Long-term survival without graft-versus-host-disease following infusion of allogeneic myeloma-specific Vβ T cell families

Background

Despite chemo-induction therapy and autologous stem cell transplantation (ASCT), the vast majority of patients with Multiple Myeloma (MM) relapse within 7 years and the disease remains incurable. Adoptive Allogeneic T-cell therapy (ATCT) might be curative for MM, however current ATCT protocols often lead to graft versus host disease (GvHD). Transplanting only tumor reactive donor T cells that mediate a graft-versus-myeloma (GvM) but not GvHD may overcome this problem.

Methods

We used an MHC-matched/miHA-disparate B10.D2 → Balb/c bone marrow transplantation (BMT) murine model and MOPC315.BM MM cells to develop an ATCT protocol consisting of total body irradiation, autologous-BMT and infusion of selective, myeloma-reactive lymphocytes of T cell receptor (TCR) Vβ 2, 3 and 8.3 families (MM-auto BMT ATCT).

Results

Pre-stimulation ex vivo of allogeneic T cells by exposure to MOPC315.BM MM cells in the presence of IL-2, anti-CD3 and anti-CD28 resulted in expansion of the myeloma-reactive T cell TCRVβ 2, 3 and 8.3 subfamilies. Their isolation and infusion into MM-bearing mice resulted in a vigorous GvM response without induction GvHD and long-term survival. Repeated infusion of naïve myeloma-reactive T cell TCRVβ 2, 3 and 8.3 subfamilies was also effective.

Conclusions

These data demonstrate that a transplantation protocol involving only selective tumor-reactive donor T cell families is an effective immunotherapy and results in long-term survival in a mouse model of human MM. The results highlight the need to develop similar ATCT strategies for MM patients that result in enhanced survival without symptoms of GvHD.

Incidence and risk factors for moderate-to-severe veno-occlusive disease of the liver after allogeneic stem cell transplantation using a reduced intensity conditioning regimen

The incidence and outcome of moderate-to-severe veno-occlusive (VOD) disease was analyzed in 271 consecutive patients with hematological malignancies who underwent allogeneic SCT (allo-SCT) using the same reduced intensity regimen (RIC). RIC consisted of fludarabine, BU and antithymocyte globulin (ATG). Twenty-four out of 271 patients (8.8%) developed VOD, which was severe in only 4 (1.4%) out of 24 cases. All four patients with severe VOD finally succumbed to their disease. In multivariate analysis, i.v. administration of BU was associated with significant reduced incidence of VOD as compared with per os administration. In conclusion, VOD remains a serious complication of allo-SCT using RIC regimens containing BU. Although the incidence of severe VOD is very low, the overall mortality rate in the group of patients with severe VOD remains extremely high and therefore novel treatment approaches are needed.

Comparing i.v. BU dose intensity between two regimens (FB2 vs FB4) for allogeneic HCT for AML in CR1: a report from the Acute Leukemia Working Party of EBMT

This retrospective analysis compared two regimens of fludarabine combined with i.v. BU 6.4 mg/kg (FB2) or BU 12.8 mg/kg (FB4) for allografting of AML in first CR. A total of 437 patients (median age: 50 years) were administered FB2 (n = 225, 51%) or FB4 (n = 212, 49%). Median follow-up time was 28 months. Use of FB2 resulted in a longer time to neutrophil engraftment (17 vs 15 days, P < 0.0001) but no difference in incidence of grade II-IV acute (P = 0.54) or chronic GVHD (P = 0.51). In patients < 50 years of age, FB2 was associated with a higher 2-year cumulative incidence of relapse (33 ± 6% vs 20 ± 4%, P = 0.04), but there was no difference in 2-year leukemia-free survival (LFS) (P = 0.45), OS (P = 0.53) or non-relapse mortality (P = 0.17). In recipients ⩾ 50 years of age, FB2 resulted in better 2-year LFS (63 ± 4% vs 42 ± 7%, P = 0.02) and OS (68 ± 4% vs 45 ± 7%, P = 0.006); a lower 2-year non-relapse mortality, albeit not statistically significant (15 ± 3% vs 29 ± 6%, P = 0.06), was observed with FB2. FB2 is an effective and well-tolerated regimen in patients ⩾ 50 years of age and does not compromise survival when used in patients <50 years undergoing allogeneic transplantation for AML in first CR.

The number of infused CD34+ cells does not influence the incidence of GVHD or the outcome of allogeneic PBSC transplantation, using reduced-intensity conditioning and antithymocyte globulin

The influence of graft composition on the outcome of reduced-intensity (RIC) allogeneic PBSC transplantation (allo-PBSC) remains controversial. In this study, we analyzed the impact of CD34+ cell dose on the incidence of GVHD, and on the outcome after allo-PBSC, in 103 patients with hematological malignancies, using a uniform RIC regimen. The following variables were included in statistical analysis: (1) number of C34+ cells, (2) high-risk vs low-risk disease status, (3) matched related vs matched unrelated donor, (4) female donor to male recipient vs any other combination, (5) age of recipient (above vs below the median). Univariate and multivariate analysis did not reveal any association between CD34+ cell dose and acute grade-2 to grade-4, cGVHD, non-relapse mortality (NRM), relapse rate (RR) and OS. High-risk disease status was the only variable independently associated with increased NRM (P=0.001), increased RR (P=0.012) and decreased OS (P<0.001). The same results were obtained when analysis was restricted to a subgroup of 55 patients with myeloid neoplasms. The influence of graft composition on the outcome of RIC allo-PBSC should be further investigated via well-controlled randomized prospective studies.

Assessment of CD4 T-lymphocyte reactivity by the Cylex ImmuKnow assay in patients following allogeneic hematopoietic SCT

After allogeneic hematopoietic SCT (alloHSCT), immunosuppressed patients are susceptible to opportunistic infections, and uncontrolled function of the graft can result in GVHD. Accurate immune monitoring may help early detection and treatment of these severe complications. Between October 2005 and November 2007, a total of 170 blood samples were collected from 40 patients after alloHSCT in the Hadassah Hebrew University Medical Center and from 13 healthy controls. We utilized the Cylex ImmuKnow assay for CD4 ATP levels to compare known clinically immunocompromised vs immunocompetent patients after alloHSCT. We also compared the reconstitution of WBC count to the ImmuKnow results and clinical status. The patients' clinical course correlated with the stratification of immune response established by the ImmuKnow assay for solid organ transplantation (immunocompetent vs immunocompromised), and this often differed from their WBC count. On the basis of our observations, we conclude that the ImmuKnow assay is a simple and fast immune-monitoring technique for patients undergoing alloHSCT, with potential to predict clinical course and facilitate prompt management of post-HSCT complications. The assay should be evaluated prospectively in clinical trials.

