Suspected delayed immune recovery against cytomegalovirus after reduced-intensity stem cell transplantation using anti-thymocyte globulin

Clinical impact of multiple DNA virus infections in nondepleted haploidentical and unrelated allogeneic hematopoietic stem cell transplantation

Few studies have compared the clinical impact of multiple DNA-virus infections in haploidentical hematopoietic stem cell transplantation (haplo-HSCT) with posttransplant cyclophosphamide (PTCy) and unrelated donor allogeneic hematopoietic stem cell transplantation (UD-HSCT) with thymoglobulin, so we retrospectively analyzed viral infections in the first 6 mo posttransplant in these scenarios. Fifty-nine patients underwent to haplo-HSCT, and 68 to UD-HSCT. The most frequent infection was cytomegalovirus (CMV) (76.3% in haplo-HSCT and 69.1% in UD-HSCT) (P = .878) and in the group of patients with CMV reactivation, maximal CMV viral load over 2500 UI/ml correlated with worse overall survival-hazard ratio (HR) 1.93 (95% confidence interval [CI] 1.04-3.59) P = .03. The cumulative incidence of multiple DNA virus within 180 d of posttransplant was 78.7% for one virus and 28.4% for two or more viruses with no difference regarding the type of transplant. Viral infections, age, and acute graft versus host disease (GVHD) grades II-IV were risk factors for worse overall survival in multivariate analyses: one virus HR 2.53 (95% CI 1.03-6.17) P = .04, two or more viruses HR 3.51 (95% CI 1.37-9) P < .01, age HR 1.03 (95% CI 1.02-1.05) P < .01 and acute GVHD II-IV HR 1.97 (95% CI 1.13-3.43) P = .01. Also, age over 50 y HR 4.25 (95% CI 2.01-8.97) P < .001, second CMV reactivation or having both CMV and BK polyomavirus (BKV) HR 2.65 (95% CI 1.26-5.56) P = .01 and acute GVHD grades II-IV HR 2.23 (95% CI 1.12-4.43) P = .022 were risk factors for nonrelapse mortality in the multivariate analyses. In conclusion, multiple DNA-virus infections are frequent in both haplo-HSCT and UD-HSCT and a risk factor for worse overall survival.

Viral Infections in HSCT: Detection, Monitoring, Clinical Management, and Immunologic Implications

In spite of an increasing array of investigations, the relationships between viral infections and allogeneic hematopoietic stem cell transplantation (HSCT) are still controversial, and almost exclusively regard DNA viruses. Viral infections per se account for a considerable risk of morbidity and mortality among HSCT recipients, and available antiviral agents have proven to be of limited effectiveness. Therefore, an optimal management of viral infection represents a key point in HSCT strategies. On the other hand, viruses bear the potential of shaping immunologic recovery after HSCT, possibly interfering with control of the underlying disease and graft-versus-host disease (GvHD), and eventually with HSCT outcome. Moreover, preliminary data are available about the possible role of some virome components as markers of immunologic recovery after HSCT. Lastly, HSCT may exert an immunotherapeutic effect against some viral infections, notably HIV and HTLV-1, and has been considered as an eradicating approach in these indications.

Immune Reconstitution and Early Infectious Complications Following Nonmyeloablative Hematopoietic Stem Cell Transplantation

