Reduced-intensity conditioned allogeneic SCT in adults with AML

Leukemia circulation kinetics revealed through blood exchange method

Leukemias and their bone marrow microenvironments undergo dynamic changes over the course of disease. However, little is known about the circulation kinetics of leukemia cells, nor the impact of specific factors on the clearance of circulating leukemia cells (CLCs) from the blood. To gain a basic understanding of CLC dynamics over the course of disease progression and therapeutic response, we apply a blood exchange method to mouse models of acute leukemia. We find that CLCs circulate in the blood for 1-2 orders of magnitude longer than solid tumor circulating tumor cells. We further observe that: (i) leukemia presence in the marrow can limit the clearance of CLCs in a model of acute lymphocytic leukemia (ALL), and (ii) CLCs in a model of relapsed acute myeloid leukemia (AML) can clear faster than their untreated counterparts. Our approach can also directly quantify the impact of microenvironmental factors on CLC clearance properties. For example, data from two leukemia models suggest that E-selectin, a vascular adhesion molecule, alters CLC clearance. Our research highlights that clearance rates of CLCs can vary in response to tumor and treatment status and provides a strategy for identifying basic processes and factors that govern the kinetics of circulating cells.

Novel risk assessment for the intensity of conditioning regimen in older patients

Reduced-intensity conditioning (RIC) regimens have long-term outcomes that are generally comparable with those of myeloablative conditioning (MAC) because of a lower risk of nonrelapse mortality (NRM) but a higher risk of relapse. However, it is unclear how we should select the conditioning intensity in individual cases. We propose the risk assessment for the intensity of conditioning regimen in elderly patients (RICE) score. We retrospectively analyzed 6147 recipients aged 50 to 69 years using a Japanese registry database. Based on the interaction analyses, advanced age (≥60 years), hematopoietic cell transplantation-specific comorbidity index (≥2), and umbilical cord blood were used to design a scoring system to predict the difference in an individual patient's risk of NRM between MAC and RIC: the RICE score, which is the sum of the 3 factors. Zero or 1 implies low RICE score and 2 or 3, high RICE score. In multivariate analyses, RIC was significantly associated with a decreased risk of NRM in patients with a high RICE score (training cohort: hazard ratio [HR], 0.73; 95% confidence interval [CI], 0.60-0.90; P = .003; validation cohort: HR, 0.57; 95% CI, 0.43-0.77; P < .001). In contrast, we found no significant differences in NRM between MAC and RIC in patients with a low RICE score (training cohort: HR, 0.99; 95% CI, 0.85-1.15; P = .860; validation cohort: HR, 0.81; 95% CI, 0.66-1.01; P = .061). In summary, a new and simple scoring system, the RICE score, appears to be useful for personalizing the conditioning intensity and could improve transplant outcomes in older patients.

Leukemia circulation kinetics revealed through blood exchange method

Leukemias and their bone marrow microenvironment are known to undergo dynamic changes over the course of disease. However, relatively little is known about the circulation kinetics of leukemia cells, nor the impact of specific factors on the clearance of circulating leukemia cells (CLCs) from the blood. To gain a basic understanding of leukemia cell dynamics over the course of disease progression and therapeutic response, we apply a blood exchange method to mouse models of acute leukemia. We find that CLCs circulate in the blood for 1-2 orders of magnitude longer than solid tumor circulating tumor cells. We further observe that: i) leukemia presence in the marrow can limit the clearance of CLCs in a model of acute lymphocytic leukemia (ALL), and ii) CLCs in a model of relapsed acute myeloid leukemia (AML) can clear faster than their untreated counterparts. Our approach can also directly quantify the impact of microenvironmental factors on CLC clearance properties. For example, data from two leukemia models suggest that E-selectin, a vascular adhesion molecule, alters CLC clearance. Our research highlights that clearance rates of CLCs can vary in response to tumor and treatment status and provides a strategy for identifying basic processes and factors that govern the kinetics of circulating cells.

