A second unrelated bone marrow transplant: successful quantitative monitoring of mixed chimerism using a highly discriminative PCR-STR system.

A second bone marrow transplant (BMT) might be considered as an option in patients with leukaemia with graft failure after BMT. We report the successful treatment of a patient with graft failure by a second stem cell transplant from another unrelated donor. We evaluated the usefulness of an unrelated donor as the source of the second BMT in this clinical setting. In addition to this, a penta PCR-STR system was tested and shown to be sensitive for monitoring of marrow engraftment. The conditioning regimen for the first transplantation consisted of busulfan and cyclophosphamide while anti-thymocyte globulin and CY were used for the second BMT. The patient successfully engrafted at day +11 after second BMT.     

Relationship between mixed chimerism and rejection after bone marrow transplantation in thalassaemia

Background

Thalassaemia is a genetic disease that requires a hypertransfusion regimen to treat the anaemia caused by enhanced red blood cell destruction. The only radical cure for thalassaemia is to correct the genetic defect by bone marrow transplantation from an HLA-identical donor capable of producing and maintaining a normal haemoglobin level in the recipient. Complete donor haematopoiesis is not essential for sustained engraftment and the simultaneous presence of haematopoietic cells of both donor and recipient origin is not a rare event after a transplant.

Patients and methods

The evolution of marrow engraftment of 93 transplanted thalassaemic patients, all from Middle East or Asian countries, was monitored by analysis of short tandem repeats.

Results

Forty-three of 93 (46%) patients experienced a status of mixed chimerism early after bone marrow transplantation. Results of further engraftment analysis in these patients showed in 27 complete donor engraftment; rejection occurred in seven, while eight maintained the presence of both host and donor-derived cells. Interestingly, five out of the seven patients who rejected their transplant showed more than 25% residual host cells early after transplantation.

Discussion and conclusion

Our study confirmed that the presence of large amounts of residual host cells within the first 2 months after a transplant is a risk factor for graft rejection also in a group of patients with wide ethnic heterogeneity, irregular transfusion regimens and/or poor chelation treatment. Ten percent of the transplanted thalassaemic patients maintained coexistence of donor and recipient cells, showing a stable functional graft, characterized by normal production of beta globin chains and high levels of haemoglobin. A mechanism responsible for peripheral tolerance induction, such as the production of specific regulatory T-cell clones, seems to play a key role in the induction of long-term tolerance after the transplant.     

Matched and mismatched unrelated donor bone marrow transplantation for juvenile chronic myeloid leukaemia

Juvenile chronic myeloid leukaemia (JCML) is a rare haematological condition of childhood curable only by bone marrow transplantation (BMT). We report our experience using matched and mismatched unrelated donor BMT for JCML in five patients. Although the procedure is hazardous in terms of toxicity and relapse, two patients are alive and disease-free 28 and 49 months post BMT.     

Determinants of survival after human leucocyte antigen-matched unrelated donor bone marrow transplantation in adults

Unrelated donor (URD) bone marrow transplantation (BMT) in adults can be associated with high non-relapse mortality (NRM). Therefore, factors determining survival in 136 human leucocyte antigen (HLA)-A, B, DRB1-matched adult BMT recipients were reviewed. Fifty-four per cent of patients had chronic myelogenous leukaemia (CML) and 36% had acute leukaemia or myelodysplasia. Graft-versus-host disease (GvHD) prophylaxis was either cyclosporin A (CSA)/methotrexate (64%) or T-cell depletion and CSA/corticosteroids (34%). The probability of donor engraftment by d 45 was 97% (95% CI: 94-100). Incidence of grades III-IV acute GvHD was 18% (95% CI: 12-24) at 100 d, and chronic GvHD was 42% (95% CI: 32-52) at 2 years. At 2 years, 14% (95% CI: 8-20) had relapsed. Multiple regression analysis showed that adverse risk factors for survival were non-CML diagnosis, age > 35 years, diagnosis to transplant time of > 18 months [chronic-phase CML (CML-CP) only]; and grades III-IV acute GvHD. Patients 35 years with early CML-CP was 55% (95% CI: 33-77), 40% (95% CI: 19-61) in advanced CML and 14% (95% CI:1-27) in non-CML. Future efforts should focus on improving the outcome for older BMT recipients, especially those with diagnoses other than CML.     

