Reduced intensity conditioning: enhanced graft-versus-tumor effect following dose-reduced conditioning and allogeneic transplantation for refractory lymphoid malignancies after high-dose therapy

Large granular lymphocytosis after transplantation

Post-transplant lymphoproliferative disorders (PTLD) represent a heterogeneous group of diseases that occur following transplantation. Large granular lymphocytic (LGL) lymphocytosis is one type of PTLD, ranging from reactive polyclonal self-limited expansion to oligo/monoclonal lymphocytosis or even to overt leukaemia. LGL lymphocytosis in transplant recipients may present as a relatively indolent version of the condition and may be more common than reported, but its natural history and clinical course have not been well described, and the lack of a reliable classification system has limited studies on this disease. Patients with unexplained cytopenias, autoimmune manifestations, or unexpected remissions may be mislabelled. The purpose of this review was to evaluate the clinical features, immunophenotypes, etiopathogenesis, diagnosis, outcomes and treatment of post-transplantation LGL lymphocytosis. In conclusion, LGL lymphocytosis is a frequent occurrence after transplantation that correlates with certain procedural variables and post-transplant events. LGL lymphocytosis should be considered in patients with unexplained lymphocytosis or when pancytopenia develops after transplantation. The diagnosis of LGL lymphocytosis requires a demonstration of monoclonality, but clonality does not indicate malignancy. Additional studies are necessary to further delineate the potential effects of large granular lymphocytes in the long-term prognosis of post-transplant patients.

Recovery of Lymphocyte and Dendritic Cell Subsets Following Reduced Intensity Allogeneic Bone Marrow Transplantation

Approaches using reduced conditioning regimens have been developed to obtain minimal procedure-related toxicity. Such novel therapeutic options are being explored with good preliminary results concerning feasibility and engraftment. However, many aspects remain under-evaluated and few data are available about immune and dendritic cell (DC) reconstitution after these highly immunosuppressive regimens. We present here our data in 20 patients receiving allogeneic bone marrow transplantation (allo-BMT) using a reduced preparative regimen. We evaluated in the first 3 months following allo-BMT, several immunological parameters including DC subsets, and compared these to historical results obtained in a group of myeloablative allo-BMT patients. We found an early recovery of leukocytes, CD8+ and NK lymphocytes. We also found a trend towards an improved B cell recovery. These results are somewhat in contrast to the altered immune recovery observed in the myeloablative setting. In addition, we found a significant early circulating DC recovery. Circulating blood DCs were also found to be of full donor origin as assessed by FISH in sex-mismatched pairs. Nevertheless, naive CD4 + CD45RA + T cells were found to be profoundly reduced following such regimens.Collectively, these data further enhance the overall benefits of reduced intensity regimens and the need for a stringent biological monitoring for assessment of the potential advantages of reduced intensity allo-BMT in comparison with conventional allo-BMT.

Outcome of lower-intensity allogeneic transplantation in non-Hodgkin lymphoma after autologous transplantation failure

We studied the outcome of allogeneic hematopoietic stem cell transplantation after lower-intensity conditioning regimens (reduced-intensity conditioning and nonmyeloablative) in patients with non-Hodgkin lymphoma who relapsed after autologous hematopoietic stem cell transplantation. Nonrelapse mortality, lymphoma progression/relapse, progression-free survival (PFS), and overall survival were analyzed in 263 patients with non-Hodgkin lymphoma. All 263 patients had relapsed after a previous autologous hematopoietic stem cell transplantation and then had undergone allogeneic hematopoietic stem cell transplantation from a related (n = 26) or unrelated (n = 237) donor after reduced-intensity conditioning (n = 128) or nonmyeloablative (n = 135) and were reported to the Center for International Blood and Marrow Transplant Research between 1996 and 2006. The median follow-up of survivors was 68 months (range, 3-111 months). Three-year nonrelapse mortality was 44% (95% confidence interval [CI], 37%-50%). Lymphoma progression/relapse at 3 years was 35% (95% CI, 29%-41%). Three-year probabilities of PFS and overall survival were 21% (95% CI, 16%-27%) and 32% (95% CI, 27%-38%), respectively. Superior Karnofsky Performance Score, longer interval between transplantations, total body irradiation-based conditioning regimen, and lymphoma remission at transplantation were correlated with improved PFS. Allogeneic hematopoietic stem cell transplantation after lower-intensity conditioning is associated with significant nonrelapse mortality but can result in long-term PFS. We describe a quantitative risk model based on pretransplantation risk factors to identify those patients likely to benefit from this approach.

