired immunodeficiencies. The low number of TRECs, which has in fact been extensively documented in untreated HIV-infected subjects, has been shown to increase following antiretroviral therapy. Differently, KREC number, which is in the normal range in these patients, has been shown to decrease following long-lasting therapy. Whether changes of KREC levels have relevance in the biology and in the clinical aspects of primary and acquired immunodeficiencies remains to be firmly established.

Autologous purified peripheral blood stem cell transplantation compare to chemotherapy in childhood acute lymphoblastic leukemia after low-risk relapse

BACKGROUND

The treatment of childhood B-cell precursor acute lymphoblastic leukemia (ALL) after isolated extramedullary or late relapse is mostly based on chemotherapy or allogeneic transplantation. The aim of this study is to provocatively assess the role of purified autologous transplantation compared with best chemotherapy results in the same setting.

PROCEDURE

We reported a series of 30 pediatric patients who underwent purified peripheral blood autologous transplantation for ALL in CR2, after isolated extramedullary (7), or late medullary (23) relapse from January 1997 and March 2004. Among 246 patients treated with chemotherapy within Berlin-Frankfurt-Münster relapse protocols during the same period, we found 103 controls who matched our 30 cases, according to site of relapse, CR1 duration, time elapsed in CR2, and period of relapse.

RESULTS

Event-free survival and survival at 5 years after relapse were 73.3% (SE 8.1) and 86.5% (SE 8.2) for auto-transplanted cases and 40.0% (SE 9.7) and 62.5%(SE 9.6) for chemotherapy-treated controls (P-values: 0.012 and 0.025, respectively). The risk of relapse after auto-transplantation at 1 and 4 years was approximately half and one-fifth, respectively, of the same risk obtained with chemotherapy.

CONCLUSIONS

This matched analysis showed an advantage of purified autologous transplantation compared with chemotherapy in low-risk relapsed ALL, possibly explained by the single-center effect, the myeloablation of total body irradiation, the documented low tumor burden at mobilization and the stem cell isolation procedure.

Lymphoproliferative response to herpes simplex virus type 1, cytomegalovirus, Epstein-Barr virus, varicella zoster virus, human herpes virus 6, 7, and 8 antigen stimulation in pediatric allogeneic stem cell transplant recipients

We evaluate the recovery of CMI to various herpes viruses by measuring in vitro LPR to specific recall antigens. CMI was evaluated by the in vitro LPR of PBMC to specific purified HSV-1, VZV, CMV, EBV, HHV-6, -7, -8, antigens. Results were expressed as SI. SI > or = 3 was regarded as positive LPR. Serial measurements were taken prospectively from pretransplant till 12-month post-transplant. Thirty-six patients (M = 19; F = 17) with median age 10.5 yr old were recruited. Most transplants were from MSD with PBSC as the stem cell source. Altogether 50% of subjects started to show positive LPR to HSV-1, CMV, and VZV antigens at two-month post-transplant, major upsurges were noted until 6-month post-transplant. Subjects showed positive LPR to EBV, HHV-6, HHV-7, and HHV-8 antigens were all along <50% throughout the study period. The antibody status of donor and recipient for HSV-1, CMV, and VZV were associated with the timing of recovery of CMI. Choice of donor and stem cell source were important determinants of eventual LPR to various herpes viruses at 3-month post-transplant. At 12-month post-transplant, there was no statistical difference in any parameters in affecting LPR to different herpes viruses.

Results and factors influencing outcome after fully haploidentical hematopoietic stem cell transplantation in children with very high-risk acute lymphoblastic leukemia: impact of center size: an analysis on behalf of the Acute Leukemia and Pediatric Disease Working Parties of the European Blood and Marrow Transplant group

T cell–depleted haploidentical hematopoietic stem cell transplantation (haploHSCT) is an option to treat children with very high-risk acute lymphoblastic leukemia (ALL) lacking an HLA-identical donor. We analyzed 127 children with ALL who underwent haploHSCT in first (n = 22), second (n = 48), or third (n = 32), complete remission or in relapse (n = 25). The 5-year leukemia-free survival (LFS) was 30%, 34%, 22%, and 0%, respectively. A risk-factor analysis was performed for patients who underwent transplantation in remission (n = 102). Five-year nonrelapse mortality (NRM), relapse incidence (RI), and LFS were 37%, 36%, and 27%, respectively. A trend of improved LFS rate and decreased RI was observed for children given a graft with higher number of CD34+ cells (adjusted P = .09 and P = .07, respectively). In a multivariate analysis, haploHSCT performed in larger centers (performing ≥ 231 allotransplantations in the studied period) was associated with improved LFS rate and decreased RI (adjusted P = .01 and P = .04, respectively), adjusting for different patient-, disease-, and transplant-related factors such as number of previous autotransplantations, cytomegalovirus serology status, type of T-cell depletion, and use of total body irradiation and antithymocyte globulin. In conclusion, higher CD34+ cell dose and better patient selection may improve outcomes of children with ALL who undergo a haploHSCT. Transplant centers initiating programs on haploHSCT for children may collaborate with more experienced centers.