Allogeneic bone marrow transplantation from unrelated donors using in vivo anti-T-cell globulin

Despite improvements in HLA typing, graft-versus-host disease (GVHD) continues to impair the results after volunteer unrelated donor bone marrow transplantation (VUD-BMT) in adult patients compared with matched sibling BMT. Here, the outcome after VUD-BMT using a specific regimen with high-dose anti-T-lymphocyte globulin (ATG) was analysed. Fifty-five adult patients, median age 34 years (range 17-55 years), with acute or chronic leukaemia or myelodysplastic syndrome (MDS) were transplanted in first complete remission (CR1)/first chronic phase (CP1) (early disease) (n = 21) or in advanced (CR2/CP2, no remission) disease (n = 34) from an unrelated marrow donor. GVHD prophylaxis consisted of ATG-S (Fresenius) 60-90 mg/kg b.w. prior to transplantation, in addition to cyclosporin A and short-course methotrexate. Graft failure did not occur and white blood cell count (WBC) > 1.0 x 10(9)/l was reached at median day +16. The cumulative incidence of acute (a)GVHD grade II-IV was 15% [95% CI (8%, 28%)] and of chronic GVHD was 51% [95% CI (38%, 68%)]. The cumulative incidence of relapse within 1 year was 0% [95% CI (0%, 19%)] and 21% [95% CI (11%, 40%)] for patients with early and advanced disease respectively. With a median follow-up of 28 months (range 16-45 months), 2-year disease-free and overall survival for patients transplanted in CR1/CP1 was 81% and 81% [95% CI (64%, 98%)], respectively, and for patients with advanced disease was 33% [95% CI (17%, 50%)] and 40% [95% CI (23%, 57%)] respectively. Complete and persistent donor chimaerism was seen in 77.5% of 40 patients evaluated. All 14 chronic myeloid leukaemia (CML)-CP1 patients became bcr-abl negative within 250 d. High-dose ATG pretransplant results in a low incidence of severe aGVHD without compromising donor chimaerism or elimination of minimal residual disease. Our results are similar to data obtained after matched sibling donor transplantation.     

A clinical comparison of unrelated cord blood transplantation and unrelated bone marrow transplantation for adult patients with acute leukaemia in complete remission

We performed a clinical comparison of unrelated cord blood transplantation (UCBT) and unrelated bone marrow transplantation in adult acute leukaemia patients in complete remission (CR) who received the same conditioning regimen, graft-versus-host disease (GvHD) prophylaxis and supportive treatment. The incidence of acute GvHD was almost the same between the two groups, but the haematopoietic recovery was delayed and the incidence of chronic GvHD was higher in the UCBT group. The probability of 2 year disease-free survival was similar between the two groups. These results suggest that adult acute leukaemia patients in CR without a suitable donor should be considered as candidates for UCBT.     

Cytomegalovirus seropositivity adversely influences outcome after T-depleted unrelated donor transplant in patients with chronic myeloid leukaemia: the case for tailored graft-versus-host disease prophylaxis

