CD28-Directed T Cell Costimulation Blockade with Abatacept to Prevent GvHD During High-Risk Unrelated HSCT: A First-in-Disease Feasibility Trial,

Blood ◽  
2011 ◽  
Vol 118 (21) ◽  
pp. 4078-4078
Author(s):  
Leslie S. Kean ◽  
Amelia Langston ◽  
Muna Qayad ◽  
H. Jean Khoury ◽  
Divya Tiwari ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Acute Gvhd ◽  
Chronic Gvhd ◽  
Hematologic Malignancies ◽  
Feasibility Trial ◽  
Effector Memory ◽  
Unrelated Donor ◽  
Gvhd Prophylaxis ◽  
The Mean

Abstract Abstract 4078 Background: Acute GvHD remains the major cause of complications and death following unrelated-donor HSCT. In a non-human primate model, we have previously shown that in vivo costimulatory blockade of donor T-cells could provide effective protection against GVHD. To begin to explore its clinical utility, we are conducting a trial (Clinical Trials.Org # NCT01012492) to determine the feasibility of combining abatacept (CTLA4-Ig) with cyclosporine and methotrexate as acute GVHD prophylaxis for patients undergoing unrelated marrow and peripheral blood stem cell transplants for hematologic malignancies. Methods: Patients older than 12 with advanced hematologic malignancies, conditioned with either TBI/Cytoxan, Busulfan/Cytoxan or Fludarabine/Melphalan are eligible. Abatacept is administered IV on days −1, +5, +14, and +28 at 10 mg/kg in addition to standard GvHD prophylaxis consisting of cyclosporine (day −2 to day 100), and methotrexate (15 mg/m2 on day +1 and 10 mg/m2 on days +3, 6 and 11). Patients are then followed for clinical outcomes and immunologic reconstitution through day +365. Results: 9 patients (planned enrollment = 11 patients) have thus far been enrolled on the study of which 5 are evaluable for engraftment, toxicity and acute GvHD. The other four patients consist of 2 who are currently receiving abatacept, 1 who was discovered to have an ongoing viral infection at the start of the first abatacept infusion so was removed from the treatment regimen, and 1 who is awaiting transplant. The median age for the 5 evaluable patients is 47 years (17–74 years). 3 patients had AML and 2 had ALL. Patients were conditioned with Bu/Cy (n=1), TBI/Cy (n=2) and Flu/Melphalan (n=2). 4 donor-recipient pairs were allele matched at 9 of 10 loci (A, B, C, DRB1 and DQB1), while 1 was fully matched. Four of the 5 patients are currently alive and in remission and 1 relapsed at day +98 (and died on day +121 with refractory AML). The four other patients are surviving without relapse with a follow-up of 155–313 days. All 5 patients received the 4 scheduled abatacept doses. No infusional side effects were noted. All patients achieved neutrophil engraftment (median day +20 (11–47). 4 of 5 patients have achieved platelet engraftment (median day +27 (14–35). Donor engraftment (100% CD33 and 99–100% CD3 at Day +30) occurred in all cases. All patients have demonstrated rapid lymphocyte engraftment, with the mean ALC reconstituting to >500 cells/μL by day +21 post-transplant. At day +100, the mean CD3+ count was 673 +/− 251 cells/μL. Both CD8+ and CD4+ T cells reconstituted by day 100, with the mean CD8+ count = 384 +/− 148 cells/μL and the mean CD4+ count = 229 +/− 119 cells/μL. T cell reconstitution was accompanied by a shift away from naïve (Tn, CCR7+/CD45RA+) toward a CCR7-/CD45RA- effector memory (Tem)-predominant phenotype. Thus, the average proportion of CD4+ Tem cells in the recipient increased from 22 +/− 6% pre-transplant to 46 +/− 7% at day +100 with a concomitant loss of CD4+ Tn cells. Likewise, the proportion of CD8+ Tem also significantly increased, from an average of 15 +/− 4% pre-transplant to 32 +/− 7% at day +100, also with a reciprocal decrease in CD8+ Tn cells. One patient developed steroid responsive grade 3 acute GVHD involving the skin and the liver, followed by steroid responsive liver chronic GvHD. This patient is currently weaning corticosteroids. Another patient developed steroid responsive late-onset (day +217) acute GVHD (liver and GI) during cyclosporine weaning, which was also steroid responsive, and is also currently weaning corticosteroids. No other systemic acute or chronic GvHD has occurred. No unexpected complications or life-threatening infections were observed. 3 patients have experienced 5 episodes of CMV reactivation, all responsive to antiviral therapy. One patient developed polyclonal EBV-related PTLD (plasmacytic hyperplasia) in the absence of EBV viremia, which regressed without intervention. No other EBV-related disease has occurred. Conclusions: These preliminary data suggest that abatacept can be safely added to cyclosporine and methotrexate for GVHD prophylaxis in recipients of hematopoietic grafts from unrelated donors, with encouraging rates of acute GVHD. As such, they support the conduct of a larger, randomized phase 2 study. Disclosures: Off Label Use: Abatacept: It is an immunosuppressive agent that targets the CD28/B7 T cell costimulation pathway. It is approved for use in Rheumatoid arthritis.

HLA-Mismatch Is Associated With Worse Outcomes After Unrelated Donor Reduced Intensity Conditioning Hematopoietic Cell Transplantation: A Cibmtr Analysis

Blood ◽  
2013 ◽  
Vol 122 (21) ◽  
pp. 547-547 ◽  
Author(s):  
John Koreth ◽  
Kwang Woo Ahn ◽  
Joseph Pidala ◽  
James L. Gajewski ◽  
Hailin Wang ◽  
...  
Keyword(s):  
T Cell ◽  
Acute Gvhd ◽  
Hematopoietic Cell Transplantation ◽  
Chronic Gvhd ◽  
Cell Depletion ◽  
Unrelated Donor ◽  
T Cell Depletion ◽  
Gvhd Prophylaxis ◽  
Conditioning Intensity

