Update on stem cell transplantation for acute leukemias

The treatment strategies for acute leukemia are undergoing very rapid change. Particularly for last 10 years, due to the rapid development of molecular targeted therapy and cell/gene therapies, the role of HSCT in the treatment scheme of acute leukemia has been changing. In the author's view, these recent changes should secure the role of HSCT in the comprehensive treatment scheme of acute leukemia. By appropriately combining the new agents with HSCT, therapy for acute leukemia is anticipated to become more effective. HSCT will provide the centerpiece for the treatment scheme, by setting up the "platform" for further interventions. Keeping these changes in mind, transplant physicians should now be exploring new areas of research such as interactions between these new agents and GVHD/GVL.

Efficacy of Pharmacokinetics-Directed Busulfan, Cyclophosphamide, and Etoposide Conditioning and Autologous Stem Cell Transplantation for Lymphoma: Comparison of a Multicenter Phase II Study and CIBMTR Outcomes

Busulfan, cyclophosphamide, and etoposide (BuCyE) is a commonly used conditioning regimen for autologous stem cell transplantation (ASCT). This multicenter, phase II study examined the safety and efficacy of BuCyE with individually adjusted busulfan based on preconditioning pharmacokinetics. The study initially enrolled Hodgkin lymphoma (HL) and non-Hodgkin lymphoma (NHL) patients ages 18 to 80 years but was amended due to high early treatment-related mortality (TRM) in patients > 65 years. BuCyE outcomes were compared with contemporaneous recipients of carmustine, etoposide, cytarabine, and melphalan (BEAM) from the Center for International Blood and Marrow Transplant Research. Two hundred seven subjects with HL (n = 66) or NHL (n = 141) were enrolled from 32 centers in North America, and 203 underwent ASCT. Day 100 TRM for all subjects (n = 203), patients > 65 years (n = 17), and patients ≤ 65 years (n = 186) were 4.5%, 23.5%, and 2.7%, respectively. The estimated rates of 2-year progression-free survival (PFS) were 33% for HL and 58%, 77%, and 43% for diffuse large B cell lymphoma (DLBCL; n = 63), mantle cell lymphoma (MCL; n = 29), and follicular lymphoma (FL; n = 23), respectively. The estimated rates of 2-year overall survival (OS) were 76% for HL and 65%, 89%, and 89% for DLBCL, MCL, and FL, respectively. In the matched analysis rates of 2-year TRM were 3.3% for BuCyE and 3.9% for BEAM, and there were no differences in outcomes for NHL. Patients with HL had lower rates of 2-year PFS with BuCyE, 33% (95% CI, 21% to 46%), than with BEAM, 59% (95% CI, 52% to 66%), with no differences in TRM or OS. BuCyE provided adequate disease control and safety in B cell NHL patients ≤ 65 years but produced worse PFS in HL patients when compared with BEAM.

Intravenous Busulfan-Based Myeloablative Conditioning Regimens Prior to Hematopoietic Cell Transplantation for Hematologic Malignancies

Busulfan (Bu)-containing regimens are commonly used in myeloablative conditioning regimens before allogeneic hematopoietic cell transplantation (HCT). Yet, there is considerable variability on how Bu is administered related to frequency (4 times a day [Q6] or daily [Q24]) and combinations with other chemotherapeutic agents (cyclophosphamide [Cy] or fludarabine [Flu]). We performed a prospective cohort study of recipients of Bu-based conditioning according to contemporary practices to compare different approaches (BuCy Q6, n = 495; BuFlu Q24, n = 331; BuCy Q24, n = 96; BuFlu Q6, n = 91) in patients with myeloid malignancies between 2009 and 2011. BuFlu Q24 recipients were more likely to be older and tended to have worse performance status and a higher comorbid burden. The cumulative incidences of hepatic veno-occlusive disease (P = .40), idiopathic pneumonia (P = .50), and seizures (P = .50) did not differ across groups. One-year HCT-related mortality ranged from 12% to 16% (P = .80), 3-year relapse incidence ranged from 32% to 36% (P = .80), and 3-year overall survival ranged from 51% to 58% (P = .20) across groups. This study demonstrates that HCT conditioning regimens using i.v. Bu Q6 or Q24 alone or in combination with Cy or Flu have similar outcomes in the myeloablative setting for treatment of myeloid malignancies.