Stem cell source and outcome after hematopoietic stem cell transplantation (HSCT) in children and adolescents with acute leukemia

Allogeneic hematopoietic stem cell transplantation from siblings, unrelated donors or HLA mismatched family members has become an important procedure to offer a chance of cure to children and adolescents with acute leukemia at high risk of relapse and those with certain genetic diseases. Bone marrow (BM) was the only stem cell source for many years. During the past 15 years, peripheral blood stem cells from granulocyte colony-stimulating factor (G-CSF) mobilized healthy donors, or umbilical cord blood from related or unrelated donors, have become available. Each stem cell source has different risks/benefits for patients and donors, the choice depending not only on availability, but also on HLA compatibility and urgency of the HSCT. This review will analyze the advantages and limitations of each of these options, and the main criteria which can be applied when choosing the appropriate stem cell source for pediatric transplant recipients with acute leukemia.

Long-term outcome of cord blood transplantation from unrelated donors as an initial transplantation procedure for children with AML in Japan

To assess the outcome of unrelated umbilical cord blood transplantation (UCBT), 141 children with AML who underwent UCBT (39 in first CR (CR1), 33 in CR2, 4 in CR3 and 65 at more advanced stages (not in CR)) were analyzed in a retrospective multicenter study in Japan. Short-term MTX was used for prophylaxis of acute GVHD in 80 cases (57%). The cumulative incidences of neutrophil recovery, platelet recovery and acute GVHD (grades 2-4) were 78.7, 62.4 and 40.1%, respectively, and the 100-day transplantation-related mortality (TRM) was 10.8%. Multivariate analysis showed that an infused CD34(+) cell dose of 1.35 x 10(5) cells per kg or more was associated with favorable neutrophil and platelet recovery, and that short-term MTX was associated with a lower 100-day TRM. The 6-year relapse rate was 38.8% and was associated with disease status. Six-year overall survival was 45.8% (70.4+/-8.3% in CR1, 59.3+/-11.3% in CR2, 75.5+/-21% in CR3 and 20.6+/-6.2% for children with non-CR). We conclude that the results of UCBT are particularly promising for children with a karyotype suggesting a poor prognosis, and for those who receive transplants in CR2 and CR3 after an early relapse.

Haploidentical SCT in children: an update and future perspectives

Transplantation of haploidentical stem cells has become a well-established approach, which makes a potential donor available for almost all patients. This review focuses on current results and new strategies, especially in pediatric patients with malignant diseases. CD34(+) positive selection was the most common procedure for graft manipulation in the past years, whereas T and B cell depletion is a promising new method. GVHD could herewith be effectively reduced and primary engraftment was reported in 83-100% of patients after transplantation of high stem cell doses. For patients with ALL in remission, disease-free survival at 3 years ranged between 22 and 48%. TRM, mainly because of viral infections, was improved by the use of reduced-intensity conditioning (which helped to speed up T cell recovery) and by close monitoring of viral loads and prophylactic/preemptive therapy. The role of donor-derived Ag-specific T cells against viral and fungal antigens is currently under investigation. Patients with active disease at the time of transplantation had a poor outcome and several attempts to improve these results are currently evaluated, such as co-infusion of natural killer cells, co-transplantation of MSC, use of new antileukemic drugs and post-transplant immunotherapy.

G-CSF-mobilized haploidentical peripheral blood stem cell transplantation in children with poor prognostic nonmalignant disorders

Haploidentical hematopoietic stem cell transplantation (HSCT) is currently one of the alternative curative treatment options for some nonmalignant but also for malignant diseases. However, concerns regarding its safety cause delays in time and a successful outcome. Between 2000 and 2005, twenty-one children with poor prognostic nonmalignant disorders, 13 boys and 8 girls, with a median age of 12 months, underwent 28 haploidentical peripheral HSCT. Immunomagnetic bead depletion device (CliniMACS) was used for indirect T-cell depletion. Indications for transplant were severe combined immunodeficiency (n=16), osteopetrosis (n=2), MDS (n=1), amegakaryocytic thrombocytopenia (n=1), and aplastic anemia (n=1). Five patients (24%) had lung infection at the time of transplantation. The patients received a median of 25.67 x 10(6) G-CSF-mobilized peripheral CD34(+) progenitor cells and a median of 4.19 x 10(4) T-lymphocytes per kilogram of body weight with a T-cell depletion rate of median 4.59 logs. The rate of total engraftment was 66.6%. Median times for leukocyte and platelet engraftment were 14 and 16 days, respectively. The 6-year projected survival was 32% for all patients and 29.76% for patients with severe combined immunodeficiency (SCID). The rates of transplant-related mortality, graft failure, and severe GvHD were 14.2, 33.4%, and 8.3%, respectively. Infection was the main cause of death. The poor outcome may be explained with the poor prognostic factors of our patients such as the type of SCID in most cases (T-B- SCID), the median age over 6 months and the presence of lung infection in some children at the time of transplantation.