Comparison of reduced intensity and myeloablative conditioning regimens for stem cell transplantation in patients with malignancies: a meta-analysis

OBJECTIVE

The reduced intensity conditioning (RIC) stem cell transplantation is widely employed for the treatment of many hematologic malignancies, but the survival effectiveness is still unclear. This study conducted an updated meta-analysis to determine whether any significant difference could be found by using RIC vs. myeloablative conditioning (MAC) regimen for transplantation in patients with malignancies.

METHODS

We electronically searched the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, Embase, and relevant articles (1987.01-2009.12). Comparative studies were carried out on clinical therapeutic effect of RIC and MAC on the survival outcomes and the transplantation-related complications.

RESULTS

We obtained 1776 records, and 29 studies totaling 6235 patients have been assessed. Compared with MAC regimen, the RIC regimen had a higher overall survival (OS) at one-yr and no difference at two-yr later after transplantation. RIC regimen had significantly lower rates of disease-free survival (DFS) after two-yr follow-up, lower incidences of ≥ II degree acute graft-versus-host disease (aGVHD), and lower TRM [OR, 0.61, 95% CI (0.53, 0.69)], but with a higher relapse rate [OR, 1.88(1.41, 2.51)]. No significant difference was found in rates of cytomegalovirus (CMV) infection and chronic GVHD between the regimens.

CONCLUSIONS

This meta-analysis confirmed that compared with MAC condition regimen, the RIC regimen had a consistently equivalent or even better rate in OS, but with lower DFS at longer follow-up.

MTX or mycophenolate mofetil with CsA as GVHD prophylaxis after reduced-intensity conditioning PBSCT from HLA-identical siblings

Mycophenolate mofetil (MMF) in combination with CsA seems to lead to earlier post transplant hematological recovery and less mucositis than MTX, with a similar incidence of GVHD. In this study we analyzed the post transplant outcomes of two cohorts of patients who underwent an HLA-identical sibling reduced intensity conditioning transplantation (allo-RIC) with GVHD prophylaxis consisting of CsA in combination with either MMF or a short course of MTX. We included 145 consecutive allo-RIC transplants performed between April 2000 and August 2007. The median follow-up for survivors was 41 months (4-105 months). The study group included 91 males. Median age was 55 years (range 18-71 years). Diagnoses included myeloid (n=65) and lymphoid (n=80) malignancies. GVHD prophylaxis consisted of CsA/MMF in 52 and CsA/MTX in 93 patients. The conditioning regimen was based on fludarabine in combination with BU (n=59) or melphalan (n=86). The occurrence of grade 2-4 mucositis was higher in the CsA/MTX group than in the CsA/MMF group (57 vs 23%, P=0.001). The cumulative incidence of acute and chronic GVHD was similar, 48 vs 50% and 71 vs 68%, respectively (P>0.7). The 2-year relapse and OS were similar in the CsA/MTX and CsA/MMF groups (29 vs 21%, P=0.3 and 52 vs 51%, P=0.7, respectively). Our results support further prospective studies comparing the use of the CsA/MMF combination with CsA/MTX as GVHD prophylaxis in HLA-identical sibling donor allo-RIC recipients.

Second hematopoietic SCT for lymphoma patients who relapse after autotransplantation: another autograft or switch to allograft?

Although autologous hematopoietic SCT (auto-HSCT) is the only potentially curative treatment for lymphoma that has relapsed after conventional chemotherapy, the prognosis of patients with disease recurrence after auto-HSCT is poor. Some highly selected patients can benefit from second transplants. One-third with late recurrence after initial auto-HSCT may attain a prolonged remission after second auto-HSCT. Non-myeloablative or reduced-intensity conditioning (RIC) allogeneic hematopoietic SCT (allo-HSCT) has been used successfully after auto-HSCT failures, especially in subjects who have an HLA-compatible donor, chemosensitive disease and good performance status. Patients with chemosenstive disease recurrence who have completed at least 1 year after their first auto-HSCT should be considered for a second auto-HSCT. Patients who have chemoresistant disease are best served by participation in a well-designed clinical trial examining novel antitumor agents.