Assessing patient attitudes toward genetic testing for hereditary hematologic malignancy

Since 2003, more than 15 genes have been identified to predispose to hereditary hematologic malignancy (HHM). Although the yield of germline analysis for leukemia appears like that of solid tumors, genetic referrals in adults with leukemia remain underperformed. We assessed leukemia patients' attitudes toward genetic testing and leukemia-related distress through a survey of 1093 patients diagnosed with acute or chronic leukemia, myelodysplastic syndrome, or aplastic anemia. Principal component analysis (PCA) was used to analyze patient attitudes. Distress was measured through the Impact of Event Scale-Revised (IES-R). Exactly 19.8% of eligible respondents completed the survey. The majority reported interest in (77%) or choosing to have (78%) genetic testing for HHM. Slightly over half identified worry about cost of genetic testing (58%) or health insurance coverage (61%) as possible barriers. PCA identified relevant themes of interest in genetic testing, impact on leukemia treatment, discrimination and confidentiality, psychosocial and familial impacts, and cost of testing. The majority reported low distress. Leukemia patients report high interest in genetic testing, few barriers, and relatively low distress.

Clinical and healthcare burden of disease associated with cytomegalovirus in allogeneic hematopoietic stem cell transplantation - A retrospective single-center study

BACKGROUND

CMV infection is a common complication in allogeneic hematopoietic stem cell transplantation (HSCT). We investigated the association of clinically significant CMV (CS-CMV) infection with clinical outcomes and healthcare resource utilization in allogeneic HSCT patients in Finland.

METHODS

This retrospective study included adult patients who received their first allogeneic HSCT between January 1, 2013, and December 31, 2018, at the Turku University Hospital. Data were collected from the hospital data lake. Clinical and healthcare outcomes were investigated at one year and mortality up to three years.

RESULTS

The study included 251 patients. CMV seroprevalence was 69.7%. CS-CMV infection occurred in 59.0% of the patients, and of those, 14.2% had ≥2 infections. The median time to CS-CMV infection was 34.5 days (Q₁ -Q₃ , 27.0-45.0). Recipient and donor seropositivity, and lymphoproliferative diseases were associated with higher, and HLA identical sibling donors with lower CS-CMV infection risk. CS-CMV infection was not associated with mortality in three years of follow-up. One hundred thirty-three (89.8%) and 75 (72.8%) patients with and without CS-CMV infection, respectively, were readmitted to the hospital. Patients with CS-CMV infection had more hospital readmissions (incidence rate ratio [IRR] 1.38, 95% confidence interval [CI] 1.10-1.73, p = .005) and patients with one CS-CMV infection (IRR 1.48, 95% CI 1.12-1.94, p = .005) or ≥2 infections had longer length of hospital stay (IRR 2.71, 95% CI 1.76-4.35, p < .001).

CONCLUSION

CMV seroprevalence is relatively high among Finnish allogeneic HSCT patients. CS-CMV infection was common and associated with a higher readmission rate and longer length of hospital stay.

Vedolizumab for acute gastrointestinal graft-versus-host disease: A systematic review and meta-analysis

OBJECTIVE

To determine the safety and efficacy of vedolizumab for the prophylaxis and treatment of gastrointestinal involvement of acute graft-versus-host disease (GVHD) (GI-aGVHD).

METHODS

Literature search within PubMed, EMBASE, Web of Science, and Cochrane Library for observational studies and clinical trials that evaluated the effect of vedolizumab on GI-aGVHD was done through 17 May 2022. A bivariate and random-effect meta-analysis derived the pooled observational percentages and pooled risk ratios (RRs) from baseline of primary endpoints including overall response, complete response, mortality, and adverse events.

