Purified autologous grafting in childhood acute lymphoblastic leukemia in second remission: evidence for long-term clinical and molecular remissions

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.

Hematopoetic stem cell transplantation in children

Bone marrow transplantation is called hematopoetic stem cell transplantation (HSCT), since peripheral blood and umbilical cord blood can also be used as sources of stem cell currently. In children, bone marrow transplantation is used as a definite treatment method in many diseases including hemoglobinopaties, immune deficiencies, bone marrow failure and congenital metabolic diseases in addition to hematological malignancies. In addition to the underlying disease, the most important factors which have an impact on prognosis include infections which develop during the process of transplantation and graft-versus-host disease. In this article, it was aimed to give brief information on stem cell sources, preparation therapies, HSCT indications and post-transplantation complications in children.

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.

PCR-based clonality assessment in patients with lymphocytic leukaemias: a single-institution experience

PCR-based clonality testing can be performed in all lymphoproliferations by analysing gene rearrangements of antigen receptors, rearrangements that are unique for each kind of lymphocyte. Reactive lymphoproliferations have polyclonally rearranged Ig/TCR genes, whereas malignant proliferations (leukaemias and lymphomas) show clonal rearrangements. The aim of this study was to assess the clinical benefits of clonality testing with previously evaluated consensus primers in leukaemia patients. The study included peripheral blood and bone marrow samples of 67 leukaemia patients (32 B-CLL, 24 B-ALL and 11 T-ALL). Clonality testing was based on PCR amplification of rearranged IgH and TCR genes. During diagnosis, monoclonal pattern was found in all analysed B-CLL and T-ALL samples. Testing in B-ALL patients showed positive results in all bone marrow and one peripheral blood samples. Results of clonality testing in B-CLL patients during follow-up were concordant between peripheral blood and bone marrow. Obtained results corresponded to clinical course in all but one patient. In B-ALL group, results of molecular testing in peripheral blood and bone marrow confirmed remission estimated according to clinical criteria in all except one patient. Before any clinical sign of relapse, monoclonal pattern was found in six/seven patients by bone marrow and in three/seven patients by peripheral blood analysis, respectively. Results of molecular monitoring in T-ALL patients did not confirme clinical evaluation in two patients. Obtained results indicate high accuracy of re-evaluated primers for clonality assessment in ALL and CLL patients at the time of diagnosis. Results of clonality testing in B-ALL patients indicate that bone marrow analysis has higher sensitivity compared to analysis of peripheral blood.

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.

Hematopoietic stem cell transplantation after first marrow relapse of non-T, non-B acute lymphoblastic leukemia: a pediatric oncology group pilot feasibility study

BACKGROUND

Relapsed acute lymphoblastic leukemia (ALL) in children is associated with a poor outcome, especially for those patients whose relapse occurs during the first 36 months after diagnosis. The best therapy for these patients is not known. This study was designed to evaluate the feasibility of enrolling children with recurrent ALL in a standardized treatment protocol that included receipt of a hematopoietic stem cell transplant (HSCT).

PROCEDURE

Eligible patients with a bone marrow relapse of non-T, non-B ALL underwent a common induction and consolidation followed by receipt of either an allogeneic HSCT from a human leukocyte antigen (HLA)-identical sibling or an autologous HSCT purged with B-4 blocked ricin. A common conditioning regimen was used for all patients.

RESULTS

Twenty-eight patients from eight institutions were enrolled. Fourteen patients did not receive a transplant during the study, because of toxicity (4), relapse (1), inadequate purging (1), and parental or physician preference for an alternative donor transplant (8). Six patients received allogeneic HSCTs. Five of them have remained in remission for a median of 78 months. Eight patients received autologous HSCTs purged with B4-blocked ricin. Four have remained in remission for a median of 94 months. Of the nine patients who received alternative donor transplants, only two remain in remission.

CONCLUSION

We conclude that well designed and controlled prospective studies are necessary to define the role of HSCTs in children with recurrent ALL. In order to be successful, such studies must have the full support of participating centers. Autologous HSC transplantation may have a role in the treatment of relapsed ALL, but further studies are needed.

