Second allogeneic bone marrow transplantation in acute leukemia: a multicenter study from the Gruppo Italiano Trapianto Di Midollo Osseo (GITMO)

Thirty-eight second allogeneic bone marrow transplants (BMT) for acute leukemia relapsed after first BMT were performed in 13 Italian centers between 1987 and 1994. Twenty-one patients had acute myelogenous leukemia (AML), 17 acute lymphoblastic leukemia (ALL); at second BMT 24 patients were in complete remission (CR) and 14 in relapse. The median time to relapse after first BMT was 10 months (range 1-70). Grade II or greater acute graft-versus-host disease (GVHD) after second transplant occurred in 34.2% of patients and a chronic GVHD in 31.5% of patients. Twenty-four patients died: seven from early transplant-related mortality (TRM), 13 from relapse and four from late toxicity. As of 31 July 1996, at a median follow-up of 47 months (range 22-85), there are 14 survivors. The three-year probability of TRM, relapse and event-free survival (EFS) is 28%, 40% and 42% respectively. In 20 of 27 evaluable patients, remission duration after second BMT was longer than after the first BMT. A diagnosis of AML was correlated with a better outcome. These data support the usefulness of second allograft in selected patients with AML relapsing after a first BMT.     

The clinical indications for identical pathogenesis of isolated and non-isolated testicular relapses in acute lymphoblastic leukaemia

In the present population-based study, we compared the clinical data of testicular relapses with and without concurrent bone marrow relapse and clinical data of the relapses in other locations among boys with acute lymphoblastic leukaemia (ALL), in order to study the possible evidence of early sequestration and local regulation of leukaemic lymphoblast in the testis of humans. The results suggest that the pathogenesis of isolated testicular relapse (T) and testicular relapse with a concurrent bone marrow relapse (T + BM) is likely to be similar. Isolated and non-isolated testicular relapses appeared late after the achievement of remission (T 34 +/- 16 months, T + BM 32 +/- 15 months) in ALL compared to relapses in other locations (CNS 23 +/- 11 months, BM 25 +/- 19 months). The better prognosis after testicular relapses (estimated second event free survival probability, 2-EFS: T 0.63, T + BM 0.32) compared to bone marrow relapse (2-EFS: BM 0.13) further suggests that testicular relapse with a concurrent bone marrow relapse possibly originates from the isolated testicular relapse, and that the isolated testicular relapse is a separate entity and not a manifestation of systemic recurrence. Higher frequencies of isolated and non-isolated testicular relapses (T 9%, T + BM 5%) were observed among boys with onset of ALL in early puberty (10-12 y) compared to those among younger (T 4%, T + BM 2%) and older (T 0%, T + BM 0%) boys. The late occurrence, the possible association with hormonal maturation and the good prognosis after testicular relapses suggest a possible local regulation of the residual leukaemic lymphoblast in human testis.     

Allogeneic cell therapy with donor peripheral blood cells and recombinant human interleukin-2 to treat leukemia relapse after allogeneic bone marrow transplantation

Allogeneic bone marrow transplantation (BMT) is the only effective treatment for hematologic malignancies resistant to conventional chemotherapy. Until recently, no cure existed for patients who relapsed post-BMT. We present our long-term observations on remission induction, after relapse post-BMT, by allogeneic cell therapy (allo-CT) and the feasibility of remission induction in allo-CT-resistant patients by activation of antileukemia effector cells with recombinant human interleukin-2 (rhIL-2) in vitro and in vivo. The longest observation of successful allo-CT (event-free survival, greater than 8 years) was made in a patient with resistant pre-B lymphoblastic leukemia who received infusions with graded increments of donor (female) peripheral blood lymphocytes (PBL) as soon as bulky hematologic and extramedullary relapse was noticed early post-BMT. The patient is currently without evidence of residual host (male) cells as determined by polymerase chain reaction (PCR). Of 17 patients with acute and chronic leukemia in relapse after BMT, 10 were reinduced into complete remission. Four patients with cytogenetic relapse responded to allo-CT alone, while five of six patients with overt hematologic relapse responded only after additional activation of donor with rhIL-2. Allo-CT can, therefore, successfully reverse chemoradiotherapy-resistant relapse of both acute and chronic leukemia. Moreover, in patients resistant to donor lymphocyte infusion, remission can be accomplished by additionally activating donor PBL in vitro and/or in vivo with rhIL-2. Based on our observations, after BMT, allo-CT should be considered the treatment of choice for patients with hematologic malignancies resistant to conventional anticancer modalities. Allogeneic activated cell therapy (allo ACT) should be considered for patients with tumor cells resistant to allo-CT. Although allo-CT, followed if indicated by allo-ACT, can be effective for patients with overt hematologic relapse, reversal of persistent minimal residual disease or documented molecular/cytogenetic relapse early after BMT may also be considered as a possible indication for allo-CT.     