A fludarabine, thiotepa reduced toxicity conditioning regimen designed specifically for allogeneic second haematopoietic cell transplantation after failure of previous autologous or allogeneic transplantation

We present a phase II study of fludarabine 5 x 30 mg/m(2), thiotepa 3 x 5 mg/kg as preparative regimen specifically for allogeneic second haematopoietic stem cell transplantation (HCT) after failure of previous HCT. Forty-nine patients (median age 52 years, range 27-68) received an allogeneic second HCT after failed autologous (n=29) or allogeneic (n=20) HCT. Diagnoses were AML (n=18), ALL (n=3), multiple myeloma (n=11), lymphoma (n=16) and CML (n=1). GVHD prophylaxis consisted of CYA and mainly low dose alemtuzumab (40 mg). The median follow-up for patients alive is 528 days (range 217-1344). In 43 of 49 (88%) evaluable patients response rates were CR=19, PR=14 and SD=10 at one month. At one year, the probability (95% confidence interval) of relapse is 55.1 (38.2-72)% and the nonrelapse mortality (NRM) is 29 (14.2-44.4)%. Estimated survival at one year is 42.6 (28.7-56.6)% and event free survival is 38.1 (24.4-51.8)%. Survival was significantly better for patients experiencing relapse beyond one year, than for patients relapsing within one year from first transplantation (51.2 (33.5-68.9)% vs 27 (7-48.5)%; P=0.013). We conclude that this regimen is feasible and well tolerated for allogeneic second HCT.

Hyperacute GVHD: risk factors, outcomes, and clinical implications

Acute graft-versus-host disease (GVHD) is a major limiting factor in allogeneic hematopoietic stem cell transplantation (HSCT), and the timing of acute GVHD may affect patient outcomes. We evaluated the incidence, risk factors, clinical manifestations, and outcomes of hyperacute GVHD, defined as that occurring within 14 days after transplantation, among 809 consecutive HSCTs at the University of Texas M.D. Anderson Cancer Center. Of 265 patients with grade II-IV acute GVHD, 27% had biopsy-proven hyperacute GVHD. Skin involvement was significantly more common (88% versus 44%) and more severe (stage III-IV, 88% versus 66%) in the hyperacute group compared with acute GVHD diagnosed after day 14. On multivariate analysis, significant risk factors for hyperacute GVHD included a mismatched related or matched unrelated donor, a myeloablative conditioning regimen, more than 5 prior chemotherapy regimens, and donor-recipient sex mismatch. Hyperacute GVHD was associated with a significantly lower response rate to first-line therapy and a higher rate of nonrelapse mortality in patients with a mismatched related or matched unrelated donor graft. In conclusion, hyperacute GVHD accounts for a substantial proportion of grade II-IV acute GVHD after HSCT. Patients at high risk or with a diagnosis of hyperacute GVHD should be included in clinical studies.

Allogeneic stem cell transplantation with T cell-depleted grafts for lymphoproliferative malignancies

In non-Hodgkin lymphoma allogeneic stem cell transplantation (SCT) can be curative, but with standard dose conditioning patients may have substantial morbidity and mortality from graft-versus-host disease (GVHD); for aggressive malignancies, reduced intensity conditioning may result in higher recurrence. Patients with advanced follicular lymphoma (n = 12), transformed B cell malignancy (n = 11), and non-CD30+T cell lymphomas (n = 17) responsive to chemotherapy who had an HLA-identical sibling were offered T cell depleted (CAMPATH-1 G or H antibodies) SCT. Conditioning was with ablative doses of chemotherapy or radiotherapy. Before SCT, patients with follicular lymphoma had a median of 3 treatment courses, and those with transformed B cell and those diagnosed with T cell non-Hodgkin lymphoma had 2 (range, 1-3). At SCT the median age was 46 years (range, 21-59 years) and the number of CD34+ cells infused was 2.85 x 10(6)/kg. All patients showed engraftment but 7 patients (17.5%) developed GVHD. In total 12 subjects expired of transplant-related causes (n = 6) or from disease recurrence. One-year transplant-related mortality was 15%. There was no difference in survival across diagnostic groups. At a median of 1051 days, 70% survived and 68% are without disease. By reducing the incidence and severity of GVHD, patients can tolerate myeloablative doses of chemotherapy satisfactorily. This has resulted in low treatment-related mortality and adequate protection from disease recurrence.

