allo-SCT Recipients Research Articles

Circulating Leukemic Myeloid Dendritic Cells from Patient with Leukemia Elicit CDK2-Specific CTLs from Allogeneic HLA-A24+ Naive CD8+ T Cells.

Aberrantly expressed self-antigens in leukemic cells are a kind of leukemia-associated-antigens (LAAs). Although such self-antigen-derived LAAs potentially induce high avidity CTLs in patients with leukemia, these CTLs usually do not persist in the patients because they undergo apoptosis upon encountering with leukemic cells. In allogeneic stem cell transplant (allo-SCT) recipients with leukemia, LAAs-specific high avidity CTL may be elicited from donor-derived naive T cells that are sensitized by residual leukemic cells. Cyclin-dependent kinase 2 (CDK2) is a cell cycle regulator protein that is aberrantly expressed by leukemia cells. We previously reported that two CDK2-derived peptides (CDK2 158-166, CDK2 178-186) avidly bound to HLA-A24 molecule to elicit each peptide-specific CTLs from HLA identical donor of a AML patient, and CDK2-specific CD8 + T cells preferentially killed the recipient AML cells which aberrantly expressed CDK2 protein (Blood. 108 (11): a3173. 2006). When we assessed cryopreserved PBMCs obtained before and after allo-SCT from 16 HLA-A24+ patients (6 AML, 1 MDS, 1 CML, 2 ALL, 4 NHL and 2 RCC) using CDK2 158/A24 and CDK2 178/A24 pentamers, small populations (0.1–1.0%) of CDK2 158 and CDK2 178-specific CTL were detectable in 6 patients after SCT but not before SCT. All of the 6 patients had MRD at the time of SCT and achieved molecular CR after SCT. None of the 3 patients relapsed after SCT did not show CDK2 immunity. There is no relationship between the appearance of CDK2-specific CTLs and the development of GvHD (Figure). Leukemic myeloid dendritic cells (mDC) are known to present in vivo in patients with leukemia, and be able to trigger a protective antileukemic immune response by allogeneic T-cells. We hypothesized that residual circulating leukemic mDCs may sensitize donor-derived T cells by cross-presenting CDK2-peptides early after allo-SCT and elicit high avidity CTLs specific to leukemic cells. mDCs subset was identified with by three-color staining using mAbs against CD85k, CD33, CD14 and CD16. Circulating mDCs represented 5.4% of PBMCs in a patient with CML-CP at diagnosis. Leukemic mDCs from the patient were purified with CD1c mAb-conjugated maginetic beads and were assessed for their ability to stimulate allogeneic T cells to acquire specific cytotoxicity against CDK2-peptides. The purity of the mDCs as determined by flow cytometry was 92% of living isolated cells. Naive CD8 + T cells isolated from healthy individual were cultured with the leukemic mDCs for 12 days and subjected to pentamers staining. After the coculturing, the proportion of CDK2 158/A24 and CDK2 178/A24 pentamers + CD8 T cells increased 0.6% to 2.2% and 0.6% to 2.6%, respectively. These data suggest that CDK2-specific CTLs can be induced from donor-derived T cells due to in vivo sensitization of donor T cells by residual leukemic mDCs and this may be a mechanism responsible for the generation of CDK2-specific CTLs in allo-SCT recipients with MRD without vaccination of CDK2-peptides. Vaccination with CDK2-peptides after allo-SCT may be useful in both enhancing CDK2-specific immunity in patients with MRD and in generating CDK2 immunity in those without MRD. [Display omitted]

Risk of Hepatitis B and Efficacy of Treatment with Lamivudine in Patients Undergoing Allogeneic Stem Cell Transplant.

Hepatitis B virus (HBV) positive patients undergoing allogeneic stem cell transplantation (allo-SCT) and recipients of allo-SCT from HBV positive donors are at risk of hepatitis reactivation and fatal liver failure. Prophylaxis with lamivudine (LAM) in this setting is still unclear. Since 2005 patients undergoing allo-SCT at risk of HBV reactivation at our Center were treated with LAM prophylaxis to prevent hepatitis B reactivation. Ninety-seven patients undergoing allo-SCT between 1999 and 2007 entered the study. Only 84 patients with a follow-up longer than 3 months (median 17 months, range 3–87) were analysed. Patients, median age of 51 years (21–66), were transplanted for multiple myeloma (50), acute myeloid leukemia (14), chronic lymphatic leukemia (8), lymphoma (7), chronic myeloproliferative disease (4) and aplastic anemia (1). The conditioning regimens consisted of busulfan-cyclophosphamide (7), thiothepa-cyclophosphamide (11), and 2 Gy total body irradiation +/− fludarabine (64); 2 patients received 2 allo-SCT from the same donor for disease progression. Stem cell source was peripheral blood in 83 patients and bone marrow in 1. Sixty-five patients had a HLA-matched sibling donor and 19 an unrelated donor. Sixty subjects were not considered at risk of HBV reactivation (recipients hepatitis B surface antigen -HBsAg- and anti-hepatitis B core antigen antibodies -antiHBc- negative, with donors HBsAg-negative). Of note, 4 donors were antiHBc-positive. None of them experienced HBV related hepatitis during follow-up. The other 24 patients were considered at risk and divided in 3 groups: Group A: 2 HBsAg-negative recipients from HBsAg-positive donors; Group B: 1 HBsAg-positive recipient from negative donor; Group C: 21 antiHBc-positive recipients from 5 positive and 16 negative donors. Group A: Recipients were treated with LAM. None of them developed hepatitis B at a follow up of 24 and 18 months, respectively, and serum HBV-DNA remained undetectable. Group B: One patient with pre-transplant HBV-DNA of 19500 UI/mL received LAM. HBV-DNA became negative 3 months after allo-SCT and the patient did not develop acute hepatitis after a follow-up of 10 months. Group C: Twelve patients were not treated and 9 received prophylactic LAM for a median time of 11 months (range 6–29). Of these, one discontinued LAM after 8 months due to intolerance. Hepatitis developed in 3 untreated patients (2 patients undergoing allo-SCT before 2005 and 7 months after LAM discontinuation in the subject who stopped prophylactic LAM) and in none of the patients on prophylaxis. No detectable serum HBV-DNA was observed in patients on LAM prophylaxis. Two/3 patients with hepatitis received allo-SCT from antiHBc-negative donors. In conclusions, this retrospective study confirms:1.a null risk of hepatitis B in HBsAg and antiHBc-negative recipients, transplanted with HBsAg-negative donors, regardless of donor's antiHBc serology;2.a significant (23%) risk of hepatitis B in antiHBc-positive recipients from negative donors, untreated with prophylactic LAM;3.the efficacy of prophylactic LAM in HBsAg-negative and antiHBc-positive recipients;4.the efficacy of LAM in controlling HBV replication and hepatitis B reactivation in both HBsAg-positive recipients from negative donors and in HBsAg-positive donors used in negative recipients.