Proceedings from the Second Haploidentical Stem Cell Transplantation Symposium-Haplo2014, San Francisco, California, December 4, 2014

Significant progress has been made over the past decade in haploidentical transplantation, with the development of novel methods to control intense alloreactive reactions generated in the major HLA-mismatched setting. Application of post-transplantation cyclophosphamide has gained worldwide acceptance as an effective and low-cost way to perform this type of transplantation, with outcomes now similar to those from HLA-matched unrelated donors. These advances have resulted in improved treatment-related mortality, whereas disease relapse has emerged as the most common cause of treatment failure. In addition, improvements in immunologic reconstitution after transplantation are much needed, not only in haploidentical transplantation but in all forms of stem cell transplantation. This symposium has focused on some of the most promising methods to control alloreactivity in this form of transplantation and application of cellular therapy to prevent disease relapse after transplantation, as well as understanding immunologic reconstitution and foreseeable approaches to improve immune recovery after transplantation.

Phase 3 trial of defibrotide for the treatment of severe veno-occlusive disease and multi-organ failure

Hepatic veno-occlusive disease (VOD), also called sinusoidal obstruction syndrome (SOS), is a potentially life-threatening complication of hematopoietic stem cell transplantation (HSCT). Untreated hepatic VOD/SOS with multi-organ failure (MOF) is associated with >80% mortality. Defibrotide has shown promising efficacy treating hepatic VOD/SOS with MOF in phase 2 studies. This phase 3 study investigated safety and efficacy of defibrotide in patients with established hepatic VOD/SOS and advanced MOF. Patients (n = 102) given defibrotide 25 mg/kg per day were compared with 32 historical controls identified out of 6867 medical charts of HSCT patients by blinded independent reviewers. Baseline characteristics between groups were well balanced. The primary endpoint was survival at day +100 post-HSCT; observed rates equaled 38.2% in the defibrotide group and 25% in the controls (23% estimated difference; 95.1% confidence interval [CI], 5.2-40.8;P= .0109, using a propensity-adjusted analysis). Observed day +100 complete response (CR) rates equaled 25.5% for defibrotide and 12.5% for controls (19% difference using similar methodology; 95.1% CI, 3.5-34.6;P= .0160). Defibrotide was generally well tolerated with manageable toxicity. Related adverse events (AEs) included hemorrhage or hypotension; incidence of common hemorrhagic AEs (including pulmonary alveolar [11.8% and 15.6%] and gastrointestinal bleeding [7.8% and 9.4%]) was similar between the defibrotide and control groups, respectively. Defibrotide was associated with significant improvement in day +100 survival and CR rate. The historical-control methodology offers a novel, meaningful approach for phase 3 evaluation of orphan diseases associated with high mortality. This trial was registered at www.clinicaltrials.gov as #.

The Notch Ligand DLL4 Defines a Capability of Human Dendritic Cells in Regulating Th1 and Th17 Differentiation

Notch signaling regulates multiple helper CD4(+) T cell programs. We have recently demonstrated that dendritic cells (DCs) expressing the Notch ligand DLL4 are critical for eliciting alloreactive T cell responses and induction of graft-versus-host disease in mice. However, the human counterpart of murine DLL4(+) DCs has yet to be examined. We report the identification of human DLL4(+) DCs and their critical role in regulating Th1 and Th17 differentiation. CD1c(+) DCs and plasmacytoid DCs (pDCs) from the peripheral blood (PB) of healthy donors did not express DLL4. In contrast, patients undergoing allogeneic hematopoietic stem cell transplantation had a 16-fold more DLL4(+)CD1c(+) DCs than healthy donors. Upon activation of TLR signaling, healthy donor-derived CD1c(+) DCs dramatically upregulated DLL4, as did pDCs to a lesser extent. Activated DLL4(+) DCs were better able to promote Th1 and Th17 differentiation than unstimulated PB DCs. Blocking DLL4 using a neutralizing Ab decreased Notch signaling in T cells stimulated with DLL4(+) DCs, and it reduced the generation of Th1 and Th17 cells. Both NF-κB and STAT3 were crucial for inducing DLL4 in human DCs. Interestingly, STAT3 directly activated DLL4 transcription and inhibiting STAT3 alone was sufficient to reduce DLL4 in activated PB DCs. Thus, DLL4 is a unique functional molecule of human circulating DCs critical for directing Th1 and Th17 differentiation. These findings identify a pathway for therapeutic intervention for inflammatory disorders in humans, such as graft-versus-host disease after allogeneic hematopoietic stem cell transplantation, autoimmunity, and tumor immunity.