Graft-versus-host disease (GVHD) remains a major cause of morbidity and mortality after haematopoietic stem cell transplantation from matched unrelated donors (MUD). The role of T-cell depletion (TCD) as a strategy to prevent GVHD is controversial because of the associated increased risk of leukaemic relapse, graft failure and delayed immune reconstitution. The demonstration that donor lymphocyte infusion (DLI) is effective salvage therapy if patients relapse after transplantation for chronic myeloid leukaemia (CML) prompted us to examine the proposal that TCD may be a form of GVHD prophylaxis particularly suited to this disease in patients undergoing MUD transplantation. We analysed the outcome of 106 consecutive patients with CML in first chronic phase who underwent MUD transplantation. Patients were conditioned with cyclophosphamide and total body irradiation (TBI), and received in vivo TCD, using CD52 monoclonal antibody, as GVHD prophylaxis. Donor lymphocytes were infused at the time of leukaemic relapse. The projected survival at 5 years for all patients was 52.6%. The probability of developing severe acute GVHD (grade 3 or 4) was 14.5%. The only significant predictor of overall survival in univariate and multivariate analysis was patient cytomegalovirus (CMV) serostatus: in CMV-negative patients survival at 5 years was 60% vs. 42% in CMV-positive patients (P = 0.006). The use of TCD was associated with an increased risk of relapse (62% probability at 5 years after transplant), but 80% of patients who received DLI achieved molecular remission that was durable in all but two cases. In vivo TCD, in conjunction with DLI at relapse, is a valuable GVHD prophylactic regimen in CMV-seronegative recipients of MUD allografts, but in CMV-seropositive patients this approach is associated with an increased non-relapse mortality. Consequently, GVHD prophylactic regimens in MUD transplantation should be tailored according to the patient and donor pretransplant characteristics.     

Genotypic analysis using a Y-chromosome-specific probe following bone marrow transplantation

To monitor successful engraftment after bone marrow transplantation, we performed Southern hybridization analysis or dot blot analysis of DNA in a set of sex-mismatched cases using a Y-chromosome-specific DNA probe (pHY10). This method was extremely sensitive and rapid for checking which cells contain the Y-chromosome. Using this probe, analysis of cells from peripheral blood and bone marrow after transplantation demonstrated the usefulness of confirming engraftment of donor cells and of detecting mixed lymphohematopoietic chimerism.     

PCR-positivity in harvested bone marrow predicts relapse after transplantation with autologous purged bone marrow in children in second remission of precursor B-cell acute leukaemia

Purging of autologous bone marrow (BM) grafts of children in second remission after a relapse of precursor B acute lymphoblastic leukaemia (ALL) in the BM has been carried out in our laboratory since 1987, initially by complement mediated cell lysis. This protocol was extended by performing an immunorosette depletion before lysis with complement. The aim of the present study was to assess by polymerase chain reaction the presence of residual leukaemic cells in the BM grafts before and after purging. The results were then correlated to clinical outcome. In 24/28 patients a PCR product was obtained by amplification of IgH and/or TcR junctional regions. BM before purging was available for analysis in 13 patients. We found that leukaemic cells could be detected in 8/13 (62%) of these grafts before purging . All these eight patients experienced a relapse, regardless of whether the purging procedure had been successful (defined as achievement of PCR-negativity) or not. In contrast, none of the five patients with PCR-negative grafts before purging relapsed ( P  = 0.0008). One patient died due to transplant-related toxicity. Of the remaining 23 patients, nine patients received a PCR-positive BM graft after purging. All these nine patients experienced a relapse as compared to 6/14 whose BM was PCR-negative after purging ( P  = 0.0072). Two of eight PCR-positive BM grafts could be purged to PCR-negativity. Thus, improvements both in treatment of leukaemia and in purging efficacy are still needed.     

Unrelated donor bone marrow transplantation in children and young adults with acute myeloid leukaemia in remission

The role of unrelated donor bone marrow transplantation (UD-BMT) in the management of patients with acute myeloid leukaemia (AML) is uncertain. We describe 18 patients with a median age of 13 years (range 4–31) who received an ex vivo T-cell-depleted UD-BMT for AML (13 in second complete remission (CR2) and five in first complete remission (CR1) with high-risk features). Nine donor recipient pairs were fully matched; eight of these donor–recipient pairs had a single class I HLA mismatch; one patient had both single class I and class II HLA mismatches. Grade II GVHD of the skin occurred in four patients (22%) and limited chronic GVHD in two patients (11%). There have been four deaths: one from relapse and three from infection. With a median follow-up of 27 months, 14 patients survive and the actuarial event-free survival at 2 years is 70 ± 20% (95% confidence interval). We conclude that unrelated donor BMT can result in prolonged disease-free survival in children and young adults with AML.     

