Effect of time to relapse on overall survival in patients with mantle cell lymphoma following autologous haematopoietic cell transplantation.

In young and fit patients with mantle cell lymphoma (MCL), intensive induction therapy followed by a consolidative autologous haematopoietic cell transplant (autoHCT) is the standard of care in the front-line setting. Recently, time-to-event analysis has emerged as an important risk assessment tool in lymphoma, though its impact in MCL is not well defined. We utilized the Center for International Blood and Marrow Transplant Research database to evaluate the effect of post-autoHCT time to relapse on overall survival (OS) over time in 461 patients who underwent autoHCT within 12 months of MCL diagnosis. On multivariate analysis, the impact of relapse on OS was greatest at the six-month [hazard ratio (HR) = 7·68], 12-month (HR = 6·68), and 18-month (HR = 5·81) landmark timepoints. Using a dynamic landmark model we demonstrate that adjusted OS at five years following each landmark timepoint improved with time for relapsing and non-relapsing patients. Furthermore, early relapse (<18 months) following autoHCT defines a high-risk group with inferior post-relapse OS. This retrospective analysis highlights the impact of time to relapse on OS in MCL patients undergoing up-front autoHCT and emphasizes the need to consider novel therapeutic approaches for patients suffering early relapse.

Effect of Aging and Predonation Comorbidities on the Related Peripheral Blood Stem Cell Donor Experience: Report from the Related Donor Safety Study.

The development of reduced-intensity approaches for allogeneic hematopoietic cell transplantation has resulted in growing numbers of older related donors (RDs) of peripheral blood stem cells (PBSCs). The effects of age on donation efficacy, toxicity, and long-term recovery in RDs are poorly understood. To address this we analyzed hematologic variables, pain, donation-related symptoms, and recovery in 1211 PBSC RDs aged 18 to 79 enrolled in the Related Donor Safety Study. RDs aged > 60 had a lower median CD34+ level before apheresis compared with younger RDs (age > 60, 59 × 106/L; age 41 to 60, 81 × 106/L; age 18 to 40, 121 × 106/L; P < .001). This resulted in older donors undergoing more apheresis procedures (49% versus 30% ≥ 2 collections, P < .001) and higher collection volumes (52% versus 32% > 24 L, P < .001), leading to high percentages of donors aged > 60 with postcollection thrombocytopenia <50 × 109/L (26% and 57% after 2 and 3days of collection, respectively). RDs aged 18 to 40 had a higher risk of grades 2 to 4 pain and symptoms pericollection, but donors over age 40 had more persistent pain at 1, 6, and 12 months (odds ratio [OR], 1.7; P = 0.02) and a higher rate of nonrecovery to predonation levels (OR, 1.7; P = .01). Donors reporting comorbidities increased significantly with age, and those with comorbidities that would have led to deferral by National Marrow Donor Program unrelated donor standards had an increased risk for persistent grades 2 to 4 pain (OR, 2.41; P < .001) and failure to recover to predonation baseline for other symptoms (OR, 2.34; P = .004). This information should be used in counseling RDs regarding risk and can assist in developing practice approaches aimed at improving the RD experience for high-risk individuals.

Related peripheral blood stem cell donors experience more severe symptoms and less complete recovery at one year compared to unrelated donors.

Unlike unrelated donor registries, transplant centers lack uniform approaches to related donor assessment and deferral. To test whether related donors are at increased risk for donation-related toxicities, we conducted a prospective observational trial of 11,942 related and unrelated donors aged 18-60 years. Bone marrow (BM) was collected at 37 transplant and 78 National Marrow Donor Program centers, and peripheral blood stem cells (PBSC) were collected at 42 transplant and 87 unrelated donor centers in North America. Possible presence of medical comorbidities was verified prior to donation, and standardized pain and toxicity measures were assessed pre-donation, peri-donation, and one year following. Multivariate analyses showed similar experiences for BM collection in related and unrelated donors; however, related stem cell donors had increased risk of moderate [odds ratios (ORs) 1.42; P<0.001] and severe (OR 8.91; P<0.001) pain and toxicities (OR 1.84; P<0.001) with collection. Related stem cell donors were at increased risk of persistent toxicities (OR 1.56; P=0.021) and non-recovery from pain (OR 1.42; P=0.001) at one year. Related donors with more significant comorbidities were at especially high risk for grade 2-4 pain (OR 3.43; P<0.001) and non-recovery from toxicities (OR 3.71; P<0.001) at one year. Related donors with more significant comorbidities were at especially high risk for grade 2-4 pain (OR 3.43; P<0.001) and non-recovery from toxicities (OR 3.71; P<0.001) at one year. Related donors reporting grade ≥2 pain had significant decreases in Health-Related Quality of Life (HR-QoL) scores at one month and one year post donation (P=0.004). In conclusion, related PBSC donors with comorbidities are at increased risk for pain, toxicity, and non-recovery at one year after donation. Risk profiles described in this study should be used for donor education, planning studies to improve the related donor experience, and decisions regarding donor deferral. Registered at clinicaltrials.gov identifier:00948636.

