Hematopoietic stem cell transplant-associated thrombotic microangiopathy: current paradigm and novel therapies.

Hematopoietic stem cell transplantation-associated thrombotic microangiopathy (TA-TMA) remains a difficult complication to address due to its high mortality rate, lack of standard diagnostic criteria and limited therapeutic options. Underscoring this challenge is the complex pathophysiology involved and multiple contributing factors that converge on a final pathway involving widespread endothelial injury and complement activation. In addressing our current understanding of TA-TMA, we highlight the risk factors leading to endothelial damage and a pathophysiological cascade that ensues. We have also compared the different definition criteria and biomarkers that can enable early intervention in TA-TMA patients. Current first-line management includes discontinuation or alteration of the immunosuppressive regimen, treatment of co-existing infectious and GVHD, aggressive hypertension control and supportive therapy. We discuss current pharmacological therapies, including newer agents that target the complement cascade and nitric oxide pathways.

Neurologic complications after allogeneic hematopoietic stem cell transplantation: risk factors and impact.

Neurologic complications (NCs) may be a significant source of morbidity and mortality after hematopoietic cell transplantation (HCT). We performed a retrospective study of 263 consecutive patients undergoing allogeneic HCT for hematological malignancies to determine the incidence, risk factors and clinical impact of NCs in the first 5 years after HCT. We determined the incidence of central nervous system (CNS) infection, intracranial hemorrhage, ischemic stroke, metabolic encephalopathy, posterior reversal encephalopathy syndrome, seizure and peripheral neuropathy. In all, 50 patients experienced 63 NCs-37 early (⩽day +100), 21 late (day +101 to 2 years) and 5 very late (2 to 5 years). The 1- and 5-year cumulative incidences of all NCs were 15.6% and 19.2%, respectively, and of CNS complication (CNSC; all of the above complications except peripheral neuropathy) were 12.2 and 14.5%. Risk factors for CNSC were age (hazard ratio (HR)=1.06 per year, P=0.0034), development of acute GvHD grade III-IV (HR=2.78, P=0.041), transfusion-dependent thrombocytopenia (HR=3.07, P=0.025) and delayed platelet engraftment (>90th centile; HR=2.77, P=0.043). CNSCs negatively impacted progression-free survival (HR=2.29, P=0.0001), overall survival (HR=2.63, P<0.0001) and non-relapse mortality (HR=8.51, P<0.0001). NCs after HCT are associated with poor outcomes, and usually occur early after HCT.

GvHD after umbilical cord blood transplantation for acute leukemia: an analysis of risk factors and effect on outcomes.

Using the Center for International Blood and Marrow Transplant Research (CIBMTR) registry, we analyzed 1404 umbilical cord blood transplantation (UCBT) patients (single (<18 years)=810, double (⩾18 years)=594) with acute leukemia to define the incidence of acute GvHD (aGvHD) and chronic GvHD (cGvHD), analyze clinical risk factors and investigate outcomes. After single UCBT, 100-day incidence of grade II-IV aGvHD was 39% (95% confidence interval (CI), 36-43%), grade III-IV aGvHD was 18% (95% CI, 15-20%) and 1-year cGvHD was 27% (95% CI, 24-30%). After double UCBT, 100-day incidence of grade II-IV aGvHD was 45% (95% CI, 41-49%), grade III-IV aGvHD was 22% (95% CI, 19-26%) and 1-year cGvHD was 26% (95% CI, 22-29%). For single UCBT, multivariate analysis showed that absence of antithymocyte globulin (ATG) was associated with aGvHD, whereas prior aGvHD was associated with cGvHD. For double UCBT, absence of ATG and myeloablative conditioning were associated with aGvHD, whereas prior aGvHD predicted for cGvHD. Grade III-IV aGvHD led to worse survival, whereas cGvHD had no significant effect on disease-free or overall survival. GvHD is prevalent after UCBT with severe aGvHD leading to higher mortality. Future research in UCBT should prioritize prevention of GvHD.