Minimal residual disease status as a predictor of relapse after allogeneic bone marrow transplantation for children with acute lymphoblastic leukaemia

We have analysed the behaviour of minimal residual disease (MRD) after allogeneic bone marrow transplantation (allo-BMT) in 71 children with acute lymphoblastic leukaemia (ALL). The method relied on PCR of IgH, TCRdelta and/or TCRgamma gene rearrangements followed by electrophoretic size resolution and allele-specific oligoprobing. Patients were similarly conditioned; 55 received marrow from unrelated donors and 16 from related donors. MRD was assessed at various time-points up to 24 months after BMT. Three children were not evaluable due to transplant-related mortality. MRD was detected in 28/32 patients (88%) who relapsed post-BMT; 16 were positive at all times and 12 were initially negative but became positive at a median of 3 months (range 1.5-11) prior to relapse. In contrast, only eight of 36 (22%) patients who remained in continuing complete remission (CCR) (median follow-up 43 months, range 20-94) showed MRD at any time after BMT (P<0.0001). In these eight patients MRD was found up to 9 months after transplant and at low levels (0.01-0.001%). All eight (median follow-up 39 months, range 24-87) had at least two MRD-negative samples tested subsequently and five of the eight had evidence of grade I-II acute graft-versus-host disease (GvHD), raising the possibility of a graft-versus-leukaemia effect. In general, any evidence of MRD after allo-BMT is a poor prognostic sign. However, if immunotherapy were to be targeted towards patients with evidence of persisting MRD after BMT, the method described would expose only a small proportion of patients to unnecessary additional toxicity.     

Importance of mixed chimerism to predict relapse in persistently BCR/ABL positive long survivors after allogeneic bone marrow transplantation for chronic myeloid leukemia

Determination of hematological chimerism could be helpful in understanding the biology of leukemic relapse after allogeneic bone marrow transplant (BMT) for chronic myeloid leukemia (CML), because the detection of malignant residual cells carrying the bcr/abl message by qualitative RT-PCR is of limited value in predicting disease progression for individual patients. We have studied the chimerism pattern and the bcr/abl status by Southern-blot in 15 CML patients (M/F:6/9) transplanted with unmanipulated BM from HLA identical sibling donors, persistently bcr/abl positive by RT-PCR. The median age of the series was 31 years (18-49) and disease status at BMT was: chronic phase: 11, accelerated phase: 3 and blast crisis: 1 patient. Of the 15 patients, 9 are alive and in complete remission (CR), 4 have died in CR and 2 are alive but suffered relapse at + 19 and +26 months post-BMT. The median follow-up is 81 months (13,7-168). Rearrangement of the BCR gene was performed by Southern-blot using P32-labeled transprobe-1. PCR analysis of chimerism was assessed using primers for the following VNTR loci: D1S80, D1S111, 33.1, APO-B, YNZ-22, lambdag3 and DXS52. Seventy-nine samples were analyzed (median per patient 5 (range 2-9)). Thirteen patients showed complete chimerism and lacked BCR rearrangement over time by Southern-blot. The 2 patients who relapsed showed mixed chimera status from +9 and +5 months respectively until the end of the study. Persistent BCR rearrangement was observed in these 2 patients from +12 and +11 months respectively. Our data suggest that mixed chimerism may predict hematologic or cytogenetic relapse by several months in those patients who are persistently PCR-positive post-BMT.     

Bulky lymphadenopathy in acute myeloid leukemia

Two cases of acute myeloid leukemia (AML) presenting with bulky adenopathy are reported. Both patients were febrile at admission and showed massive and diffuse lymph node involvement, hepatomegaly, and splenomegaly. Erythematopapular leukemic skin lesions were present in one case at the onset and developed in the other at the time of relapse. Anemia, thrombocytopenia, and moderate leukocytosis were present in both. The presence of immature cells in peripheral blood and bone marrow allowed a rapid diagnosis of AML, FAB M1, in one patient. In the other case, owing to the paucity of immature cells in peripheral blood and bone marrow, lymph node biopsy with histology, imprint cytology, and immunocytochemistry were essential for the diagnosis (AML, FAB M2, with trilineage dysplasia and basophilic involvement). Both patients achieved complete remission (CR), followed by an early relapse 3 months later. They underwent allogeneic bone marrow transplantation (BMT) from HLA identical siblings. One patient is actually alive and in CR at 6 months after BMT; the other patient showed a leukemic regrowth after transplantation and died 4 months later.     