Abstract In myeloablative unrelated donor allogeneic hematopoietic cell transplantation (HCT) a 1-locus HLA-mismatch (-A, -B, -C, -DRB1) is associated with lower survival compared to fully matched pairs. However data in reduced-intensity and non-myeloablative conditioning (together called RIC) HCT are limited. We analyzed adult AML/ALL/CML/MDS recipients of first 8/8 HLA-matched or 1-locus mismatched unrelated donor (MUD, MMUD) RIC HCT performed in the period 1999-2011 and registered in the CIBMTR. HLA-A, -B, -C and -DRB1 loci were typed in all pairs at high resolution; -DQB1 and -DPB1 loci could not be evaluated in all pairs. Transplants involving ex-vivo T-cell depletion, CD34+ selection, or post-transplant cyclophosphamide were excluded. Overall survival (OS) was the primary outcome. Secondary outcomes included non-relapse mortality (NRM), relapse, disease-free survival (DFS) and acute and chronic GVHD. Individual locus mismatch was also assessed. Apart from HLA matching, variables related to patient (age, race, sex, KPS, diagnosis, disease-risk), donor (age, parity), both (sex match/ABO match/CMV match) treatment (conditioning intensity, TBI use, in-vivo T-cell depletion (ATG), graft source (PB, BM) and GVHD prophylaxis (CyA-, Tac-based)) were considered. 2588 RIC HCT (8/8 MUD: 2025; 7/8 MMUD: 563) from 144 centers and 12 countries were analyzed. Median follow up in 8/8 MUD and 7/8 MMUD was 38 and 48 months respectively. Diagnoses were AML (65%), ALL (8%), CML (7%), MDS (20%). Conditioning intensity was RIC (79%), NMA (21%). 58% received in-vivo T-cell depletion. Graft source was PBSC (85%), BM (15%). GVHD prophylaxis was Tac-based (70%), CyA-based (27%). Mismatches involved HLA-A (188), -B (81), -C (219), and -DRB1 (75); with -DPB1 and -DQB1 typing available in 1382 and 2502 cases respectively. Compared to 8/8 MUD, 7/8 MMUD recipients were more likely to be younger and ethnic minorities and to have older and parous donors. In univariate analyses DQB1- and -DPB1 mismatch was not associated with worse OS, DFS, or NRM and was not further evaluated. There was a trend toward more grade II-IV acute GVHD in -DPB1 double (p=0.02) but not single mismatches. In multivariate models 7/8 MMUD RIC HCT had worse grade II-IV and III-IV acute GVHD, NRM, DFS and OS, but not relapse or chronic GVHD (Table). No significant interactions were identified between degree of HLA matching and other clinical variables. Adjusted 1- and 3-year NRM for 8/8 MUD vs. 7/8 MMUD was 20.4% vs. 28.9% (p<0.0001) and 29.2% vs. 38.1% (p<0.0007) respectively. Adjusted 1- and 3-year OS was 54.7% vs. 48.8% (p=0.01) and 37.4% vs. 30.9% (p=0.005) respectively (Figure). There was no difference between allele and antigen mismatches. HLA-A, -B, -C, and -DRB1 locus mismatches were each associated with 1 or more impaired outcomes (acute GVHD, NRM, DFS, and/or OS). Table 1 7/8 vs. 8/8 HLA HR (95% CI) p-value Acute GVHD II-IV 1.29 (1.09-1.53) 0.003 Acute GVHD III-IV 1.69 (1.00-3.36) 0.05 Chronic GVHD 1.11 (0.96-1.28) 0.15 Relapse 1.01 (0.87-1.17) 0.92 NRM 1.52 (1.29-1.79) <0.0001 DFS 1.20 (1.07-1.34) 0.0015 OS 1.25 (1.11-1.40) 0.0001 Compared to 8/8 MUD, both 7/8 allele and antigen MMUD RIC HCT have greater treatment toxicity and worse survival, of a magnitude similar to that seen in myeloablative transplantation. An isolated mismatch at HLA-A, -B, -C, or -DRB1 was associated with 1 or more adverse outcomes. In unrelated donor RIC HCT, matching for all alleles of HLA-A, -B, -C and -DRB1 loci results in superior outcomes. Disclosures: No relevant conflicts of interest to declare.

Comparison of Early Post-Transplant Outcomes in Ex Vivo αβ+ T Cell-Depleted Haploidentical HSCT with or without Pharmacologic Gvhd Prophylaxis

Blood ◽  
2016 ◽  
Vol 128 (22) ◽  
pp. 3379-3379 ◽  
Author(s):  
Eun Seok Choi ◽  
Sung Han Kang ◽  
Hyery Kim ◽  
Kyung-Nam Koh ◽  
Ho Joon Im ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Acute Gvhd ◽  
Ex Vivo ◽  
Post Transplant ◽  
Cell Dose ◽  
Gvhd Prophylaxis ◽  
The Mean ◽  
Mean Time ◽  
Αβ T Cells

Abstract Background and purpose: One of the key obstacles to successful haploidenitcal hematopoietic cell transplantation (HHCT) is a development of fatal GVHD. Although much progress in immunosuppressant (IS) has effectively prevented the development of acute GVHD, they have many serious toxicity and drug interactions requiring serial monitoring of drug levels. Recent advances in ex vivo depletion technique enabled to effectively reduce T cells or their subset, αβ+ T cells, leading to residual αβ+ T cells in grafts well below 5×104/kg of recipient weight. We eliminated post-transplant pharmacologic GVHD prophylaxis along with targeting αβ+ T cell dose ≤ 5×104/kg since November 2015. In this study, we compared early post-transplant outcomes between with (IS+) or without (IS-) post-transplant immunosuppressants after ex vivo αβ+ T cell-depleted HHCT. Methods: Between May 2012 and July 2016, 69 pediatric patients received HHCT using TCRαβ-depleted grafts from haploidentical family donors at Asan Medical Center Children's Hospital. Fifty patients received tacrolimus and mycophenolate mofetil to prevent acute GVHD, while 19 did not receive any immunosuppressant after transplant. All donors received G-CSF for 4 consecutive days and peripheral blood stem cells were collected on days -1 and 0. The αβ+ T cells were depleted by negative selection using the CliniMACS® system (Miltenyi-BioTec, Bergisch-Gladbach, Germany) according to manufacturer's instruction. In the earlier trial of IS+, the final doses of αβ+ T cells were adjusted to 1-5×105 cells/kg by add-back from the raw bag. Since November 2015, the cell dose was targeted at ≤ 5×104 αβ+T cells/kg with no post-transplant immunosuppressants (IS-). Results: The median infused CD34+ cells, αβ+ T cells, γδ+ T cells and CD3-CD56+ NK cells per kg of recipient weight were 8.9×106, 33.8×104, 20.0×106, 45.9×106 in IS+ group and 6.1×106, 4.6×104, 17.5×106, 24.6×106 in IS- group, respectively. All 69 patients achieved neutrophil engraftment at a median of 10 days (range, 9-17). Three patients out of 50 in IS+ group experience graft rejection (GR), while no GR occurred in IS- group. The cumulative incidences of acute GVHD grade II-IV were similar (31% vs 33%). Severe acute GVHD ≥ grade III developed in 7 in IS+ group, while none in IS- group developed ≥ grade III. As of July 2016, the median follow-ups were 24 months (range 9.5-50.8) for IS+ group and 5 months (0.5-9.1) for IS- group. Two out of 50 patients in IS+ group died of TRM leading to 2.2% at 6 months and 4.9% at 1 year after HHCT, while no patients in IS- group died of TRM during the follow-up period. The mean time from transplant to discharge were longer in IS+ group compared to IS- group (32 days versus 21 days, P=0.049). While the mean time of hospital stay within 100 days post-HHCT for patients who survived more than 100 days was not different between two groups (47 days versus 34 days, P>0.05). Conclusions: The major findings of our study were less severe acute GVHD and shorter hospital stay from HHCT to discharge in IS- group, even with less T cell dose, compared to IS+ group. Therefore, this HHCT using ex vivo αβ-depleted graft containing αβ+ T cells ≤ 5×104/kg is an effective treatment strategy to prevent acute GVHD without post-transplant IS. In addition, the early clinical outcomes were comparable between with and without post-transplant IS. Disclosures No relevant conflicts of interest to declare.