Non-myeloablative stem cell transplantation (NMT) has been increasingly used in compromised patients who would otherwise have been unable to undergo allotransplant. There is little understanding of the kinetics of immune reconstitution and its influence on infective complications following NMT. The aim of present study was to evaluate lymphocyte subset reconstitution over the first 12 months post-transplant in 15 adult patients receiving NMT with comparison to that of 30 patients grafted with a conventional hemopoietic stem cell transplantation (HSCT). NMT recipients were conditioned with fludarabine-based conditioning regimens. Peripheral blood stem cell (PBSC) was the source of stem cells in 13 NMT recipients and in 24 conventional HSCT recipients. Absolute numbers of helper (CD4+) T cells, naive (CD4+ CD45RA+) and memory (CD4+ CD45RO+) T cells as well as suppressor (CD8+) T cells, CD19+ B cells and NK cells were comparable in the two groups at all time points after transplantation. A median value of 200 CD4+ T cells/microl was achieved at 2 months post-transplant by the NMT and HSCT recipients. The CD4:CD8 ratio remained severely depressed throughout the study period. Almost all CD4+ lymphocytes expressed CD45RO antigen in the both groups of patients B lymphocytes showed low counts throughout the entire study period in both groups. Bacteremia and CMV antigenemia occurred respectively in 13 and 36% of the patients in the NMT group and in 15 and 39% of the patients in the HSCT group. Our preliminary data indicate that patients receiving a NMT have a lymphocyte reconstitution similar to that observed in patients who received a conventional HSCT. The incidence of bacteremia and CMV infection were not significantly different between the groups. Nevertheless, due to the small sample size, these results should be considered suggestive rather than definitive.

A randomized controlled trial of plasma real-time PCR and antigenemia assay for monitoring CMV infection after unrelated BMT

Preemptive therapy is the standard strategy for preventing CMV disease after allogeneic hematopoietic SCT. In this study, unrelated BMT recipients were randomly assigned to a plasma real-time PCR group or an antigenemia group to compare the value of these monitoring tools for CMV reactivation. Ganciclovir (GCV) was started at 5 mg/kg/day when PCR reached 300 copies per ml or when antigenemia reached three positive cells per two slides. A total of 88 patients were randomized into the antigenemia group (n=45) or the PCR group (n=43). A significantly higher number of patients reached the threshold in the antigenemia group than in the PCR group (73.3 vs 44.2%, P=0.0089). However, only three patients (one in the antigenemia group and two in the PCR group) developed early CMV disease. These patients exclusively had colitis and were successfully treated with GCV or foscarnet. The median number of antigenemia-positive cells at the start of GCV was 47 in the PCR group. These findings suggest that antigenemia assay with the current cutoff was too sensitive and led to unnecessary use of GCV. However, the appropriateness of the threshold may be different by the methodology used, and therefore, it is difficult to generalize.

Fludarabine-based reduced intensity conditioning transplants have a higher incidence of cytomegalovirus reactivation compared with myeloablative transplants

Two hundred and ten adult CMV seropositive patients undergoing myeloablative conditioning (MAC) [n=127] or reduced intensity conditioning (RIC) [n=83] transplants (HCT) were serially monitored for CMV reactivation and disease, using a qualitative polymerase chain reaction (PCR) followed by quantitation with pp65 antigen or quantitative PCR. CMV reactivation occurred in 53 RIC (63.9%) and 61 MAC (48%; P=0.03) transplants at a median of 47 days (range: 24-1977). Risk factors identified included acute GVHD (P=0.001), RIC regimen (P=0.03), unrelated donor (P=0.02), use of anti-thymocyte globulin/alemtuzumb (P=0.02) and use of bone marrow in MAC transplants (P=0.011). On multivariate analysis, RIC transplants and acute GVHD remained independent predictors. Treatment with antiviral drugs resulted in CMV negativity rates of 86.8% in MAC and 88.6% in RIC transplants. CMV disease occurred in 10.8% of RIC and 4.7% of MAC transplants (P=0.15). At a median follow-up of 26 months (range: 3-88), 48.1% of RIC and 50.3% of MAC transplants are alive. The higher incidence of CMV reactivation among RIC transplants suggests the need for novel prophylactic or pre-emptive strategies in this high-risk group of patients.