Reducing Treatment-Related Mortality Did Not Improve Outcomes of Allogeneic Myeloablative Hematopoietic Cell Transplantation for High-Risk Multiple Myeloma: A University of Michigan Prospective Series

Despite the ongoing advent of more effective immunomodulators and proteasome inhibitors, multiple myeloma (MM) remains incurable and no effective therapy is available for advanced aggressive disease. Although allogeneic (Allo) hematopoietic cell transplantation (HCT) has a curative potential, the outcomes remain poor because of high treatment-related mortality (TRM), mostly due to regimen-related toxicities and graft-versus-host disease (GVHD) in case of myeloablative conditionings, high relapse rate in case of reduced-intensity or nonmyeloablative regimens, and possibly other unknown MM-specific issues. In an attempt to improve TRM, without compromising conditioning intensity, we prospectively explored the feasibility and efficacy of a myeloablative but reduced-toxicity conditioning regimen, consisting of fludarabine and busulfan (FluBu4; fludarabine 40 mg/m(2)/day and busulfan 3.2 mg/kg/day i.v. × 4 days) in 22 patients with high-risk or advanced refractory MM. The majority (14 of 22, 64%) had prior autologous HCT. The median HCT-specific comorbidity index score was 3 (range, 0 to 6), with 46% having a Karnofsky performance score < 80%. Ten patients had unrelated donors, 3 of whom were 7/8 HLA-loci matched. GVHD prophylaxis was tacrolimus and methotrexate in 20 (91%). Most patients had active MM at transplantation, with a partial response in 12 of 22 (46%) and stable disease in 1 of 22 (4.5%). All 22 patients tolerated the FluBu4 conditioning well, without early toxic deaths or graft failure. Common regimen-related toxicities included mild to moderate mucositis (18 of 22, 82%) and mild transient liver function abnormality (9 of 22, 41%). There were no grade 4 toxicities but grade 3 mucositis occurred in 7 of 22 patients (32%). The cumulative incidence of severe, grades III and IV acute GVHD at day 180 was 23% (95% confidence interval [CI], 10% to 47%) and that of chronic GVHD was 68% (95% CI, 46% to 88%). The cumulative incidences of TRM at 100 days, 1 year, and 3 years were 9% (95% CI, 2% to 33%), 19% (95% CI, 7% to 44%), and 29% (95% CI, 13% to 55%), respectively. Two TRMs were due to idiopathic pneumonia syndrome and 1 was due to cirrhosis. They all had decreased pre-HCT corresponding organ function, with HCT-specific comorbidity index scores of > 3. With a median follow-up of 58.7 (range, 39 to 82) months, the cumulative incidences of relapse at 1 and 3 years were 37% (95% CI, 20% to 61%) and 50% (95% CI, 29% to 75%); those for 1-year and 3-year overall survival (OS) were 58% (95% CI, 40% to 83%) and 29% (95% CI, 15% to 57%), respectively, and those for the 1-year and 3-year progression-free survivals (PFS) were 40% (95% CI, 23% to 67%) and 15% (95% CI, 5% to 42%), respectively. In summary, the use of the myeloablative FluBu4 conditioning Allo-HCT for high-risk MM resulted in decreased TRM, compared with that of Allo-HCT using conventional myeloablative regimens; however, the relapse rate was high, including in those developing moderate-to-severe chronic GVHD. This suggested a less robust graft-versus-myeloma effect against high-risk MM, thus resulting in poor PFS and OS. Nonetheless, the FluBu4 regimen may be used as a lower-TRM platform to combine with other strategies, eg, addition of an MM-targeted agent and/or maintenance therapy with these agents, to decrease relapse or progression in patients with high-risk MM.

Seatbelts in CAR therapy: How Safe Are CARS?

T-cells genetically redirected with a chimeric antigen receptor (CAR) to recognize tumor antigens and kill tumor cells have been infused in several phase 1 clinical trials with success. Due to safety concerns related to on-target/off-tumor effects or cytokine release syndrome, however, strategies to prevent or abate serious adverse events are required. Pharmacologic therapies; suicide genes; or novel strategies to limit the cytotoxic effect only to malignant cells are under active investigations. In this review, we summarize results and toxicities of investigations employing CAR redirected T-cells, with a focus on published strategies to grant safety of this promising cellular application.