Busulfan-conditioned bone marrow transplantation results in high-level allogeneic chimerism in mice made tolerant by in utero hematopoietic cell transplantation

OBJECTIVE

In utero hematopoietic cell transplantation (IUHCT) is a non-ablative approach that achieves mixed allogeneic chimerism and donor-specific tolerance. However, clinical application of IUHCT has been limited by minimal engraftment. We have previously demonstrated in the murine model that low-level allogeneic chimerism achieved by IUHCT can be enhanced to near-complete donor chimerism by postnatal minimally myeloablative total body irradiation (TBI) followed by same-donor bone marrow transplantation. Because of concerns of toxicity related to even low-dose TBI in early life, we wondered if a potentially less toxic strategy utilizing a single myelosuppressive agent, Busulfan (BU), would provide similar enhancement of engraftment.

METHODS

In this study, mixed chimerism was created by IUHCT in a fully allogeneic strain combination. After birth, chimeric mice were conditioned with BU followed by transplantation of bone marrow cells congenic to the prenatal donor.

RESULTS

We demonstrate that: 1) low-level chimerism after IUHCT can be converted to high-level chimerism by this protocol; 2) enhancement of chimerism is BU dose-dependent; and 3) BU reduces the proliferative potential of hematopoietic progenitor cells thus conferring a competitive advantage to the non-BU-treated postnatal donor cells.

CONCLUSION

This study confirms the potential of IUHCT for facilitation of minimally toxic postnatal regimens to achieve therapeutic levels of allogeneic engraftment.

Long-term outcome of nonmyeloablative allogeneic transplantation in patients with high-risk multiple myeloma

Conventional treatment or autologous transplantation has not been able to achieve long-term remission in patients with multiple myeloma (MM). Nonmyeloablative allogeneic transplantation might offer an option for cure without the high mortality associated with conventional conditioning. Here we present a retrospective analysis of patients with high-risk MM treated with nonmyeloablative allogeneic transplantation. In all, 52 patients with relapsed MM or high-risk features at diagnosis received 2 Gy TBI alone (n=3) or with fludarabine (n=49) as conditioning. Patients were heavily pretreated with a median of eight cycles of conventional chemotherapy and one or more autologous transplants for all but one patient. Regimen-related toxicity was low. Acute graft-versus-host disease II-IV occurred in 37% of patients, and 70% experienced chronic graft-versus-host disease (cGvHD). Median follow-up was 567 days, and transplant-related mortality was 17% in total. Estimated progression-free and overall survival at 18 months was 29.4 and 41.1%, respectively. Patients with cGvHD had a significantly higher progression-free survival, as did patients with up to eight cycles of pretreatment chemotherapy vs those with nine or more. In this highly pretreated patient group, disease control was unsatisfactory and our results suggest that a potential strategy might be to perform allogeneic transplant earlier in the course of the disease.

Campath-1 Abs ‘in the bag’ for hematological malignancies: the Cape Town experience

BACKGROUND

We examined the strategy of T-cell depletion of HLA-identical sibling grafts for the prevention of GvHD, as well as disease control and overall survival.

PATIENTS AND METHODS

The myeloablative conditioning was radiation based. The source of stem cells was BM in 62, and cytokine-mobilized PBPC in 68 patients. GvHD prophylaxis was by ex vivo incubation of the stem-cell concentrates with Campath-1G (anti-CD52; n=76) or Campath-1H (n=54).

RESULTS

Patients receiving PBPC grafts were older (median 38.5) than those undergoing BMT (median 31; P=0.002). More patients in the PBPC group developed chronic GvHD (p<0.01). While no post-transplant GvHD prophylaxis was given to BMT recipients, prednisone 30 mg daily was prescribed to 12 and CYA for 90 days to a further 32 patients who had received PBPC grafts. Median follow-up was 1055 (range 28-4867) days. Although there was no difference in the survival between patients who received BMT or PBPC, death was from disease recurrence in 16 and nine (p=0.03; chi(2) test) subjects, respectively. Multivariate analysis showed that outcome was particularly favorable in those who were given<20 mg Campath-1 (survival: 28/39 versus 12/29; P=0.01), and in the subgroup of 30 patients who received Campath-1H and post-transplantation CYA.