A prospective molecular study of chimaerism in patients with haematological malignancies receiving unrelated cord blood or bone marrow transplants: detection of mixed chimaerism predicts graft failure with or without early autologous reconstitution in cord blood recipients

We prospectively studied the chimaerism status in the bone marrow (BM) and peripheral blood (PB) of 23 patients receiving umbilical cord (UCB, 14 cases) or BM (nine cases) transplants from unrelated donors by PCR amplification of four individual-specific VNTR genetic loci. Haematological engraftment, with persistent full donor pattern. was observed in 10/14 (72%) patients receiving UCB and in 9/9 (100%) patients transplanted with marrow from an unrelated donor (MUD). In contrast, the remaining four patients converted to an autologous pattern. Three out of these four patients had an early autologous haematological reconstitution reaching a neutrophil level >0.5 x 10(9)/l at days 27, 33 and 37 after transplant, respectively. In all three of these patients, chimaerism analysis demonstrated an early appearance of donor cells (i.e. within 35 d after UCB transplant) showing a transient full donor (one case) or mixed chimaerism condition (two cases). Despite the early autologous haemopoietic reconstitution, one of the three patients died of GVHD at day 60, which was explained by the demonstration of low levels of donor lymphoid cells. In the MUD group all nine patients converted to a persistent full donor pattern with haematological reconstitution, accompanied in two of them by transient mixed chimaerism lasting to days 60 and 270 after transplant. Our data show that monitoring of chimaerism may predict graft failure with or without early autologous haemopoietic reconstitution in patients receiving unrelated UCB transplants. Furthermore, chimaerism analysis may identify, in patients with autologous reconstitution, those at risk of severe GVHD in whom immunosuppressive therapy should not be discontinued.     

Single-centre experience with allogeneic bone marrow transplantation for acute lymphoblastic leukaemia in childhood: similar survival after matched-related and matched-unrelated donor transplants

Seventy percent of children with acute lymphoblastic leukaemia (ALL) who may benefit from bone marrow transplant (BMT) lack a human leucocyte antigen (HLA)-matched related donor (MRD). For these children, BMT from a matched unrelated donor (MUD) represents a therapeutic option. We reviewed the course of 62 children with ALL who received fully matched marrow allografts at our institution between 1990 and 1998: 36 with MRDs and 26 with MUDs. Clinical characteristics were similar in the two groups. The interval from attainment of pre-BMT complete remission to transplant was significantly longer in the MUD group. Conditioning (etoposide/total body irradiation) and graft-versus-host disease (GVHD) prophylaxis regimens were the same for all patients, and all received T cell-replete bone marrow. There was no significant difference in probability of engraftment, or time to engraftment, in the two groups. MUD BMT recipients had a significantly greater incidence of grade II-IV acute GVHD (58% versus 24% in the MRD group; P = 0.02), and demonstrated a trend towards more chronic GVHD (39% versus 15%; P = 0.06). Three years post BMT, the probabilities of transplant-related mortality were 33 +/- 11% and 20 +/- 8% in MUD and MRD groups respectively (P = 0.38); the probabilities of relapse were 28 +/- 12% and 41 +/- 9% respectively (P = 0.19). Lansky or Karnofsky performance scores in event-free survivors were 90-100 in 87% of the MUD group and 83% of the MRD group. With a median follow up of 38 months (range, 3-97), 3-year event-free survival was 49 +/- 11% and 47 +/- 9% in the MUD and MRD BMT groups respectively (P = 0.71). These results suggest that MUD BMT is a valuable therapy for children with ALL in whom BMT is indicated, and underscore the importance of efforts aimed at expediting unrelated donor searches for patients lacking a MRD.     