Quantitative monitoring of multi-donor chimerism: a systematic, validated framework for routine analysis

Despite therapeutic advantages, double-donor (DD) HSCTs present technical problems for molecular chimerism (CHM) monitoring. These DD chimeras contain three matched DNAs, so that the genomes of donor(s) and recipient often share the same alleles. In the STR assay, shared recipient/donor alleles are common and have identical physico-chemical properties. As a consequence of the latter, they co-migrate in the same band ('shared peak'), which prevents measuring each allele separately. Without individual allelic measurements, the direct calculation of the chimeric recipient/donor DNA ratio is precluded. This is the first study to document and systematically examine these problems. Its goal was to provide a validated framework for accurate, routine monitoring based on a stepwise analytic paradigm for approximating percent CHM (%CHM) from shared STR-alleles. Analysis of STR-DNA from DD loci showed that at least four of six alleles were typically shared. Despite such extensive allelic sharing, we show how simple arithmetic procedures can be applied for standardized calculation of %CHM based on peak measurements. Criteria for selecting loci suitable for such analysis are provided. Validation of the computational results required analyzing 18 'informative' loci with pre-established reference values for %CHM. In all cases, the results for %CHM, calculated from peak measurements, were +/-5% of the reference value. The conclusions of the study are as follows: (1) Multi-donor chimeras, with shared alleles, can be accurately and simply analyzed within the usual limits of STR measurement error; (2) by examining these various facets of DD CHM analysis, this novel study has provided a basis for standardized, routine quantitative monitoring using the STR/VNTR assay.

Allogeneic CD3/CD28 cross-linked Th1 memory cells provide potent adjuvant effects for active immunotherapy of leukemia/lymphoma

The breaking of peripheral T-cell tolerance toward self-antigens expressed by tumor cells and the subsequent establishment of an effective tumor protective immune response remains a major challenge for cancer immunotherapy. We report that both protective and therapeutic anti-tumor immune responses can be achieved in a mouse leukemia/lymphoma tumor model through the strong adjuvant effects provided by allogeneic CD3/CD28 cross-linked Th1 memory cells. The adjuvant effect of these cells is mediated by their ability to produce a variety of 'danger signals' which serve to deviate native non-protective Th2 anti-leukemia immune responses to effective Th1 immune responses.

Peliosis hepatis following treatment with androgen-steroids in patients with bone marrow failure syndromes

Androgens widely used in the treatment of bone marrow failure syndromes can in rare cases cause hepatic peliosis, a pathological entity characterized by multiple blood-filled cavities in the liver parenchyma. Bone marrow failure syndromes per se are associated with a low coagulation status, which is further magnified by bone marrow transplantation for aplastic anaemia due to deep thrombocytopenia. Both these conditions can cause bleeding; their combination is especially dangerous. We describe two cases of aplastic anaemia due to paroxysmal nocturnal hemoglobinuria and Fanconi syndrome, in which patients developed peliosis hepatis after prolonged treatment with androgens. One patient developed severe subcapsular bleeding, successfully treated with catheterization of the right hepatic artery and embolization of the bleeding site. The second patient bridged over deep post-transplant aplasia with high frequency platelet transfusions, and demonstrated an uncomplicated post-BMT course. We suggest avoiding or interrupting treatment with androgens in patients preparing for BMT.

Allogeneic hematopoietic stem cell transplantation in the elderly

The development of reduced intensity or non-myeloablative conditioning (NST) in preparation for allogeneic stem cell transplantation (SCT) revolutionized the field and led to reconsideration of the dogma of upper age limit that was set up by the transplant centers as an eligibility parameter. Analysis of the literature data showed that NST regimens are associated with decreased transplant related mortality, and graft-versus-host disease, in comparison with standard myeloablative conditioning, in patients above the age of 50-55 years, or in younger patients with significant comorbidities. However we have to mention, that our considerations are based on the retrospective analysis of the literature data, and that well controlled prospective randomized studies are needed in order to definitely assess the role of NST. Comorbidity indices might be proved as the most important parameters for the choice of the most proper regimen for each patient in need and should be included in future trials.

Allogeneic stem cell transplantation from matched related and unrelated donors in thalassemia major patients using a reduced toxicity fludarabine-based regimen

The only radical cure for thalassemia major patients today is the replacement of the defective hematopoietic system by allogeneic stem cell transplantation (allo-SCT). The major obstacles for the application of allo-SCT even from matched family members have been the transplant-related morbidity and mortality and graft failure that is usually associated with the recurrence of the thalassemia hematopoiesis. The outcome of allo-SCT from HLA-identical family donors is largely dependent on the age of the recipient as well as on pretransplant parameters reflecting the degree of organ damage from iron overload. In this study we report our experience of allo-SCT from matched related and unrelated donors, using a reduced toxicity conditioning consisting of fludarabine, busulfan or more recently busulfex and antithymocyte globulin, in a cohort of 20 patients with thalassemia major. The regimen-related toxicity was minimal, while the incidence of acute grade II-IV and chronic GVHD was 25 and 25%, respectively. With a median follow-up period of 39 months (range: 5-112 months) the overall survival was 100%, while thalassemia-free survival was 80%. Although the results of our study look promising, larger cohorts of patients and prospective clinical trials are required to confirm the benefits of our approach as a possible better alternative to the existing protocols.