In vivo purging with high-dose cytarabine followed by high-dose chemoradiotherapy and reinfusion of unpurged bone marrow for adult acute myelogenous leukemia in first complete remission

PURPOSE: To evaluate in a prospective study the efficacy of autologous bone marrow transplantation (BMT) in adult patients with acute myelogenous leukemia (AML) in first remission, using a single course of high-dose Cytarabine (HD Ara-C) consolidation therapy as in vivo purging. PATIENTS AND METHODS: Sixty consecutive adult patients with AML in first complete remission (CR) were treated with HD Ara-C consolidation therapy as a method of in vivo purging before marrow collection. High-dose therapy consisted of fractionated total-body irradiation (FTBI) 12 Gy, intravenous etoposide 60 mg/kg, and cyclophosphamide 75 mg/kg, followed by reinfusion of cryopreserved marrow. RESULTS: Sixty patients underwent consolidation treatment with HD Ara-C with the intent to treat with autologous BMT. Sixteen patients were unable to proceed to autologous BMT (10 patients relapsed, one died of sepsis, one developed cerebellar toxicity, two had inadequate blood counts, and two refused). Forty-four patients underwent autologous BMT and have a median follow-up time of 37 months (range, 14.7 to 68.7) for patients who are alive with no relapse. The cumulative probability of disease-free survival (DFS) at 24 months in the intent-to-treat group is 49% (95% confidence interval [CI], 37% to 62%) and in those who actually underwent autologous BMT is 61% (95% CI, 46% to 74%). The probability of relapse was 44% (95% CI, 31% to 58%) and 33% (95% CI, 20% to 49%) for the intent-to-treat and autologous BMT patients, respectively. CONCLUSION: This approach offers a relatively high DFS rate to adult patients with AML in first CR. The results of this study are similar to those achieved with allogeneic BMT.     

Minimal residual disease status before allogeneic bone marrow transplantation is an important determinant of successful outcome for children and adolescents with acute lymphoblastic leukemia

The efficacy of allografting in acute lymphoblastic leukemia (ALL) is heavily influenced by remission status at the time of transplant. Using polymerase chain reaction (PCR)-based minimal residual disease (MRD) analysis, we have investigated retrospectively the impact of submicroscopic leukemia on outcome in 64 patients receiving allogeneic bone marrow transplantation (BMT) for childhood ALL. Remission BM specimens were taken 6 to 81 days (median, 23) before transplant. All patients received similar conditioning therapy; 50 received grafts from unrelated donors and 14 from related donors. Nineteen patients were transplanted in first complete remission (CR1) and 45 in second or subsequent CR. MRD was analyzed by PCR of Ig or T-cell receptor delta or gamma rearrangements, electrophoresis, and allele-specific oligoprobing. Samples were rated high-level positive (clonal band evident after electrophoresis; sensitivity 10(-2) to 10(-3)), low-level positive (MRD detected only after oligoprobing; sensitivity 10(-3) to 10(-5)), or negative. Excluding 8 patients transplanted in CR2 for isolated extramedullary relapse (all MRD-), MRD was detected at high level in 12 patients, low level in 11, and was undetectable in 33. Two-year event-free survival for these groups was 0%, 36%, and 73%, respectively (P <.001). Follow-up in patients remaining in continuing remission is 20 to 96 months (median, 35). These results suggest that MRD analysis could be used routinely in this setting. This would allow identification of patients with resistant leukemia (who may benefit from innovative BMT protocols) and of those with more responsive disease (who may be candidates for randomized trials of BMT versus modern intensive relapse chemotherapy).     