Rituximab therapy increased post-transplant cytomegalovirus complications in Non-Hodgkin's lymphoma patients receiving autologous hematopoietic stem cell transplantation

The use of monoclonal antibody, rituximab, had been reported to be associated with some severe viral infections. The inference of rituximab therapy and post-transplant cytomegalovirus (CMV) infectious complications in non-Hodgkin's lymphoma (NHL) patients is still unclear now. From 2002 to 2005, 46 patients with relapsed indolent or high-risk aggressive B cell NHL who received rituximab (17 patients) or not (29 patients) before autologous hematological stem cell transplantation (HSCT) in one institute were retrospectively analyzed for the risk factors of CMV complications after transplantation. Pre-transplant and post-transplant CMV infectious conditions, conditioning regimens, transplant types, and post-transplant complications were recorded. Post-transplant infectious complications were followed up until 6 months after transplantation. Seventeen of 46 patients received rituximab before HSCT. Three of them suffered from CMV infection and two of them developed CMV disease. All of the patients with CMV disease recovered after ganciclovir and CMV-specific immunoglobulin therapy. Twenty-nine of 46 patients without rituximab treatment before HSCT did not have CMV complications after HSCT. The risks to develop CMV infections after autologous HSCT were higher in rituximab-treated patients (17.6% vs 0%, p = 0.045, Fisher exact test, two-sided). The risks to develop CMV diseases had higher trend with rituximab therapy than without rituximab therapy (11.7% vs 0%, p = 0.131, Fisher exact test, two-sided). The NHL patients receiving rituximab therapy had higher risk to develop CMV infectious complications after autologous HSCT.

Subcutaneous alemtuzumab vs ATG in adjusted conditioning for allogeneic transplantation: influence of Campath dose on lymphoid recovery, mixed chimerism and survival

Sixty-nine consecutive patients (median age 54 years) were prospectively enrolled in a single-institution protocol for allogeneic transplantation with adjusted non-myeloablative fludarabine-melfalan-based conditioning including cyclosporin A and MMF, and one of three modes of serotherapy. Thirty-one donors (45%) were unrelated. The first cohort of 29 had ATG (Thymoglobulin 2 mg/kg x 3 days), the subsequent 26 had Campath 30 mg x 3 days subcutaneously, and the final cohort of 14 had 30 mg Campath once. The groups were similar as regards age, diagnosis and risk factors. Campath-patients had no acute toxicity, fewer days with fever and antibiotics, and required fewer transfusions than ATG-treated patients. 3-d-Campath patients showed lower lymphocyte counts from day +4, and CD4+, CD8+, CD19+ and NK cells recovered slower than in ATG-treated patients. More Campath patients developed mixed chimerism that required DLI. 3-d-Campath induced more serious and opportunistic infections than ATG, which resulted in a greater non-relapse mortality and an impaired overall survival despite a low tumor-related mortality. The change of the Campath dosing schedule to one dose abrogated the deleterious effect of 3-d-Campath on immune recovery, severe infections and survival. Subcutaneous Campath is simple and provides strong immune suppression with no early toxicity, but dose limitation to 30 mg once is recommended.

High-grade cytomegalovirus antigenemia after hematopoietic stem cell transplantation

Clinical impact of high-grade (HG) cytomegalovirus (CMV) antigenemia after hematopoietic stem cell transplantation has not been clarified. Therefore, in order to investigate the risk factors and outcome for HG-CMV antigenemia, we retrospectively analyzed the records of 154 Japanese adult patients who underwent allogeneic hematopoietic stem cell transplantation for the first time from 1995 to 2002 at the University of Tokyo Hospital. Among 107 patients who developed positive CMV antigenemia at any level, 74 received risk-adapted preemptive therapy with ganciclovir (GCV), and 17 of these developed HG-antigenemia defined as > or = 50 positive cells per two slides. The use of systemic corticosteroids at > or = 0.5 mg/kg/day at the initiation of GCV was identified as an independent significant risk factor for HG-antigenemia. Seven of the 17 HG-antigenemia patients developed CMV disease, with a cumulative incidence of 49.5%, which was significantly higher than that in the low-grade antigenemia patients (4%, P<0.001). However, overall survival was almost equivalent in the two groups. In conclusion, the development of HG-antigenemia appeared to depend on the profound immune suppression of the recipient. Although CMV disease frequently developed in HG-antigenemia patients, antiviral therapy could prevent a fatal outcome.