Longitudinal studies of a B cell-derived signature of tolerance in renal transplant recipients.

Biomarkers of transplant tolerance would enhance the safety and feasibility of clinical tolerance trials and potentially facilitate management of patients receiving immunosuppression. To this end, we examined blood from spontaneously tolerant renal transplant recipients and patients enrolled in two interventional tolerance trials using flow cytometry and gene expression profiling. Using a previously reported tolerant cohort as well as newly identified tolerant patients, we confirmed our previous finding that tolerance was associated with increased expression of B cell-associated genes relative to immunosuppressed patients. This was not accounted for merely by an increase in total B cell numbers, but was associated with the increased frequencies of transitional and naïve B cells. Moreover, serial measurements of gene expression demonstrated that this pattern persisted over several years, although patients receiving immunosuppression also displayed an increase in the two most dominant tolerance-related B cell genes, IGKV1D-13 and IGLL-1, over time. Importantly, patients rendered tolerant via induction of transient mixed chimerism, and those weaned to minimal immunosuppression, showed similar increases in IGKV1D-13 as did spontaneously tolerant individuals. Collectively, these findings support the notion that alterations in B cells may be a common theme for tolerant kidney transplant recipients, and that it is a useful monitoring tool in prospective trials.

Prognostic understanding, quality of life and mood in patients undergoing hematopoietic stem cell transplantation.

Little is known about how patients undergoing hematopoietic stem cell transplantation (HCT) and their family caregivers (FC) perceive their prognosis. We examined prognostic understanding in patients undergoing HCT and their FC and its relationship with quality of life (QOL) and mood. We conducted a longitudinal study of patients (and FC) hospitalized for HCT. We used a questionnaire to measure participants' prognostic understanding and asked the oncologists to estimate patients' prognosis prior to HCT. We assessed QOL and mood weekly and evaluated the relationship between prognostic understanding, and QOL and mood using multivariable linear mixed models. We enrolled 90 patients undergoing (autologous (n=30), myeloablative (n=30) or reduced intensity allogeneic (n=30)) HCT. About 88.9% of patients and 87.1% of FC reported it is 'extremely' or 'very' important to know about prognosis. However, 77.6% of patients and 71.7% of FC reported a discordance and more optimistic prognostic perception compared to the oncologist (P<0.0001). Patients with a concordant prognostic understanding with their oncologists reported worse QOL (ß=-9.4, P=0.01) and greater depression at baseline (ß=1.7, P=0.02) and over time ((ß=1.2, P<0.0001). Therefore, Interventions are needed to improve prognostic understanding, while providing patients with adequate psychological support.

Endometrial stromal fibroblasts from women with polycystic ovary syndrome have impaired progesterone-mediated decidualization, aberrant cytokine profiles and promote enhanced immune cell migration in vitro.