DISCUSSION

In patients receiving BMT, Campath-1 Abs effectively prevent GvHD. For those treated with PBPC grafts, the combination of T-cell depletion and post-transplantation CYA is equally effective, without an obvious increase in disease recurrence.

Infectious complications following allogeneic HLA-identical sibling transplantation with antithymocyte globulin-based reduced intensity preparative regimen

In the setting of reduced-intensity conditioning (RIC) regimens for allogeneic stem cell transplantation (allo-SCT), the epidemiology of transplant-related infections is still poorly defined. In 101 high-risk patients who received an HLA-identical sibling allo-SCT after RIC, including fludarabine, busulfan and antithymocyte globulin (ATG), we report during the first 6 months a cumulative incidence of positive CMV antigenemia of 42% (95% CI 32-52%), developing at a median of 37 (range 7-116) days without evidence of CMV disease (median follow-up, 434 days). The cumulative incidence of bacteremia was 25% (95% CI 17-33%), occurring at a median of 67 (range 7-172) days, while patients had recovered a full neutrophil count. In all, 65% of the bacteremia (95% CI 49-81%) were gram negative. The cumulative incidence of fungal infections was 8% (95% CI 3-13%), with a median onset of 89 (range 7-170) days. In multivariate analysis, stem cell source (bone marrow; P=0.0002) was significantly associated with the risk of positive CMV antigenemia, while higher doses of prednisone (>2 mg/kg) represented the major risk factor for bacteremia (P=0.0001). Infectious-related mortality was 5% (95% CI 1-9%), with aspergillosis being the principal cause. Collectively, these results suggest that prospective efforts are warranted to develop optimal antimicrobial preventive strategies after RIC allo-SCT.

Bone marrow as stem cell source for allogeneic HLA-identical sibling transplantation following reduced-intensity preparative regimen

OBJECTIVE

Reduced-intensity conditioning regimens (RIC) and peripheral blood stem cells (PBSC) are increasingly used for allogeneic stem cell transplantation (allo-BMT). RIC has been shown to allow engraftment with minimal early transplant-related mortality (TRM). However, in the context of RIC, the use of bone marrow (BM) as stem cell source is still little evaluated.

PATIENTS AND METHODS

In this report, we analyzed the outcome of 32 high-risk patients with hematological malignancies who received an HLA-identical sibling allo-BMT after RIC including fludarabine, busulfan, and anti-thymocyte globulin (ATG).

RESULTS

Sustained neutrophil and platelet recovery occurred at a median of 13 days (range, 10-19) and 17 days (range, 0-45) respectively. Early and durable full donor chimerism could be established as soon as the first month after allo-BMT. Also, a sustained and early CD8(+) T-cell recovery was observed, but the CD4(+) T-cell compartment remained profoundly low. The cumulative incidences of grade II-IV acute GVHD and chronic GVHD were 26% (95% CI, 11-41%) and 31% (95% CI, 15-47%) respectively. The overall cumulative incidence of TRM was 28% (95% CI, 12-44%) occurring mainly in patients aged over 50. In this setting, GVHD showed a protective effect on disease progression or relapse with better progression-free survival for patients with GVHD as compared to patients without GVHD (p=0.03).

CONCLUSIONS

Collectively, these results confirm that the use of BM grafts for RIC is feasible with durable donor engraftment and no detrimental GVHD.

Mixed chimerism following in utero hematopoietic stem cell transplantation in murine models of hemoglobinopathy

OBJECTIVE

Mixed hematopoietic chimerism after bone marrow transplantation can provide effective treatment for beta-thalassemia because of the selective advantage that exists for donor erythropoiesis. In utero hematopoietic stem cell transplantation (IUHSCTx) can achieve mixed hematopoietic chimerism, particularly when a selective advantage exists for donor cells. To investigate the biology of IUHSCTx in hemoglobinopathies, we performed fully allogeneic IUHSCTx in murine models of beta-thalassemia (Thal) and sickle cell disease (SCD).