Early Detection of Plasma Cytomegalovirus DNA by Real-Time PCR after Allogeneic Hematopoietic Stem Cell Transplantation

Cytomegalovirus (CMV) infection is an important cause of morbidity and mortality after allogeneic hematopoietic stem cell transplantation. Therefore, preemptive ganciclovir therapy based on early detection of CMV reactivation is widely used to prevent CMV disease. Real-time polymerase chain reaction (PCR) has been widely used for monitoring CMV reactivation as well as the antigenemia assay that detects CMV structural phosphoprotein with a molecular weight of 65,000 (pp65). We developed a real-time PCR assay system for CMV based on a double-stranded DNA-specific dye, SYBR Green I, and quantified DNA, which was extracted automatically from plasma. This real-time PCR assay and the pp65 antigenemia assay were compared in parallel with 357 blood samples obtained from 64 patients who underwent allogeneic hematopoietic stem cell transplantation (allo-HSCT). Real-time PCR assay results correlated with those of the pp65 antigenemia assay (p < 0.0001). It is noteworthy that the detection of CMV DNA by PCR preceded the first positive antigenemia by 14 days. In this study, 10 of 64 patients developed CMV disease. The antigenemia assay detected CMV reactivation earlier than the development of CMV disease only in four of 10 patients. In contrast, our real-time PCR detected CMV-DNA before the development of CMV diseases in eight of 10 patients. The real-time PCR with SYBR Green I as a detection signal is simple and readily performed, and may be a useful system for early detection of CMV reactivation after allo-HSCT.

Evaluation of cytomegalovirus-specific T-cell reconstitution in patients after various allogeneic haematopoietic stem cell transplantation using interferon-gamma-enzyme-linked immunospot and human leucocyte antigen tetramer assays with an immunodominant T-cell epitope

Cytomegalovirus (CMV) infection is a major complication for patients who received allogeneic haematopoietic stem cell transplantation (HSCT). Accurate monitoring of CMV-specific T-cell reconstitution is required for appropriate decision on treatment, such as anti-viral drugs, which have adverse effects. Although human leucocyte antigen (HLA) tetramer and interferon-gamma-enzyme-linked immunospot (IFN-gamma-ELISPOT) assays have been used to measure CMV-specific T cells, detailed comparison of these assays and kinetics of anti-CMV T-cell reconstitution between reduced-intensity transplantation (RIST) and conventional HSCT has not yet been performed. In this study, we performed prospective comparative monitoring of CMV-specific T cells using HLA tetramer and IFN-gamma-ELISPOT assays with a single immunodominant CMV(495) peptide in 28 HLA-A*0201 and 9 HLA-A*0206 patients after various allogeneic HSCTs. The IFN-gamma-ELISPOT assay was more sensitive for evaluation of functional T cells than the HLA tetramer assay, and CMV-specific T cells were reconstituted earlier in patients who received RIST without anti-thymocyte globulin (ATG) than those receiving RIST with ATG or conventional HSCT. The threshold level for protection from CMV reactivation was estimated as over 1 x 10(6) cells/l peripheral blood with the IFN-gamma-ELISPOT assay. These results demonstrate that the IFN-gamma-ELISPOT assay with CMV(495) provides more accurate evaluation on CMV immunity in HLA-A*0201 and -A*0206 patients, and may be useful for determining timing of various treatments.