The Hyper-CVAD chemotherapy regimen has an adverse long-term impact on the ability to mobilize peripheral blood stem cells, which can be readily circumvented by using the early cycles for mobilization

The Hyper-CVAD chemotherapy regimen is being increasingly applied to a number of haematological malignancies. We assessed the impact of Hyper-CVAD on peripheral blood stem cell (PBSC) yields and examined the optimal timing of PBSC collection when using this regimen. Seventy-four consecutive patients were identified in whom an attempt was made to collect PBSC, usually on recovery from cycle A or B. Where PBSC collection was attempted after cycle 3B, only 18% (3/17) of patients successfully mobilized. Fifty-seven patients were mobilized on recovery from cycle 1B (n = 13), 2A (n = 22), 2B (n = 14) or 3A (n = 8). Compared with cycle 2A, 1B was not superior in achieving the minimum of > or =2 x 10(6)/kg CD34+ cells (100% vs. 77%, p = 0.13), but was superior in terms of total CD34+ yield (21.4 vs. 3.2 x 10(6)/kg, p < 0.001), achieving the target CD34+ cell count of > or =5 x 10(6)/kg (92% vs 36%, p = 0.002), and obtaining both a minimum (92% vs. 18%, p < 0.001) and target (77% vs. 0%, p < 0.001) graft with a single apheresis. There were no significant differences in PBSC yields following cycles 2A, 2B and 3A. Hyper-CVAD has substantial stem cell toxicity which can be readily circumvented by using the early chemotherapy cycles for mobilization.

The Role of Cytotoxic Therapy with Hematopoietic Stem Cell Transplantation in the Therapy of Acute Lymphoblastic Leukemia in Children: An Evidence-Based Review

Evidence supporting the role of hematopoietic stem cell transplantation (SCT) in the therapy of acute lymphoblastic leukemia (ALL) in children is presented and critically evaluated in this systematic evidence-based review. Specific criteria were used for searching the published literature and for grading the quality and strength of the evidence and the strength of the treatment recommendations. Treatment recommendations based on the evidence are presented in a table in this review (Summary of Treatment Recommendations Made by the Expert Panel for Pediatric Acute Lymphoblastic Leukemia) and were reached unanimously by a panel of ALL experts. The priority areas of needed future research in pediatric ALL are unrelated marrow or blood donor versus unrelated cord blood donor allogeneic SCT; alternative, nonfamily allogeneic donor versus autologous SCT; better methods for identifying high-relapse-risk patients; assessments of the effect of current chemotherapy regimens on early relapse; and use of pre-SCT detection of minimal residual disease to predict post-SCT outcomes.

Prognostic factors for relapsed childhood acute lymphoblastic leukemia: impact of allogeneic stem cell transplantation--a report from the Kyushu-Yamaguchi Children's Cancer Study Group

BACKGROUND

The treatment results of childhood acute lymphoblastic leukemia (ALL) with a first relapse were retrospectively analyzed to determine prognostic factors. In particular, an attempt was made to clarify whether stem cell transplantation (SCT) had any advantages over chemotherapy.

PROCEDURES

Of the 407 children with ALL diagnosed between 1984 and 1996, 117 suffered from a relapse before December 1999. The patients were treated differently according to the protocols of each institution. The potential prognostic factors examined were: the time of initial diagnosis, gender, immunophenotype of leukemic blasts and the NCI-risk classification at initial diagnosis, the site of relapse, the time of relapse (early: within 18 months after diagnosis, intermediate: other than either early or late relapse, late: later than 6 months after the discontinuation of front-line chemotherapy), and the treatment after relapse (chemotherapy alone and SCT).

RESULTS

A second complete remission (CR2) was achieved in 90 patients (77%) and thirty of them maintained CR2, thus resulting in an event-free survival rate (EFS) of 25.1% and an overall survival rate of 26.1%. The significant prognostic factors identified by a multivariate analysis included the time of relapse (EFS: early 16.2%, intermediate 23.9%, late 35.1%, P = 0.012) and the treatment after relapse (EFS: SCT 30.3%, chemotherapy 22.0%, P = 0.049). When patients with an isolated bone marrow relapse and continuous CR2 for more than 3 months were analyzed, the treatment in CR2 was the only independent prognostic factor (EFS: SCT 60.2%, chemotherapy 25.7%, P = 0.005).

CONCLUSIONS

In children with ALL and a first relapse, the time of relapse and the treatment after relapse were found to be independent prognostic factors. Allogeneic SCT in CR2 showed significantly better results than chemotherapy in patients with an isolated bone marrow relapse.