scholarly journals T-Cell Reconstitution after Unrelated Donor HSCT Using Immunotherapy with CD25/71 Allodepleted Donor T Cells: Results of the Randomised Icat Study

Blood ◽  
2019 ◽  
Vol 134 (Supplement_1) ◽  
pp. 1995-1995
Author(s):  
Karl S Peggs ◽  
Sarah J Albon ◽  
Catherine Irving ◽  
Rachel Richardson ◽  
Joan Casanovas-Company ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Cell Count ◽  
Chronic Gvhd ◽  
Control Group ◽  
Unrelated Donor ◽  
Donor T Cells ◽  
The Mean ◽  
And Control ◽  
To Receive

Karl S Peggs and Sarah J Albon contributed equally to the work and are joint first author Introduction Alemtuzumab reduces the incidence of GVHD after unrelated donor stem cell transplant (MUD SCT) but delays immune reconstitution resulting in high morbidity/mortality from viral infections. Previous studies have suggested that adoptive transfer of allodepleted donor T cells (ADTs) improves immunity after SCT but this has never been tested in a randomised study. We developed a methodology for selective immunomagnetic depletion of alloreactive T-cells upregulating CD25 and CD71 after activation with host dendritic cells (DC) and showed that ADTs retain anti-viral responses with minimal host alloreactivity (Samarasinghe et al Blood 2010). We have now tested whether ADTs can safely be used to improve immune reconstitution after MUD SCT for haematological malignancies in a randomised Phase II multi-centre clinical study; ICAT (NCT01827579). Methods Patients undergoing Alemtuzumab-based peripheral blood SCT from a 9/10 or 10/10 MUD for haematological malignancy were randomised 2:1 to receive either the ATIMP (ADTs) or standard of care. Two weeks prior to SCT, patients randomised to ATIMP underwent a leucapheresis from which DCs were generated. Irradiated patient-derived DCs were then co-cultured with peripheral blood mononuclear cells (PBMC) from an unstimulated leucapheresis/500ml blood draw from the donor to activate alloreactive T cells. Four days later, the co-culture was depleted of CD25+ and CD71+ fractions by immunomagnetic depletion on the CliniMACs, sampled for residual alloreactivity and sterility, and cryopreserved. Patients randomised to the ATIMP were scheduled to receive 3 escalating doses of ADTs (0.1x106/Kg at day 30, 0.3x106/Kg at day 60 and 1x106/Kg at day 90 post-SCT) until either there was >grade 1 aGVHD or they had normal circulating T cells (>700/µL). The primary end-point of the study was circulating CD3+ T cell count at 4 months post-SCT with one-sided 15% significance level. Acute/chronic GVHD were graded using the Seattle/NIH criteria respectively. Results Twenty one patients were treated, 13 on the ATIMP arm and 8 on the control arm. The median age was 53 years and 67% (14) were male. 12 were AML/Myelodysplasia, 5 NHL, 3 CLL/CML and 1 HL. The median follow-up time is 14 months. Five of 13 ATIMP patients received 1 dose of ADTs, 4/13 2 doses and 4/13 all 3 doses. The incidence of acute and chronic GVHD was comparable between the arms. Overall, 7/13 ATIMP patients developed significant (>Grade 2) acute GVHD compared to 4/8 of the control arm (p>0.99). 3/13 patients in the ATIMP arm and 2/8 patients in the control arm developed severe aGVHD (all Grade 3). Three of 13 ATIMP cohort patients developed chronic GVHD (1 mild, 1 moderate, 1 severe), compared to 3/8 (all mild) in the control cohort. At 4 months, the circulating CD3+ T cell count mean was 730/µL (range 10-4080) in the ATIMP group and 212.5/µL (range 10-500) in the control group (1-sided p=0.11). However, the data was not normally distributed (Wilcoxon 1-sided p=0.18). Three ATIMP patients had high CD3+ T cell count at 4 months (>1000/µL). At 6 months, the mean circulating CD3+ T cell count was 833.6/µL (range 20-2690) and 327.5/µL (range 10-860). At month 4, the mean PHA stimulation index in the ATIMP arm was 16.8 (range 0.67- 73.1) vs 3.8 (range 1.1-8.2) in the control group. At 4 and 6 months post-SCT, spectratyping analysis showed no evidence of a difference in Vβ diversity between the 2 arms in both CD4+ and CD8+ cells. The 1-year survival rate in the ATIMP cohort is 92% vs 88% in the control, and 1-year disease free survival rate 67% in the ATIMP cohort vs 70% in the control. Conclusions These data suggest that adoptive transfer of ADTs improves T cell reconstitution in some patients after MUD SCT and that the GVHD rates were similar between ATIMP and control groups. Figure 1: Kinetics of T cell recovery after transplant in ATIMP (blue) and Control (red) patients. Mean +/- SEM shown. Figure 1 Disclosures Peggs: Gilead: Consultancy, Speakers Bureau; Autolus: Membership on an entity's Board of Directors or advisory committees. Ghorashian:UCLB: Patents & Royalties: UCLB; Celgene: Honoraria; novartis: Honoraria. Amrolia:UCLB: Patents & Royalties.