Allogeneic transplantation with myeloablative FluBu4 conditioning improves survival compared to reduced intensity FluBu2 conditioning for acute myeloid leukemia in remission

The optimal intensity of conditioning for allogeneic hematopoietic stem cell transplantation (HCT) in acute myeloid leukemia (AML) remains undefined. Traditionally, myeloablative conditioning regimens improve disease control, but at the risk of greater nonrelapse mortality. Because fludarabine with myeloablative doses of intravenous busulfan using pharmacokinetic monitoring has excellent tolerability, we reasoned that this regimen would limit relapse without substantially elevating toxicity when compared to reduced intensity conditioning. We retrospectively analyzed 148 consecutive AML patients in remission receiving T cell replete HCT conditioned with fludarabine and intravenous busulfan at doses defined as reduced (6.4 mg/kg; FluBu2, n = 63) or myeloablative (12.8 mg/kg; FluBu4, n = 85). Early and late nonrelapse mortality (NRM) was similar among FluBu4 and FluBu2 recipients, respectively (day + 100: 4 vs 0 %; 5 years: 19 vs 22 %; p = 0.54). NRM did not differ between FluBu4 and FluBu2 in patients >50 years of age (24 vs 22 %, p = 0.75). Relapse was lower in recipients of FluBu4 (5 years: 30 vs 49 %; p = 0.04), especially in patients with poor risk cytogenetics (22 vs 59 %; p = 0.02) and those >50 years of age (28 vs 51 %; p = 0.02). Overall survival favored FluBu4 recipients at 5 years (53 vs 34 %, p = 0.02), a finding confirmed in multivariate analysis (HR: 0.57; 95 % CI: 0.34-0.95; p = 0.03). These data suggest that myeloablative FluBu4 may provide equivalent NRM, reduced relapse, and improved survival compared to FluBu2, emphasizing the importance of busulfan dose in conditioning for AML.

Paradigm shifts in the management of poor-risk chronic lymphocytic leukemia

With the growing complexity of treatment options for chronic lymphocytic leukemia (CLL) and variables that influence the underlying biology of this disease, providing allogeneic stem cell transplant (alloSCT) to appropriate candidates poses a challenge for transplant physicians. Novel small molecule inhibitors hold unprecedented promise for poor-risk subgroups, which will likely alter decision-making and referral patterns for transplant. In this review, we analyze what is known and may still remain true about indications for transplant based on outcomes reported in the literature recently and over the last decade.

Improved survival after transplantation of more donor plasmacytoid dendritic or naïve T cells from unrelated-donor marrow grafts: results from BMTCTN 0201

PURPOSE

To characterize relationships between specific immune cell subsets in bone marrow (BM) or granulocyte colony-stimulating factor-mobilized peripheral blood (PB) stem cells collected from unrelated donors and clinical outcomes of patients undergoing transplantation in BMTCTN 0201.

PATIENTS AND METHODS

Fresh aliquots of 161 BM and 147 PB stem-cell allografts from North American donors randomly assigned to donate BM or PB stem cells and numbers of transplanted cells were correlated with overall survival (OS), relapse, and graft-versus-host disease (GvHD).

RESULTS

Patients with evaluable grafts were similar to all BMTCTN 0201 patients. The numbers of plasmacytoid dendritic cells (pDCs) and naïve T cells (Tns) in BM allografts were independently associated with OS in multivariable analyses including recipient and donor characteristics, such as human leukocyte antigen mismatch, age, and use of antithymocyte globulin. BM recipients of > median number of pDCs, naïve CD8(+) T cells (CD8Tns), or naïve CD4(+) T cells (CD4Tns) had better 3-year OS (pDCs, 56% v 35%; P = .025; CD8Tns, 56% v 37%; P = .012; CD4Tns, 55% v 37%; P = .009). Transplantation of more BM Tns was associated with less grade 3 to 4 acute GvHD but similar rates of relapse. Transplantation of more BM pDCs was associated with fewer deaths resulting from GvHD or from graft rejection. Analysis of PB grafts did not identify a donor cell subset significantly associated with OS, relapse, or GvHD.