Cytomegalovirus infection in recipients of related and unrelated donor bone marrow transplants: no evidence of increased incidence in patients receiving unrelated donor grafts

Recent reports suggest an increased incidence of cytomegalovirus (CMV) infection in recipients of unrelated donor (UD) bone marrow transplantation (BMT).
In this study we have collated the incidence of CMV infection and disease in sequential UD ( n  = 119) and related donor (RD; n  = 79) BMT performed in a single institution over a 7-year period. Low-risk patients (CMV seronegative recipient and donor) accounted for 51% of UD BMT ( n  = 61) and 62% of RD BMT ( n  = 49), with CMV excretion documented in one RD BMT only. The remaining high-risk patients received identical prophylaxis regimens with aciclovir and intravenous immunoglobulin (IVIG). Two groups consisting of 58 UD BMT (median age 9.0 years, range 0.7–45.3 years) and 30 RD BMT (median age 13.6 years, range 1.6–47.6 years) were analysed. CMV reactivation/re-infection was documented in 15 UD BMT (26%) and 10 RD BMT (33%) ( P  = 0.72), and CMV disease in four UD BMT (8%) and four RD BMT (13%) ( P  = 0.533). In this series the risk of CMV excretion and disease following UD BMT was similar to that following RD BMT.     

Peripheral blood cells chimerism after unrelated cord blood transplantation in children: kinetics,predictive factors and impact on post‐transplant outcome

This study aimed to describe kinetics of complete donor chimerism occurrence (cDC, >99·9% donor) after unrelated cord blood transplantation (UCBT), to identify its predictive factors and its impact on post‐transplant outcome. Ninety‐four children who received single UCBT after a myeloablative conditioning regimen had blood chimerism evaluation at predefined post‐transplant dates, using a real‐time polymerase chain reaction method with 0·1% sensitivity. Cumulative incidence of cDC at 1 year post‐transplantation was 61·8%. Three predictive factors were identified in multivariate analysis: history of malignant disease (P = 0·03), older age (above 2·16 years, the first quartile of age, P = 0·0055) and higher level of cord/recipient human leucocyte antigen mismatch (4/6 vs. 5‐6/6, P < 0·001) increased the probability of post‐transplant cDC. Although graft cell dose had a strong impact on haematological recovery, it did not apparently influence cDC occurrence. Early cDC (i.e. more than 99·9% donor chimerism on days 15–30 post‐transplant) appeared useful to predict engraftment (P = 0·003) as well as acute and chronic graft‐versus‐host disease (GvHD). Severe acute or chronic GvHD never occurred in patients with DC ≤99·9%, suggesting than even minimal residual host haematopoiesis is associated with a very low risk of GvHD after UCBT.     

Autotransplantation versus HLA-matched unrelated donor transplantation for acute myeloid leukaemia: a retrospective analysis from the Center for International Blood and Marrow Transplant Research

Most acute myeloid leukaemia (AML) patients lack human leucocyte antigen-identical sibling donors for transplantation. Autotransplants and unrelated donor (URD) transplants are therapeutic options. To compare autologous versus URD transplantation for AML in first (CR1) or second complete remission (CR2), we studied the outcomes of 668 autotransplants were compared with 476 URD transplants reported to the Center for International Blood and Marrow Transplant Research. Proportional hazards regression adjusted for differences in prognostic variables. In multivariate analyses transplant-related mortality (TRM) was significantly higher and relapse lower with URD transplantation. Adjusted 3-year survival probabilities were: in CR1 57 (53-61)% with autotransplants and 44 (37-51)% URD (P = 0.002), in CR2 46 (39-53)% and 33 (28-38)% respectively (P = 0.006). Adjusted 3-year leukaemia-free survival (LFS) probabilities were: CR1 53 (48-57)% with autotransplants and 43 (36-50)% with URD (P = 0.021), CR2 39 (32-46)% and 33 (27-38)% respectively (P = 0.169). Both autologous and URD transplantation produced prolonged LFS. High TRM offsets the superior antileukaemia effect of URD transplantation. This retrospective, observational database study showed that autotransplantation, in general, offered higher 3-year survival for AML patients in CR1 and CR2. Cytogenetics, however, were known in only two-thirds of patients and treatment bias cannot be eliminated.     