Targeted immunotherapy with intentionally mismatched rIL-2 activated donor lymphocytes in an attempt to eliminate minimal residual disease in patients with high-risk metastatic cancer

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Background: Graft-versus-leukemia and graft-versus-tumor (GVT) effects following stem cell transplantation are well established, however, procedure related toxicity and mortality are unavoidable. In addition to limited efficacy following stem cell transplantation (SCT), graft-versus-host disease (GVHD) is unavoidable. Our protocol was designed to induce more potent anti-cancer immunotherapy by rIL-2 activated intentionally mismatched donor lymphocytes (MDL) at the stage of minimal residual disease (MRD) outpatient procedure with no SCT avoiding GVHD. Methods: Optimizing MDL was accomplished by cyclophosphamide 1,500 mg/m2 and 2 injections of alpha interferon (3x106IU) for more effective immunotherapy, aiming for depletion of regulatory T cells, followed by infusion of haploidentically mismatched lymphocytes activated with rIL-2 (6,000 IU/ml) for 4 days. On the day of cell infusion, patients received rIL-2 6x106 IU subcutaneously outpatient for 5 days. Results: A total of 41 (age 5–73, median 52) high risk patients were included: metastatic breast 13; colorectal 3; gastric 3; pancreatic 3; melanoma 3; head & neck 3; glioblastoma 2; and 6 with other solid tumors. Five patients had resistant hematological malignancies: multiple myeloma 2; non-Hodgkin's lymphoma 2 and Hodgkin's disease 1. 6 patients received lymphocytes with bispecific antibodies for targeted cell-therapy (3 with catumaxomab against CD3 & epithelial cell adhesion molecule (EpCAM); 3 with ertumaxomab directed against CD3 & Her-2/neu WHO toxicity >grade 2 was noted. 14 of evaluable patients are alive. 10/32 with solid tumors are alive, 7 with no evidence of disease > 9–91 (median 17) months (4 breast; 1 squamous cell; 1 head & neck; 1 prostate). Of 5 patients with hematological malignancies 4 are alive and disease free >18–96 (median 46) months. Conclusions: Safe induction of GVT effects may be accomplished by MDL, preferably targeted with bispecific antibodies after cyclophosphamide conditioning lymphocytes are more potent and act faster than matched lymphocytes and GVHD is avoided by rejection of donor lymphocytes. When applied at a stage of MRD, such treatment may result in operational cure.

No significant financial relationships to disclose.

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.

Mycosis fungoides associated with B-cell malignancies

BACKGROUND

The coexistence of mycosis fungoides, a peripheral T-cell lymphoma, and B-cell malignancies or Hodgkin's lymphoma in the same patient is unusual. Most descriptions are isolated case reports and case series are strikingly sparse.

OBJECTIVES

To detect cases of mycosis fungoides associated with B-cell malignancies or Hodgkin's lymphoma and to analyse the characteristics of and the interplay between the lymphoproliferative neoplasms.

METHODS

Patients with mycosis fungoides who had B-cell malignancies or Hodgkin's lymphoma were selected from among 398 patients either treated or followed up in two tertiary medical centres during a 7-year period.

RESULTS

Eleven patients with mycosis fungoides and B-cell malignancy were detected (seven of non-Hodgkin's lymphoma, three of chronic lymphocytic leukaemia, one of multiple myeloma). No case of Hodgkin's lymphoma was found. In seven patients the mycosis fungoides preceded the B-cell malignancy whereas in four it was the B-cell malignancy which occurred first. The time elapsed between onset of the two malignancies ranged from 4 to 22 years (average: 12 years). Patients who had mycosis fungoides as the first neoplasm presented with earlier stages of mycosis fungoides (four of seven: IA, three of seven: IB) than those who had mycosis fungoides as their second neoplasm (of four, one: IB, one: folliculotropic, two: IIB). Among the four patients in whom the appearance of mycosis fungoides followed the B-cell malignancy, three had been treated with multiagent chemotherapy. Two patients who presented with early-stage mycosis fungoides (IA) as the first lymphoma developed mycosis fungoides tumours after becoming immunosuppressed. In two patients infiltrates composed of both malignant T- and B-cell populations were found in a single biopsy. One showed two distinct populations of the malignant cells in the skin tumour, thus constituting a classical composite lymphoma of mycosis fungoides and chronic lymphocytic leukaemia, while in the other patient the two malignant populations of marginal B-cell lymphoma and mycosis fungoides (as evidenced by both phenotypic and genotypic findings) were intermingled.

CONCLUSIONS

This case series indicates that while the coexistence of Hodgkin's lymphoma and mycosis fungoides is extremely rare, the association of mycosis fungoides and B-cell malignancies is not as rare as reflected in the literature, with non-Hodgkin's lymphoma constituting the most common associated B-cell malignancy. In this series as well as in the cases reported in the literature mycosis fungoides usually preceded the development of B-cell malignancies, which may be in accordance with previous reports of an increased risk of developing a second haematological neoplasm. The importance of a competent immune system for patients with mycosis fungoides is well demonstrated in these cases. It is suggested that for greater precision the criteria for diagnosis of composite lymphoma of the skin should include both phenotypic and genotypic features.

A patient with progressive multiple myeloma treated successfully with arsenic trioxide after allogeneic bone marrow transplantation

Multiple myeloma (MM) is an incurable progressive disease. Many therapeutic options are available to delay progression, including autologous and allogeneic bone marrow transplantation. At advanced stages, MM is often refractory to treatment. We report a heavily pretreated patient with graft-versus-host disease after bone marrow transplantations, treated at a terminal stage with a modified protocol for arsenic trioxide (ATO). This patient with poor clinical status tolerated the treatment very well. He had a remarkable clinical response and achieved complete remission. The mechanisms of ATO are presented and the potential role of ATO for MM is discussed.

Treatment of post-hematopoietic stem cell transplantation hemorrhagic cystitis with intravesicular sodium hyaluronate

Hemorrhagic cystitis (HC) is a well-known complication of HSCT. Its overall incidence has been reported to vary from 7-68%. The spectrum of clinical presentation varies from asymptomatic microhematuria to life-threatening bleeding. Sodium hyaluronate is a glycosaminoglycan present on the bladder mucosa, which serves as an important protective substance against uroepithelial damage. Preparations of this component have been shown to be effective in the treatment of interstitial cystitis. We report our experience in the treatment of post-transplant HC with intravesical instillation of sodium hyaluronate. Five out of the seven patients included in this study achieved complete response, while one patient had only partial response. Sodium hyaluronate administration was not associated with any local or systemic adverse effects. We consider that the results of our study are promising and the efficacy of sodium hyaluronate in the treatment of post-transplant HC should be tested in larger cohorts of patients.