Long-term outcome of allogeneic or autologous haemopoietic cell transplantation for acute lymphoblastic leukaemia in second remission in children. GETMON experience 1983–1998

We present a retrospective study of long-term outcome and predictive factors of survival and relapse in 219 paediatric patients with acute lymphoblastic leukaemia (ALL) in second remission. They received allogeneic (allo) or autologous (auto) haemopoietic cell transplantation (HCT) depending on the availability of a matched sibling donor. The probability of event-free survival (EFS) for the total patient group was 0.35+0.03 at 14 years. No significant differences were observed for EFS between allo- and auto-HCT: 0.39+0.05 vs 0.32+0.04 (P=0.43). A better EFS was seen in patients with a late relapse (LR) (P=0.06 and 0.02, for allogeneic and autologous respectively). Significantly better EFS was observed in allo-HCT patients under 10 years of age and in auto-HCT patients with leukocytes at diagnosis below 25 x 109/l and late relapse. Predictive factors of failure in both groups were early relapse (ER), medullary relapse and age over 10 years. The probability of relapse (RP) for the total group of patients was 0.57+0.03, and it was significantly higher in auto-HCT patients: 0.65+0.04 vs 0.42+0.06 (P=0.002). Factors predictive for relapse were medullary and early relapse, auto-HCT and WBC >25 x 109/l at diagnosis.

Low Efficiency of a Newly Introduced High-Density Microparticles Method for B Cell Depletion in Multiple Myeloma Patients Undergoing Autologous Hematopoietic Stem Cell Transplantation

Autologous peripheral blood stem cell (PBSC) transplantation proved to increase complete remission (CR) and DFS in multiple myeloma (MM) patients. CD34(+) cell selection has been used to reduce possible myeloma cell contamination in the graft, but it has not been showed to offer substantial advantages when compared to unpurged grafts; on the contrary, an increase of infectious complications was observed. We investigated the feasibility of a new negative-selection method in this setting. B cell negative selection was performed by using Eligix B cell HDM method. B cell contamination in the yield and in the final product was investigated by flow cytometry. Three patients with newly diagnosed MM entered the study. CD34(+) cell recovery in the three procedures was 73, 97, and 106%, and CD3(+) cell recovery was 88, 86, and 102%, respectively. CD20(+) cell depletion was 100% in all procedures, while CD19(+) cell depletion was 0.37, 1.21, and 0.07 log, respectively. We found an unexpected unreliability and a low efficiency in this B cell depletion method and suggest the need for further extensive testing before its introduction in the preclinical and clinical settings, at least in MM patients. In fact, reasons of such unsatisfactory results are still controversial: platelet contamination/activation in the preselection product, plasma protein interference, reduced CD19 antigen expression on immature B cells, lack of specificity of anti-CD19 monoclonal antibodies, instable binding between anti-CD19-coated high-density microparticles (HDM) and CD19 antigen may, alone or in combination, be involved in the system's low performance.

Impact of marrow unrelated donor search duration on outcome of children with acute lymphoblastic leukemia in second remission

We analyzed the outcome of 167 consecutive children with second CR acute lymphoblastic leukemia (ALL), for whom an unrelated donor (UD) search was activated between 1989 and 1998 at a median time of 2 months after relapse. A suitable donor was identified for 70 patients at 1 year and 6.5 months before and after 1995 from search activation, respectively; a further leukemia relapse occurred during the search in 94 children at a median of 4 months after search activation, 36 of whom underwent UD (14) or other types of transplant (22), beyond second CR, while 58 died of progressive disease. Of 73 patients not experiencing a second relapse, 64 underwent UD (46) or other types of transplant (18), while nine proceeded with chemotherapy, and only four of them survived. The 3-year disease-free survival (DFS) from second CR for the 167 patients is 15.1%, whereas 3-year DFS after transplant for the 60 UD and 40 alternative donor transplanted children is 31.6 and 25.4%, respectively. In conclusion, a further relapse is the main factor adversely affecting outcome of children with second CR ALL. Thus, for these patients, the search should be activated early after relapse and either a UD or an alternative transplant should be performed as early as possible.

Red blood cell support and alloimmunization rate against erythrocyte antigens in patients undergoing hematopoietic stem cell transplantation

We retrospectively analyzed red blood cell (RBC) support and alloimmunization rate in 218 consecutive patients - 128 from the Pediatric Department and 90 from the adult Hematology Department - undergoing hematopoietic stem cell transplantation (HSCT) between 1994 and 2000. In the pre-HSCT period, the pediatric patients undergoing auto-HSCT required more RBC support. In the post-HSCT period, pediatric patients transplanted with an unrelated donor required more RBC support (median 13.5 U/10 kg bw) than patients receiving HSCT from a related donor (median 6 U/10 kg bw) or from an autologous source (median 4 U/10 kg bw, P=0.0004). In the pre-HSCT period, 159 out of 218 patients (73%) received a total of 1843 RBC units, with an overall median of 9 U/patient over a median of 24 months (range 4-62); 10 patients (6%) developed a total of 12 alloantibodies, with an alloimmunization rate of 5.4/1000 RBC units. In the post-HSCT period, all but three patients were given a total of 2420 RBC units, with an overall median of 6 U/patient over a median of 4 months (range 1-18); all but one of the pre-existing alloantibodies disappeared and three patients (1%) developed new alloantibodies with an alloimmunization rate of 1.2/1000 RBC units. These newly produced alloantibodies (one anti-M and two anti-E) were detected at +58, +90 and +210 days after HSCT. These findings might suggest a different approach to alloantibody screening tests in patients receiving HSCT, with a subsequent reduction of costs and laboratory workload.