Post‐transplant bendamustine reduces GvHD while preserving GvL in experimental haploidentical bone marrow transplantation

Advances in haploidentical bone marrow transplantation (h‐BMT) have drastically broadened the treatment options for patients requiring BMT. The possibility of significantly reducing the complications resulting from graft‐versus‐host disease (GvHD) with the administration of post‐transplant cyclophosphamide (PT‐CY) has substantially improved the efficacy and applicability of T cell‐replete h‐BMT. However, higher frequency of disease recurrence remains a major challenge in h‐BMT with PT‐CY. There is a critical need to identify novel strategies to prevent GvHD while sparing the graft‐versus‐leukaemia (GvL) effect in h‐BMT. To this end, we evaluated the impact of bendamustine (BEN), given post‐transplant, on GvHD and GvL using clinically relevant murine h‐BMT models. We provide results indicating that post‐transplant bendamustine (PT‐BEN) alleviates GvHD, significantly improving survival, while preserving engraftment and GvL effects. We further document that PT‐BEN can mitigate GvHD even in the absence of Treg. Our results also indicate that PT‐BEN is less myelosuppressive than PT‐CY, significantly increasing the number and proportion of CD11b⁺Gr‐1^hi cells, while decreasing lymphoid cells. In vitro we observed that BEN enhances the suppressive function of myeloid‐derived suppressor cells (MDSCs) while impairing the proliferation of T‐ and B‐cells. These results advocate for the consideration of PT‐BEN as a new therapeutic platform for clinical implementation in h‐BMT.     

Improved outcome in haemophagocytic lymphohistiocytosis after bone marrow transplantation from related and unrelated donors: a single-centre experience of 12 patients

Haemophagocytic lymphohistiocytosis (HLH) is an autosomal recessive disease with histiocytic and lymphocytic infiltrations in multiple organs. Cure seems possible only by allogeneic bone marrow transplantation (BMT), but matched sibling donors (MSD) are restricted and high mortality rates are associated with BMT from unrelated donors (URD). We report on 12 consecutive HLH patients with an improved outcome following URD transplants. Eight patients received BMT from URD, four from MSD. Five patients had signs of active HLH at the time of BMT. The conditioning regimen consisted of 20 mg/kg busulphan, 60 mg/kg VP-16 and 120 mg/kg cyclophosphamide and, in case of URD, 90 mg/kg antithymocyte globulin. The doses of busulphan and VP-16 were reduced during the programme to 16 mg/kg and 30 mg/kg, respectively. Using a fivefold graft-versus-host disease (GVHD) prophylaxis, GVHD was absent or mild in 10, and moderate or severe in two patients undergoing unrelated transplants. One patient with URD experienced graft failure and was retransplanted on day 37. Major toxicities were hepatic veno-occlusive disease in five, capillary leak syndrome in two, pneumonia in three, sepsis in one, severe mucositis in one and seizures in two patients. All patients are alive without HLH after a median follow-up of 24.5 months. One patient has chronic GVHD, another patient has severe retardation. Three patients show slight to moderate development delay. These results indicate that in HLH, BMT from matched unrelated donors should be performed. Incomplete resolution of disease activity need not impede a successful outcome.     

NKG2D gene polymorphism has a significant impact on transplant outcomes after HLA-fully-matched unrelated bone marrow transplantation for standard risk hematologic malignancies

Background

NKG2D, an activating and co-stimulatory receptor expressed on natural killer cells and T cells, plays pivotal roles in immunity to microbial infections as well as in cancer immunosurveillance. This study examined the impact of donor and recipient polymorphisms in the NKG2D gene on the clinical outcomes of patients undergoing allogeneic T-cell-replete myeloablative bone marrow transplantation using an HLA-matched unrelated donor.

Design and Methods

The NKG2D polymorphism was retrospectively analyzed in a total 145 recipients with hematologic malignancies and their unrelated donors. The patients underwent transplantation following myeloablative conditioning; the recipients and donors were matched through the Japan Marrow Donor Program.