STUDY QUESTION: Do endometrial stromal fibroblasts (eSF) in women with polycystic ovary syndrome (PCOS) (eSFpcos) exhibit altered estrogen and/or progesterone (P4) responses, which may explain some of the adverse reproductive outcomes and endometrial pathologies in these women? SUMMARY ANSWER: In vitro, eSF from women with PCOS exhibit an aberrant decidualization response and concomitant changes in pro-inflammatory cytokine, chemokine and matrix metalloproteinase (MMP) release and immune cell chemoattraction. In vivo these aberrations may result in suboptimal implantation and predisposition to endometrial cancer. WHAT IS KNOWN ALREADY: The endometrium in women with PCOS has several abnormalities including progesterone (P4) resistance at the gene expression level, likely contributing to subfertility, pregnancy complications and increased endometrial cancer risk in PCOS women. STUDY DESIGN, SIZE, DURATION: Prospective, university-based, case-control, in vitro study. PARTICIPANTS/MATERIALS, SETTING, METHODS: Cultures of eSFPCOS (n = 12, Rotterdam and NIH criteria) and eSFControl (Ctrl) (n = 6, regular cycle length, no signs of hyperandrogenism) were treated with vehicle, estradiol (E2, 10 nM) or E2P4 (10 nM/1 µM) for 14 days. Progesterone receptor (PGR) mRNA was assessed with quantitative real-time PCR (qRT-PCR) and eSF decidualization was confirmed by insulin-like growth factor-binding protein-1 (IGFBP-1) transcript and protein expression. Fractalkine (CX3CL1), granulocyte-macrophage colony-stimulating factor (GM-CSF), interleukin (IL) 6, 8 and 11, macrophage chemoattractant protein (MCP) 1 and 3, CCL5 (RANTES) and MMPs (MMP1, 2, 3, 7, 9, 10 and 12) were measured in conditioned media by Luminex multiplex assays, and chemotactic activity of the conditioned media was tested in a migration assay using CD14+ monocyte and CD4+ T-cell migration assay. Effects of IL-6 (0.02, 0.2, 2 or 20 ng/ml) or IL-8 (0.04, 0.4, 4, or 40 ng/ml) or combination (0.2 ng/ml IL-6 and 4.0 ng/ml IL-8) on 14-d decidualization were also tested. ANOVA with pre-planned contrasts was used for statistical analysis. MAIN RESULTS AND THE ROLE OF CHANCE: Hormonal challenge with E2P4 to induce decidualization revealed two distinct subsets of eSFPCOS. Eight eSFPCOS (dPCOS) and all eSFCtrl (dCtrl) cultures showed a normal decidualization response to E2P4 as determined by morphology and IGFBP-1 secretion. However, 4 eSFPCOS cultures showed blunted decidualization (ndPCOS) in morphological assessment and low IGFBP-1 levels even though all three groups exhibited normal estrogen-mediated increase in PGR expression. Interestingly dPCOS had decreased IL-6 and GM-SCF secretion compared with dCtrl, whereas the ndPCOS cultures showed increased IL-6 and 8, MCP1, RANTES and GM-CSF secretion at base-line and/or in response to E2 or E2P4 compared with dCtrl and/or dPCOS. Furthermore, even though PGR expression was similar in all three groups, P4 inhibition of MMP secretion was attenuated in ndPCOS resulting in higher MMP2 and 3 levels. The conditioned media from ndPCOS had increased chemoattractic activity compared with dCtrl and dPCOS media. Exogenously added IL-6 and/or 8 did not inhibit decidualization in eSFCtrl indicating that high levels of these cytokines in ndPCOS samples were not likely a cause for the aberrant decidualization. LIMITATIONS, REASONS FOR CAUTION: This is an in vitro study with a small sample size, utilizing stromal cell cultures from proliferative and secretory phase endometrium. The effect of PCOS on endometrial epithelium, another major histoarchitectural cell compartment of the endometrium, was not evaluated and should be considered in future studies. Furthermore, results obtained should also be confirmed in a larger data set and with mid/late secretory phase in vivo samples and models. WIDER IMPLICATIONS OF THE FINDINGS: The alterations seen in ndPCOS may contribute to endometrial dysfunction, subfertility and pregnancy complications in PCOS women. The results emphasize the importance of understanding immune responses related to the implantation process and normal endometrial homeostasis in women with PCOS. STUDY FUNDING/COMPETING INTERESTS: Sigrid Juselius Foundation, Academy of Finland, Finnish Medical Foundation, Orion-Farmos Research Foundation (to T.T.P.), the NIH Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD) U54HD 055764-07 Specialized Cooperative Centers Program in Reproduction and Infertility Research (to L.C.G.), the NICHD the Ruth L. Kirschstein National Research Service Awards grant 1F32HD074423-03 (to J.C.C.). The authors have no competing interests.

Engraftment syndrome: double-edged sword of hematopoietic cell transplants.