Liposomal amphotericin B prophylaxis of invasive mold infections in children post allogeneic stem cell transplantation

Invasive mold infections (IMI) are a leading cause of infectious mortality in allogeneic stem cell transplant (AlloSCT) recipients. Fluconazole, the current standard for fungal prophylaxis, is ineffective against molds. We initiated a pilot study to determine the safety and activity of prophylactic liposomal amphotericin B (AMB) in preventing IMI in pediatric and adolescent AlloSCT recipients during the first 100 days. Fifty-one patients (57 AlloSCT) were given AMB (3 mg/kg/day) intravenously, day 0-100. Median age 6 years, 32 males, 19 females. Donors: 33 unrelated and 2 related cord blood, 13 related and 1 unrelated peripheral blood stem cell and 8 related bone marrow (BM); 30 received myeloablative and 27 reduced intensity conditioning. Graft-versus-host disease (GVHD) prophylaxis comprised tacrolimus and mycophenolate mofetil. Median follow-up is 557 days. AMB was generally well tolerated. The probability of developing >/=grade II acute GVHD and extensive chronic GVHD was 45% and 7%, respectively. Estimated 1-year OS is 62.4% for all patients with 78.8% and 26.7% for average-risk and poor-risk, respectively. The incidence of IMI was 0%. These results suggest prophylactic AMB is tolerable and may prevent IMI, especially Aspergillus, during the first 100 days post AlloSCT in pediatric and adolescent patients. A randomized study is needed to determine the efficacy of this approach.

Observation-Based Early Warning Scores to Detect Impending Critical Illness Predict In-Hospital and Overall Survival in Patients Undergoing Allogeneic Stem Cell Transplantation

Observation-based early warning scoring systems (EWSS) have been developed to improve the outcome of critically ill patients by triggering early critical care intervention. To date, none of these scoring systems have been evaluated in cancer patients or stem cell transplant (SCT) recipients. The aim of this study was to validate 3 established EWSS (modified early warning score [MEWS], patient-at-risk score [PARS], and Leed’s early warning score [LEWS]) in adult recipients of Allogeneic SCT (Allo-SCT) and to determine their usefulness at predicting survival. We retrospectively analyzed the physiologic observations during the initial admission of 43 Allo-SCT recipients. Respiratory dysfunction was the most common (40 patients, 93%) event. All 3 EWSS revealed high accuracy in predicting in-hospital survival. The cutoff level associated with a high risk of in-hospital mortality was 7. Of 8 patients with a LEWS = 7, 6 died during their initial admission, whereas no patient with a lower score died (specificity 95%, sensitivity 100%). Acute clinical deterioration during the initial admission appeared to have an adverse effect on overall survival: in-hospital survivors with a LEWS >3 during their admission had a shorter median survival than patients with LEWS ≤3, P = .018. This is the first study to validate EWSS in Allo-SCT and demonstrate that these systems are highly predictive of in-hospital and overall survival.

Assessment of disseminated adenovirus infections using quantitative plasma PCR in adult allogeneic stem cell transplant recipients receiving reduced intensity or myeloablative conditioning

Disseminated adenovirus (AdV) infections following allogeneic stem cell transplantation (allo-SCT) are increasingly recognised, particularly in children. This study evaluated the clinical relevance of disseminated AdV infections in adult allo-SCT recipients, after different conditioning regimens. In a cohort of 107 adult allo-SCT recipients, receiving either reduced intensity conditioning (RIC, n = 48) or myeloablative conditioning (MAC, n = 59), AdV DNA levels in plasma were determined retrospectively at 1, 3 and 6 months following transplantation. Results of this screening regimen were compared with a cohort of 58 paediatric allo-SCT recipients, in whom AdV DNA load was monitored prospectively, as part of a pre-emptive treatment strategy. In positive cases, the course of AdV DNA load and clinical outcome were assessed. AdV DNA levels > or =1000 copies/mL were detected in five adults (4.7%) and eight children (13.8%). Screening for AdV viraemia at 1, 3 and 6 months would have detected seven of eight paediatric patients. One adult, receiving MAC, died with disseminated AdV disease and in four (three RIC and one MAC) AdV viraemia was transient without clinical symptoms specifically attributable to AdV. Seven paediatric patients with AdV viraemia were pre-emptively treated with ribavirin or cidofovir and in three of them disseminated AdV infection was related to a fatal outcome. Disseminated AdV infections following allo-SCT was a rare event in the adults and cause morbidity in a minority of these patients. In four of five adult patients, spontaneous clearance of AdV viraemia occurred. Results did not differ between the conditioning regimens that were applied in the adult cohort.

212: Adenovirus (ADV) infections following allogeneic stem cell transplant (alloSCT) in children and adolescent recepients