GvHD Prophylaxis with Everolimus and Mycophenolate in Allogeneic Hematopoietic Cell Transplantation - A Phase I/II Study.

Blood ◽  
2009 ◽  
Vol 114 (22) ◽  
pp. 4642-4642
Author(s):  
Reinhard Marks ◽  
Alf Zerweck ◽  
Razvan George Racila ◽  
Hartmut Bertz ◽  
Jürgen Finke
Keyword(s):  
T Cells ◽  
T Cell ◽  
Research Funding ◽  
Malignant Disease ◽  
Acute Gvhd ◽  
Hematopoietic Cell Transplantation ◽  
Chronic Gvhd ◽  
Tolerance Induction ◽  
Treg Function ◽  
Gvhd Prophylaxis

Abstract Abstract 4642 Next to the control of malignant disease, tolerance induction of the grafted cells remain to be a critical issue for longterm survivors after allogeneic hematopoietic cell transplantation (HCT). Regulatory T cells (Tregs) are believed to be involved in the process of tolerance induction to solid organ grafts and in the regulation of alloreactivity, e.g. graft versus host disease (GvHD) and graft versus leukemia effect (GvL), after allogeneic HCT. Since GvHD causes substantial morbidity, medication with calcineurin inhibitors (CI) like cyclosporine are established prophylactic measures for the prevention of GvHD after HCT. Next to the substantial renal toxicity of CI, tolerance induction might be hampered in HCT patients due to deteriorated Treg function. In contrast, data from in vitro and animal experiments suggest that inhibition of the mammalian target of rapamycin (mTOR) has not only an antiproliferative effect on many malignant cell lines but also results in an inhibition of proliferation of alloreactive T cells with sustained Treg function in a murine HCT model. Therefore we initiated a phase I/II, monocenter trial using everolimus and mycophenolate sodium (MMF-Na) as GvHD prophylaxis in patients undergoing allogeneic HCT with peripheral stem cell (PBSC) grafts after conditioning with fludarabine, melphalan, and BCNU (FBM). No additional T cell depleting agents were used for conditioning/GvHD prophylaxis. Enrolment was started in april 2008, and up to august 2009 10 patients were included (median age: 50.7 years, range: 26-64). The diagnoses included de novo AML (n=3), sAML (n=4), RAEB II (n=1), CML (n=1), T-PLL (n=1). 6/10 patients were regarded as high risk (not in CR1) for early relapse. PBSC grafts were obtained from unrelated (n=5) and related (n=5) HLA-matched donors. With no graft failures, engraftment kinetics for myeloid cells were normal, and reconstitution of the T cell compartment reached median cell counts of 251 CD4+ cells/μl and 163 CD8+ cells/μl at day +30. No grade IV/V toxicities (according to CTC criteria) were observed due to the study medication. After a median follow-up of 6 month two patients have died. The causes were acute GvHD, refractory to several lines of treatment, in a patient with CML, and severe pulmonary toxicity/BOOP in a patient with sAML. Out of 9 patients reaching CR after HCT, only one high risk patient relapsed after 6 month. In total 6 patients are alive and show complete donor chimerism for time periods of 1-14 months post transplant. The observed early recovery of T cell immunity correlated in 8/10 patients with an early brief period of acute GvHD, with 4 patients experiencing grade III/IV severities. Most of the cases could be controlled with steroids alone. Chronic GvHD could be observed in 6/7 patients, with mild to moderate forms in 5 cases, mainly involving skin, mucosa and liver. Interestingly, while early tapering of MMF-Na did not cause any problems, reduction of everolimus earlier as 6 month after HCT resulted in an induction of GvHD symptoms. Although viral reactivation (CMV, HHV6) did occur in patients receiving additional immunosuppression with steroids, no severe bacterial or fungal infections were observed even in cases with prolonged everolimus treatment. In conclusion, GvHD prophylaxis with everolimus and MMF-Na is feasible but results in an increased frequency of mild to moderate chronic GvHD. Since this sustained mild alloreactivity might reduce the risk of relapse, this GvHD prophylaxis could well be suited for patients undergoing HCT with advanced or uncontrolled malignant disease. Disclosures: Marks: Novartis: Research Funding. Off Label Use: Everolimus for prophylaxis of GvHD. Finke:Novartis: Research Funding.

scholarly journals Acute Gvhd Induce the Critical Depletion of Naïve Pool in Regulatory T Cells: Implication for Linked Pathogenesis into Chronic Gvhd

Blood ◽  
2015 ◽  
Vol 126 (23) ◽  
pp. 923-923
Author(s):  
Takanori Yoshioka ◽  
Yusuke Meguri ◽  
Takeru Asano ◽  
Yuriko Kishi ◽  
Miki Iwamoto ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Regulatory T Cells ◽  
Immune Tolerance ◽  
Cd4 T Cells ◽  
Acute Gvhd ◽  
Chronic Gvhd ◽  
T Cell Subsets ◽  
Effector Memory ◽  
Ki 67