Plerixafor Plus Granulocyte Colony-Stimulating Factor for Patients with Non-Hodgkin Lymphoma and Multiple Myeloma: Long-Term Follow-Up Report.

The purpose of this report is to analyze long-term clinical outcomes of patients exposed to plerixafor plus granulocyte colony-stimulating factor (G-CSF) for stem cell mobilization. This was a study of patients with non-Hodgkin lymphoma (NHL; n = 167) and multiple myeloma (MM; n = 163) who were enrolled in the long-term follow-up of 2 pivotal phase III studies (NCT00741325 and NCT00741780) of 240 µg/kg plerixafor plus 10 µg/kg G-CSF, or placebo plus 10 µg/kg G-CSF to mobilize and collect CD34+ cells for autologous hematopoietic stem cell transplantation. Overall survival (OS) and progression-free survival (PFS) were evaluated over a 5-year period following the first dose of plerixafor or placebo. The probability of OS was not significantly different in patients with NHL or MM treated with plerixafor or placebo (NHL: 64%; 95% confidence interval [CI], 56% to 71% versus 56%; 95% CI, 44% to 67%, respectively; MM: 64%; 95% CI, 54% to 72% versus 64%; 95% CI, 53% to 73%, respectively). In addition, there was no statistically significant difference in the probability of PFS over 5 years between treatment groups in patients with NHL (50%; 95% CI, 44% to 67% for plerixafor versus 43%; 95% CI, 31% to 54% for placebo) or those with MM (17%; 95% CI, 10% to 24% for plerixafor versus 30%; 95% CI, 21% to 40% for placebo). In this long-term follow-up study, the addition of plerixafor to G-CSF for stem cell mobilization did not affect 5-year survival in patients with NHL or patients with MM.

Effectiveness and toxicity of high-dose cyclophosphamide in obese versus non-obese patients receiving allogeneic hematopoietic stem cell transplant.

PURPOSE: To determine if there is a difference in toxicity and effectiveness between obese and non-obese patients who receive high-dose cyclophosphamide (Cy) prior to allogeneic hematopoietic stem cell transplant (allo-HCT). METHODS: Patients were included in this study if they were at least 18 years of age and received high-dose Cy in combination with total body irradiation (CyTBI) or busulfan (BuCy) prior to allo-HCT between 1 January 2008 and 29 February 2012. The primary endpoint was the difference in overall toxicity between obese and non-obese patients. Secondary objectives examined differences in effectiveness between groups assessed by relapse at day +100, relapse at 1 year, death at 1 year, chimerisms at days +30, +60, and +90, and incidence of acute graft versus host disease (aGVHD). RESULTS: Sixty-one patients met the inclusion criteria, 28 obese and 33 non-obese. Overall toxicity was greater in obese patients compared to non-obese patients (82% vs. 52%, OR 4.3 [95% CI 1.3-14.1]; p = 0.01), which was driven by a greater incidence of renal dysfunction (79% vs. 48%, OR 3.9 [95% CI 1.3-12.1]; p = 0.02). There were no differences in rates of grade 3 or 4 toxicity, hepatic dysfunction, or any measure of effectiveness between groups. CONCLUSION: Obese patients receiving high-dose Cy and allo-HCT are at increased risk for toxicity, although there appears to be no difference in the rate of relapse or survival between obese and non-obese patients.