Results

In patients with standard-risk disease, the donor NKG2D-HNK1 haplotype, a haplotype expected to induce greater natural killer cell activity, was associated with significantly improved overall survival (adjusted hazard ratio, 0.44; 95% confidence interval, 0.23 to 0.85; p=0.01) as well as transplant related mortality (adjusted hazard ratio, 0.42; 95% confidence interval, 0.21 to 0.86; p=0.02), but had no impact on disease relapse or the development of grade II–IV acute graft-versus-host disease or chronic graft-versus-host disease. The NKG2D polymorphism did not significantly influence the transplant outcomes in patients with high-risk disease.

Conclusions

These data suggest an association between the donor HNK1 haplotype and better clinical outcome among recipients, with standard-risk disease, of bone marrow transplants from HLA-matched unrelated donors.     

Autologous bone marrow transplantation for acute myeloid leukaemia in remission: a preliminary report

Autologous bone marrow transplantation, using unpurged cryopreserved autologous marrow, was performed on ten adult patients with acute myeloid leukaemia in remission. Seven patients were in first chemotherapy-induced remission of their disease, while three were in later remission. Patients ages ranged from 24 to 52 years, with a median of 38.5 years. Conditioning therapy consisted of oral busulphan 16 mg/kg over four days and intravenous cyclophosphamide 60 mg/kg on two days. Bone marrow cells were thawed and infused two days later. All patients showed signs of marrow engraftment, however this was delayed in comparison with patients receiving allogeneic transplants. All patients developed fever requiring antibiotic therapy and one patient died of overwhelming sepsis. Another patient died of hepatic veno-occlusive disease two months after transplant. Serious, but non-fatal, hepatic complications occurred in two other patients. One patient, transplanted in third remission, relapsed 16 months post-autograft. No other relapses have been seen, with one second remission patient remaining leukaemia-free at 24 months, and six first remission patients in continuing remission 11 to 23 (median 20) months post transplant. These encouraging results require confirmation in a randomised clinical trial comparing autologous marrow transplantation versus standard chemotherapy.     

A phase II trial of partially incompatible bone marrow transplantation for high-risk acute lymphoblastic leukaemia in children: prevention of graft rejection with anti-LFA-1 and anti-CD2 antibodies

Bone marrow transplantation (BMT) from matched sibling donors has been useful for the treatment of acute lymphoblastic leukaemia in children with a poor prognosis but is not available to more than two-thirds of patients who do not have a matched allogeneic donor. This study was undertaken to assess one strategy of marrow graft rejection prevention when alternative marrow sources such as HLA-phenoidentical unrelated volunteers and HLA-partially incompatible relatives were used. Results have been compared with two matched groups of children with the same risks factors and disease status who underwent HLA-genoidentical or autologous BMT. The conditioning regimen was the same for the three groups of patients; in the study group anti-LFA-1 and anti-CD2 monoclonal antibodies combined with T-cell depletion of the marrow was added to prevent graft rejection and graft-versus-host disease.   Nineteen patients were included and followed for a median of 25 months (14 months to 3 years). Bone marrow engraftment occurred in 83% of the evaluable patients. Post-transplantation infectious diseases were the most frequent causes of death in the study group, occurring in 31% of patients. No fatal infections occurred in the two control groups. Post-transplantation relapse of leukaemia occurred in 26% of study group's patients, in 58% of autologous BMT control group's patients and in 5% of HLA-genoidentical allogeneic group's patients. The event-free survival was 83% in the HLA-genoidentical control group, and 30% and 24% in the study group and in the autologous control group, respectively.   In conclusion, a high rate of engraftment was achieved by the use of anti-LFA-1 and anti-CD2 antibodies. Occurrence of a long-lasting immunodeficiency, however, led to a high incidence of lethal infections and relapses. Combined approaches are therefore to be investigated accelerating immune reconstitution after transplantations of T-depleted HLA partially incompatible marrow.