Engraftment syndrome (ES) after hematopoietic cell transplantation (HCT) is increasingly diagnosed. Common features include fever, pulmonary vascular leak, rash and organ dysfunction. Different diagnostic criteria likely account for the wide (7-90%) range of reported incidences. ES typically occurs within 4 days of granulocyte recovery although a recently described seemingly similar syndrome occurs >1 week before granulocyte recovery after umbilical cord blood cell transplants. Although the clinical manifestations of ES may be identical to those of acute GVHD, ES also has been well described in patients without acute GVHD. The data are conflicting as to whether ES is associated with a higher nonrelapse mortality and worse survival after HCT. The pathophysiology of ES is unclear, but endothelial injury and activated granulocytes in the setting of proinflammatory cytokines may be important. ES typically is self-limited, but, like acute GVHD, responds to corticosteroids. Because ES and acute GVHD may have overlapping features and response to therapy, these disease processes may often not be distinct events. Moreover, features of ES may overlap with those of drug- and radiation-induced toxicities and infection. Further research to better characterize the clinical spectrum and etiology of ES and to determine its relationship to GVHD is needed.

Long-term results in recipients of combined HLA-mismatched kidney and bone marrow transplantation without maintenance immunosuppression.

We report here the long-term results of HLA-mismatched kidney transplantation without maintenance immunosuppression (IS) in 10 subjects following combined kidney and bone marrow transplantation. All subjects were treated with nonmyeloablative conditioning and an 8- to 14-month course of calcineurin inhibitor with or without rituximab. All 10 subjects developed transient chimerism, and in seven of these, IS was successfully discontinued for 4 or more years. Currently, four subjects remain IS free for periods of 4.5-11.4 years, while three required reinstitution of IS after 5-8 years due to recurrence of original disease or chronic antibody-mediated rejection. Of the 10 renal allografts, three failed due to thrombotic microangiopathy or rejection. When compared with 21 immunologically similar living donor kidney recipients treated with conventional IS, the long-term IS-free survivors developed significantly fewer posttransplant complications. Although most recipients treated with none or two doses of rituximab developed donor-specific antibody (DSA), no DSA was detected in recipients treated with four doses of rituximab. Although further revisions of the current conditioning regimen are planned in order to improve consistency of the results, this study shows that long-term stable kidney allograft survival without maintenance IS can be achieved following transient mixed chimerism induction.

Mesenchymal stem/progenitors and other endometrial cell types from women with polycystic ovary syndrome (PCOS) display inflammatory and oncogenic potential.

CONTEXT: Endometrium in polycystic ovary syndrome (PCOS) presents altered gene expression indicating progesterone resistance and predisposing to reduced endometrial receptivity and endometrial cancer. OBJECTIVE: We hypothesized that an altered endocrine/metabolic environment in PCOS may result in an endometrial "disease phenotype" affecting the gene expression of different endometrial cell populations, including stem cells and their differentiated progeny. DESIGN AND SETTING: This was a prospective study conducted at an academic medical center. PATIENTS AND MAIN OUTCOME MEASURES: Proliferative-phase endometrium was obtained from 6 overweight/obese PCOS (National Institutes of Health criteria) and 6 overweight/obese controls. Microarray analysis was performed on fluorescence-activated cell sorting-isolated endometrial epithelial cells (eEPs), endothelial cells, stromal fibroblasts (eSFs), and mesenchymal stem cells (eMSCs). Gene expression data were validated using microfluidic quantitative RT-PCR and immunohistochemistry. RESULTS: The comparison between eEP(PCOS) and eEP(Ctrl) showed dysregulation of inflammatory genes and genes with oncogenic potential (CCL2, IL-6, ORM1, TNAIFP6, SFRP4, SPARC). eSF(PCOS) and eSF(Ctrl) showed up-regulation of inflammatory genes (C4A/B, CCL2, ICAM1, TNFAIP3). Similarly, in eMSC(PCOS) vs eMSC(Ctrl), the most up-regulated genes were related to inflammation and cancer (IL-8, ICAM1, SPRR3, LCN2). Immunohistochemistry scoring showed increased expression of CCL2 in eEP(PCOS) and eSF(PCOS) compared with eEP(Ctrl) and eSF(Ctrl) and IL-6 in eEP(PCOS) compared with eEP(Ctrl). CONCLUSIONS: Isolated endometrial cell populations in women with PCOS showed altered gene expression revealing inflammation and prooncogenic changes, independent of body mass index, especially in eEP(PCOS) and eMSC(PCOS), compared with controls. The study reveals an endometrial disease phenotype in women with PCOS with potential negative effects on endometrial function and long-term health.