Abstract CD4+Foxp3+ regulatory T cells (Treg) play a central role in establishing immune tolerance after allogeneic hematopoietic stem cell transplantation (HSCT). We previously reported that the long-term severe lymphopenia could result in the collapse of Treg homeostasis leading to the onset of chronic GVHD (Matsuoka et al. JCI 2010). We recently found that, not only in the chronic phase but also in the acute phase, the homeostasis of Treg is more susceptible to the post-transplant environment as compared to other lymphocyte subsets (Yoshioka et al. ASH 2014). However, the impact of acute GVHD on Treg homeostasis and the pathogenesis of following chronic GVHD has not been well studied. In this study, we examined Treg reconstitution in the early phase after transplant in patients with or without acute GVHD. For the purpose, we obtained peripheral blood samples at 2, 4, 8 and 12 weeks after transplant from 52 patients who received allogeneic HSCT, and then analyzed CD4+CD25med-highCD127lowFoxp3+ Treg comparing with CD4+CD25neg-lowCD127highFoxp3- conventional T cell (Tcon) and CD8+ T cells. CD4 T cell subsets are further divided into subpopulations by the expression of CD45RA and CD31. The expressions of Helios, Ki-67 and Bcl-2 on these subsets were also examined. After transplant, total lymphocyte counts in examined patients were significantly lower than the counts before the start of conditioning (median lymphocytes 95/ul at 2 weeks and 302/ul at 4 weeks vs 600/ul before conditioning, P<0.01 and P<0.01, respectively). As we reported before, Treg showed the active proliferation without diminishing Bcl-2 levels in the severe lymphopenia, resulted in the increased %Treg of CD4 T cells at 4 weeks after transplant (%Treg of CD4 T cells; 12.2% at 4 weeks, 4.6% in healthy controls, P<0.005). 18 patients who developed acute GVHD were studied Treg homeostasis before and after the onset of GVHD more in detail. Before the onset of acute GVHD, % Ki-67+ cells in Treg and Tcon were in the equivalent levels in these patients. After the onset of acute GVHD, % Ki-67+ cells in Treg was dramatically increased from 19.1% to 61.2% (median) and this was significantly higher than % Ki-67+ cells in Tcon after acute GVHD (P<0.05). %Treg of total CD4 T cells were significantly increased after GVHD (% Treg; Median 7.2% vs 12.2%, P<0.004). Expanded Treg after acute GVHD showed a predominant Helios+CD45RA-CD31- effector/memory phenotype with the lower level of Bcl-2 expression as compared to CD45RA+ naïve Treg. As a consequence, naïve Treg pool including CD45RA+CD31+ recent thymic emigrant Treg (RTE-Treg) were critically decreased during acute GVHD (%CD45RA+ cells; 12.7% into 6.5%, P<0.004: CD45RA+CD31+ cells; 3.6% into 2.1%, P<0.003). In contrast, Tcon still retained a relatively higher level of naïve pool (%CD45RA+ cells; 20.5%, % CD45RA+CD31+ cells; 10.9%) after acute GVHD. These data indicated that Treg proliferation was rapidly promoted in face with the inflammatory condition during acute GVHD and this appears to contribute the amelioration of developing GVHD. However, the prompt reaction resulted in the depletion of naïve Treg pool which is important to maintain stable Treg homeostasis in the long period. In conclusion, our findings suggest that acute GVHD drives aggressive Treg proliferation resulting in the increased percentage of this subset but this also induce the severe alteration of Treg homeostasis by depleting naïve Treg, which may provide the linked pathogenesis of the subsequent onset of chronic GVHD. The careful monitoring of Treg from the point of view might provide important information to promote immune tolerance. Disclosures No relevant conflicts of interest to declare.

scholarly journals Abatacept Is Effective for Gvhd Prophylaxis after Unrelated Donor Stem Cell Transplantation (URD SCT) for Severe Sickle Cell Disease (SCD)

Blood ◽  
2019 ◽  
Vol 134 (Supplement_1) ◽  
pp. 370-370
Author(s):  
Alexander I. Ngwube ◽  
Niketa C. Shah ◽  
David Jacobsohn ◽  
Edward Dela Ziga ◽  
Shalini Shenoy
Keyword(s):  
T Cell ◽  
Graft Versus Host Disease ◽  
Acute Gvhd ◽  
Chronic Gvhd ◽  
Unrelated Donor ◽  
Host Disease ◽  
Graft Versus Host ◽  
Gvhd Prophylaxis ◽  
Low Incidence ◽  
One Year

Background In 2016, results from the first URD SCT for SCD (the SCURT Trial) revealed a 2-year overall survival (OS) and event-free survival (EFS) of 79% (95% CI 59-90) and 69% (95% CI, 48-82) respectively following reduced intensity conditioning (RIC).1 Though the RIC approach provided successful engraftment in the majority, the transplant approach was not considered safe for widespread adoption due to high rates of graft-versus-host disease (GVHD) especially in children &gt;13 years, a predominant cause of mortality. Strategies to minimize GVHD were essential if URD SCT was to be considered with curative intent in SCD. Aim/Method Multicenter trial (NCT03128996) with the primary objective of determining EFS in non-malignant disorders at one-year was amended as follows. The phase I SCD cohort included conditioning with hydroxyurea, proximal alemtuzumab, fludarabine, and melphalan in patients with 8/8 HLA-matched URD (-A, -B, - C and -DRB1).1 Thiotepa (8 mg/kg) was added in 7/8 HLA-mismatched SCT. GVHD prophylaxis included a calcineurin inhibitor and methotrexate as previously described. Abatacept (10 mg/kg) was administered on days -1, +5, +14, +28, +60, +100, +180, +270 and +365 based on efficacy described against acute GVHD with early dosing after SCT for malignant disorders.2,3 The latter 3 doses were omitted in cord transplant recipients. Result Thirteen children (7-21 years) underwent SCT (8/8 URD marrow- 7; 7/8 URD marrow or cord-6) primarily for stroke (N=6), ≥3 severe vaso-occlusive pain crises (N=4) or ≥2 acute chest syndrome episodes per year (N=3). The conditioning regimen was well tolerated. One patient had primary graft rejection after CMV infection (7%) and had autologous recovery. All other patients engrafted; neutrophils at median of 18 days (10-24), platelets at median of 28 days (16-39) and are surviving free of SCD with median follow-up of 12 months (range 4-59). Myeloid lineage donor chimerism was &gt;95% and lymphoid was 39%- 100% at day+100. Two-year OS and EFS was 100% and 92.3% (95% CI, 6.57-35.7), respectively. The day+100 incidence of grade II-IV and III-IV acute GVHD incidence was 23% and 15% respectively. One-year incidence of chronic GVHD was 38%. However, only one patient (7%) developed extensive cGVHD. One patient (7%) developed posterior reversible encephalopathy syndrome and recovered. Viral replication in blood was detected in 7 of 13 patients (7 CMV, 1 EBV reactivation). No patient developed EBV PTLD or required EBV-related intervention. Conclusion In comparison to previous experience1 with RIC and URD SCT, our early observations are (1) a lower incidence of PRES (7 vs 34%) (2) low incidence of severe acute GVHD (15% vs 17% grade III -IV) despite mismatched donors, (3) low incidence of extensive chronic GVHD (7% vs 38%) and (4) no mortality despite patient age (10/13 were &gt;13 years old). We attribute this gain to avoiding steroid use, and the benefit of including abatacept into the treatment regimen. The engraftment, safety, and immune reconstitution profile continue to be monitored in this ongoing trial now accruing in a Phase II cohort. As we and others work toward expanding donor options for SCD transplants, we submit that all alternate donor transplants for severe SCD are experimental and should be performed on clinical trials that track success and pitfalls. Reference: 1. Shenoy S et al. A trial of unrelated donor marrow transplantation for children with severe sickle cell disease. Blood. 2016 Nov 24; 128(21): 2561-2567. 2. Koura et al. In vivo T cell costimulation blockade with abataceptfor acute graft-versus-host disease prevention: a first-in-disease trial. Biol Blood Marrow Transplant. 2013 Nov; 19(11): 1638-49. 3. Watkins BK et al. T cell co-stimulation blockade with CTLA-4 Ig (Abatacept) for acute GVHD prevention in HLA-matched and mismatched unrelated donor transplantation: Results of a Phase 2 trial. Abstract 65. ASTCT Meetings, Houston 2019. Figure Disclosures Shah: Jazz pharmaceuticals: Speakers Bureau. OffLabel Disclosure: Abatacept, FDA approved for rheumatoid arthritis is a fusion protein that inhibits T-cell activation by binding to CD80/CD86 on antigen-presenting cells (APCs).It is used for acute graft-versus-host disease (aGVHD) prevention during unrelated-donor hematopoietic cell transplantation in this study