Fludarabine-Based Reduced Intensity Conditioning for Stem Cell Transplantation of Fanconi Anemia Patients from Fully Matched Related and Unrelated Donors

Reduced intensity conditioning has been suggested as a desirable therapeutic modality for the treatment of patients with malignant and nonmalignant indications, but it seems particularly attractive for patients with Fanconi anemia due to their increased sensitivity to chemoradiotherapy. Between November 1996 and September 2003, 7 patients (1 male and 6 female; age range, 3-31 years; median age, 9.5) were conditioned with a fludarabine-based protocol for stem cell transplantation without radiation. In vivo T-cell depletion was accomplished with anti-thymocytic globulin or Campath-1H (alemtuzumab). Graft-versus-host disease prophylaxis consisted of low-dose cyclosporine alone. Eight transplantations were carried out for 7 patients using bone marrow, peripheral blood, and/or cord blood as sources of stem cells. All patients received transplants from HLA-A, -B, -C, and -DR matched donors, 5 from family members and 2 from matched unrelated donors. One patient did not engraft her first matched unrelated donor and underwent a second transplantation from another matched unrelated donor, after which she engrafted well. All 7 patients are alive and well, fully reconstituted with donor cells, and with 100% performance status. In conclusion, fludarabine-based preparative protocols are well tolerated, facilitate rapid engraftment with minimal toxicity, and should be considered an essential component of choice for patients with Fanconi anemia.

A prospective, double-blind phase II study evaluating the safety and efficacy of a topical histamine gel for the prophylaxis of oral mucositis in patients post hematopoietic stem cell transplantation

The aim of this study was to evaluate the safety, tolerability and efficacy of a topical gel containing histamine dihydrochloride (HDC) versus a placebo gel in preventing oral mucositis in hematopoietic stem cell transplantation (HSCT) patients. A total of 45 patients post-HSCT were enrolled in a prospective longitudinal, placebo-controlled, double-blind study. Patients were evaluated twice weekly for oral mucositis (OMAS, NCI score), oral pain (VAS), oral function and salivary flow rate. Compliance was assessed using a patient diary. Oral mucositis developed in 85% of the HDC group and 63% of the placebo group. The mean maximal intensity for NCI score was 1.45+/-1 in the HDC group and 1.21+/-1.27 in the placebo group (P=0.37). The mean duration of oral mucositis was 4.7+/-3.6 and 2.33+/-2.23 days in the HDC and placebo groups, respectively (P=0.06). The same trends were measured with OMAS. Visual analogue scale for oral pain and oral function was not significantly different between the two groups. Histamine dihydrochloride was found to be safe. In the search for topical agents for the prevention of mucositis, we found that HDC neither improves nor worsens oral mucositis in HSCT patients. The balance between the pro- and anti-inflammatory effects of HDC should be investigated further in order to acquire a clinically effective topical medication based on its anti-inflammatory properties.

Rapid response to alefacept given to patients with steroid resistant or steroid dependent acute graft-versus-host disease: a preliminary report

We evaluated the effect of alefacept (Amevive), a novel dimeric fusion protein, in steroid resistant/dependent acute graft-versus-host-disease (aGVHD). Seven patients were treated in eight aGVHD episodes. GVHD grade at treatment initiation and at peak ranged 2-4 (median 2.5) and 2-4 (median 4), respectively. System involvement at GVHD peak included skin (n=7), gastrointestinal tract (n=5) and liver (n=3). All patients responded. However, one patient with skin GVHD and two with gastrointestinal GVHD featuring an early initial response (IR) exacerbated and CR was not achieved. Skin GVHD responded rapidly with a median of 1 day to IR and 7 days to CR. Intestinal response was slower with median 7.5 days to IR. Of the four patients that achieved IR, CR was achieved in only one (40 days to CR). None of the patients had significant hepatic GVHD before treatment so no hepatic effect of alefacept could be determined. No immediate alefacept-related side effects were observed. Late side effects included infections (aspergillus sinusitis, pneumonia, bacteremia, pharyngeal thrush), pancytopenia and hemorrhagic cystitis. Three patients had CMV reactivation while on alefacept. We conclude that alefacept may have a beneficial effect in controlling aGVHD. Further investigations in larger cohorts of patients and controlled studies are warranted.

Nonmyeloablative stem cell transplantation using lymphoablative rather than myeloablative conditioning in the prefludarabine era by ATG and limiting doses of cyclophosphamide

The feasibility of using lymphoablative rather than myeloablative conditioning for durable engraftment of allogeneic stem cells and subsequent cell therapy with donor lymphocytes was pioneered in the prefludarabine era in patients with resistant lymphoma and metastatic solid tumors. Between July 1995 and August 1996, 15 patients, five males and 10 females, median age 50 (range 20-57) years, were enrolled in a protocol that consisted of different doses of cyclophosphamide (Cy), 50 mg/kg/day for 1, 2, 3 or 4 consecutive days in parallel with a fixed dose of rabbit antithymocyte globulin (ATG) (Fresenius) 10 mg/kg/day for 4 consecutive days. All patients, except one treated with a single dose of Cy, achieved full tri-lineage engraftment and no late graft failure was observed. Only three patients suffered from grade III-IV graft-versus-host disease (GVHD). Three patients out of the 15 survived long term (follow-up >93 to >96 months). We concluded that lymphoablative conditioning with ATG and intermediate-to-high-dose Cy is well tolerated and can result in durable engraftment with acceptable GVHD in heavily pretreated patients with advanced malignancies. Hence, induction of tolerance to donor alloantigens by lymphoablative conditioning while avoiding myeloablative chemotherapy or radiation therapy may serve as a platform for subsequent cell therapy with donor lymphocytes.