RESULTS

There was a total of 122 participants in eight eligible studies, including one study on the prophylactic use of vedolizumab and seven studies on vedolizumab for the treatment of GI-aGVHD. Of seven studies that reported details on baseline grades of GI-aGVHD, a total of 47 patients (47.95%) were of stage 4, 31 patients (31.63%) were of stage 3, 10 patients (10.2%) were of stage 2, and 10 patients (10.2%) were of stage 1. The use of vedolizumab for the treatment of GI-aGVHD yielded a significantly improved objective response rate (ORR) at 14 days (pooled ORR = 60.53%, pooled RR = 14.14, 95% CI: 2.95-67.71), 28 days (pooled ORR = 50%, RR = 7.36, 95% CI = 2.14-25.37), and 12 months (pooled ORR = 76.92%, RR = 13.66, 95% CI = 3.5-53.35) from baseline. Likewise, the use of vedolizumab was followed by a significantly improved complete response (CR) at 12 months (pooled CR = 27.27%, RR = 5.50, 95% CI = 1.01-29.95), yet the CR at 14 days and 28 days did not reach statistical significance. Fifty-seven out of 87 (pooled overall survival, OS = 34.5%) and 46 out of 65 (pooled OS = 29.2%) patients expired at 6 and 12 months after the use of vedolizumab, respectively. Prophylactic use of vedolizumab was not associated with any specific type of reported adverse events, while patients with GI-aGVHD on vedolizumab presented with significantly increased risks of adverse events including infections (RR = 7.55) and impaired metabolism or nutritional complications (RR = 9.00). All analyses were of a low heterogeneity (all I-squares = 0%).

CONCLUSION

Vedolizumab was safe and effective for the prophylaxis and management of early grade GI-aGVHD. More clinical evidence is warranted to validate these findings.

SYSTEMATIC REVIEW REGISTRATION

https://www.crd.york.ac.uk/prospero/display_record.php?RecordID=345584, identifier CRD42022345584.

Anti-thymocyte globulin could potentially overcome an adverse effect of acute GVHD in matched-related PBSCT

BACKGROUND

Previous Japanese studies have shown that bone marrow transplantation (BMT) is associated with a better survival compared with peripheral blood stem cell transplantation (PBSCT) from matched related donors (MRDs). PBSCT recipients showed a higher incidence of severe graft-versus-host disease (GVHD) and non-relapse mortality (NRM) than BMT recipients. In recent years, the efficacy and safety of anti-thymocyte globulin (ATG) for PBSCT recipients has been reported from around the world.

OBJECTIVE

We aimed to compare BMT and PBSCT to identify current improvements and unmet needs among PBSCT recipients from MRDs. Moreover, we evaluated the impact of ATG administration on the outcomes for PBSCT recipients.

STUDY DESIGN

We retrospectively analyzed patients aged 16 years or older with acute leukemia, myelodysplastic syndrome, or chronic myeloid leukemia who received their first BMT or PBSCT from MRDs between 2009 and 2018 in Japan.

RESULTS

In total, 3599 transplantations were performed (BMT, 1218; PBSCT without ATG [PBSCT-ATG(-)], 2288; and PBSCT with ATG [PBSCT-ATG(+)], 93). The PBSCT-ATG(-) group had a higher NRM rate (hazard ratio [HR], 1.30; 95% confidence interval [CI], 1.08-1.57; p = 0.005) and lower overall survival (OS) rate (HR, 1.16; 95% CI, 1.04-1.30; p = 0.011) than the BMT group. Furthermore, the PBSCT-ATG(-) group had a higher incidence of grade III-IV, stage 2-4 gut, high-risk, and steroid-refractory acute GVHD than the BMT group. Acute GVHDs had a negative impact on NRM and OS rates. PBSCT-ATG(-) was also associated with a higher risk of chronic GVHD (HR: 1.89; 95% CI: 1.24-1.57; p < 0.001) and extensive chronic GVHD (HR: 1.44; 95% CI: 1.23-1.68; p < 0.001). The incidence of acute GVHD, chronic GVHD, and NRM and chronic GVHD-free relapse-free survival rates were comparable between the PBSCT-ATG(+) and BMT groups. The OS rate of patients with acute GVHD in the three donor groups was similar. Patients treated with reduced-intensity conditioning in the PBSCT-ATG(+) group had a higher relapse rate and lower OS rate than those in the BMT group.