ADV is a serious cause of morbidity and mortality in patients undergoing alloSCT. ADV infection rates are 4-6% in adults and as high as 47% in children following alloSCT (Hoffman et al BBMT 2001). The reported mortality rate for disseminated ADV ranges from 8-54 % with higher rates reported in patients with ADV pneumonia (73%) and disseminated disease (61%) (Ljungman, Eur J Clin Microbiol & Infect Dis, 2004). We sought to determine the incidence, demographics, site of disease, treatment course, and outcome of ADV infection in children and adolescents following alloSCT from 1/1/2000-12/31/04. Eighty three children and adolescents underwent 91 alloSCT. Median age 6.5 (0.5 – 21.75) years, sex: M/F (52/39). AlloSCT donors included: Matched Family Donor (MFD), Bone Marrow (BM)/Peripheral Blood (PB) – 34 (37.4%), Unrelated Cord Blood(UCB) – 51 (56%), Related Cord Blood(RCB) - 3 (3.3%), Matched Unrelated Donor(MUD) – 3 (3.3%). Conditioning: 36 (40%) ablative conditioning, 55 (60%) reduced intensity conditioning. The majority (>90%) received Mycophenolate Mofetil/Tacrolimus GVHD prophylaxis (Osunkwo/Cairo et al, BBMT 2004). Recipients at risk for CMV received Foscarnet/Ganciclovir prophylaxis (Shereck/Cairo et al PBC 2006). ADV swabs and tissue biopsies samples cultured in remel microtest viral media. Ten (11%) systemic and/or invasive ADV infections were identified. Underlying diagnosis: 5 malignant (1ALL, 1 AML, 1 NHL, 2 NBL), 5 non-malignant (1WAS, 4 SAA). Donor source: 4 UCB, 1 MUD, 2 MFDPB, 1 MFDBM, 2 MFDBM + PB. Sites of ADV + culture: Gastroenteritis (GE) – 4, GE/Pneumonitis – 3, GE/Nasopharyngeal – 2, Cystits – 1. Treatment (Tx): cidofovir (CDV) (1mg/kg TIW) [n=8], observation [n=1], ADV found on post-mortem culture [n=1]. Outcome: 8 expired (6 non-ADV infection, 1 GVHD, 1 CNS hemorrhage); 2 survivors (1 post tx with no evidence of ADV, 1 ADV + no tx.) There were no ADV related deaths for 0% mortality. Adenovirus infection is an important contributor to post alloSCT morbidity and mortality. In patients transplanted at our center from 1/2000 –12/31/04 there was an 11 % incidence of adenovirus infection. Tx with CDV improves the outcome of patients with ADV infection in the post-transplant period. More rapid diagnosis with PCR-based technology will allow earlier diagnosis of systemic disease in alloSCT recipients resulting in prompt therapeutic intervention which may lead to improved outcomes. ADV is a serious cause of morbidity and mortality in patients undergoing alloSCT. ADV infection rates are 4-6% in adults and as high as 47% in children following alloSCT (Hoffman et al BBMT 2001). The reported mortality rate for disseminated ADV ranges from 8-54 % with higher rates reported in patients with ADV pneumonia (73%) and disseminated disease (61%) (Ljungman, Eur J Clin Microbiol & Infect Dis, 2004). We sought to determine the incidence, demographics, site of disease, treatment course, and outcome of ADV infection in children and adolescents following alloSCT from 1/1/2000-12/31/04. Eighty three children and adolescents underwent 91 alloSCT. Median age 6.5 (0.5 – 21.75) years, sex: M/F (52/39). AlloSCT donors included: Matched Family Donor (MFD), Bone Marrow (BM)/Peripheral Blood (PB) – 34 (37.4%), Unrelated Cord Blood(UCB) – 51 (56%), Related Cord Blood(RCB) - 3 (3.3%), Matched Unrelated Donor(MUD) – 3 (3.3%). Conditioning: 36 (40%) ablative conditioning, 55 (60%) reduced intensity conditioning. The majority (>90%) received Mycophenolate Mofetil/Tacrolimus GVHD prophylaxis (Osunkwo/Cairo et al, BBMT 2004). Recipients at risk for CMV received Foscarnet/Ganciclovir prophylaxis (Shereck/Cairo et al PBC 2006). ADV swabs and tissue biopsies samples cultured in remel microtest viral media. Ten (11%) systemic and/or invasive ADV infections were identified. Underlying diagnosis: 5 malignant (1ALL, 1 AML, 1 NHL, 2 NBL), 5 non-malignant (1WAS, 4 SAA). Donor source: 4 UCB, 1 MUD, 2 MFDPB, 1 MFDBM, 2 MFDBM + PB. Sites of ADV + culture: Gastroenteritis (GE) – 4, GE/Pneumonitis – 3, GE/Nasopharyngeal – 2, Cystits – 1. Treatment (Tx): cidofovir (CDV) (1mg/kg TIW) [n=8], observation [n=1], ADV found on post-mortem culture [n=1]. Outcome: 8 expired (6 non-ADV infection, 1 GVHD, 1 CNS hemorrhage); 2 survivors (1 post tx with no evidence of ADV, 1 ADV + no tx.) There were no ADV related deaths for 0% mortality. Adenovirus infection is an important contributor to post alloSCT morbidity and mortality. In patients transplanted at our center from 1/2000 –12/31/04 there was an 11 % incidence of adenovirus infection. Tx with CDV improves the outcome of patients with ADV infection in the post-transplant period. More rapid diagnosis with PCR-based technology will allow earlier diagnosis of systemic disease in alloSCT recipients resulting in prompt therapeutic intervention which may lead to improved outcomes.

CDK2-Specific CTLs Can Be Generated In Vivo from Donor Derived T Cells in HLA-A24+ Patients with Leukemia in Remission after Allogeneic Stem Cell Transplantation.

Aberrantly expressed self-antigens in leukemic cells serve as leukemia-associated-antigens (LAAs) of leukemia reactive T cells. Although such self-antigen-derived LAAs potentially induce high avidity CTLs in patients with leukemia, these CTLs usually do not persist due to apoptosis upon encountering leukemic cells. In allogeneic stem cell transplant (allo-SCT) recipients with leukemia, residual leukemic cell may sensitize donor-derived T cells by LAA in vivo and induce high avidity CTLs specific to leukemic cells. Cyclin-dependent kinase 2 (CDK2) is a cell cycle regulator protein that is aberrantly expressed in AML, MDS, ALL and MCL cells. We previously reported that CDK2-derived nonamer peptides (CDK2158: TYTHEVVTL, CDK2167: WYRQPEILL, CDK2178: KYYSTAVDI) avidly bound to HLA-A24 molecule to elicit each peptide-specific CTL from peripheral blood mononuclear cells (PBMCs) of healthy individuals (Blood. 106 (11): a3103. 2005). When we generated CDK2158-specific CD8+ T cells from an HLA identical sibling donor of a patient with AML by stimulating donor PBMCs with CDK2158-coated HLA-A24-transfected T2, CDK2158-specific CD8+ T cells preferentially killed the recipient AML cells which aberrantly expressed CDK2 proteins. The percentages of specific lysis in the 51Cr-release assay at an E/T ratio of 40 were 36.8% for AML cells and 24.8% for autologous PBMCs. To determine if CDK2-specific CD8+ T cells are present in PBMCs from allo-SCT patients, we studied 14 patients possessing HLA-A24 [6 patients with AML (2 AML-M0, 3 AML-M2, 1 AML with multilinage dysplasia), 1 with MDS, 1 with CML, 2 with ALL, 2 with MCL and 2 with RCC] using CDK2158/A24 and CDK2178/A24 multimers. Cryopreserved PBMCs obtained before and 4–73 months after allo-SCT were assayed for multimer staining. The source of graft was unrelated BM in 4, related BM in 2, related PBMC in 3 and CB in 5 patients. All CB and 1 BM graft were HLA mismatched. Seven patients were in complete remission (CR) at the time of SCT while 7 were in non-CR. Ten patients remained in CR 4–79 months after SCT. Small populations (0.13–0.77 % of lymphocyte) of CDK2158 and CDK2178-specific CTL were detectable in 5 patients (3 with AML-M2, 1 with CML and 1 with ALL) 10–73 months after SCT. All of the 5 remained in CR 11–79 months after SCT. Only one of them had active cGvHD at sampling. On the other hand, among 7 patients who did not show an increase in the proportion of neither CDK2158 nor CDK2178-specific CTLs, 2 patients with AML-M0 relapsed 4 and 5 months after SCT, respectively. Both of them had active cGvHD at sampling. CDK2-specific CTLs were also undetectable in 2 patients with RCC after allo-SCT. These data provide evidence for the first time that CDK2-specific CTLs can be induced from donor-derived T cells without peptide immunization possibly due to in vivo sentitization of donor T cells by residual leukemic cells. Vaccination with CDK2-derived peptides after allo-SCT may therefore be useful in inducing CDK2-specific CTLs and thereby preventing relapse of leukemia. [Display omitted]