MATERIALS AND METHODS

We serially assessed and compared levels of mononuclear cell (MNC) and erythroid chimerism after IUHSCTx of either adult bone marrow (BM)- or fetal liver (FL)-derived allogeneic donor cells in the two hemoglobinopathy models, which differ significantly in their degree of anemia (Thal>>SCD) and red cell half-life (Thal<<SCD).

RESULTS

The mean level of donor MNC chimerism was higher for SCD and Thal chimeras receiving FL- compared to adult BM-derived donor cells and tended to increase over time in the FL recipients. Donor hemoglobin (Hb) levels also were higher in all groups receiving FL compared to adult BM. Donor Hb levels in chimeric Thal mice were significantly higher than those in SCD or wild-type mice. Hematologic parameters such as Hb, hematocrit (Hct), mean cell volume (MCV), membrane-associated denatured Hb, and the oxygen equilibration curve were improved in chimeric hemoglobinopathy mice. However, the improvement in Hb, Hct, and MCV was not sustained despite stable levels of donor leukocyte engraftment.

CONCLUSION

The severity of the hemoglobinopathy being treated and the source of donor cells may be important determinants of success in the treatment of hemoglobinopathy by IUHSCTx.

Allogeneic stem cell transplantation after reduced-intensity conditioning in lymphoid malignancies

Allogeneic stem cell transplantation (allo-SCT) is an effective therapeutic option for a wide range of hematological malignancies. The toxicity of the conditioning regimen and graft-versus-host disease (GVHD) occurring after the infusion of the graft remain the most important factors leading to high morbidity and mortality. Reduced-intensity conditioning regimens have recently been developed in an effort to reduce the toxicity associated with conventional allo-SCT while preserving the curative potential of the graft-versus-tumor (GVT) effect. Most patients with lymphoproliferative disorders are not ideal candidates for allo-SCT due to higher age at diagnosis, which together with the advanced stage of disease at the time of transplantation can lead to a high transplant-related mortality (TRM). Preliminary experience indicates that reduced-intensity allo-SCT is feasible in such patients. The immediate TRM is low in comparison with conventional procedures and overall results seem promising, thus indicating the existence of a GVT effect. Nevertheless, all series are still low in numbers and follow-up is too short to draw definitive conclusions. Acute and chronic GVHD remain a significant problem with incidences comparable to the conventional setting in some series. Thus, therapeutic strategies must be sought to decrease GVHD without abrogating the GVT effect.

Nonmyeloablative allogeneic stem-cell transplantation for hematologic malignancies: a systematic review

BACKGROUND

Increasingly, clinicians advocate the use of nonmyeloablative allogeneic stem-cell transplants (NM-allo-SCTs, "mini-transplants") to manage hematologic malignancies. They hypothesize that NM-allo-SCT is equally efficacious to standard allo-SCT but produces less regimen-related toxicity.

METHODS

To analyze available evidence on the benefits and harms of "mini-transplants," we identified 23 manuscripts, 1 abstract, and 1 letter that reported the outcome of mini-transplants in hematologic malignancies.

RESULTS

Data were compiled on 603 treated patients, with 118 transplants using stem cells from matched unrelated donors. All studies were small prospective case series, and most lacked concurrent or historical controls. Outcomes of interest were not uniformly reported. The studies were heterogeneous and used different patient selection criteria, conditioning regimens, and timing of transplant with respect to disease status. The transplant-related mortality rate was 32%, the relapse rate was 15%, and toxicities included acute and chronic graft-vs-host disease and veno-occlusive disease. The aggregate rate of complete remission was 45%. Survival at 1 year or longer ranged from 30% to 60% at 1 to 5 years of follow-up. All studies reported successful chimerism.

CONCLUSIONS

Disease-specific studies with longer follow-up are needed to evaluate this potentially promising therapy.

Is there a role for reduced-intensity haematopoietic stem cell transplantation for indolent non-Hodgkin's lymphoma?

The therapeutic options for the indolent non-Hodgkin's lymphomas have evolved significantly over the years. However, at present, allogeneic haematopoietic stem cell transplantation (HSCT), despite its significant transplant associated complications, is still the only option which may be delivered with curative potential. The debut of reduced-intensity conditioning regimens has extended the applicability of allogeneic transplants to groups of patients ineligible for conventional myeloablative allografts. However, there are still substantial hurdles to overcome, namely that of relapse, graft-versus-host disease and infection. Whilst follow-up is still relatively limited for a disease group with a median survival of up to 10 years, early results are extremely encouraging and further studies are warranted.