CONCLUSIONS

In this Japanese cohort, standard calcineurin inhibitor-based GVHD prophylaxis was not sufficient for PBSCT recipients from MRDs because of the high incidence of severe acute GVHD. Moreover, prophylactic ATG was found to be a promising strategy against GVHD.

Outcomes of non-myeloablative allogeneic stem cell transplant in older patients with acute myeloid leukaemia in first remission

The benefits of non-myeloablative stem cell transplant in older patients with acute myeloid leukaemia are unclear. We compare the long-term outcomes of this regimen in those aged 55-65 years in first remission with a chemotherapy only cohort that achieved durable morphologic remission. Five-year overall survival was similar (32% vs 33%, P = 0.90), as was relapse-free survival (23% vs 20%, P = 0.37). There was a trend for decreased relapse that was balanced against increased non-relapse mortality with transplantation.

A concise review on factors influencing the hematopoietic stem cell transplantation main outcomes

BACKGROUND AND AIMS

As a curative procedure, hematopoietic stemcell transplantation (HSCT) is an approved treatment for many malignant orbenign hematologic and non-hematologic diseases. There are different outcomes of HSCT, as well as several parameters influencing these outcomes.

METHODS

We had searched scientific sources like Web ofScience and PubMed with a combination of keywords such as HSCT, engraftment,survival, outcomes, etc. Totally, 80 articles were included.

RESULTS

Here we have reviewed the effective factors onmain outcomes of HSCT including engraftment, survival, graft versus hostdisease, and Mobilization. Also, the prediction of hematological reconstitutionand some novel suggestions leading to better outcomes are reviewed.

CONCLUSION

The study will be applicable for improvedmanagement of autologous and allogeneic HSCT process to increase the procedureefficiency.

Circulatory miR-155 correlation with platelet and neutrophil recovery after autologous hematopoietic stem cell transplantation, a multivariate analysis

The involvement of microRNAs in the regulation of hematopoietic stem cells paves the way for their use in the management of autologous HSC transplantation (AHSCT). We aimed to evaluate the predictive value of circulatory microRNAs in extracellular vesicles (EVs) and plasma in platelet and neutrophil engraftment. Circulatory miR-125b, mir-126, miR-150, and miR-155 expression was assessed in isolated EVs and plasma in samples collected from AHSCT candidates. Multivariate analysis, COX models, and ROC assessment were performed to evaluate the predictive values of these microRNAs in platelet and neutrophil engraftment. miR-155 expression following conditioning with other clinical factors such as chemotherapy courses after diagnosis was the most significant predictors of platelet/neutrophil engraftment. A CD34⁺ cell count ≥ 3.5 × 10⁶/kg combined with miR-155 could be used as an engraftment predictor; however, in cases where the CD34⁺ cell count was < 3.5 × 10⁶/kg, this parameter lost its predictive value for engraftment and could be replaced by miR-155. The correlation between miR-155 and platelet/neutrophil engraftment even with lower numbers of CD34⁺ cells suggests the importance of this microRNA in the prediction of AHSCT outcome. Moreover, miR-155 could be utilized in therapeutic approaches to provide a better outcome for patients undergoing AHSCT.