The beneficial role of inhibitory KIR genes of HLA class I NK epitopes in haploidentically mismatched stem cell allografts may be masked by residual donor-alloreactive T cells causing GVHD

HLA allele mismatches will provoke T-cell alloreactivity after allogeneic stem cell transplantation. As donors and recipients are usually HLA matched, the public HLA epitopes that are recognized by natural killer (NK) cells (NK epitopes) are rarely mismatched, and therefore there is rarely potential for NK alloreactivity arising from the absence of ligands for inhibitory killer immunoglobulin-like receptors (KIR). Transplants using related donors sharing only one haplotype (haploidentical donors) represent a setting in which NK epitopes are often mismatched, thus resulting in the potential for NK alloreactivity. We have analyzed engraftment, acute graft vs host disease (GVHD), leukemia relapse, and survival in 62 haploidentical transplants in relationship with potential NK alloreactivity, inhibitory, and activating KIR genes of class I HLA NK epitopes. Potential NK alloreactivity in the rejection direction was not associated with any outcome variable. Potential NK alloreactivity in the GVHD direction was associated with an increased incidence of severe GVHD and poorer patient survival but not with non-engraftment nor leukemia relapse. A higher number of activating KIR receptors in the genome of the donor was associated with a higher prevalence of GVHD. These results suggest that lack of extensive T-cell depletion in haploidentical transplantation is associated with high GVHD rates and diminishes the benefits of NK-cell alloreactivity.

CO2 laser in oral graft-versus-host disease: a pilot study

This paper is the first to report the benefits of CO2 laser treatment for pain control in severe oral chronic graft-versus-host disease (GVHD). A CO2 laser device was used during 17 treatment sessions in four patients. The CO2 laser was applied over the mucosal lesions using 1 W for 2-3 s/1 mm(2). This treatment resulted in a consistent and significant decrease in pain, measured using a standard visual analogue scale. These results suggest that the CO2 laser can be used for the alleviation of pain in oral chronic GVHD.

Low transplant-related mortality with allogeneic stem cell transplantation in elderly patients

Historically, age >60 years was considered a contraindication for allogeneic stem cell transplantation (allo-SCT). In recent years, elderly (>60 years) patients have become eligible for allo-SCT due to the application of reduced intensity conditioning (RIC). The present report summarizes our cumulative experience in a cohort of 17 elderly patients (age 60-67, median 62.5 years) with hematological malignancies treated with 18 allo-SCT procedures, mostly nonmyeloablative. In all, 14 patients received fludarabine and busulfan/busulfex regimen, three patients were conditioned with the fludarabine and low-dose TBI and one patient received busulfan alone. All patients displayed tri-lineage engraftment. The time to recovery of absolute neutrophil count >/=0.5 x 10(9)/l was 9-27 days (median 14 days). The time interval to platelet recovery >/=20 x 10(9)/l was 3-96 days (median 11 days). Veno-occlusive disease occurred only in 3/18 procedures and subsided with conventional treatment. Nonfatal transplant-related complications occurred in 6/18 (33.3%) procedures including: renal failure, arrhythmia, CNS bleeding, cystitis, typhlitis and gastrointestinal bleeding. Transplant-related mortality occurred in 6/18 (33.3%) episodes. Of the 17 patients, 12 (12/18 episodes) were discharged. Five of 17 (29%) patients survived (median follow-up 11 m, range 8-53 m). Our data suggest that RIC-allo-SCT may be safely applied in the elderly, suggesting that allogeneic immunotherapy may become an important tool for treatment of hematological malignancies without an age limit.

Low incidence of pulmonary complications following nonmyeloablative stem cell transplantation

Bone marrow transplantation is associated with pulmonary opportunistic infections and immune-mediated pulmonary processes such as idiopathic pneumonia syndrome and bronchiolitis obliterans. The aim of the present study was to test the hypothesis that nonmyeloablative stem cell transplantation (NST) has less adverse effects on the lungs. A review was undertaken of the pulmonary complications occurring in 53 patients with various haematological malignancies, some of whom were considered high-risk patients with chemoresistant disease, who underwent fludarabine-based irradiation-free conditioning for NST performed between March 1996 and October 1998. All data related to transplant procedure, disease outcome, graft-versus-host disease (GVHD), chest imaging, microbial cultures and lung biopsies, were retrieved from information collected prospectively at the time of transplantation. The median follow-up period after transplantation was 45 months, with 35 patients surviving > 100 days. Approximately half of the patients displayed some form of GVHD, with 11% developing severe chronic GVHD. In 17 (32%) patients, the lungs were somehow adversely affected. Only two (3.8%) patients developed a clinical picture consistent with idiopathic pneumonia syndrome and none developed diffuse alveolar haemorrhage or bronchiolitis obliterans. Dose-reduced conditioning is associated with a low rate of pulmonary toxicity and side-effects. These findings may extend understanding of significant immune-mediated complications occurring after bone marrow transplantation.

Tube thoracostomy during allogeneic stem cell transplantation does not carry an increased risk for infections or bleeding

BACKGROUND

Candidates for stem cell transplantation may occasionally suffer from massive pleural effusions related to their disease and require tube thoracostomy. The additional risk of this procedure during allogeneic transplantation procedure is not known.

METHODS

Four high-risk patients transplanted in our institution during a 2-yr period had chest drainage by tube thoracostomy. The characteristics of the fluid, the clinical course, and the outcome were assessed.

RESULTS

A total of nine chest drains were inserted (range 1-5). No bleeding complications related to the procedure were noted. None of the patients developed any clinical signs of local infection at the tube insertion site or within the pleural fluid. All cultures taken from the drained fluid or from the insertion wound were negative.

CONCLUSIONS

Tube thoracostomy in itself does not seem to pose additional risks in the transplant procedure, despite all patients in this series being considered to be at high-risk for complications.

Rhinolalia as a presenting sign of pneumomediastinum complicating post peripheral blood stem cell transplantation bronchiolitis obliterans

A 26-year-old male with graft vs. host disease (GVHD) presented with rhinolalia (a squeaky voice of nasal quality) as a presenting sign for pneumonasopharynx and pneumomediastinum secondary to bronchiolitis obliterans. The patient underwent HLA-identical related peripheral blood stem cells transplantation 8 months before the diagnosis. Three weeks after transplantation he began to suffer from GVHD Grade III that involved the gut, liver, and skin and later on the lungs. Due to severe obstructive bronchiolitis obliterans the patient developed intensive cough evolving into pneumomediastinum and pneumonasopharynx with rhinolalia. The patient was treated conservatively with complete resolution. Although rare, pneumomediastinum and pneumonasopharynx can be a life-threatening event, and one should be aware of the signs and symptoms on physical examination, which may be as subtle as rhinolalia alone.