Reconstitution of Regulatory T Cell Subpopulations After Allogeneic Hematopoietic Stem Cell Transplantation and Graft-Versus-Host-Disease

Blood ◽  
2012 ◽  
Vol 120 (21) ◽  
pp. 1948-1948
Author(s):  
Alienor Xhaard ◽  
Helene Moins ◽  
Marc Busson ◽  
Maryvonnick Carmagnat ◽  
Marie Robin ◽  
...  
Keyword(s):  
Stem Cells ◽  
T Cells ◽  
T Cell ◽  
Malignant Disease ◽  
Acute Gvhd ◽  
Chronic Gvhd ◽  
Cd4 T Cell ◽  
Effector Memory ◽  
Hematopoietic Stem ◽  
Graft Versus Host

Abstract Abstract 1948 Previous studies on the reconstitution of regulatory T cells (Treg) after allogeneic hematopoietic stem cell transplantation (HSCT) have shown a delayed reconstitution in patients (pts) with acute graft-versus-host-disease (GvHD) (Magenau, 2010) and an association between impaired Treg reconstitution and the development of extensive chronic GvHD (Matsuoka, 2010). However, no studies have analyzed naive (nTreg) versus memory (mTreg) Treg reconstitution in a longitudinal cohort with large numbers of pts. From 2006 to 2009, 165 consecutive pts were prospectively analyzed in our center post-HSCT. Fresh whole blood samples were obtained 3 (n=155), 6 (n=162), 12 (n=165) and 24 (n=94) months after HSCT and analyzed by flow cytometry to quantify CD4 T cells, including naive, activated, central memory and effector memory subsets (Sallusto, 1999), as well as Treg (CD4+ CD25+ CD127neg/lo), including nTreg (CD45RA+) and mTreg (CD45RAneg). The results are presented as median values of circulating cells. Median age was 41 years (range: 6–68). The indication for HSCT was malignant disease in 92%. The conditioning regimen was reduced-intensity (RIC) in 51%. The donor was an HLA-identical sibling in 56%. The source of stem cells was peripheral blood (PBSC), bone marrow (BM) and cord blood (CB) in 65%, 28% and 7%, respectively. All pts received cyclosporine as GvHD prophylaxis. GvHD was defined as acute if occurring before day 100 and chronic thereafter. Total Treg (tTreg) increased from 13/μL at 3 months to 44/μL at 24 months, but always remained inferior to healthy controls (HC) (66/μL). nTreg increased from 1.8/μL at 3 months to 4.8/μL at 24 months (HC: 24/μL). mTreg increased from 10.7/μL at 3 months to 33.3/μL at 24 months (HC: 42/μL). The CD4/Treg ratio remained stable at 12.6 at 3 months and 11.6 at 24 months while the nCD4/nTreg ratio increased from 17.4 at 3 months to 42.7 at 24 months, showing a larger expansion of naive cells in the CD4 T cell compartment than in the Treg compartment (Figure 1) and a larger expansion of memory cells in the Treg than within the CD4 cells. At 3 months post-HSCT, tTreg, nTreg and mTreg were significantly higher in PBSC recipients (18.4, 2.7 and 14.5/μL) than in BM (8.1, 0.9 and 6.5/μL) and CB recipients (6.5, 0.6 and 5.3/μL) (p=0.0001), respectively. Pts transplanted after a RIC regimen had significantly more tTreg and mTreg than pts transplanted after a standard regimen (17 and 14/μL, compared with 9.8 and 8/μL, p=0.004 and 0.008 respectively). Pts transplanted for an aplastic anemia had significantly fewer nTreg than pts transplanted for a malignant disease (0.4 and 1.9/μL, p=0.001). At 6 months post-HSCT, tTreg, nTreg and mTreg were significantly higher (p=≤0.01) in pts transplanted from an HLA-identical sibling (19.5, 1.9 and 17.2/μL) compared with pts transplanted from an unrelated donor (13.2, 1.2 and 11/μL). At 12 and 24 months post-HSCT, younger pts (≤15 years) had significantly more nTreg than older pts (9.8 and 28.7/μL compared with 2.1 and 4.2, p=0.001). In pts with previous acute GvHD, tTreg and mTreg were significantly lower at 3 (8.5 and 7.7/μL) and 6 months (14.6 and 12.5/μL) compared with pts without (15.6 and 13.8/μL at 3 months, p=0.005 and 21.3 and 18.2/μL at 6 months, p≤0.007), respectively. Absolute numbers of tTreg, nTreg and mTreg, and the frequencies of Treg relative to activated, effector memory and central memory CD4 T cells at 3, 6 and 12 months post-HSCT did not predict the occurrence of a later episode of chronic GvHD up to 2 years post-HSCT. In our population, total, naive and memory Treg reconstitution was delayed post-HSCT and remained below the normal range up to 2 years after HSCT. tTreg reconstitution post-HSCT was mostly due to mTreg expansion. RIC regimen and PBSC as source of stem cells were associated with a better short-term reconstitution. At 6 months, pts transplanted from siblings had a better reconstitution while nTreg long-term reconstitution was mainly influenced by recipient age (better if ≤15 years). While previous acute GvHD impaired Treg reconstitution, Treg subsets (absolute numbers and frequencies relative to CD4 T cell subsets) at 3, 6 and 12 months post-HSCT were unable to predict chronic GvHD in this large cohort of patients. We believe these data are of particular interest regarding the recently increasing number of Treg interventional studies in humans in the context of HSCT. Disclosures: No relevant conflicts of interest to declare.