Bone marrow transplantation for children less than 2 years of age with acute myelogenous leukemia or myelodysplastic syndrome

We analyzed results of 40 infants less than 2 years of age who received bone marrow transplants (BMT) between May 1974 and January 1995 for treatment of acute myelogenous leukemia (AML; N = 34) or myelodysplastic syndrome (MDS; N = 6) to determine outcome and survival performance. Among the AML patients, 13 were in first remission, 9 were in untreated first relapse or second remission, and 12 were in refractory relapse. Patients were conditioned with cyclophosphamide in combination with either total body irradiation (TBI; N = 29) or busulfan (N = 11). Source of stem cells included 6 autologous donors, 15 HLA genotypically identical siblings, 14 haploidentical family members, and 5 unrelated donors. Graft-versus-host disease (GVHD) prophylaxis was methotrexate (MTX) for 17, MTX plus cyclosporine (CSP) for 14, or CSP plus prednisone for 3. Incidence of severe (grade 3-4) regimen-related toxicity was 10% and transplant-related mortality was 10%. Acute GVHD (grades II-III) occurred in 39% of allogeneic patients, and chronic GVHD developed in 40%. Relapse, the most significant problem for patients in this study, occurred in 1 MDS patient and 23 AML patients and was the cause of death for 19 patients. The 2-year probabilities of relapse are 46%, 67%, and 92%, respectively, for patients transplanted in first remission, untreated first relapse or second remission, and relapse. One MDS and 8 AML patients received second marrow transplants for treatment of relapse, and 5 of these survive disease-free for more than 1.5 years. All 6 MDS patients and 11 of 34 AML patients survive more than 1.5 years later. The 5-year probabilities of survival and disease-free survival are 54% and 38% for patients transplanted in first remission and 33% and 22% for untreated first relapse or second remission. None of the patients transplanted with refractory relapse survive disease-free. Outcome was significantly associated with phase of disease at transplantation and pretransplant diagnosis of extramedullary disease. Long-term sequelae included growth failure and hormonal deficiencies. Survival performance was a median of 100% (80% to 100%) and neurologic development for all survivors was appropriate for age. This study indicates that infants with AML have similar outcome after BMT compared with older children and that BMT should be performed in first remission whenever possible. In addition, allogeneic BMT provides effective therapy for the majority of infants with MDS.     

Amplification of a Y-chromosomal DNA sequence by the polymerase chain reaction for documentation of residual recipient cells in small samples from bone marrow, peripheral blood and cerebrospinal fluid after bone marrow transplantation

The long arm of the human Y-chromosome contains about 800 to 5000 copies of the tandemly repeated DNA sequence DYZ1. A major part of the repeating unit (pHY10) has been cloned and sequenced. Primers were designed to match a part of this repeat sequence for the amplification of a 154 bp fragment spanning the EcoRI restriction site of the unit. Typical dilution experiments showed that this polymerase chain reaction (PCR) method allows the detection of 5 to 10 male cells among 100,000 female cells, or in 500 microL of cerebrospinal fluid containing only one cell per microL. In addition, the quality of the DNA used for the amplification reaction is less critical, thus allowing analysis of long-term stored samples such as bone marrow smears or dried blood stains spotted onto filter paper, which might contain partially degraded DNA. We applied this technique to detect residual host cells in the clinical setting of human sex-mismatched bone marrow transplantation (BMT). Fourteen patients, receiving transplantations because of leukemias could be supervised so far. Throughout the whole period of monitoring (days +14 until +911 post BMT; median: 160 days), residual host cells were detected in all but three patients. Persistence of host cells in the early phase post-BMT was mostly transient and probably due to long-term surviving host T-lymphocytes. Reappearance of host cells several months after BMT is highly suspicious of relapse from the underlying malignancy. Due to its high sensitivity, PCR is a valuable tool in monitoring the switch from recipient to donor cell population.(ABSTRACT TRUNCATED AT 250 WORDS)     

Donor lymphocyte infusion for the treatment of relapse after allogeneic hematopoietic stem cell transplantation

The results of donor lymphocyte infusion (DLI) for treatment of relapse after bone marrow transplantation (BMT) are reviewed. Durable complete remission can be achieved at the molecular level for a majority (more than 70%) of patients with CML, when treated at early relapse. Results are less favourable for acute leukemias, although useful responses have been reported. Data are scarce though promising for myelodysplastic syndromes and multiple myeloma. Major treatment-associated toxicities are GVHD and bone marrow aplasia. The latter complication can be predicted by evaluating the level of residual donor-derived hematopoiesis. Modification of infused cells (CD8 negative selection or transduction with a suicide gene), addition of peripheral blood stem cells, and early implementation of escalating doses may counteract the complications and increase the response rate. Response rate is variably influenced by the presence of chronic GVHD after initial BMT, T-cell depleted BMT, underlying disease and stage at relapse, and the level of mixed chimerism. DLI is a direct demonstration of the graft-versus-leukemia effect (GVL). Because GVL after BMT is sometimes the predominant cause of cure, it may be advisable in such situations to redirect the conditioning regimens for BMT towards engraftment and less immediate cytotoxicity.     