T-Cell Receptor Vbeta Repertoire after Myeloablative and Reduced Intensity Conditioning Allogeneic Haematopoietic Stem Cell Transplantation

T cells play an important role in the adaptive immune system. After haematopoietic stem cell transplantation (HSCT), T-cell function is impaired. This is reflected by the emergence of opportunistic infections, infections that are often difficult to treat because of the patient's insufficient immune function. T-cell receptor reconstitution was studied using CDR3 spectratyping to analyze the diversity of the T-cell repertoire at 3, 6 and 12 months after myeloablative and reduced intensity conditioning (RIC) HSCT in 23 patients. Immune function in vitro was tested by lymphocyte stimulation at 3, 6 and 12 months after HSCT. Lower diversity in the CDR3 repertoire was demonstrated in CD4+ cells after RIC HSCT at 3 and 6 months and in CD8+ cells at 3 months compared with healthy donors. After myeloablative HSCT, lower diversity was seen at 3, 6 and 12 months in CD4+ cells and at 6 and 12 months in CD8+ cells after HSCT. Acute and chronic graft-versus-host-disease (GVHD) did not affect diversity. Responses to phytohaemagglutinin (PHA), Concanavalin A (Con A) and Staphylococcus aureus protein A were significantly lower compared with healthy donors during the first 6 months after RIC HSCT. After myeloablative HSCT, lymphocyte response to Con A was significantly lower at 3 months compared with healthy donors. Decreased responses to cytomegalovirus and varicella zoster virus antigens were seen in patients suffering from acute GVHD grade II or chronic GVHD. The T-cell repertoire is skewed under the first year after HSCT, and immune reconstitution after HSCT with myeloablative and RIC conditioning seems to be comparable. GVHD, infections and age are more important for immune reconstitution than type of conditioning.

Incidence of invasive aspergillosis after allogeneic hematopoietic stem cell transplantation with a reduced-intensity regimen compared with transplantation with a conventional regimen

To evaluate the clinical characteristics of invasive aspergillosis (IA) after reduced-intensity stem cell transplantation (RIST) compared with those after conventional stem cell transplantation (CST), we examined the medical records of 486 CST and 178 RIST recipients. The overall incidence of IA after allogeneic transplantation was 35 (5.3%) of 664, which gave a 3-year cumulative incidence of 5.6%. The estimated 3-year incidence of IA in CST and RIST was 4.5% and 8.2% (P = .045), respectively, but the mortality rates were similar (76% and 86%). The median onset of IA after RIST (day 127) occurred significantly later than that after CST (day 97). A multivariate analysis revealed that IA was associated with age older than 50 years (relative risk, 2.12; 95% confidence interval, 1.08-4.17; P = .03) and the presence of acute and/or chronic GVHD (relative risk, 6.2; 95% confidence interval, 2.4-16.4; P = .0002). IA remains an important complication after allogeneic transplantation, regardless of the type of conditioning regimen.

Low incidence of infectious complications after nonmyeloablative compared with myeloablative allogeneic stem cell transplantation

Allogeneic stem cell transplantation (SCT) using a myeloablative (MA) conditioning regimen is limited to relatively young patients because of increased transplant-related mortality in elderly patients. Nonmyeloablative (NMA) conditioning regimens have been developed aiming to reduce transplant mortality. In this study, we set out to evaluate the post-transplant occurrence of infectious complications in recipients of grafts from human leukocyte antigen (HLA)-identical sibling donors treated with either NMA or MA conditioning regimens. Data of 78 consecutively treated patients were analyzed. An NMA conditioning regimen was used in 40 patients and an MA regimen in 38 patients. A significantly lower rate of episodes of febrile neutropenia (0% vs. 34%, P<0.01) and post-transplant Epstein-Barr virus reactivations (0% vs. 18%, P<0.05) was found in SCT recipients treated with an NMA conditioning regimen compared with an MA conditioning regimen. Furthermore, fewer invasive fungal infections (2% vs. 12%, not significant) were diagnosed in the NMA group. The incidence of cytomegalovirus (CMV) reactivations and bacterial infections was low in both groups (CMV reactivations: 13% in both groups; bacterial infections: 10% in the NMA group vs. 8% in the MA group), while CMV disease developed in only 1 patient. Overall, compared to our MA regimen, we found a very low rate of infectious complications after NMA SCT.