Outpatient Myeloablative Allogeneic Stem Cell Transplantion: A Comprehensive Approach Yields Decreased Hospital Utilization and Low Transplant Related Mortality.

Myeloablative allogeneic stem cell transplantation (allo-SCT) is accompanied by a high risk of transplant related toxicity (TRT), traditionally requiring recipients to stay hospitalized until recovery from the cytopenic phase. The median hospital stay for allo-SCT in most institutions ranges from 25 to 30 days. We developed a comprehensive outpatient approach to the management of patients undergoing myeloablative allo-SCT. Although potential benefits include decreased hospital utilization/costs and increased patient satisfaction, there is little data regarding its feasibility and safety. We reviewed the clinical outcomes of 100 consecutive matched-related donor (MRD) myeloablative allo-SCT recipients transplanted at a single institution between March 2000 and February 2006. Excluding the planned admission for stem cell infusion on Day 0, all other aspects of their management (myeloablative conditioning, supportive care) were to be performed outpatient. Expectant admission occurred for complications more safely managed in the hospital (febrile neutropenia, decreased oral intake, uncontrolled pain, etc.). Exceptions to this model occurred for patients with circumstances that might compromise the safety of outpatient management, otherwise this was standard practice. One hundred consecutive transplant recipients (median age of 44 years [range 21–64]), underwent MRD myeloablative allo-SCT for high risk (58%) or standard risk (42%) hematologic malignancies, receiving either high-dose busulfan- (81%) or TBI- (19%) based preparative regimens. Peripheral blood was the stem cell source for 89 patients, bone marrow for 10, and one received a mixed graft. Only thirteen patients required hospital admission to receive at least a portion of their preparative regimen for reasons of compliance/communication barriers (4), GI toxicity (3), fever (1), or medical condition(5). Sixty patients were stable for hospital discharge either the day of or day after stem cell infusion. The median time from stem cell infusion to the first readmission was Day +7 (range 3–69). The median hospital length of stay (LOS) from the start of the preparative regimen through Day +30 was 12 days (range 1–44 days). The median 100 day LOS was 15 days (range 1–66). Median times to neutrophil and platelet engraftment were 12 and 19 days, respectively. Neutropenic fever occurred in 45 patients and was the primary cause for hospital readmission. Early suspected invasive fungal infections (before Day +30) occurred in 10 patients. CMV reactivation before Day +100 occurred in 28 patients. Acute (grade II-IV) and chronic graft versus host disease occurred in 34% and 56% of patients, respectively. Rates of 100 day and 6 month non-relapse mortality were 10% and 16%, respectively. With a median follow-up of 3.6 years (range 0.5–6.5), the estimated 5 year disease-free and overall survival (OS) were 49% and 51%, respectively. Stratifying for disease risk, OS in patients with standard versus high risk disease was 64% and 41%, respectively. In summary, outpatient myeloablative allo-SCT with expectant inpatient management for TRT can be done safely with transplant outcomes comparable to those reported in the literature for conventional allo-SCT. This approach significantly decreases the length of inpatient hospitalization for allo-SCT, with the potential to free up inpatient resources, improve quality of life, and decrease costs.

High-vs low-dose cytarabine combined with interferon alfa in patients with first chronic phase chronic myeloid leukemia. A prospective randomized phase III study

A prospective randomized phase III study was performed to evaluate whether intensified cytarabine would induce a higher response rate and longer event-free interval as compared to low-dose cytarabine in chronic myeloid leukemia (CML). One hundred and eighteen patients with CML in early chronic phase entered the study. Twenty-eight out of 32 patients assigned to group A received two cycles of a combination of intensified cytarabine and idarubicin followed by interferon alfa (IFN-α) maintenance, 28 patients in group B received standard treatment by a combination of low-dose cytarabine and IFN-α. Forty-nine patients with a human leukocyte antigen-identical sibling donor proceeded to allogeneic stem cell transplantation (allo-SCT) and nine patients were excluded from the analysis. Hematological response was observed in 97% of the patients in group A vs 86% of the patients in group B during the first year of treatment. In group A, 16 patients (50%) achieved a major cytogenetic response, which compared to seven patients (25%) with a major cytogenetic response in group B. With a median follow-up of 58 months (range 34–76), event-free survival was not significantly different between arms A and B. The estimated 5-year survival rate was 56% in the intensified arm and 77% in the low-dose arm (P = 0.05). Recipients of allo-SCT showed a 5-year estimated survival rate of 55%. Although intensified cytarabine induced a higher initial percentage of major and complete cytogenetic responses, responses were not sustained by IFN-α maintenance therapy.