Dynamical System Modeling of Immune Reconstitution after Allogeneic Stem Cell Transplantation Identifies Patients at Risk for Adverse Outcomes.

Systems that evolve over time and follow mathematical laws as they evolve are called dynamical systems. Lymphocyte recovery and clinical outcomes in 41 allograft recipients conditioned using antithymocyte globulin (ATG) and 4.5-Gy total body irradiation were studied to determine if immune reconstitution could be described as a dynamical system. Survival, relapse, and graft-versus-host disease (GVHD) were not significantly different in 2 cohorts of patients receiving different doses of ATG. However, donor-derived CD3(+) cell reconstitution was superior in the lower ATG dose cohort, and there were fewer instances of donor lymphocyte infusion (DLI). Lymphoid recovery was plotted in each individual over time and demonstrated 1 of 3 sigmoid growth patterns: Pattern A (n = 15) had rapid growth with high lymphocyte counts, pattern B (n = 14) had slower growth with intermediate recovery, and pattern C (n = 10) had poor lymphocyte reconstitution. There was a significant association between lymphocyte recovery patterns and both the rate of change of donor-derived CD3(+) at day 30 after stem cell transplantation (SCT) and clinical outcomes. GVHD was observed more frequently with pattern A, relapse and DLI more so with pattern C, with a consequent survival advantage in patients with patterns A and B. We conclude that evaluating immune reconstitution after SCT as a dynamical system may differentiate patients at risk of adverse outcomes and allow early intervention to modulate that risk.

Peripheral-blood stem cells versus bone marrow from unrelated donors.

BACKGROUND: Randomized trials have shown that the transplantation of filgrastim-mobilized peripheral-blood stem cells from HLA-identical siblings accelerates engraftment but increases the risks of acute and chronic graft-versus-host disease (GVHD), as compared with the transplantation of bone marrow. Some studies have also shown that peripheral-blood stem cells are associated with a decreased rate of relapse and improved survival among recipients with high-risk leukemia. METHODS: We conducted a phase 3, multicenter, randomized trial of transplantation of peripheral-blood stem cells versus bone marrow from unrelated donors to compare 2-year survival probabilities with the use of an intention-to-treat analysis. Between March 2004 and September 2009, we enrolled 551 patients at 48 centers. Patients were randomly assigned in a 1:1 ratio to peripheral-blood stem-cell or bone marrow transplantation, stratified according to transplantation center and disease risk. The median follow-up of surviving patients was 36 months (interquartile range, 30 to 37). RESULTS: The overall survival rate at 2 years in the peripheral-blood group was 51% (95% confidence interval [CI], 45 to 57), as compared with 46% (95% CI, 40 to 52) in the bone marrow group (P=0.29), with an absolute difference of 5 percentage points (95% CI, -3 to 14). The overall incidence of graft failure in the peripheral-blood group was 3% (95% CI, 1 to 5), versus 9% (95% CI, 6 to 13) in the bone marrow group (P=0.002). The incidence of chronic GVHD at 2 years in the peripheral-blood group was 53% (95% CI, 45 to 61), as compared with 41% (95% CI, 34 to 48) in the bone marrow group (P=0.01). There were no significant between-group differences in the incidence of acute GVHD or relapse. CONCLUSIONS: We did not detect significant survival differences between peripheral-blood stem-cell and bone marrow transplantation from unrelated donors. Exploratory analyses of secondary end points indicated that peripheral-blood stem cells may reduce the risk of graft failure, whereas bone marrow may reduce the risk of chronic GVHD. (Funded by the National Heart, Lung, and Blood Institute-National Cancer Institute and others; ClinicalTrials.gov number, NCT00075816.).

Predictive models for ocular chronic graft-versus-host disease diagnosis and disease activity in transplant clinical practice.