Tactical vs. other simulated aerial combat maneuvers

We report here that a patient with relapsed AML after allogeneic bone marrow transplantation achieved and maintained complete remission (CR) after effective donor leukocyte transfusion (DLT), without the occurrence of GVHD and marrow aplasia, for more than 21 months. This continuous CR maintenance is mainly due to the application of DLT at molecular relapse that was diagnosed by monitoring minimal residual disease (MRD) by the quantitation of WT1 (Wilms tumor gene) expression levels (WT1 assay). The present case demonstrates that early application of DLT at molecular relapse is essential for the improvement of the efficacy of DLT for relapsed AML after BMT.     

Immunophenotyping investigation of minimal residual disease is a useful approach for predicting relapse in acute myeloid leukemia patients

A high complete remission rate is currently achieved in patients with acute myeloid leukemia (AML). However, many patients eventually relapse due to the persistence of low numbers of residual leukemic cells that are undetectable by conventional cytomorphologic criteria (minimal residual disease [MRD]). Using immunophenotypic multiparametric flow cytometry, we have investigated in sequential studies (diagnosis and follow-up) the impact of MRD detection on the outcome of 53 AML patients that had achieved morphologic remission with standard AML protocols and displayed at diagnosis an aberrant phenotype. Patients were studied at diagnosis with a panel of 35 monoclonal antibodies in triple staining combinations for detection of aberrant or uncommon phenotypic features. According to these features, a patient's probe was custom-built at diagnosis for the identification of possible residual leukemic cells during follow-up. The level of MRD at the end of induction and intensification therapy correlated with the number of relapses and relapse-free survival (RFS). Thus, patients with more than 5 x 10(-3) residual cells (5 residual cells among 1,000 normal bone marrow [BM] cells) identified as leukemic by immunophenotyping in the first remission BM showed a significant higher rate of relapse (67% v 20% for patients with less than 5 x 10(-3) residual cells; P = .002) and a lower median RFS (17 months v not reached; P = .01). At the end of intensification, with a cut-off value of 2 x 10(-3) leukemic cells, AML patients also separated into two distinct groups with relapse rates of 69% versus 32% (P = .02), respectively, and median RFS of 16 months versus not reached (P = .04). In addition, overall survival was also significantly related to the level of residual cells in the marrow obtained at the end of induction and particularly after intensification therapy (P = .008). Furthermore, we have explored whether residual disease was related with the functional expression of multidrug resistance (MDR-1) at diagnosis as assessed by the rhodamine123 assay. Patients with > or =5 x 10(-3) residual leukemic cells at the end of induction therapy had a significantly higher rhodamine-123 efflux (mean, 56% +/- 24%) than those with less than 5 x 10(-3) residual cells (mean, 32% +/- 31%; P = .04). Finally, multivariate analysis showed that the number of residual cells at the end of induction or intensification therapy was the most important prognostic factor for prediction of RFS. Overall, our results show that immunophenotypical investigation of MRD strongly predicts outcome in patients with AML and that the number of residual leukemic cells correlates with multidrug resistance.     

Colony growth in cultures from bone marrow and peripheral blood after curative treatment for leukemia and severe aplastic anemia

The recovery of colony-forming cell numbers after curative treatment for leukemia and severe aplastic anemia (SAA) was studied. We examined 191 patients (85 acute myeloid leukemia [AML], 48 acute lymphocytic leukemia [ALL], 32 chronic myeloid leukemia [CML], 17 SAA, and nine myelodysplastic syndrome [MDS]) who were in hematologic remission 6 months to 13 years after either curative chemotherapy (n = 69) or allogeneic bone marrow transplantation (BMT) (n = 122) by culturing their precursor cells from bone marrow (BM) (n = 548) and peripheral blood (PB) (n = 529) in methylcellulose. Thirty-six BM donors and 25 PB donors served as controls. BM colony-forming cell numbers were abnormally low in all patients (p < 0.002) irrespective of underlying disorder and type of treatment (chemotherapy or irradiation). These numbers did not normalize with time--colony-forming cells were still strongly reduced up to 10 years after therapy, whether or not the patient had received an allogeneic bone marrow graft (p < 0.002). We also compared patients who remained in stable hematologic remission with those who later relapsed (6 months to 2 years after treatment). BM colony-forming cell numbers were significantly lower in patients who subsequently relapsed (p = 0.004). In contrast to BM cultures, we found normal colony-forming capacity by PB precursors in all patients. We conclude that (1) after chemotherapy or BMT, colony-forming cell numbers of BM in culture are permanently reduced; (2) this defect is probably due to a dysfunction of the BM environment rather than to a numerical reduction of the precursor cell pool; and (3) very low colony-forming capacity may be related to relapse.     