GRAFT-VERSUS-HOST DISEASE

Background: Graft-Versus-Host Disease (GVHD) remains a major barrier in pediatric allogenic Stem Cell Transplant (alloSCT). Endoscopic intestinal biopsies play a significant role in the diagnosis and treatment of gut GVHD. However, complications such as bleeding, hematoma and/or perforation occur in these immunosuppressed, neutropenic and thrombocytopenic patients, further compromising their disease status. Methods: After an IRB approval of protocol, we performed a retrospective chart review of post alloSCT recipients who are diagnosed with gut GVHD through endoscopies. Biopsies were evaluated by a single expert gastrointestinal pathologist to establish the significance of the biopsy sites in the overall diagnosis of gut GVHD. Results: We evaluated 59 combined EGD and lower endoscopies which were preformed in 45 patients between 24 and 100 days after alloSCT. A total of 57 duodenal biopsies were performed, of which 41 were diagnostic for GVHD representing a 72%. From the 59 stomach biopsies only 21 were diagnostic, representing only 36%. Only 37 of the 55 (67%) lower endoscopies explored the colon beyond the splenic flexure. Rectal biopsies were positive in 44 of the 58 biopsies (76%). However, when one combined an upper endoscopy with a flexible sigmoidoscopy 100% of all patients with GVHD were identified. Conclusions: In the upper endoscopies, duodenal biopsies are the most important for the diagnosis of GVHD. The combination of upper endoscopies and left side colonoscopies was diagnostic in 100% of the procedures.

A pilot phase II study of alternate day ganciclovir and foscarnet in preventing cytomegalovirus (CMV) infections in at‐risk pediatric and adolescent allogeneic stem cell transplant recipients

Prophylaxis with ganciclovir or foscarnet post allogeneic stem cell transplant (AlloSCT) reduces cytomegalovirus (CMV) disease. Combination ganciclovir/foscarnet is more effective than monotherapy in HIV patients with CMV retinitis. We hypothesized that alternate day ganciclovir and foscarnet for the prevention of CMV during the first 100 days after AlloSCT would be safe and effective. Fifty-three pediatric and adolescent AlloSCT recipients receiving 57 AlloSCTs where donors and/or recipients were CMV seropositive received ganciclovir (5 mg/kg/48 hr) alternating with foscarnet (90 mg/kg/48 hr) from myeloid recovery (>or=ANC 750/mm3) until Day +100. Patients were: M:F 31:22; age 6 years (0.8-18 years); donor sources: 25 related peripheral blood/bone marrow, 3 unrelated adult peripheral blood, 26 unrelated cord blood, and 3 related cord blood. GVHD prophylaxis included tacrolimus/mycophenolate mofetil (MMF). Median-nucleated and CD34 cell counts were 7.3x10(8)/kg and 5.07x10(6)/kg, respectively, for BM/PBSC; 4.07x10(7)/kg and 1.69x10(5)/kg, respectively, for CB. Despite a 36.5% probability of Grades II-IV acute GVHD, no patient developed systemic CMV disease. Five percent had Grade IV hematological toxicity that required discontinuation of ganciclovir. Twenty-five percent required discontinuation of foscarnet secondary to electrolyte abnormalities and/or renal dysfunction that were presumed to be multifactorial in origin. Probability of 1-year overall survival was 58.8%. Alternate day ganciclovir/foscarnet in AlloSCT recipients where recipient and/or donor is seropositive appears to be tolerable and 100% effective in preventing CMV systemic disease. A randomized study will be required to determine if this approach is superior to other CMV prophylactic designs.

Clinical relevance of quantitative varicella-zoster virus (VZV) DNA detection in plasma after stem cell transplantation.

Detection of Varicella-Zoster virus (VZV) DNA in plasma can facilitate the early recognition of complicated VZV-infection in immunocompromised hosts. The correlation of VZV-DNA in plasma with clinical presentations of VZV-infection and subsequent aciclovir treatment in allogeneic stem cell transplant (allo-SCT) recipients was studied. In 81 consecutive VZV-IgG positive allo-SCT recipients, VZV-DNA was measured at regular time points (1, 2 and 4 months) following allo-SCT and patient records were screened for VZV-related symptoms and aciclovir treatment. Subsequently, possible VZV-cases were studied in detail for the course of VZV-DNA and treatment effects. During the initial screening, VZV-DNA was detectable in seven patients. The survey of VZV-related symptoms revealed five additional possible VZV-cases. In cases where suitable plasma samples were available (10 out of 12), VZV-DNA was present almost simultaneously with the first clinical manifestations. No evidence of a preceding phase detectable by VZV-DNA only could be observed. Treatment with aciclovir was associated with a prompt reduction of VZV-DNA load. Detection of VZV-DNA in plasma in allo-SCT recipients accurately reflected the clinical presentation of VZV-infection and treatment with aciclovir. VZV-DNA detection in plasma of allo-SCT recipients appears clinically relevant as this may support early recognition and therapeutic management of VZV-infections following allo-SCT.

Oral valganciclovir as pre-emptive therapy has similar efficacy on cytomegalovirus DNA load reduction as intravenous ganciclovir in allogeneic stem cell transplantation recipients

The efficacy and safety of oral valganciclovir was compared to ganciclovir i.v. in pre-emptive treatment of cytomegalovirus (CMV) in T-cell-depleted allogeneic stem cell transplant (allo-SCT) recipients. A therapeutic guideline was developed to allow the safe application of valganciclovir in allo-SCT recipients requiring CMV therapy. In total, 107 consecutive transplant recipients were evaluated. Cytomegalovirus DNA load in plasma was monitored longitudinally; details on antiviral therapy and treatment responses were analyzed retrospectively. Fifty-seven CMV treatment episodes were recorded in 34 patients: 20 with valganciclovir (900 mg twice-daily) and 37 with ganciclovir (5 mg/kg twice-daily). Median CMV DNA load reduction was 0.079 and 0.069 log10 copies/ml/day in the ganciclovir and valganciclovir group, respectively. Good response on CMV DNA load (reduction below 3.0 log10 copies/ml) was observed in 75.7% of ganciclovir and 80.0% of valganciclovir treatment episodes. Severe adverse effects were not observed and CMV-related disease did not occur. However, the percentage of patients receiving erythrocyte transfusion was higher in the group of patients receiving ganciclovir as compared to valganciclovir (41 versus 20%, P=0.116). In conclusion, pre-emptive treatment with valganciclovir and ganciclovir, led to similar reduction of CMV DNA load. Oral valganciclovir is an attractive and safe alternative for pre-emptive CMV treatment in T-cell-depleted allo-SCT recipients.