scholarly journals Family Mismatched Donor Transplantation for Myelofibrosis: A Retrospective Analysis of the EBMT Chronic Leukaemia Working Party

Blood ◽  
2016 ◽  
Vol 128 (22) ◽  
pp. 4655-4655 ◽  
Author(s):  
Kavita Raj ◽  
Eduardo Olavarria ◽  
Diderik-Jan Eikema ◽  
Liesbeth C de Wreede ◽  
Linda Koster ◽  
...  
Keyword(s):  
Stem Cell ◽  
Cumulative Incidence ◽  
Graft Failure ◽  
Acute Gvhd ◽  
Chronic Gvhd ◽  
Unrelated Donor ◽  
Stem Cell Source ◽  
Gvhd Prophylaxis ◽  
Cell Source ◽  
Mismatched Donor

Abstract Background: Allogeneic stem cell transplantation is a treatment option for patients with advanced myelofibrosis. Problems encountered include an increased risk of delayed or poor engraftment and in the mismatched unrelated donor setting a higher rate of GVHD and particularly poor outcomes. As for other indications for allogeneic stem cell transplants, patients for whom either a matched sibling or matched unrelated donor is not available are considered for either a double umbilical cord blood, a mismatched unrelated donor or haploidentical stem cell transplant. Data on the latter option are limited and we reviewed registry data on all family mismatched donor transplants performed between 2001 and 2015 and reported to the EBMT registry. Results: Records retrieved 69 patients with myelofibrosis transplanted between November 2001 and November 2015. 44 (64%) were male. 50 (74%) had primary myelofibrosis,18 (27%) had secondary myelofibrosis (6 from ET, 5 from PRV and 7 others) and unknown 1(2%). Of 25 patients for whom the JAK2 V617F mutation status was known, 15 (22%) harboured the mutation. Patient Karnofsky performance status was > 70% in 98%. Of the mismatched family donors, 47 (68%) were male and 22 (31%) female. Donors were HLA mismatched at 1 locus in 12 (17%) and 2 or more loci in 48 (69%). Donor-recipient serology combinations were CMV -/- in 8 (12%), +/- in 4 (6%), -/+ in 15 (22%) and +/+ in 34 (49%) missing 8 (12%). Bone marrow was the stem cell source in 34 (49%) and peripheral blood in 35 (51%). The median total nucleated cell count (TNC) infused was 7.5x108/kg (range 2.3-21x108/kg) from data available in 17 patients. The median CD34+ cell dose was 6.9x106/kg (range 1.9-18.18x106/kg) from data available in 19 patients. Conditioning was myeloablative in 48 (70%) and RIC in 21 (30%) The conditioning regimes were varied but the predominant ones were Fludarabine, Busulphan, ATG (FBATG) and Thiotepa, Busulphan, Fludarabine (TBF). TBI was administered in 8 (12%) and in vivo T cell depletion in 22 (32%), ex-vivo T cell depletion in 5 (7%) patients. GVHD prophylaxis varied with post transplant Cyclophosphamide administered in 34/67 (49%) and ATG in 19/67 patients (28%). Neutrophil engraftment was established in 53 (82%) at a median of 20 days (range 11-83). Primary graft failure occurred in 8 (12%) and secondary graft failure in 4 (6%). This occurred at a median of 12 months (range 4.5-35 months). Eleven of these patients had a second allograft at a mean interval of 6.4 months. Responses to the first allograft (censoring for patients who had a second allograft) with data available in 45 patients, showed that complete remission was achieved in 35 patients (78%), 6 (13%) were never in CR and 4 (9%) were not evaluable. The cumulative incidence of grade II-IV acute GvHD at 100 days was 12% (95% CI 4-21%) and for grade III-IV acute GvHD at 100 days it was 5% (95% CI 3-11%). Data for chronic GVHD was valid in 49 patients. The cumulative incidence of chronic GvHD at 2 years was 62% (95% CI 47-76%). The cumulative incidence of limited cGvHD was 45% (95% CI 31-59%) whereas the cumulative incidence of extensive cGvHD was 10% (95% CI 2-19%). The median follow up was 24 months (95% CI 13-35 months). The 2-year OS was 51% (95% CI 37-76%) and the 5-year OS was 38% (95% CI 21-55%). The 2-year RFS was 44% (95% CI 30-59%) and the 5-year RFS was 31% (95% CI 15-48%). The 2 year cumulative incidence of relapse was 14% (95% CI 5-24%). The 2 year NRM was 41% (95% CI 28-55%), which increased to 54% (95% CI 37-72%) at 5 years. The main causes of death were infection (16, 24%), GVHD (7, 10%) organ damage or failure (3, 5%), relapse/disease progression (1, 2%) and secondary malignancy or PTLD (1, 2%). On univariate analysis there was no significant effect of recipient gender, donor gender, degree of HLA mismatch 1 vs >1 Ag MM, CMV matching between donor and recipient, primary or secondary MF, disease stage at transplant (chronic versus advanced phase), conditioning intensity, conditioning regimen, GVHD prophylaxis with ATG or post transplant cyclophosphamide or stem cell source on overall survival. Conclusion: Concerns regarding engraftment and secondary graft failure have excluded patients with myelofibrosis from clinical trials of mismatched related donor transplant. The data suggest that engraftment is feasible, and PFS and OS can be attained with limited severe chronic GVHD with family mismatched donors in this setting. Disclosures Ciceri: MolMed SpA: Consultancy.

Sirolimus, Tacrolimus and Reduced-Dose Methotrexate as Graft Versus Host Disease (GVHD)Prophylaxis after Non-Myeloablative Stem Cell Transplantation: Low Incidence of Acute GVHD Compared with Tacrolimus/Methotrexate or Cyclosporine/Prednisone.