A new minimally ablative stem cell transplantation procedure in high-risk patients not eligible for nonmyeloablative allogeneic bone marrow transplantation

Nonmyeloblative stem cell transplantation (NST, SCT) aims to induce host-versus-graft tolerance for subsequent immunotherapy of underlying disease with alloreactive donor lymphocytes, focusing on well-tolerated conditioning suitable for elderly individuals or for other risk factors. However, there is a subset of high-risk patients who cannot tolerate NST. A new protocol consisting of fludarabine 30 mg/m(2) x 6 days (days -8 to -2), very-low-dose busulfan (2 mg/kg x 2 days, days -6 to -5), without anti thymocyte globulin (ATG), was employed in 11 high-risk patients aged 26-58 years. Graft-versus-host-disease (GVHD) prophylaxis consisted of low-dose and short-course cyclosporine-A (CSA) alone. One patient died during the nadir due to pulmonary complications. Other patients showed rapid three-lineage engraftment, without complete aplasia; 6/10 patients did not require platelet transfusion and 8/10 had full donor chimerism without transient mixed chimerism. Owing to intentional selection of highly poor-risk patients, overall mortality was high and only one patient survived. Acute GVHD (>/=grade I) occurred in 8/10 evaluable patients, 5/8 while off CSA; 5/8 developed grade III-IV acute GVHD. It appears that our modified, minimally ablative stem cell transplantation (MST) may be used for high-risk patients in need of allo-SCT. Furthermore, although the MST conditioning is not myeloablative, it results in myeloablation of the host hematopoietic system, mediated by alloreactive lymphocytes.

Factors associated with survival in patients with progressive disease following autologous transplant for lymphoma

Our objectives were to assess survival and predictors for survival among lymphoma patients whose disease had progressed after autologous bone marrow (ABMT) or stem cell transplantation (ASCT). Patients transplanted at Hadassah University Hospital between October 1983 and February 1999 were included. We compared survival of patients with Hodgkin's disease (HD) and non-Hodgkin's lymphoma (NHL) after relapse or progression. Predictors for survival were assessed in a multivariate model. Of 88 transplanted patients with HD and 152 with NHL, relapse/progression occurred in 27 (31%) and 75 (49%), respectively. Median survival postrelapse was 25 months for HD and 7.5 months for NHL (P=0.12). Seven relapsed patients with HD (26%) and 10 (13%) with NHL survived >4 years. In NHL, longer postrelapse survival was associated with indolent histologies (P=0.007). On multivariate analysis, factors associated with survival included attainment of remission postrelapse (for both diseases), use of prophylactic immunotherapy (for HD), LDH level and time from transplant to relapse (for NHL). The short-term prognosis for patients with disease progression postautologous transplant may be somewhat better for HD compared to NHL. Long-term survival is poor in both diseases. However, the survival times in the current study are twice as long as those previously reported. Treatment regimens with the potential for achieving remission may have an impact on survival.

Fludarabine in combination with cyclophosphamide decreases incidence of GVHD and maintains effective graft-versus-leukemia effect after allogeneic stem cell transplantation in murine lymphocytic leukemia

Graft-versus-host disease (GVHD) is a severe disorder and despite therapeutic efforts to decrease its distressing clinical manifestations, treatment is still not optimal. Here we report the results of studies, in which the purine analogue, fludarabine phosphate, was used in an attempt to modify and decrease GVHD after stem cell transplantation, across major histocompatibility barriers for murine leukemia. B-cell leukemia (BCL-1) bearing (BALB/c x C57BL/6) F1 mice received two cycles of fludarabine (0.8 mg/kg) for 5 days every 2 weeks, followed by 400 mg/kg cyclophosphamide i.p. Animals were then transplanted with C57BL/6 precursor cells and the development of leukemia and extent of GVHD was monitored both clinically and histopathologically. In the fludarabine-treated group, only nine of 28 (32%) mice developed leukemia, compared to 25 of 33 (76%) of control animals (P=0.0006 ). Mice treated with fludarabine-containing regimens prior to transplantation also had much less GVHD both clinically and at autopsy, while graft-versus-leukemia appeared to be augmented in the same animals.

Allergy development after bone marrow transplantation from a non-atopic donor

BACKGROUND

Transfer of allergy from atopic bone marrow donors to recipients is known to occur. Development of allergy in a non-atopic patient transplanted from a non-atopic donor is an unfamiliar phenomenon in clinical practice.

OBJECTIVES

To clarify the course of events causing a bone marrow recipient to acquire an allergic disease in such non-conducive circumstances.

METHODS

Full medical history, prick and intradermal skin tests, and serum IgE levels were obtained from both donor and recipient patients. DNA and red blood cell phenotype analyses were used to detect the degree of chimerism.

RESULTS

Only the recipient patient showed positive specific IgE antibodies and skin tests to house dust mite. The recipient patient displayed 100% donor chimera, based on all engraftment markers sought.

CONCLUSION

Full engraftment after allogeneic bone marrow transplantation may be associated with modulation of T and B cell function, which in turn could cause the onset of allergic disease after bone marrow transplantation.

Invasive airway aspergillosis with new airflow obstruction mimicking post-BMT bronchiolitis obliterans

A 52-year-old male with severe gastrointestinal graft-versus-host disease (GVHD), developed dyspnea and irreversible airflow obstruction, 11 weeks post-allogeneic bone marrow stem cell transplantation. Based on the clinical picture and presence of 'mosaic attenuation' pattern on chest high-resolution computerized tomography (HRCT), he was presumed to have bone marrow transplantation-related bronchiolitis obliterans. Post-mortem examination revealed invasive airway aspergillosis with no evidence of bronchiolitis obliterans.