Expression of α4ß7 integrin on memory CD8(+) T cells at the presentation of acute intestinal GVHD.

Acute intestinal GVHD remains a major source of morbidity after allogeneic hematopoietic cell transplantation (HCT). α4ß7 integrin is a cell surface molecule that mediates lymphocyte trafficking to intestinal tissue. In this analysis, peripheral blood was collected at the time of presentation of symptoms of acute GVHD and before any treatment. In all, 45 samples were collected and divided into three groups on the basis of subsequent evaluation: intestinal GVHD (n=15), skin GVHD (n=20) and no GVHD (n=10). Two patients developed intestinal GVHD after DLI. The no-GVHD group comprised 10 patients who presented with suspicious symptoms, but evaluation yielded other etiologies. Analysis by flow cytometry showed that intestinal GVHD patients had a significantly higher percentage of α4ß7 integrin-expressing memory CD8(+) T cells (median 7.69%; lower and upper quartiles, 1.06% and 11.64%, respectively) compared with patients with skin GVHD (1.26%; 0.57% and 2.49%) and no GVHD (0.96%; 0.44% and 1.85%), P=0.03. No differences were found in α4ß7 expression in any CD4(+) T-cell subsets or naive CD8(+) T cells. This study adds to the evidence that α4ß7 integrin is involved in lymphocyte trafficking in acute intestinal GVHD.

Mechanisms of donor-specific tolerance in recipients of haploidentical combined bone marrow/kidney transplantation.

We recently reported long-term organ allograft survival without ongoing immunosuppression in four of five patients receiving combined kidney and bone marrow transplantation from haploidentical donors following nonmyeloablative conditioning. In vitro assays up to 18 months revealed donor-specific unresponsiveness. We now demonstrate that T cell recovery is gradual and is characterized by memory-type cell predominance and an increased proportion of CD4⁺ CD25⁺ CD127⁻ FOXP3⁺ Treg during the lymphopenic period. Complete donor-specific unresponsiveness in proliferative and cytotoxic assays, and in limiting dilution analyses of IL-2-producing and cytotoxic cells, developed and persisted for the 3-year follow-up in all patients, and extended to donor renal tubular epithelial cells. Assays in two of four patients were consistent with a role for a suppressive tolerance mechanism at 6 months to 1 year, but later (≥ 18 months) studies on all four patients provided no evidence for a suppressive mechanism. Our studies demonstrate, for the first time, long-term, systemic donor-specific unresponsiveness in patients with HLA-mismatched allograft tolerance. While regulatory cells may play an early role, long-term tolerance appears to be maintained by a deletion or anergy mechanism.

Acute renal endothelial injury during marrow recovery in a cohort of combined kidney and bone marrow allografts.

An idiopathic capillary leak syndrome ('engraftment syndrome') often occurs in recipients of hematopoietic cells, manifested clinically by transient azotemia and sometimes fever and fluid retention. Here, we report the renal pathology in 10 recipients of combined bone marrow and kidney allografts. Nine developed graft dysfunction on day 10-16 and renal biopsies showed marked acute tubular injury, with interstitial edema, hemorrhage and capillary congestion, with little or no interstitial infiltrate (≤10%) and marked glomerular and peritubular capillary (PTC) endothelial injury and loss by electron microscopy. Two had transient arterial endothelial inflammation; and 2 had C4d deposition. The cells in capillaries were primarily CD68(+) MPO(+) mononuclear cells and CD3(+) CD8(+) T cells, the latter with a high proliferative index (Ki67(+) ). B cells (CD20(+) ) and CD4(+) T cells were not detectable, and NK cells were rare. XY FISH showed that CD45(+) cells in PTCs were of recipient origin. Optimal treatment remains to be defined; two recovered without additional therapy, six were treated with anti-rejection regimens. Except for one patient, who later developed thrombotic microangiopathy and one with acute humoral rejection, all fully recovered within 2-4 weeks. Graft endothelium is the primary target of this process, attributable to as yet obscure mechanisms, arising during leukocyte recovery.