Blood ◽  
2004 ◽  
Vol 104 (11) ◽  
pp. 730-730 ◽  
Author(s):  
Edwin P. Alyea ◽  
Shuli Li ◽  
Haesook Kim ◽  
Corey Cutler ◽  
Vincent Ho ◽  
...  
Keyword(s):  
Serum Level ◽  
Low Dose ◽  
Acute Gvhd ◽  
Chronic Gvhd ◽  
Unrelated Donor ◽  
Peripheral Blood Stem Cells ◽  
Dose Methotrexate ◽  
Gvhd Prophylaxis ◽  
Low Incidence

Abstract Sirolimus (rapamycin) is a macrocyclic lactone similar in structure to tacrolimus and cyclosporine (CSA) but with a distinct mechanism of action. Sirolimus binds to both FKBP12 and mTOR and inhibits signal transduction and cell cycle progression. The drug is synergistic with tacrolimus but has a distinct toxicity profile, thereby allowing their use in combination. We report results of a phase II trial combining sirolimus with tacrolimus and low-dose methotrexate (MTX) as GVHD prophylaxis in matched related and unrelated donor NST. Results of this trial were compared with patients who had previously undergone NST receiving tacrolimus/MTX alone or CSA/prednisone(pred). All patients received fludarabine (30 mg/m2/d x 4days) and intravenous busulfan (0.8mg/kg/d x 4 days) as conditioning. All patients received G-CSF mobilized peripheral blood stem cells with a targeted cell dose of 1 x 107 CD34+ cells/kg. G-CSF 5 mcg/kg was started on day 1. Sirolimus containing GVHD prophylaxis included sirolimus 12 mg loading dose on day −3 and then 4 mg po qd targeting a serum level of 3–12 ng/ml. Tacrolimus was initiated at 0.05 mg/kg po b. i.d. beginning day −3 with a targeted serum level of 5–10 ng/ml. MTX (5 mg/m2) was given days, 1, 3 and 6. Planned taper of the GVHD medications was ~30% at days 60, and 120 with discontinuation by day 180. The median follow up is 14 months for patients receiving sirolimus and all evaluable patients have been followed for >100 days. 40 patients have been transplanted, 20 from related and 20 from unrelated donors. The median age was 57 years (range 20–69). Diseases included: NHL (9), MDS (7), Hodgkin’s disease (6), CLL (6), AML(5), CML (5), MM (1) and CMML(1). 18 patients (45%) had received prior myeloablative transplantation. 31 patients (78 %) had advanced disease at the time of transplantation. Patients receiving tacrolimus/MTX (n=36) and CSA/pred (n=49)had similar characteristics. Sirolimus was well tolerated and no severe adverse events related to the drug were noted. Acute grade 2–4 GVHD was significantly reduced in patients receiving sirolimus/tacrolimus/MTX, 8% vs 18% in patients receiving tacrolimus/MTX and 37% in those receiving CSA/Pred (p=0.003). Time to neutrophil engraftment was slower in methotrexate containing regimens (13 days vs 9 days, p=0.01), but there was no difference between sirolimus/tacrolimus/MTX and tacrolimus/MTX alone. Median donor derived hematopoiesis, measured 1–2 months after transplant, was high in all groups (sirolimus/tacrolimus/MTX 91%, tacrolimus/MTX 95% and CSA/pred 90%, p=0.91). The 1 year overall survival was sirolimus/tacrolimus/MTX 71%, tacrolimus/MTX 48% and CSA/pred 45% (p=0.17). 1-year progression free survival was 49%, 27% and 37%, respectively (p=0.11). The addition of sirolimus to tacrolimus and low dose MTX is well tolerated and is associated with a low incidence of acute GVHD. The addition of sirolimus does not delay engraftment compared with tacrolimus/MTX and results in a similar high level of donor derived hematopoiesis. Further patient accrual and longer follow-up is needed to yield information on the incidence of chronic GVHD and overall outcome.

Phenotypic and Functional Analysis of T-Cells Mobilized in HLA-Matched Sibling Donors Following Treatment with the Chemokine Antagonist AMD3100.

Blood ◽  
2006 ◽  
Vol 108 (11) ◽  
pp. 3001-3001 ◽  
Author(s):  
Michael Rettig ◽  
Steven M. Devine ◽  
Julie Ritchey ◽  
John F. DiPersio
Keyword(s):  
T Cells ◽  
T Cell ◽  
Peripheral Blood ◽  
Acute Gvhd ◽  
T Cell Subsets ◽  
Effector Memory ◽  
Phenotypic Properties ◽  
Functional Changes ◽  
Cd8 Cells ◽  
Matched Sibling

Abstract We are currently evaluating a novel method for the procurement of peripheral blood stem cells from HLA matched sibling donors using a direct antagonist of the CXCR4/SDF-1 interaction called AMD3100 (A). Donors receive a single subcutaneous injection of A and then undergo a 20 liter leukapheresis (LP) four hours later. The LP product is then cryopreserved and subsequently transplanted following ablative conditioning. To date, we have performed 15 transplants with allografts collected following A alone. In comparison to allografts collected following five days of G-CSF, A mobilized allografts contain approximately 50% less CD34+ cells but 2–3 times more CD3+ cells. Nevertheless, the kinetics of neutrophil and platelet engraftment have been virtually identical to that observed following G-mobilized allografts and grades 2–4 acute GVHD has been observed in only 20% of recipients. We sought to analyze the functional and phenotypic properties of T cells collected following A alone to understand the relatively low rates of acute GVHD despite the transplantation of higher T-cell doses. In 3 donors, extensive T cell phenotyping was performed on donor peripheral blood prior to A, 6 hours following A, and also on the LP product collected after A. Specifically, we were seeking to determine whether any alteration in CD4+ or CD8+ subsets had occurred. We analyzed T-cell subsets using well described markers for central memory, effector memory, naïve, and effector memory RA phenotypes. We also assessed expression of CD62L, CD127, CCR7, and SLAM family members (CD48, CD150, and CD244) on both CD4+ and CD8+ cells. The activation status on CD4 and CD8 cells was assessed using markers for CD25, CD30, and CD69. Finally we assessed for quantitative changes in the mobilization of regulatory T cells by assaying the proportion of CD4+CD25+FoxP3+ cells mobilized following A. In none of these analyses could we detect any significant alteration in the relative ratios of CD4 or CD8 subsets mobilized by A. Finally, the functional capacity of purified CD3+ cells collected following A was assessed using a NOD/SCID xenogeneic GVHD model we have recently developed. In that model, survival of mice transplanted with A mobilized T-cells was similar to that observed with untreated T cells, suggesting that A mobilized T cells retain their GVHD-inducing capacity. In summary, these preliminary data suggest that AMD3100 induces a “pan-mobilization” of T cell subsets without any apparent skewing toward a particular subset. These studies are in contrast to others suggesting subtle phenotypic and functional changes in donor T cells after mobilization with G-CSF. Further studies evaluating A mobilized allografts are ongoing.

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