Follow-up of residual disease using metaphase-FISH in patients with acute lymphoblastic leukemia in remission

Metaphase-FISH (fluorescence in situ hybridization) was used to detect cells with a chromosomal trisomy and/or translocation in 25 patients with acute lymphoblastic leukemia (ALL) in remission. Twelve patients were treated with chemotherapy alone and 13 patients received bone marrow transplantation after initial chemotherapy. Patients were followed up for 8-56 months (median 18 months). In this study, a total of 82 bone marrow samples were analyzed. Metaphase-FISH identified chromosome morphology, even banding, in cells from which FISH signals were studied. Thus, it is as reliable as standard karyotype analysis and does not cause false positive results. Furthermore, more than 1000 cells can be analyzed in 3-6 h which equals the time it takes to analyze 20 metaphases by standard karyotype. The time span before the first positive sample seems to be insignificant with regard to the outcome of relapse. All six patients, who had more than 1% of abnormal cells detected at any sampling or whose consecutive follow-up samples showed an increasing frequency (up to 1%) of abnormal cells, relapsed. Absence or occurrence of low numbers of abnormal cells at a frequency of 0.05-0.8% followed by their disappearance was in agreement with continuing complete clinical and hematologic remission (CR) in 16 (84%) of 19 patients. Our results indicate that metaphase-FISH is a reliable technique for quantifying residual leukemic cells. The technique is available in standard cytogenetic laboratories and can be applied to routine follow-up of ALL patients who have a suitable chromosomal aberration.     

Allogeneic peripheral blood progenitor cells for treatment of relapse after bone marrow transplantation

Donor leukocyte infusions (DLI) are an effective therapy for patients who relapse with leukemia after bone marrow transplantation (BMT). Severe graft-versus-host disease and prolonged periods of pancytopenia compromise the success of this treatment in a substantial number of patients. We used filgrastim-mobilized peripheral blood progenitor cells (PBPCs), in some cases preceded by cytoreductive therapy, to circumvent some of the problems associated with DLI. Eleven patients (median age 41 years) received a total of 20 donor cell infusions. Their diagnosis was CML in hematological (two patients) or cytogenetic relapse (two patients), six patients suffered from acute myeloid leukemia (AM; n = 5) or Philadelphia chromosome-positive acute lymphoblastic leukemia (ALL Ph+). One patient had multiple myeloma (MM). All six patients with acute leukemias received cytoreductive therapy prior to PBPC infusions; three patients with CML were pretreated with IFN alpha. Four of four patients with CML responded to PBPC infusions and currently are in complete clinical and molecular remission for time periods between 1 and 12 months. Six of six patients with acute leukemias achieved a complete remission. All of them relapsed after a median remission duration of 24 weeks (range 11-49 weeks). Three patients relapsed at extramedullary sites (CNS, testes, skin). Four of six acute leukemia patients received further cytoreductive therapy. All patients responded again and are in complete remission for time periods between 14 and 615 days. Two patients with acute leukemias have died due to dissemination of the disease. The patient with MM did not respond and is alive with disease. Severe (grade III) acute GVHD developed in two of 11 patients, three patients developed grade II disease, six patients did not show any signs of GVHD. Extensive chronic GVHD has developed in two cases to date. Patients with chemotherapy prior to PBPC infusion developed neutropenia and thrombocytopenia with a maximum duration of 20 and 14 days, respectively; prolonged periods of neutropenia did not occur. Two patients developed long-lasting thrombocytopenia in spite of PBPC infusion, in one case followed by leukemic relapse. Repeated courses of chemotherapy and PBPC infusion were generally tolerated well; no early deaths due to treatment-related toxicity or GVHD were observed. We conclude that the use of allogeneic PBPC instead of DLI in patients with relapse after BMT is technically feasible and safe. The efficacy of PBPC infusions seems comparable to DLI in patients with CML. Patients with acute leukemias also achieved complete albeit transient remissions. Aggressive chemotherapy followed by PBPC infusions resulted in only limited duration of cytopenia. The usage of PBPC infusion instead of non G-CSF-mobilized donor cells for treatment of relapse after BMT may reduce pancytopenia-related complications and merits further investigation.