Antiviral prophylaxis may prevent human herpesvirus-6 reactivation in bone marrow transplant recipients

Human herpesvirus-6 (HHV-6) infects the majority of children under the age of 2 years causing roseola infantum. Following short self-limited disease, the virus enters into a latency phase in peripheral blood lymphocytes (PBL). It has been previously reported that HHV-6 reactivation from latency, in immunocompromised patients undergoing bone marrow transplantation (BMT), could result in febrile illness, pneumonitis, meningitis, and/or encephalitis. In our study, 14 BMT patients received two different antiviral prophylactic therapies: 8 patients received acyclovir, whereas 6 patients received ganciclovir. Clinical manifestations and virus recovery were monitored pre- and post-BMT by polymerase chain reaction tests of cord blood cells cultured with the patients' PBL. No HHV-6 recovery was shown in the 6 patients treated with ganciclovir, whereas 3 of the 8 acyclovir-treated patients experienced virus reactivation 20-21 days post-BMT. One of the 3 patients was asymptomatic but had late engraftment; the second patient had prolonged fever, skin rash, and hemorrhage; the third patient experienced prolonged fever, pneumonitis, marrow rejection, and fatal encephalitis. It is concluded that viral reactivation may be prevented by prophylactic treatment with ganciclovir. Our observation awaits further documentation in prospective randomized trials in high-risk BMT recipients.

All-trans-retinoic acid (ATRA) is of no benefit in bleomycin-induced lung injury

All-trans-retinoic acid (ATRA) has anti-fibrotic and antiinflammatory properties, and may be useful as a therapeutic agent in lung fibrosis. To test this hypothesis we investigated the effect of ATRA on bleomycin-induced lung fibrosis in Sprague-Dawley rats. Treatment groups included: (1) a single intratracheal (i.t.) instillation of bleomycin and daily intraperitoneal (i.p.) injection of 0.5 mg/kg per day ATRA; (2) i.t. bleomycin and i.p. ATRA, 2 mg/kg per day, (3) i.t. bleomycin and i.p. diluent (cottonseed oil); (4) i.t. saline and i.p. ATRA, 0.5 mg/kg per day, (5) i.t. saline and i.p. ATRA, 2 mg/kg per day; and (6) i.t. saline and i.p. diluent. Animals were studied 14 days after i.t. instillation. Lung injury was evaluated by total and differential cell count in bronchoalveolar lavage fluid, by a semi-quantitative morphological index of lung injury, and by biochemical analysis of lung hydroxyproline content. Overt signs of lung injury were apparent in bleomycin-treated rats by all measures. These changes were not affected by treatment with ATRA at either dose. This study does not support the use of ATRA to prevent or ameliorate lung fibrosis.

Multimodal Treatment of Metastatic Thymic Carcinoma Including High-Dose Chemotherapy With Autologous Stem Cell Transplantation

Thymic carcinoma is a rare epithelial malignancy differentiated from thymoma by the presence of cytologically malignant cells. There are few reports of the treatment of locally advanced or metastatic thymic carcinoma. We describe a patient who sought treatment for thymic carcinoma metastatic to pleura, pericardium, retroperitoneum, and neck nodes. He was treated with neoadjuvant etoposide, ifosfamide, and cisplatin, and underwent resection. We then administered high-dose chemotherapy with autologous stem cell support, followed by radiation therapy. The patient remains in complete remission more than 4 years after diagnosis. To our knowledge, this is the first report of metastatic thymic carcinoma treated with neoadjuvant therapy and postoperative high-dose chemotherapy. Metastatic thymic carcinoma may be curable by aggressive combined therapies.

Plasmapheresis for thrombotic thrombocytopenic purpura following bone marrow transplantation

Recognition of thrombotic thrombocytopenic purpura (TTP)/hemolytic uremic syndrome (HUS) following bone marrow transplantation (BMT) has increased in recent years. The use of plasma exchange has greatly improved the outlook of de novo TTP. Fewer data are available on its use in post-BMT TTP but small uncontrolled series showed poor results with low response rates. We present here a case of a young patient who developed manifestations of TTP 10 months after BMT with complete recovery following treatment with plasma exchange for 1 month. This case suggests that plasma exchange could be life saving and should be tried in every patient with post-BMT TTP.

Nonmyeloablative stem cell transplantation for the treatment of cancer and life-threatening nonmalignant disorders: past accomplishments and future goals

Allogeneic bone marrow transplantation (BMT) or blood stem cell transplantation represents an important therapeutic tool for the treatment of otherwise incurable malignant and nonmalignant diseases. Until recently. autologous and allogeneic BMT or mobilized blood stem cell transplantation was used primarily to replace a malignant, genetically abnormal, or deficient immunohematopoietic compartment, and therefore highly toxic myeloablative regimens were considered mandatory for eradication of all undesirable host-derived hematopoietic elements. Our preclinical and ongoing clinical studies have indicated that more effective eradication of host immunohematopoietic system cells could be achieved by adoptive allogeneic cell therapy with donor lymphocyte infusion following BMT. Thus eradication of blood cancer cells, especially in patients with chronic myelogenous leukemia and less frequently in patients with other hematologic malignancies, can frequently be achieved despite complete resistance of such tumor cells to the maximum tolerated doses of chemoradiotherapy. Our cumulative experience suggests that graft vs leukemia (GVL) effects might be a useful tool for eradication of otherwise resistant tumor cells of host origin. Based on the cumulative clinical experience and experimental data in animal models of human diseases, it appears that induction of host vs graft tolerance as the first step may allow durable engraftment of immunocompetent donor lymphocytes, which may be used for induction of effective biologic warfare against host-type immunohematopoietic cells that need to be replaced, whether they are malignant, genetically abnormal, or self-reactive. Based on this rationale, we speculate that the therapeutic benefit of BMT may be increased by using safer conditioning as part of the transplantation procedure, with the goal of inducing host vs graft tolerance to enable subsequent induction of GVL, possibly graft vs tumor, or even graft vs autoimmunity effects, rather than attempting to eliminate host cells with hazardous myeloablative chemoradiotherapy. Our hypothesis suggests that effective BMT procedures might be accomplished without lethal conditioning of the host, using new, well-tolerated nonmyeloablative regimens, possibly minimizing immediate and late side effects related to myeloablative procedures. Recent clinical data suggest that effective BMT procedures may be accomplished with nonmyeloablative stem cell transplantation (NST) regimens, with no major toxicity. Thus new NST approaches may make BMT procedures safer for a spectrum of clinical indications in children and elderly individuals without lower or upper age limits, while minimizing procedure-related toxicity and mortality. Our cumulative data suggest that high-dose chemotherapy and radiation therapy may be successively replaced by more effective alloreactive donor lymphocytes, thus setting the stage for innovative therapeutic procedures with safer and more effective treatment of patients requiring BMT.