Sequential administration of sargramostim (GM-CSF) and filgrastim (G-CSF) in pediatric allogeneic stem cell transplant (allosct) recipients undergoing myeloablative (MA) conditioning: Cost-effective and more rapid platelet recovery in UCB recipients

Sequential administration of sargramostim (GM-CSF) and filgrastim (G-CSF) in pediatric allogeneic stem cell transplant (allosct) recipients undergoing myeloablative (MA) conditioning: Cost-effective and more rapid platelet recovery in UCB recipients

Higher clearance rates of mycophenolate mofetil (MMF) in pediatric allogeneic stem cell transplant (allosct) recipients

To date there are no published data on pharmacokinetics (PK) of MMF in children undergoing AlloSCT. The objective of this study is to evaluate effects of age on the PK of MMF in pediatric AlloSCT pts. From 1/04-9/05 we enrolled 26 pediatric AlloSCT with 23 being evaluable: mean age 7.6 yrs; wt 31.6 kg; M:F = 11:12; NBL PR (n = 3), SCD (n = 2), AML (CR1 [n = 3], CR2 [n = 1], CR3 [n = 1], relapsed/induction failure [n = 2]), SAA (n = 4), CML CP (n = 1), ALL (CR1 [n = 1], CR2 [n = 2], CR3 [n = 1]), HD CR2 (n = 1), ALCL refractory (n = 1); donor sources: MFD (6/6 PBSC [n = 6], 6/6 BM [n = 2], 5/6 PBSC [n = 2]), 6/6 related CB (n = 1), UCB (6/6 [n = 2], 5/6 [n = 2], 4/6 [n = 7]), and 8/10 MUD PBSC (n = 1).

PCR Screening for Epstein-Barr Virus-Related Lymphoproliferative Disease (EBV-LPD) among Allogeneic Stem Cell Transplant (AlloSCT) Recipients: The Importance of T Cell Depletion.

PCR monitoring for EBV reactivation is commonly used to confirm the diagnosis of EBV-LPD in alloSCT recipients. Previous studies using multiple PCR approaches have suggested a correlation between high EBV copy number and impending EBV-LPD, potentially allowing for the administration of preemptive rituximab and/or donor leukocytes prior to disease onset. However, subpopulations of alloSCT recipients with EBV reactivation at higher risk for EBV-LPD remain incompletely defined. We sought to determine the demographic factors among alloSCT recipients that affect the predictive value of our EBV PCR assay. Quantitative real-time PCR was performed on serum samples obtained from alloSCT recipients using primers that amplify a portion of the BNRF1-p143 locus. Clinical patient information was retrieved from institutional research databases. Patients who did not undergo appropriate EBV PCR screening (n=13), had a history of EBV-LPD prior to alloSCT (n=1) or received rituximab for prophylaxis against EBV-LPD (n=2) were excluded. 187 alloSCT recipients underwent EBV PCR monitoring between 7/03–7/05, of whom 58 (31.0%) were <18 years old, 117 (62.6%) were female and 111 (59.4%) received allografts depleted of T cells ex vivo (TCD). 56/187 (29.9%) had EBV reactivation (i.e., PCR >500 copies/mL) at some point after alloSCT. The prevalence of EBV reactivation was similar in recipients of TCD and conventional allografts (28.8% vs. 31.5%). Among patients with EBV reactivation, the risk for EBV-LPD did not differ based on age, sex, underlying disease, donor relation or HLA disparity. However, of the 56 patients with EBV reactivation, 5/32 (15.6%) recipients of TCD allografts and 0/24 (0.0%) recipients of conventional allografts developed EBV-LPD (p<0.03). The highest PCR values within one month prior to presentation of EBV-LPD varied ~1,000-fold between the 5 patients (799, 1007, 2380, 12K and 862K copies/mL). Of the alloSCT recipients without EBV-LPD, 8 had PCR values >500 for >6 months and 3 had ≥1 PCR value >100K. In our study population, the utility of the EBV PCR was maximized in recipients of TCD allografts with PCR values >500 (Table). In conclusion, EBV reactivation is common among recipients of both conventional and T cell depleted allografts, but preemptive therapy guided by EBV PCR should be primarily directed toward the latter. The effects of in vivo TCD with agents such as alemtuzumab on EBV reactivation and EBV-LPD are under investigation.Utility of the EBV PCR for predicting EBV-LPD and for guiding preemptive therapy in all patients and in only those who received T cell depleted allograftsPatient groupPCR cutoff (copies/mL)SensitivitySpecificityPositive predictive valueNegative predictive valueNumber needed to treatAll patients>500100%72%9%100%11.2>1,00080%77%9%99%12.5>5,00040%85%7%98%20>10,00040%88%9%98%14.6>100,00020%98%25%98%4.4T cell depleted>500100%75%16%100%6.4>1,00080%77%14%99%7.6>5,00040%85%11%97%12.7>10,00040%89%14%97%8.9>100,00020%98%33%96%3.4The highest PCR value within 1 year prior to LPD presentation was used for patients with LPD.

Circulating CD56 Bright Natural Killer Cells after Allogeneic Stem Cell Trasnplantation Express Functional TRAIL; Implication for a Novel Target of Immunotherapy.