Role of nonmyeloablative allogeneic stem-cell transplantation after failure of autologous transplantation in patients with lymphoproliferative malignancies

PURPOSE

Conventional allogeneic stem-cell transplantation (SCT) after a prior failed autograft is associated with a transplant-related mortality rate of 50% to 80%. The aim of the current study was to evaluate the safety and efficacy of sibling, HLA-matched, nonmyeloablative allogeneic SCT with donor lymphocyte infusion (DLI) in patients with lymphoid malignancy after failure of autologous SCT.

PATIENTS AND METHODS

A total of 38 patients with refractory, progressive, or relapsed disease after autologous SCT were entered onto this study. The conditioning regimen consisted of the humanized monoclonal antibody CAMPATH-1H, fludarabine, and melphalan. Fifteen of 35 assessable patients received DLI after SCT.

RESULTS

Sustained neutrophil engraftment was achieved in 37 recipients, and platelet engraftment was achieved in 35 patients. The estimated transplant-related mortality was 7.9% at day 100 and 20% at 14 months, the median duration of follow-up. Eight patients experienced grade I/II acute graft-versus-host disease (GVHD) after transplantation, but no grade III/IV GVHD was observed in this setting. However, grade III/IV GVHD occurred in seven patients who received DLI. The actuarial overall survival at 14 months was 53%, with a progression-free survival of 50%. DLI produced a further response in three of 15 recipients.

CONCLUSION

Nonmyeloablative allogeneic SCT after CAMPATH-1H-containing conditioning is a relatively safe option compared with conventional allogeneic transplantation for patients who have failed previous autologous SCT. The low incidence of early GVHD enabled the subsequent administration of DLI to improve further clinical responses in this poor-risk group of lymphoma and myeloma patients.

Features of large granular lymphocytes (LGL) expansion following allogeneic stem cell transplantation: a long-term analysis

Large granular lymphocyte (LGL) proliferation typically follows a chronic course during which major features are cytopenia and immune abnormalities. Elevated numbers of LGL were reported in a few cases following allogeneic stem cell transplantation (allo-SCT). In this report, we present a retrospective analysis of LGL cases that occurred following allo-SCT in a cohort of 201 consecutive patients transplanted over a period of 7 years. Six cases were identified and LGL expansion occurred more frequently following a reduced fludarabine and anti-T lymphocyte globulin-based preparative regimen (4 cases/49), than after a conventional myeloablative regimen (2 cases/152). Expansion of LGL was seen between 3 and 15 months following allo-SCT. Hematopoiesis, with mild to severe cytopenia, was a favored target for LGL. Autoimmune manifestations including polyarthritis and hypergammaglobulinemia were also observed. LGL proliferation was observed in the context of chronic antigenic stimulation associated with recurrent viral infections especially CMV. Moreover, five out of these six high risk patients achieved a long-term complete remission concomitant or following LGL expansion. These data suggest that LGL might be a subset of effector lymphocytes which may participate to the graft-versus-tumor effect.

High-level allogeneic chimerism achieved by prenatal tolerance induction and postnatal nonmyeloablative bone marrow transplantation

Clinical application of allogeneic bone marrow transplantation (BMT) has been limited by toxicity related to cytoreductive conditioning and immune response. In utero hematopoietic stem cell transplantation (IUHSCT) is a nonablative approach that achieves mixed chimerism and donor-specific tolerance but has been limited by minimal engraftment. We hypothesized that mixed chimerism achieved by IUHSCT could be enhanced after birth by nonmyeloablative total body irradiation (TBI) followed by same-donor BMT. To test this hypothesis, mixed chimerism was created by IUHSCT in a major histocompatibility complex-mismatched strain combination. After birth, chimeric animals received nonmyeloablative TBI followed by transplantation of donor congenic bone marrow cells. Our results show that: (1) low-level chimerism after IUHSCT can be enhanced to high-level chimerism by this strategy; (2) enhancement of chimerism is dependent on dose of TBI; (3) the mechanism of TBI enhancement is via a transient competitive advantage for nonirradiated hematopoietic stem cells; (4) engraftment observed in the tolerant, fully allogeneic IUHSC transplant recipient is equivalent to a congenic recipient; and (5) host-reactive donor lymphocytes are deleted with no evidence of graft-versus-host disease. This study supports the concept of prenatal tolerance induction to facilitate nonmyeloablative postnatal strategies for cellular therapy. If clinically applicable, such an approach could dramatically expand the application of IUHSCT.