Immune reconstitution following allogeneic stem cell transplantation in recipients conditioned by low intensity vs myeloablative regimen

We have investigated the immune status of patients with hematologic malignancies treated with a low intensity conditioning in preparation for allogeneic stem cell transplantation. Conditioning consisted of fludarabine, anti-T lymphocyte globulin and low-dose busulfan, followed by infusion of allogeneic blood stem cells. This protocol resulted in rapid engraftment and complete replacement of host with donor hematopoietic cells. Immunological parameters of these patients were compared to those patients who were conditioned by an aggressive myeloablative regimen. Distribution of cell surface markers of lymphocyte subsets from both groups of patients was similar, but different from that of normal control cells. Reduced intensity or non-myeloablative conditioning prior to allogeneic stem cell transplantation (NST), hardly lowered the normal T cell-dependent mitogenic response even during the early period following transplant, while the myeloablative treatments resulted in a suppressed mitogenic reaction and in slow immune recovery. Reactivity of non-MHC restricted cytotoxic T cells was also at a normal level in patients who were treated with NST. We conclude that stem cell engraftment following reduced conditioning may result in early reconstitution of immune responses assessed in vitro. We hypothesize that clinical application of NST may lead to faster development of effective immune responses against residual host-type malignant and abnormal non-malignant hematopoietic cells, although the role of fludarabine on post-transplant infections remains to be investigated in a larger cohort of patients.

Human recombinant interferon-alpha2a and interferon-alphaA/D have different effects on bleomycin-induced lung injury

BACKGROUND

Bleomycin (Bleo)-induced lung injury in mice serves as an animal model of pulmonary fibrosis. The pathogenesis of pulmonary fibrosis remains unclear, but it comprises both inflammatory and fibrotic components. The cytokine interferon (IFN)-alpha is produced by macrophages and may modulate both fibrogenesis and the determination of T lymphocyte phenotype in pulmonary fibrosis.

OBJECTIVE

To investigate the effect of two preparations of recombinant IFN-alpha (IFN-alphaA/D and IFN-alpha2a) on Bleo-induced lung injury in C57BL/6 mice.

METHODS

Mice were treated by a single intratracheal (IT) instillation of 0.06 mg of Bleo in 0.1 ml of saline or saline alone. One of two different IFN-alpha preparations, IFN-alphaA/D or IFN-alpha2a in saline, or saline alone were administered by daily intraperitoneal injections starting 1 day prior to IT instillation. The treatment groups were as follows: IT Bleo and intraperitoneal saline; IT Bleo and intraperitoneal IFN-alpha2a; IT Bleo and intraperitoneal IFN-alphaA/D; IT saline and intraperitoneal IFN-alphaA/D or IFN-alpha2a; IT saline and intraperitoneal saline. The animals were sacrificed 14 days after IT instillation. Lung injury was evaluated by total and differential cell count in bronchoalveolar lavage (BAL) fluid, by a semiquantitative morphological index of lung injury and a quantitative image analysis of cellularity and fibrosis fraction and by biochemical analysis of lung hydroxyproline content.

RESULTS

In Bleo-treated mice, IFN-alpha2a treatment caused a significant rise in BAL lymphocytes and in cellularity and fibrosis fractions in lung tissue. In contrast, IFN-alphaA/D treatment had no effect on Bleo-induced lung injury.

CONCLUSION

IFN-alpha may enhance Bleo-induced lung injury but this effect varies with different IFN preparations.

Non-myeloablative stem cell transplantation and donor lymphocyte infusion for the treatment of cancer and life-threatening non-malignant disorders

Allogeneic bone marrow or blood stem call transplantation (BMT) represents an important therapeutic tool for the treatment of otherwise incurable malignant and non-malignant diseases. Until recently, autologous and allogeneic bone marrow and mobilized blood stem cell transplantations were used primarily to replace malignant, genetically abnormal or deficient immunohematopoietic compartments, and therefore highly toxic myeloablative regimens were considered to be mandatory for the effective eradication of all undesirable host-derived hematopoietic elements. Our preclinical and ongoing clinical studies have indicated that much more effective eradication of the host immunohematopoietic system cells can be achieved by adoptive allogeneic cell therapy with donor lymphocyte infusion following BMT. Thus, eradication of blood cancer cells, especially in patients with chronic myeloid leukemia and, less frequently, in patients with other hematologic malignancies, can frequently be accomplished despite the complete resistance of such tumor cells to maximally tolerated doses of chemoradiotherapy. Our cumulative experience has suggested that graft-vs.-leukemia (GVL) effects might be a useful tool for the eradication of otherwise resistant tumor cells of host origin. Based on the cumulative clinical experience and experimental data in animal models of human diseases, it appears that the induction of host-vs.-graft tolerance as an initial step may allow the durable engraftment of donor immunocompetent lymphocytes, which may be used for the induction of effective biologic warfare against host-type immunohematopoietic cells that need to be replaced, including malignant, genetically abnormal or self-reactive cells. Based on the aforementioned rationale, we speculated that the therapeutic benefit of BMT may be improved by using safer conditioning as part of the transplant procedure, with the goal being to induce host-vs.-graft tolerance to enable subsequent induction of GVL, possibly graft-vs.-tumor or even graft-vs.-autoimmunity effects, rather than attempting to eliminate host cells with hazardous myeloablative chemoradiotherapy. This hypothesis suggested that effective BMT procedures could be accomplished without lethal conditioning of the host, using new well-tolerated non-myeloablative regimens, thus possibly minimizing immediate and late side-effects related to the myeloablative procedures until recently considered to be mandatory for the conditioning of BMT recipients. Recent clinical data presented in this review suggest that effective BMT procedures may be accomplished with well-tolerated non-myeloablative stem cell transplantation (NST) regimens, with no major toxicity. Thus, new NST approaches may offer the feasibility of safer BMT procedures for a large spectrum of clinical indications in children and elderly individuals, without lower or upper age limits, while minimizing procedure-related toxicity and mortality. Taken together, our data suggest that high-dose chemotherapy and radiation therapy may be successfully replaced by a more effective biologic tool, alloreactive donor lymphocytes, thus setting the stage for innovative therapeutic procedures for safer and more effective treatment of patients in need of BMT.