Relapse of malignancies remains to be one of the major problems after allogeneic stem cell transplantation (allo-SCT). It is well-recognized that natural killer cells (NK-cells) are predominated in early phase of immune reconstitution after allo-SCT, and several studies demonstrated that CD56 bright CD16 negative (CD56++CD16−) NK-cells, which account for only a few percentage of peripheral NK-cells in healthy individuals, constitute a large subset of NK-cells at this phase. Although CD56++CD16− NK-cells possess unique ability to proliferate and produce proinflammatory cytokines in response to monokines or IL-2, they have been regarded to be less cytotoxic and unfavorable for graft-versus leukemia effects. To verify this issue, we compared the frequency of peripheral CD56++ NK-cells among total NK-cells with subsequent relapse in 25 allo-SCT recipients. Although the ratio of CD56++ NK-cells was gradually decreased as the increased duration between phlebotomy and allo-SCT, we could divide these patients into two groups. Group 1 was consisted of patients who showed consistently elevated ratio of CD56++ NK-cells, and the remainder was categorized into group 2. The relapse after allo-SCT was seen in 1 out of 8 patients in group 1, whereas it was documented in 5 out of 17 patients in group 2. This finding suggested that CD56++ NK-cells might also have a role in preventing relapse. We have found that peripheral CD56++CD16− NK-cells from patients after allo-SCT consistently expressed TNF-related apoptosis-inducing ligand (TRAIL), although its expression was faintly detectable on circulating NK-cells from healthy volunteers. As reported, stimulation with IL-2 or IL-15 resulted in the increased expression of TRAIL on NK-cells from healthy volunteers as well as the recipients of allo-SCT. However, its expression was always stronger in the CD16- subset than CD16+ in both groups. Cultivation of purified NK-cells from healthy volunteers with 0.5 nM of IL-2 for more than 2 weeks resulted in the expansion of both NK-cell subsets, and after sorting into CD16− and CD16+ NK-cells, cytotoxic assays against Jurkat were performed in the presence or absence of concanamycin A, neutralizing anti-Fas antibody, and neutralizing anti-TRAIL antibody. Cytotoxicity was more prominent in the CD16− subset than CD16+, and blocking study revealed that TRAIL expressed on CD16− NK-cells was strongly involved in the killing of Jurkat. We could not detect TRAIL-mediated cytotoxicity in the CD16+ subset, because the expression of TRAIL was much lower in the CD16+ subset than CD16−. Next, NK-cells purified from allo-SCT recipients and healthy volunteers were overnight cultured with 0.5 nM of IL-2 and their cytotoxicity against Jurkat was examined. NK-cells from patients who received allo-SCT within 3 months and those from healthy volunteers showed equivalent cytotoxicity. In patients who showed increased ratio of CD56++CD16− NK-cells, TRAIL was strongly expressed on overnight cultured CD56++CD16− NK cells, and TRAIL-mediated cytotoxicity was also detected. In murine models, TRAIL has been reported to exert strong graft-versus-tumor effects without causing GVHD. As CD56++CD16− NK cells readily express functional TRAIL on cytokine stimulation, and they usually reconstituted shortly early after allo-SCT, they may become promising targets for immunological intervention.

Pharmacokinetics (PK) of Mycophenolate Mofetil (MMF) in Pediatric Allogeneic Stem Cell Transplant (AlloSCT) Recipients Are Associated with Significantly Higher Clearance.

We have previously reported altered PK requiring significantly higher doses of MMF in pediatric AlloSCT recipients (Osunkwo et al, BBMT 2004). The objective of this study is to further evaluate effects of age and type of conditioning regimen (ablative vs reduced intensity on the PK of MMF in pediatric AlloSCT recipients. From Jan '04 through April '05 we have enrolled 21 pediatric AlloSCT recipients in an IRB approved protocol. Mean age 6.2 yrs (0.33–15); weight 28.6 kg (5.7–129.3); M:F = 11:10; NBL PR (n=3), SCD (n=2), AML (CR1 [n=2], CR2 [n=1], CR3 [n=1], relapsed [n=1], induction failure [n=1]), SAA (n=2), CML CP (n=1), ALL (CR1 [n=1], CR2 [n=1], CR3 [n=1]), WAS (n=1), HD CR2 (n=1), ALCL refractory (n=1), SCID (n=1); donor sources included MFD (6/6 PBSC [n=5], 6/6 BM [n=1], 5/6 PBSC [n=2]), 6/6 related CB (n=1), UCB (6/6 [n=2], 5/6 [n=2], 4/6 [n=7]), and 8/10 MUD PBSC (n=1). Cohort 1 (< 6 yrs) (n=10); 2 (6–12 yrs of age) (n=6); 3 (12–16 yrs) (n=5). GVHD prophylaxis included tacrolimus and MMF (+ methotrexate for MUD). Tacrolimus was initiated on Day −1 or 1st day of conditioning (protocol dependent) at 0.03 mg/kg/d CI or 0.12 mg/kg/d PO Q8–12H to maintain concentrations 5–20 ng/mL. MMF was initiated on Day +1 at 900 mg/m2/dose IV Q6H and then converted to PO (same dose) on Day +14 or later. MMF PK was performed on Day +1, +7, and +14 (while on IV MMF) at hour 0, 0.5, 1, 2, 3, 4, and 6 post-dose. MPA plasma concentrations were determined by reverse-phase HPLC. MMF dose was adjusted to maintain MPA trough 1–3.5 mcg/mL. The mean CD34+ cell dose/kg = 23 x 105, nucleated cell dose/kg = 45 x 107. Time to neutrophil engraftment (ANC ≥ 500/mm3 x 2 d) was 22 d and platelet engraftment (untransfused count ≥ 20K x 7 d) was 28 d. The mean f/u was 241 d. Mean MPA PK on Day +14 demonstrated Cmax=12.4 mg/L, total MPA trough =0.9 mg/L, AUC0–12=32.7 mcg•hr/mL, Css=2.7 mg/L, T1/2=1.5 h, Vss=1.8 L/kg, and CL=1.4 L/kg/h at a mean MMF dose of 1080 mg/m2 IV Q6H. The breakdown of age cohorts is shown in Table 1. Gastrointestinal adverse events attributable to MMF occurred in 50% of patients (grade 2–3 nausea (n=9), grade 2–3 vomiting (n=4), abdominal pain (n=2), pneumatosis intestinalis (n=1), colitis (n=1)). Kaplan-Meier probability of grade II–IV aGVHD (18 evaluable pts) was 71.1% (CI: 46.9–95.4) and cGVHD (15 evaluable pts) was 37.7% (CI: 8.2–67.1). In comparison to MMF PK in adult AlloSCT pts receiving cyclosporine/MMF (Nash et al, BBMT 2005), pediatric pts appear to have significantly higher MMF clearance rates (1.4 vs 0.54 L/kg/h). MMF doses > 3-fold higher than those used in pediatric SOT recipients were required to achieve AUC0–12=30–60 mcg•h/mL. Short half-life (1.5 hrs) and rapid clearance of MMF in pediatric AlloSCT recipients in part appear related to a lack of enterohepatic recycling and enhanced UDP-glucuronosyltransferase activity.Table 1Age-Based MMF PK in Pediatric AlloSCT Recipients on Day +14Age Group< 6 y.o. (n=6)6–12 y.o. (n=5)12–16 y.o. (n=2)Cmax(mg/L)12.211.814.4Total MPA trough (mg/L)1.00.41.4Free MPA trough (ng/mL)18.714.817.9Mean AUC0–12 (mcg•h/mL)3429.539.9Mean total Css (mg/L)2.82.53.3T1/2 (h)1.81.11.5Vss(L/kg)2.11.80.5CL (L/kg/h)1.61.40.6

The Elevated Ratio of Peripheral Blood CD27−CD4+ T Cells in Patients Received Allogeneic Stem Cell Transplantation Implies Altered T Cell Homeostasis.