Allogeneic stem cell transplantation in children with leukemia using human leukocyte antigen-mismatched unrelated donors

Allogeneic HSCT is a curative treatment, when chemotherapy fails, for certain malignant diseases. In Europe, only 15% of the indicated children have an HLA-matched sibling available; in 65-70% of others, HLA allele-matched (9-10/10) UDs can be identified. For the rest, it is necessary to identify other alternative donors (HLA-mismatched family or unrelated cord blood). We present our data of HSCT using HLA partially allele-mismatched (7-8/10) UDs in 24 children with leukemia. Uniform GvHD prophylaxis was used (rATG, CsA and MTX). Acute GvHD grade II was diagnosed in 70.8% of the patients and grade III-IV in 12.5%. Overall incidence of chronic GvHD was 38.7% (extensive in 30%). The probability of EFS was 60.3% (95% CI 35.5-78.1) and OS was 74.9 (95% CI 49.1-88.9). No difference in survival between PBSC and BM recipients was observed. TRM at day + 100 was 4%, and overall was 12.5%. We conclude that used combination of drugs for GvHD prophylaxis is efficient even for patients transplanted with grafts from a HLA-mismatched UDs. It enables stable engraftment, good control of GvHD, full reconstitution of immunity, and is not connected with unacceptable transplant-related mortality.

Perspective on the role of haploidentical transplantation in the management of hematologic malignancies: why do it?

Haploidentical hematopoietic stem cell transplantation (HSCT) using mismatched family member donors has historically been complicated by high rates of nonrelapse toxicity and the need for laboratory expertise in depleting grafts of T lymphocytes. Over the past decade, improvements in supportive care, the increased use of peripheral-blood stem cell grafts, and improved T-cell depletion techniques have reduced the incidence of graft failure and lowered the rate of nonrelapse mortality. In addition, clinical studies have demonstrated that the donor-recipient mismatch may be beneficial in this setting, stimulating an immunologic cell-mediated antileukemia effect that results in lower disease recurrence rates. All of these advances have led to improvements in outcomes following haploidentical HSCT, making it an attractive option available to some patients. Because most patients do not have a matched related donor available and time to identify an unrelated donor may be excessive, haploidentical HSCT is a potentially curative option for these patients.

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.

Safety and efficacy of donor lymphocyte infusions following mismatched stem cell transplantation

The use of a mismatched allograft necessitates T cell depletion for prevention of uncontrolled graft-versus-host disease (GVHD), thus impairing a graft-versus-leukemia effect. Data on donor lymphocyte infusion (DLI) after mismatched stem cell transplantation are lacking. Our experience with 28 patients (treated with 59 mismatched DLIs; range, 1-7) is described. The procedure was prophylactic in 6 patients (9 DLIs) and therapeutic in 22 (50 DLIs). DLI dose ranged from 10(2) to 1.5 x 10(9) T cells/kg. In the 6 patients receiving prophylactic DLI, complete remission was maintained in 5; however, 2 died from GVHD. Clinical response to therapeutic DLI was seen in 6 of 22 (27.3%) patients; a greater tumor burden produced a lower response. GVHD appeared in 13 of 28 patients. Surprisingly, a greater HLA mismatch was associated with a lower risk of GVHD, with 3 of 19 DLIs in 3/6 matching and 16 of 29 DLIs in 5/6 matching with similar follow-up. Nevertheless, no correlation between efficacy and HLA mismatching was noted. Death was frequent and usually related to the basic disease rather than to DLI complications. We conclude that mismatched DLI is feasible and may be effective, especially if given soon after transplantation. Future developments using cell therapy with selective or targeted anticancer activity are warranted, with special attention to prophylactic treatment of T cell depleted mismatched allografts recipients.

Haematopoietic stem cell transplantation trends in children over the last three decades: a survey by the paediatric diseases working party of the European Group for Blood and Marrow Transplantation

This paper describes the trends in haematopoietic stem cell transplantation (HSCT) activity for children in Europe over the last three decades. We analysed 31,713 consecutive paediatric HSCTs reported by the European Group for Blood and Marrow Transplantation (EBMT) centres between 1970 and 2002. Data were taken from the EBMT registry and were compared according to period and centre category (paediatric or combined). Since 1996, there has been a significant increase in the number of HSCTs performed exclusively by paediatric centres, as well as in the number of alternative donor HSCTs, and in the use of peripheral blood stem cells (P<0.0001). The number of allogeneic HSCTs (allo-HSCTs) for acute lymphoblastic leukaemia, acute myeloblastic leukaemia and chronic myeloid leukaemia remained stable, whereas it increased for myelodysplastic syndromes and lymphomas, and decreased significantly for non-malignant diseases (P<0.0001). Multivariate analysis showed that younger age, human leukocyte antigen genoidentical donors, HSCT performed after 1996 and transplant centres performing more than 10 allo-HSCT/year were all associated with decreased transplant-related mortality (TRM) (P<0.0001). The number of autologus HSCTs (auto-HSCTs) for acute leukaemia decreased significantly, whereas it increased for solid tumours (P<0.0001). Multivariate analysis showed that both auto-HSCT performed before 1996 and paediatric solid tumours (P<0.0001) had higher TRM. Indications for paediatric HSCT have changed considerably during the last seven years. These changes provide tools for decision making in health-care planning and counselling.