CONCLUSION

Donor immune cells in BM but not PB stem-cell grafts were associated with survival after unrelated-donor allogeneic hematopoietic stem-cell transplantation. The biologic activity of donor immune cells in allogeneic transplantation varied between graft sources. Donor grafts with more BM-derived Tns and pDCs favorably regulated post-transplantation immunity in allogeneic hematopoietic stem-cell transplantation.

Delta-like ligand 4 identifies a previously uncharacterized population of inflammatory dendritic cells that plays important roles in eliciting allogeneic T cell responses in mice

Graft-versus-host disease (GVHD) reflects an exaggerated inflammatory allogeneic T cell response in hosts receiving allogeneic hematopoietic stem cell transplantation (HSCT). Inhibition of pan-Notch receptor signaling in donor T cells causes reduction of GVHD. However, which Notch ligand(s) in what APCs is important for priming graft-versus-host reaction remains unknown. We demonstrate that δ-like ligand-4 (Dll4) and Dll4-positive (Dll4(high)) inflammatory dendritic cells (i-DCs) play important roles in eliciting allogeneic T cell responses. Host-type Dll4(high) i-DCs occurred in the spleen and intestine of HSCT mice during GVHD induction phase. These Dll4(high) i-DCs were CD11c(+)B220(+)PDCA-1(+), resembling plasmacytoid dentritic cells (pDCs) of naive mice. However, as compared with unstimulated pDCs, Dll4(high) i-DCs expressed higher levels of costimulatory molecules, Notch ligands Jagged1 and Jagged2, and CD11b, and produced more Ifnb and Il23 but less Il12. In contrast, Dll4-negative (Dll4(low)) i-DCs were CD11c(+)B220(-)PDCA-1(-), and had low levels of Jagged1. In vitro assays showed that Dll4(high) i-DCs induced significantly more IFN-γ- and IL-17-producing effector T cells (3- and 10-fold, respectively) than Dll4(low) i-DCs. This effect could be blocked by anti-Dll4 Ab. In vivo administration of Dll4 Ab reduced donor-alloreactive effector T cells producing IFN-γ and IL-17 in GVHD target organs, leading to reduction of GVHD and improved survival of mice after allogeneic HSCT. Our findings indicate that Dll4(high) i-DCs represent a previously uncharacterized i-DC population distinctive from steady state DCs and Dll4(low) i-DCs. Furthermore, Dll4 and Dll4(high) i-DCs may be beneficial targets for modulating allogeneic T cell responses, and could facilitate the discovery of human counterparts of mouse Dll4(high) i-DCs.

Gastric antral vascular ectasia and its clinical correlates in patients with early diffuse systemic sclerosis in the SCOT trial

OBJECTIVE

To describe the prevalence and clinical correlates of endoscopic gastric antral vascular ectasia (GAVE; "watermelon stomach") in early diffuse systemic sclerosis (SSc).

METHODS

Subjects with early, diffuse SSc and evidence of specific internal organ involvement were considered for the Scleroderma: Cyclophosphamide Or Transplant (SCOT) trial. In the screening procedures, all patients underwent upper gastrointestinal endoscopy. Patients were then categorized into those with or without endoscopic evidence of GAVE. Demographic data, clinical disease characteristics, and autoantibody data were compared using Pearson chi-square or Student t tests.

RESULTS

Twenty-three of 103 (22.3%) individuals were found to have GAVE on endoscopy. Although not statistically significant, anti-topoisomerase I (anti-Scl70) was detected less frequently among those with GAVE (18.8% vs 44.7%; p = 0.071). Similarly, anti-RNP antibodies (anti-U1 RNP) showed a trend to a negative association with GAVE (0 vs 18.4%; p = 0.066). There was no association between anti-RNA polymerase III and GAVE. Patients with GAVE had significantly more erythema or vascular ectasias in other parts of the stomach (26.1% vs 5.0%; p = 0.003).

CONCLUSION

Endoscopic GAVE was present on screening in almost one-fourth of these highly selected patients with early and severe diffuse SSc. While anti-Scl70 and anti-U1 RNP trended toward a negative association with GAVE, there was no correlation between anti-RNA Pol III and GAVE. Patients with GAVE had a higher frequency of other gastric vascular ectasias outside the antrum, suggesting that GAVE may represent part of the spectrum of the vasculopathy in SSc.

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.).