Peripheral blood stem cell collection in children with acute leukemia: effectiveness of the 'DIAVE' mobilizing regimen

Few experiences of peripheral blood (PB) hematopoietic stem cell mobilization for autologous transplantation have been reported to date in children with acute leukemia (AL). The five-drug-chemotherapy 'DIAVE' (dexamethazone, idarubicine, cytosine-arabinoside, vincristine, etoposide), followed by G-CSF, previously reported as consolidation, was adopted as a mobilization regimen in 29 children (median age: 8 years, range: 3-21; median weight: 34 kg, range: 15-73) with ALL in second remission (CR2: 21), in CR3 (2) or ANLL in CR1 (6). A median peak of 94 x 10(6) CD34(+)cells/l (range: 10-604) was reached at a median time of 12 days (range: 10-18) after the beginning of the mobilizing regimen, which was well tolerated. A median of 10.9 x 10(6) CD34(+)cells/kg (range: 2.4-56.6) were collected in 25 patients (86%), approaching 40 x 10(6)/l CD34(+) cells in the PB (ALL in CR2: 20/21, in CR3: 0/2; ANLL: 5/6) by means of one (20) or two (5) leukaphereses; a median of 2.5 blood volumes was processed. Patients with ANLL mobilized more cells than patients with ALL; moreover, the shorter the interval between remission and mobilizing therapy, the higher was the yield. The products collected underwent purification, aiming at achieving complete removal of possibly contaminating leukemic cells, in 21 cases; also, unmanipulated aliquots were stored as rescues for all but one patient. All the 23 patients undergoing transplantation engrafted (ANC >0.5 x 10(9)/l) at a median of 12 days. In conclusion, the DIAVE regimen compares favorably with conventional mobilizing regimens, usually containing cyclophosphamide, in terms of low toxicity, collection time predictability, and efficacy, as shown by the high proportion of patients mobilizing, the large amounts of stem cell collected by means of one or two leukaphereses only, and the prompt engraftment after infusion.

Immature CD34+CD19- progenitor/stem cells in TEL/AML1-positive acute lymphoblastic leukemia are genetically and functionally normal

One important question in stem cell biology of childhood acute lymphoblastic leukemia (ALL) is whether immature CD34+CD19- cells are part of the leukemic cell clone. CD34+CD19- cells from the bone marrow of 9 children with TEL/AML1-positive ALL were purified by flow sorting and subjected to reverse transcriptase-polymerase chain reaction (RT-PCR), fluorescence in situ hybridization, and methylcellulose cultures. In 3 of 8 patients analyzed by RT-PCR, no TEL/AML1-positive cells could be detected in the CD34+CD19- cell fraction. Altogether, the percentage of TEL/AML1-positive cells was low: 1.6% (n = 8; SD 2.2%) by nested real-time RT-PCR and 2.5% (n = 5; SD 2.6%) by fluorescence in situ hybridization. This correlated with the percentage of contaminating CD19+ leukemic cells in the CD34+CD19- cell fraction in 6 control sorts (mean 4.6%, SD 3.6%), indicating that the low levels of leukemic cells detected in the CD34+CD19- cell fraction could be attributed to sorter errors. Methylcellulose cultures in 3 patients provided further evidence that CD34+CD19- cells represent a candidate normal cell population. The clonogenicity of the CD34+CD19- cell fraction was similar to normal progenitors, including growth of primitive granulocyte, erythroid, macrophage, megakaryocyte colony-forming units. Each of 92 colonies from cultures with CD34+CD19- cells tested negative for TEL/AML1. In conclusion, our data support the hypothesis that the leukemia in TEL/AML1-positive childhood ALL originates in a CD19+ lymphoid progenitor. This has many therapeutic implications, eg, for purging of autologous stem cell products, flow cytometric monitoring of minimal residual disease, and targeting immunotherapy against the leukemic cell clone.