Ocular chronic graft-versus-host disease is one of the most bothersome common complications following allogeneic hematopoietic stem cell transplantation. The National Institutes of Health Chronic Graft-versus-Host Disease Consensus Project provided expert recommendations for diagnosis and organ severity scoring. However, ocular chronic graft-versus-host disease can be diagnosed only after examination by an ophthalmologist. There are no currently accepted definitions of ocular chronic graft-versus-host disease activity. The goal of this study was to identify predictive models of diagnosis and activity for use in clinical transplant practice. A total of 210 patients with moderate or severe chronic graft-versus-host disease were enrolled in a prospective, cross-sectional, observational study (clinicaltrials.gov identifier: 00092235). Experienced ophthalmologists determined presence of ocular chronic graft-versus-host disease, diagnosis and activity. Measures gathered by the transplant clinician included Schirmer's tear test and National Institutes of Health 0-3 Eye Score. Patient-reported outcome measures were the ocular subscale of the Lee Chronic Graft-versus-Host Disease Symptom Scale and Chief Eye Symptom Intensity Score. Altogether, 157 (75%) patients were diagnosed with ocular chronic graft-versus-host disease; 133 of 157 patients (85%) had active disease. In a multivariable model, the National Institutes of Health Eye Score (P<0.0001) and Schirmer's tear test (P<0.0001) were independent predictors of ocular chronic graft-versus-host disease (sensitivity 93.0%, specificity 92.2%). The Lee ocular subscale was the strongest predictor of active ocular chronic graft-versus-host disease (P<0.0001) (sensitivity 68.5%, specificity 82.6%). Ophthalmology specialist measures that were most strongly predictive of diagnosis in a multivariate model were Oxford grand total staining (P<0.0001) and meibomian score (P=0.027). These results support the use of selected transplant clinician- and patient-reported outcome measures for ocular chronic graft-versus-host disease screening when providing care to allogeneic hematopoietic stem cell transplantation survivors with moderate to severe chronic graft-versus-host disease. Prospective studies are needed to determine if the Lee ocular subscale demonstrates adequate responsiveness as a disease activity outcome measure.

Autologous transplantation for Philadelphia chromosome-positive acute lymphoblastic leukemia achieves outcomes similar to allogeneic transplantation: results of CALGB Study 10001 (Alliance).

Allogeneic stem cell transplantation is the standard approach to Philadelphia chromosome positive acute lymphoblastic leukemia. We hypothesized that imatinib plus sequential chemotherapy will result in significant leukemia cell cytoreduction in patients with Philadelphia chromosome positive acute lymphoblastic leukemia, allowing collection of normal hematopoietic stem cells uncontaminated by residual BCR/ABL1(+) lymphoblasts and thus reduce the likelihood of relapse after autologous stem cell transplantation for patients under 60 years of age without sibling donors. We enrolled 58 patients; 19 underwent autologous and 15 underwent allogeneic stem cell transplantation on study. Imatinib plus sequential chemotherapy resulted in reverse-transcriptase polymerase chain reaction-negative stem cells in 9 patients and remained minimally positive in 4 (6 were not evaluable). Overall survival (median 6.0 years vs. not reached) and disease-free survival (median 3.5 vs. 4.1 years) were similar between those who underwent autologous and those who underwent allogeneic stem cell transplantation. We conclude that autologous stem cell transplantation represents a safe and effective alternative for allogeneic stem cell transplantation in Philadelphia chromosome positive acute lymphoblastic leukemia patients without sibling donors (clinicaltrials.gov identifier:00039377).

Three-Year Outcomes in Recipients of Mismatched Unrelated Bone Marrow Donor Transplants Using Post-Transplantation Cyclophosphamide: Follow-Up from a National Marrow Donor Program-Sponsored Prospective Clinical Trial.

The use of post-transplantation cyclophosphamide (PTCy) as graft-versus-host disease (GVHD) prophylaxis has resulted in reductions in GVHD and improved outcomes in allogeneic hematopoietic cell transplantation (HCT) using HLA-mismatched related donors. We report the 3-year outcomes of the first multicenter prospective clinical trial using PTCy in the setting of mismatched unrelated donor (MMUD) bone marrow HCT. The study enrolled 80 patients, treated with either myeloablative conditioning (MAC; n = 40) or reduced-intensity conditioning (RIC; n = 40), with the primary endpoint of 1-year overall survival (OS). The median follow-up for this study was 34 months (range, 12 to 46 months) in the RIC group and 36 months (range, 18 to 49 months) in the MAC group. Three-year OS and nonrelapse mortality were 70% and 15%, respectively, in the RIC group and 62% and 10% in the MAC group. No GVHD was reported after 1 year. The incidence of relapse was 29% in the RIC group and 51% in the MAC group. OS did not differ based on HLA match grade (63% in the 7/8 strata and 71% in the 4 to 6/8 strata). These encouraging outcomes, which were sustained for 3 years post-HCT, support the continued exploration of MMUD HCT using a PTCy platform. Important future areas to address include relapse reduction and furthering our understanding of optimal donor selection based on HLA and non-HLA factors.