The great debate: haploidentical or cord blood transplant.

One of the truly revolutionary advances in hematopoietic cell transplantation (HCT) is the increasingly successful use of alternative donors, thereby allowing the delivery of a potentially curative transplant to ∼75% of patients who do not have an HLA-matched sibling donor. A substantial proportion of the need has been met by HLA-matched volunteer unrelated donors, but an unmet need still exists, particularly among minority populations and for people who need a more immediate source of hematopoietic cells. Two such sources, umbilical cord blood (UCB) and haploidentical related donors, have filled most of this need, and outcomes following transplants from these donor sources are very promising. UCB has the advantages of ready availability and is less capable of causing GVHD but hematological recovery and immune reconstitution are slow. Haploidentical HCT is characterized by the nearly uniform and immediate availability of a donor and the availability of the donor for post transplant cellular immunotherapy, but is complicated by a high risk of GVHD and poor immune reconstitution when GVHD is prevented by vigorous ex vivo or in vivo T-cell depletion. This review will discuss the pertinent issues that affect the choice of one donor source over another and offer recommendations regarding the optimal utilization of these donor sources.

Double umbilical cord blood transplantation with reduced intensity conditioning and sirolimus-based GVHD prophylaxis.

The main limitations to umbilical cord blood (UCB) transplantation (UCBT) in adults are delayed engraftment, poor immunological reconstitution and high rates of non-relapse mortality (NRM). Double UCBT (DUCBT) has been used to circumvent the issue of low cell dose, but acute GVHD remains a significant problem. We describe our experience in 32 subjects, who underwent DUCBT after reduced-intensity conditioning with fludarabine/melphalan/antithymocyte globulin and who received sirolimus and tacrolimus to prevent acute GVHD. Engraftment of neutrophils occurred in all patients at a median of 21 days, and platelet engraftment occurred at a median of 42 days. Three subjects had grade II-IV acute GVHD (9.4%) and chronic GVHD occurred in four subjects (cumulative incidence 12.5%). No deaths were caused by GVHD and NRM at 100 days was 12.5%. At 2 years, NRM, PFS and OS were 34.4, 31.2 and 53.1%, respectively. As expected, immunologic reconstitution was slow, but PFS and OS were associated with reconstitution of CD4(+) and CD8(+) lymphocyte subsets, suggesting that recovery of adaptive immunity is required for the prevention of infection and relapse after transplantation. In summary, sirolimus and tacrolimus provide excellent GVHD prophylaxis in DUCBT, and this regimen is associated with low NRM after DUCBT.

B-cell immunity in the context of T-cell tolerance after combined kidney and bone marrow transplantation in humans.

Five patients with end-stage kidney disease received combined kidney and bone marrow transplants from HLA haploidentical donors following nonmyeloablative conditioning to induce renal allograft tolerance. Immunosuppressive therapy was successfully discontinued in four patients with subsequent follow-up of 3 to more than 6 years. This allograft acceptance was accompanied by specific T-cell unresponsiveness to donor antigens. However, two of these four patients showed evidence of de novo antibodies reactive to donor antigens between 1 and 2 years posttransplant. These humoral responses were characterized by the presence of donor HLA-specific antibodies in the serum with or without the deposition of the complement molecule C4d in the graft. Immunofluorescence staining, ELISA assays and antibody profiling using protein microarrays demonstrated the co-development of auto- and alloantibodies in these two patients. These responses were preceded by elevated serum BAFF levels and coincided with B-cell reconstitution as revealed by a high frequency of transitional B cells in the periphery. To date, these B cell responses have not been associated with evidence of humoral rejection and their clinical significance is still unclear. Overall, our findings showed the development of B-cell allo- and autoimmunity in patients with T-cell tolerance to the donor graft.