One of the major problems following allogeneic stem cell transplantation (allo-SCT) is the inability to reconstitute an adequate immune system for an extended period. T-cell reconstitution is also delayed for years, especially in CD4+ T cells. In addition to impaired thymic function, shortened Naive T cell survival due to altered T cell homeostasis is reported to be responsible for delayed immune reconstitution. To further investigate the mechanisms of delayed immune recovery after allo-SCT, we focused on the frequencies of effector CD4+ T cells, because according to the previous reports, progressive linear differentiation model of CD4+ T cell predicts the accumulation of terminally differentiated effector cells when transition from naïve to memory T cells and memory to effector cells are accelerated. By flowcytometric analyses we confirmed that CD27−CD4+ T cells from allo-SCT recipients uniformly express CD95, with negative expression of CCR7 and CD62L. They also produce g-interferon (IFNg) in response to the immobilized anti-CD3 and soluble anti-CD28 stimulation, which is consistent with previous reports insisting that CD27−CD4+ T cells are functionally differentiated effector T cells. Measuring the ratio of CD27−CD4+ T cells among CD4+ T cells revealed that, although healthy donors and patients received allo-SCT within a year had comparable CD27+CD4+T-cell rate (90% vs. 83%, P=0.4436), significantly decreased rate was observed in patients transplanted more than 1 year before (55% vs. 83%, P=0.0005). The ratio of CD27+CD4+ T cells kept low during the first 5 years after allo-SCT, and then it slowly begun to increase. In addition, in patients who received stem cell grafts more than 1 year before, the ratio of CD27+CD4+ T cells were significantly higher in patients transplanted from HLA-matched siblings than in those received unrelated grafts (69% vs. 42%, P=0.0002). Other factors, such as stem cell source (BM or PBSC), patient age, and the presence of chronic GVHD did not influence the ratio of CD27+CD4+ T cells. To further investigate the characteristics of CD27−CD4+ T cells in post-transplant periods, peripheral CD4+ T cells from patients who had received allo-SCT more than 1 year before as well as healthy volunteers were sorted into CD27− and CD27+ fractions, stained with CFSE, and stimulated with immobilized anti-CD3 and soluble anti-CD28 antibodies. CD27−CD4+ T cells proliferated more vigorously at 3 days after stimulation, though after another 2-day culture, there was no difference in cell divisions between both cell groups. In addition, CD27+ cells from transplanted patients lost their expression more frequently than those from volunteers, while none of the CD27− cells stored its expression. The fact of one-way transition from CD27+ to CD27− also supported that CD27−CD4+ T cells are terminally differentiated T cells. The finding that the frequencies of CD27−CD4+ T cells begin to elevate at 1 year after allo-SCT indicates that T cells infused with allograft do not easily lose the surface expression of CD27, while T cells derived from donor's stem cells do. Considering the fact that ratio of CD27−CD4+ T cells is much higher in recipients of unrelated grafts, and it gradually begin to decrease at 5 years after allo-SCT, the increased ratio of CD27−CD4+ T cells may reflect altered T cell homeostasis. The serial monitoring of the ratio of CD27−CD4+ T cells after allo-SCT may be useful in evaluating immune reconstitution status.

Critical Role for CCR1:CCL5 (RANTES) Receptor Ligand Interactions in Modulating Allogeneic T Cell Responses Following Bone Marrow Transplantation.

Acute graft versus host disease (GVHD) and leukemic relapse are the most serious complications of allogeneic (allo) stem cell transplantation (SCT), and separating desirable graft-versus-leukemia (GVL) effects from GVHD remains the ultimate challenge to successful outcomes. The recruitment of activated T cells to host target tissues (GVHD) or sites of leukemic infiltration (GVL) is likely mediated by chemokine receptor:ligand interactions. CCR1 is a chemokine receptor that binds to CC chemokines including RANTES (CCL5), and is expressed on a variety of cells including activated T cells, monocytes, and macrophages. We have previously shown that mRNA expression of both CCR1 and RANTES is increased in GVHD target tissues following allo-SCT. Using a well established murine SCT model (B6->B6D2F1) and mice deficient in CCR1, we examined the contribution of CCR1 expression to allo T cell responses in vitro and to GVH and GVL effects in vivo. Lethally (1100cGy) irradiated B6D2F1 mice received SCT either from syngeneic (B6D2F1) or allogeneic (B6) CCR1+/+ or CCR1−/− donors. The severity of GVHD was assessed by survival and a well described clinical scoring system. Syngeneic SCT recipients all survived and were indistinguishable from naïve, untransplanted controls, whereas animals receiving allo-SCT from CCR1+/+ donors developed significant GVHD. By contrast, allo-SCT with CCR1−/− donor cells resulted in significantly improved survival (92% vs. 50%) and less severe clinical GVHD (p<0.01) by day 35 compared to allo-CCR1+/+ controls. GVL effects were next assessed by adding 500 P815 tumor cells (H-2d and syngeneic to host) to the bone marrow inoculum on day 0. F1 recipients of syngeneic BMT all died from tumor infiltration by day +15. Although all allo-SCT recipients effectively rejected their tumor, mice receiving CCR1-/− SCT had significantly improved leukemia free survival (45% vs. 5%) by day 60 compared to allo controls. At higher tumor doses, significant GVL activity remained in CCR1−/− SCT recipients, but the survival advantage was lost. Further examination of allo T cell responses in vivo revealed that day 7 splenic T cell expansion and serum IFNγ levels were significantly lower following CCR1−/− SCT (p < 0.01). Surprisingly, proliferation and IFNγ secretion were also reduced by ~70% when CCR1−/− T cells were stimulated with host antigens in vitro, whereas CTL activity remained equivalent to CCR1+/+ controls. The reduction in proliferation was not secondary to a migration defect, but was dependent on interactions between CCR1 and RANTES; neutralization of RANTES with a monoclonal antibody significantly reduced proliferation of CCR1+/+ T cells in a dose dependent manner. Finally, we found that GVHD mortality was also less when RANTES−/− mice were used as recipients in a second, MHC-disparate, SCT model (p = 0.03). Collectively these data demonstrate a critical role for CCR1 in donor T cell alloreactivity following SCT. These responses contribute to both GVHD and GVL effects in vivo and are likely dependent upon interactions between CCR1 and the chemokine ligand RANTES.