Favorable outcomes in patients with high donor-derived T cell count after in vivo T cell-depleted reduced-intensity allogeneic stem cell transplantation.

Patients with hematologic malignancies were conditioned using a rabbit antithymocyte globulin-based reduced-intensity conditioning regimen for allogeneic stem cell transplantation. Donor-derived CD3(+) cell count (ddCD3), a product of CD3(+) cell chimerism and absolute CD3(+) cell count, when <110/µL at 8 weeks post-stem cell transplantation predicted a high risk of sustained mixed chimerism and relapse. Alternatively, patients with a higher ddCD3 developed graft-versus-host disease more frequently, and when partially chimeric, had higher rates of conversion to full donor chimerism after withdrawal of immunosuppression. Early data from our small cohort of patients indicate that ddCD3 at 8 weeks may be used to guide decisions regarding withdrawal of immunosuppression and administration of donor lymphocyte infusion in partially T cell-depleted reduced-intensity regimens.

Fludarabine-based conditioning for marrow transplantation from unrelated donors in severe aplastic anemia: early results of a cyclophosphamide dose deescalation study show life-threatening adverse events at predefined cyclophosphamide dose levels.

Excessive adverse events were encountered in a Phase I/II study of cyclophosphamide (CY) dose deescalation in a fludarabine-based conditioning regimen for bone marrow transplantation from unrelated donors in patients with severe aplastic anemia. All patients received fixed doses of antithymocyte globulin, fludarabine, and low-dose total body irradiation. The starting CY dose was 150 mg/kg, with deescalation to 100 mg/kg, 50 mg/kg, or 0 mg/kg. CY dose level 0 mg/kg was closed due to graft failure in 3 of 3 patients. CY dose level 150 mg/kg was closed due to excessive organ toxicity (n = 6) or viral pneumonia (n = 1), resulting in the death of 7 of 14 patients. CY dose levels 50 and 100 mg/kg remain open. Thus, CY at doses of 150 mg/kg in combination with total body irradiation (2 Gy), fludarabine (120 mg/m(2)), and antithymocyte globulin was associated with excessive organ toxicity.

Epigenetic induction of adaptive immune response in multiple myeloma: sequential azacitidine and lenalidomide generate cancer testis antigen-specific cellular immunity.

Patients with multiple myeloma (MM) undergoing high dose therapy and autologous stem cell transplantation (SCT) remain at risk for disease progression. Induction of the expression of highly immunogenic cancer testis antigens (CTA) in malignant plasma cells in MM patients may trigger a protective immune response following SCT. We initiated a phase II clinical trial of the DNA hypomethylating agent, azacitidine (Aza) administered sequentially with lenalidomide (Rev) in patients with MM. Three cycles of Aza and Rev were administered and autologous lymphocytes were collected following the 2nd and 3rd cycles of Aza-Rev and cryopreserved. Subsequent stem cell mobilization was followed by high-dose melphalan and SCT. Autologous lymphocyte infusion (ALI) was performed in the second month following transplantation. Fourteen patients have completed the investigational therapy; autologous lymphocytes were collected from all of the patients. Thirteen patients have successfully completed SCT and 11 have undergone ALI. Six patients tested have demonstrated CTA up-regulation in either unfractionated bone marrow (n = 4) or CD138+ cells (n = 2). CTA (CTAG1B)-specific T cell response has been observed in all three patients tested and persists following SCT. Epigenetic induction of an adaptive immune response to cancer testis antigens is safe and feasible in MM patients undergoing SCT.

National Marrow Donor Program-Sponsored Multicenter, Phase II Trial of HLA-Mismatched Unrelated Donor Bone Marrow Transplantation Using Post-Transplant Cyclophosphamide.