Autologous SCT with a dose-reduced BU and CY regimen in older patients with non-Hodgkin's lymphoma.

Autologous SCT is a potentially curative procedure for patients with relapsed lymphoma (NHL). We analyzed the outcomes of 34 patients > or =60 years old, including eight patients > or =70 years old, who received BU and CY and SCT for NHL. Patients received BU 0.8 mg/kg i.v. (n=25) or 1 mg/kg p.o. (n=9) q 6 h x 14 doses and CY 60 mg/kg i.v. q day x 2 days. The median age was 66 (range, 60-78) years. Twenty-two patients had large cell, 10 follicular and two-mantle cell lymphoma. Fifteen patients were in a second or greater CR and 19 patients were in a PR. The median days to ANC >500/microl and platelet count >50,000/microl were 10 and 13 days respectively. The 100-day transplant-related mortality was 0%. Toxicities included interstitial lung disease (n=2), seizures in a patient with CNS lymphoma (n=1), mild veno-occlusive disease (n=2), and transient atrial fibrillation (n=4). With a median follow-up of 40 months, the 2-year overall survival and PFS were 67 and 54% respectively. BU/CY is a well-tolerated conditioning regimen for older patients with NHL. Age alone should not be used as an exclusion criterion for autologous SCT.

Clinical outcomes of late rather than early full-donor chimerism in patients with advanced lymphomas receiving nonmyeloablative allogeneic hematopoietic SCT.

Allogeneic hematopoietic SCT (HSCT) can ideally provide long-term remission in advanced lymphoma patients by capturing a graft-vs-tumor (GVT) effect. On the basis of a murine model, we attempted to optimize a GVT effect through nonmyeloablative therapy and HLA-matched related donor HSCT with intentional induction of mixed chimerism followed by prophylactic donor lymphocyte infusion. A total of 26 advanced lymphoma patients were separated into an early and late full-donor chimerism (FDC) group using a median of 45 days post-HSCT as the defining point for FDC. Upon generating these groups, analysis by Student's t-test demonstrated that they were statistically distinct in time to develop FDC (P<0.01). There was a trend toward improved CR rates in the late group relative to the early group (62 vs 31%; P=0.12). A trend toward improved progression-free survival at 5 years was also observed in the late compared to the early group by Kaplan-Meier analysis (38 vs 8%; P=0.081). However, this did not correlate to a significant overall survival benefit. In conclusion, these data support the observation from our mouse models that the most potent GVT effect occurs in mixed chimeras with late chimerism conversion.

Preinfusion variables predict the predominant unit in the setting of reduced-intensity double cord blood transplantation.

Double cord blood transplantation (DCBT) may overcome the slow hematopoietic recovery and engraftment failure associated with infusion of a single cord blood unit. In DCBT, only one unit typically contributes to long-term hematopoiesis, but little is known about factors affecting cord predominance. As results from a phase I trial suggested that order of infusion may affect cord predominance, we analyzed the effect of preinfusion variables on chimerism patterns of 38 patients enrolled in the initial study and a subsequent phase II trial. All patients were treated with a reduced-intensity conditioning (RIC) regimen of fludarabine, melphalan and thymoglobulin followed by DCBT. By day 100, 66% of patients had hematopoiesis derived from a single cord blood unit. Higher post-thaw total nucleated cell and CD34+ cell dose were associated with cord predominance and in 68% of patients (P=0.03); the predominant cord blood unit was infused first. Only the post-thaw CD34+ cell dose of the predominant unit predicted time to both neutrophil and platelet engraftment. Although based on a small number of patients, our results identify parameters that may affect cord predominance and engraftment in the setting of DCBT following RIC and suggest possible strategies for selecting infusion order for cord blood units.