The risk of cytomegalovirus infection in non-myeloablative peripheral stem cell transplantation compared with conventional bone marrow transplantation

Non-myeloablative allogeneic peripheral stem cell transplantation (NST) is a novel therapeutic strategy for patients with hematologic malignancies. Whether non-myeloablative transplants are associated with increased risk of cytomegalovirus (CMV) infections is unknown. To clarify this issue, we compared the outcome of CMV infection following 24 allogeneic non-myeloablative peripheral blood stem cell transplants and 40 conventional bone marrow transplants (CBT). The NST regimen consisted (mg/kg). Twelve patients (50%) in the NST group and 17 (43%) in the CBT group developed positive antigenemia before day 100 (p=0.60). The time to the first appearance of positive antigenemia was not different between these two groups (p=0.40), and two groups showed similar initial and maximal antigenemia values (p=0.56 and p=0.68, respectively). Only one case of CMV colitis developed in the CBT group whereas CMV disease did not develop in the NST group. Although statistically insignificant, the treatment response against CMV antigenemia using ganciclovir was in favor of NST group. In conclusion, there was no difference in the risk of CMV infection between NST group and CBT group. Further prospective and controlled study is needed to clarify the impact of non-myeloablative procedure on the outcome of CMV infection.

Hemorrhagic cystitis after allogeneic bone marrow transplantation in children: clinical characteristics and outcome

Hemorrhagic cystitis (HC) is a well-documented adverse event experienced by patients undergoing hematopoietic stem cell transplantation. When severe, HC causes significant morbidity, leads to renal complications, prolongs hospitalization, increases health-care costs, and occasionally contributes to death. We retrospectively studied the medical records of 245 children undergoing an initial allogeneic bone marrow transplantation for malignant disease at St. Jude Children's Research Hospital between 1992 and 1999 to describe the clinical course of HC in all patients and to identify the risk factors for HC in this cohort. Conditioning regimens included cyclophosphamide, cytarabine, and total body irradiation. Grafts from unrelated or mismatched related donors were depleted of T lymphocytes, whereas matched sibling grafts were unmanipulated. All patients received cyclosporine as prophylaxis for graft-versus-host disease. Recipients of grafts from matched siblings also received pentoxifylline or short-course methotrexate. Severe HC developed in 27 patients (11.0%). The median duration of HC was 73 days (range, 5-619 days); 12 patients had ongoing HC at the time of death. In univariate analyses, patients were at increased risk of severe HC if they were male (P =.021) or had received T cell-depleted grafts (P =.017), grafts from unrelated donors (P =.021), a lower total nucleated cell dose (P =.032), or antithymocyte globulin (P =.0446). Multiple regression analysis revealed male sex (beta =.97; P =.027) and unrelated donor graft recipients (beta =.83; P =.039) to be significant factors.

Infectious complications following nonmyeloablative allogeneic hematopoietic stem cell transplantation

Nonmyeloablative hematopoietic stem cell transplantation (NST) has been explored in hematological malignancies and solid tumors in an attempt to minimize treatment-related toxicity. Whether this approach is associated with reduced risk of infectious complications is unclear. The aim of the current study was to evaluate the infectious complications in a series of 32 consecutive adult patients who received NST at our institution. Peripheral blood stem cell grafts (n=30) or marrow grafts (n=2) were infused from human leukocyte antibody (HLA)-matched sibling (n=30), partially matched related (n=1), or unrelated (n=1) donors. Neutropenia developed in two-thirds of patients and lasted 16 days. Acute graft-versus-host disease (GVHD) grade II to IV was observed in 25% of patients, whereas 35% of patients had signs of extensive chronic GVHD. Twenty-two patients (69%) had at least one significant infectious episode. Bacteremia occurred in 19% of patients (n=5 gram-positive, n=1 gram-negative microorganisms). Cytomegalovirus (CMV) infection was observed in 10 out of 28 (36%) evaluable patients; 4 of these had recurrent or persistent CMV antigenemia requiring a second-line treatment, but eventually the viremia cleared. No patients experienced CMV disease. Fungal infections were documented in five (16%) patients, comprising invasive fungal infections in two cases and mucosal fungal infections in three. Four patients died of transplant-related causes, and three of these died before day +100. Infection was considered the primary cause of death in one patient (pulmonary aspergillosis) and contributed to death in another two. The actuarial probability of nonrelapse mortality at 100 days was 10% (95% confidence interval, 3-26%). Our preliminary results suggest that NST is associated to a low incidence of bacteremia or fungal and viral infections. Whether these findings would translate into an improved overall survival needs to be confirmed in larger prospective studies.