PURPOSE: Hematopoietic cell transplantation (HCT) is curative for hematologic disorders, but outcomes are historically inferior when using HLA-mismatched donors. Despite unrelated donor registries listing > 38 million volunteers, 25%-80% of US patients lack an HLA-matched unrelated donor, with significant disparity across ethnic groups. We hypothesized that HCT with a mismatched unrelated donor (MMUD) using post-transplant cyclophosphamide (PTCy), a novel strategy successful in overcoming genetic disparity using mismatched related donors, would be feasible and increase access to HCT. PATIENTS AND METHODS: We performed a prospective phase II study of MMUD bone marrow HCT with PTCy for patients with hematologic malignancies. The primary end point was 1-year overall survival (OS), hypothesized to be 65% or better. 80 patients enrolled at 11 US transplant centers (December 2016-March 2019). Following myeloablative or reduced-intensity conditioning-based HCT, patients received PTCy on days +3, +4, with sirolimus and mycophenolate mofetil starting on day +5. We compared outcomes to Center for International Blood and Marrow Transplant Research contemporary controls receiving PTCy. RESULTS: Notably, 48% of patients enrolled were ethnic minorities. 39% of pairs were matched for 4-6 out of 8 HLA alleles. The primary end point was met, with 1-year OS of 76% (90% CI, 67.3 to 83.3) in the entire cohort, and 72% and 79% in the myeloablative and reduced-intensity conditioning strata, respectively. Secondary end points related to engraftment and graft-versus-host-disease were reached. Multivariate analysis comparing the study group with other mismatched HCT controls found no significant differences in OS. CONCLUSION: Our prospective study demonstrates the feasibility and effectiveness of HCT with an MMUD in the setting of PTCy. Remarkably, nearly half of the study participants belonged to an ethnic minority population, suggesting this approach may significantly expand access to HCT.

Successful stem cell remobilization using plerixafor (mozobil) plus granulocyte colony-stimulating factor in patients with non-hodgkin lymphoma: results from the plerixafor NHL phase 3 study rescue protocol.

In a phase 3 multicenter, randomized, double-blinded, placebo-controlled study of 298 patients with non-Hodgkin lymphoma (NHL), granulocyte colony-stimulating factor (G-CSF) plus plerixafor increased the proportion of patients who mobilized >or=5 x 10(6) CD34(+) hematopoietic stem cells (HSCs)/kg compared with placebo plus G-CSF (P < .001). Patients in either study arm who failed mobilization (< 0.8 x 10(6) CD34(+) cells/kg in 2 collections or <2 x 10(6) CD34(+) cells/kg in 4 collections) were eligible to enter the opened-label rescue protocol. Following a 7-day minimum rest period, these patients received G-CSF (10 microg/kg/day) for 4 days, followed by daily plerixafor (0.24 mg/kg) plus G-CSF and apheresis for up to 4 days. Of the 68 patients failing initial mobilization (plerixafor, n = 11; placebo, n = 57), 62 patients (91%) entered the rescue procedure (plerixafor, n = 10; placebo, n = 52). Four of 10 patients (40%) from the plerixafor group and 33 of 52 (63%) from the placebo group mobilized sufficient CD34(+) cells (>or= 2 x 10(6) cells/kg) for transplantation from the rescue mobilization alone (P = .11). Engraftment of neutrophils (11 days) and platelets (20 days) was similar to that in patients who did not fail initial mobilization, and all patients had durable grafts at the 12-month follow-up. Common plerixafor-related adverse events (AEs) included mild gastrointestinal (GI) effects and injection site reactions. There were no drug-related serious AEs. These data support that plerixafor plus G-CSF can safely and effectively remobilize patients with NHL who have failed previous mobilization.

Maintenance azacitidine after myeloablative allogeneic hematopoietic cell transplantation for myeloid malignancies.