Reduced-intensity allogeneic transplantation for lymphoma

Reduced-intensity allogeneic transplants are promising, increasingly used treatments for hematologic malignancies, exploiting graft-versus-tumor effects for eradicating malignancies. This article reviews approximately 40 published reports of reduced-intensity allogeneic transplants in lymphomas. Overall, reduced-intensity allogeneic transplants have been well tolerated and have produced encouraging results despite a diversity of transplant approaches used largely in heavily pretreated and older patients. Of 368 lymphoma patients who underwent reduced-intensity allogeneic transplants, 66.3% had responses, most of which were complete. Many had chemotherapy-refractory lymphomas, including some that relapsed after autologous transplants. Although the short follow-up periods of many studies do not permit assessments of response duration, protracted remissions were reported in some studies. Additionally, some patients entered molecular remissions, suggesting that graft-versus-tumor effects could, by themselves, cure some lymphomas. Graft-versus-host disease is the major risk of reduced-intensity allogeneic transplants, and treatment methods need refinement to reduce transplant risks while preserving graft-versus-tumor effects. Controlled trials involving patients with earlier-stage disease appear warranted to define better the role of reduced-intensity allogeneic transplants in treating lymphomas.

Allogeneic haemopoietic stem cell transplantation for non-Hodgkin's lymphoma

This chapter outlines the rationale for allogeneic haemopoietic stem cell transplantation in non-Hodgkin's lymphoma and pertinent results from published studies. Trials comparing allogeneic with autologous transplantation are discussed, as are disease-specific results for low-grade (including transformed), mantle cell and high-grade (Burkitt's and lymphoblastic) subtypes of the disease. Allogeneic transplantation for non-Hodgkin's lymphoma in the paediatric population, the use of unrelated donors, allografting after failed autologous or allogeneic transplantation, the graft-versus-lymphoma effect, the use of donor leukocyte infusions and non-myeloablative allografts are considered.

Complete allogeneic hematopoietic chimerism achieved by a combined strategy of in utero hematopoietic stem cell transplantation and postnatal donor lymphocyte infusion

In utero hematopoietic stem cell transplantation (IUHSCTx) can achieve mixed hematopoietic chimerism and donor-specific tolerance without cytoreductive conditioning or immunosuppression. The primary limitation to the clinical application of IUHSCTx has been minimal donor cell engraftment, well below therapeutic levels for most target diseases. Donor lymphocyte infusion (DLI) has been used in postnatal circumstances of mixed chimerism as targeted immunotherapy to achieve a graft-versus-hematopoietic effect and to increase levels of donor cell engraftment. In this report we demonstrate in the murine model that a combined approach of IUHSCTx followed by postnatal DLI can convert low-level, mixed hematopoietic chimerism to complete donor chimerism across full major histocompatibility complex barriers with minimal risk for graft-versus-host disease (GVHD). Time-dated embryonic day 14 (E14) to E15 Balb/c (H-2K(d), CD45.2) fetuses underwent intraperitoneal injection of 5 x 10(6) T-cell-depleted B6 (H-2K(b), CD45.2) bone marrow cells. Chimeric recipients then received transplants at either 4 or 8 weeks of age with 1 of 3 doses (5, 15, or 30 x 10(6) cells) of donor congenic splenocytes (B6-Ly5.2/Cr, H-2K(b), CD45.1). The response to DLI was dose dependent, with conversion to complete donor peripheral blood chimerism in 100% of animals that received high-dose (30 x 10(6) cells) DLI. Only 1 of 56 animals receiving this dose succumbed to GVHD. This study directly supports the potential therapeutic strategy of prenatal tolerance induction to facilitate nontoxic postnatal cellular therapy and organ transplantation, and it has broad implications for the potential treatment of prenatally diagnosed genetic disorders.