High complete response rate after allogeneic hematopoietic stem cell transplantation with reduced-intensity conditioning regimens in advanced malignant lymphoma

The possible advantage of allogeneic hematopoietic stem cell transplantation (allo-HSCT) is a graft-versus-lymphoma effect. We explored the feasibility and efficacy of allo-HSCT with reduced-intensity (RI) regimens in advanced malignant lymphoma (ML). A total of 20 patients with indolent (n=9) or aggressive lymphoma (n=11) received allo-HSCT with an RI regimen (RIST). The preparative regimen consisted of a combination of purine analog and alkylating agent with or without antithymocyte globulin. A total of 11 patients had chemorefractory disease, seven had chemosensitive relapsed disease and two had residual disease. All of the patients received G-CSF-mobilized blood stem cells from HLA-matched siblings. Of the 20 patients, 19 achieved engraftment with acceptable regimen-related toxicities. Seven patients developed grade II-IV acute GVHD and 15 developed chronic GVHD. Of the 15 patients with evaluable disease, 12 achieved a complete response. One died of invasive fusariosis, four subsequently died of GVHD complicated with fungal infection and one died of progressive disease. With a median follow-up of 358 days, the Kaplan-Meier estimates for 1-year overall and progression-free survival were both 70%. The high response rate with low relapse observed in this study suggests that RIST may be an effective alternative curative treatment for patients with advanced ML.

Development of reduced-intensity hematopoietic stem cell transplantation in the National Cancer Center Hospital, Japan

Reduced-intensity hematopoietic stem cell transplantation (RIST) is a new approach of stem cell transplantation, which has shown promising features as reported in multiple phase I and II studies. Elderly patients, who are not eligible for conventional myeloablative hematopoietic stem cell transplantation (HSCT), are now treatable with RIST. It has also reduced regimen-related toxicity and provided better prognosis in short-term follow-up than that of conventional HSCT. Favorable results have been reported particularly in hematological malignancies, such as chronic myelocytic leukemia and malignant lymphoma. Among solid tumors, metastatic renal cell carcinoma was found to respond well to RIST. Clinical studies are currently being conducted to evaluate the efficacy of RIST in other types of solid tumors. However, the mechanism of graft-versus-host disease and graft-versus-tumor remains unclear. More knowledge on the mechanism is crucial to enhance antitumor effect and to further improve the prognosis.

Reduced-intensity bone marrow transplantation from an alternative unrelated donor for myelodysplastic syndrome of first-donor origin

A male patient had a relapse of myelodysplastic syndrome (MDS) 2 years after BMT from a female matched unrelated donor. Conventional cytogenetics, FISH, and short-tandem repeat chimerism analysis proved a relapse of donor origin. He underwent reduced-intensity BMT after a conditioning with fludarabine and busulfan, since he had impaired renal, liver, and pulmonary functions. Chimerism analysis on day 28 after the second BMT showed mixed chimerism of the first and the second donors, which later turned to full second-donor chimerism on day 60. He developed grade II acute GVHD of the skin and cytomegalovirus reactivation, but both were improved with methylprednisolone and ganciclovir, respectively. He remains in complete remission 6 months after the second BMT. Reduced-intensity second BMT from an alternative donor appeared to be a tolerable treatment option for donor-derived leukemia/MDS after the first conventional transplantation.