Allogeneic hematopoietic cell transplantation (HCT) is a curative option for patients with acute myeloid leukemia (AML) and myelodysplastic syndrome (MDS), but carries a high risk of relapse. This retrospective review evaluates the effectiveness of maintenance azacitidine in high-risk AML and MDS patients to reduce the probability of relapse. Twenty-five patients who received maintenance azacitidine were matched to historical controls in a two-to-one ratio based on diagnosis, donor type, conditioning regimen intensity, and age. Over 90% of patients received myeloablative conditioning. There was no difference in time to hematologic relapse, overall survival, or non-relapse mortality. Maintenance therapy was stopped early in 72% of patients due to graft-versus-host-disease, relapse, infection, and intolerance (13 of 25 patients received less than 4 cycles). There was a trend towards higher toxicity in the azacitidine group. The use of prophylactic azacitidine following myeloablative allogeneic HCT outside a clinical trial cannot be recommended at this time.

The influence of lymphoid reconstitution kinetics on clinical outcomes in allogeneic stem cell transplantation.

Lymphoid recovery following myeloablative stem cell transplantation (SCT) displays a logistic pattern of exponential growth followed by a plateau. Within this logistic framework, lymphoid recovery is characterized by the parameters R (slope of ascent), a (time of maximal rate of ascent) and K (plateau), the 'steady-state' lymphocyte count. A retrospective analysis of allogeneic SCT performed from 2008 to 2013 was undertaken to compare lymphoid recovery and clinical outcomes in 131 patients with acute myelogenous leukemia, acute lymphocytic leukemia, and myelodysplastic syndromes. Using Prism software, a logistic curve was successfully fit to the absolute lymphocyte count recovery in all patients. Patients were classified according to the magnitude and rate of lymphoid recovery; pattern A achieved an absolute lymphocyte counts (ALC) of >1000/µL by day 45, pattern B an ALC 500 < x < 1000/µL, and pattern C an ALC <500/µL. Pattern A was characterized by a higher mean K (p < .0001) compared with patterns B and C. Patients with patterns B and C were more likely to have mixed T cell chimerism at 90 d following SCT (p = .01). There was a trend towards improved survival (and relapse-free survival) in those with pattern A and B at 1 year compared to pattern C (p = .073). There was no difference in cGVHD (p = .42) or relapse (p = .45) between pattern types. Cytomegalovirus (CMV), aGVHD, and all relapse were heralded by deviation from logistic behavior. Pattern C patients were more likely to require donor lymphocyte infusion (DLI) (p = .017). Weaning of tacrolimus post-transplant was associated with a second, separate logistic expansion in some patients. This study demonstrated that lymphoid reconstitution follows a prototypical logistic recovery and that pattern observed correlates with T cell chimerism and need for DLI, and may influence survival.

A preliminary investigation into the action of anagrelide: thrombopoietin-c-Mpl receptor interactions.

OBJECTIVE: Many studies have validated the clinical efficacy of anagrelide to reduce platelet counts in thrombocythemic conditions. With the ability to support human megakaryopoiesis in vitro using thrombopoietin (TPO), specific investigation of changes in platelet levels can be carried out in human systems. Using CD34(+) stem cells and murine BaF3 cells transfected with the human or murine TPO receptor, c-Mpl (BaF3mpl), the effect of anagrelide on cell differentiation, proliferation, and signaling was examined in the presence of TPO. METHODS: Inhibition of TPO-mediated cell differentiation by anagrelide was evaluated by fluorescein-activated cell sorting analysis. Cell proliferation was monitored by 3-(4,5-dimethylthiazol-2-yl)-5-3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium (MTS) assays. Effect of anagrelide on TPO-mediated phosphotyrosine (pTyr) activity was examined by Western analysis of whole cell lysates. RESULTS: In the presence of TPO, anagrelide reduced the number of CD41(+) cells without a reduction in the total mononuclear cell number in a dose-dependent manner. Growth inhibition was also observed in BaF3 cells transfected with human c-Mpl. Anagrelide also reduced TPO-specific pTyr activity in a species-specific manner. No inhibitory effect could be demonstrated with interleukin-3 stimulation. CONCLUSION: Parallel dose-response effects were found in both CD41(+) number and TPO-specific pTyr activity. These results suggest that anagrelide reduces TPO-mediated megakaryocyte proliferation of CD34(+) cells through a mechanism that leads to inhibition of intracellular signaling events. Furthermore, data also suggest that it is a species-specific effect, with no inhibitory activity against the murine receptor. Because there is a less than 10% difference in DNA sequence homology between human and murine receptors, the difference in sequence-specific activity must reside in these amino acid differences.