Conditioning Intensity for Allogeneic Hematopoietic Cell Transplantation in Acute Myeloid Leukemia Patients with Poor-Prognosis Cytogenetics in First Complete Remission

The optimal intensity of conditioning regimen may be dependent on not only age and comorbidities but also disease characteristics and risk of relapse after allogeneic hematopoietic cell transplantation (HCT). We, therefore, analyzed the transplant outcomes of 840 adult patients with cytogenetically poor-risk acute myeloid leukemia (AML) in first complete remission (CR1) who received first allogeneic HCT with either myeloablative conditioning (MAC; n = 652) or reduced-intensity conditioning (RIC; n = 188) between 2006 and 2017. The median age at HCT was 50.5 years (range: 16 to 77 years). The multivariate analysis showed that patients receiving MAC had a significantly higher overall survival and lower leukemia-related mortality than those receiving RIC (P = .011 and P = .025, respectively). In the subgroup analysis, these results applied to patients aged 16 to 59 years, with HCT-comorbidity index scores ≥3, and with cytogenetic remission. Among MAC regimens, there was a trend for worse survival and nonrelapse mortality with the busulfan/fludarabine-based regimen compared with the total body irradiation (TBI) ≥8 Gy-based regimen (P = .082 and P = .062, respectively), whereas the busulfan/cyclophosphamide-based regimen and the fludarabine/melphalan-based regimen had similar outcomes with the TBI-based regimen. These data suggest that MAC is preferable to RIC for patients with cytogenetically poor-risk AML undergoing allogeneic HCT in CR1.

Donor-derived CAR-T Cells Serve as a Reduced-intensity Conditioning Regimen for Haploidentical Stem Cell Transplantation in Treatment of Relapsed/Refractory Acute Lymphoblastic Leukemia: Case Report and Review of the Literature

BACKGROUND

Reduced-intensity conditioning (RIC) regimens with low tolerable toxicities have been used for allogeneic hematopoietic stem cell transplantation (allo-HSCT). However, the relapse rate by this treatment is high. Treatment of CD19 B-cell relapsed/refractory acute lymphoblastic leukemia (r/r ALL) with allogeneic chimeric antigen receptor-modified T (CAR-T) cells is safe and effective. Use of allogeneic CD19-CAR-T cells as a part of RIC regimens for treatment of r/r ALL patients with haploidentical HSCT has not been investigated yet.

CASE PRESENTATION

A 12-year-old girl with CD19 r/r ALL underwent haploidentical HSCT. The patient received fludarabine, busulfan, and cyclophosphamide combined with haploidentical donor-derived CD19-CAR-T cells as the conditioning regimen. Granulocyte colony-stimulating factor-mobilized peripheral blood stem cells and granulocyte colony-stimulating factor-mobilized bone marrow were infused on days 1 and 2, respectively. Mycophenolate mofetil and tacrolimus were administered on day 1, antithymocyte globulin was administered on days +14 and +15, and a short course of methotrexate was administered to prevent graft-versus-host disease. The time of peak CAR-T cell proliferation was detected after the first infusion of CAR-T cells on day 7. The patient's engraftment and full-donor cell engraftment were established. The disease was in complete remission with minimal residual disease, which was undetectable by flow cytometry. No graft-versus-host disease or serious cytokine-release syndrome was found.

CONCLUSIONS

Treatment of r/r ALL with RIC including CD19-CAR-T cells followed by allo-HSCT was safe and effective, which suggest that CAR-T cells can be used as a part of RIC regimens in the treatment of r/r ALL in haploidentical HSCT.

The effect of melphalan dose and total body irradiation as reduced-intensity conditioning for acute lymphoblastic leukemia patients undergoing allogeneic stem cell transplantation

To evaluate the prognostic impact of melphalan dose and total body irradiation (TBI) in acute lymphoblastic leukemia (ALL) patients undergoing reduced-intensity allogeneic transplantation, we retrospectively compared the outcomes between higher-dose melphalan (120-140 mg/m²) with (HDM/TBI+, n = 118) or without 2-4 Gy TBI (HDM/TBI-, n = 152) and lower-dose melphalan (80-110 mg/m²) with TBI (LDM/TBI+, n = 237). At 3 years, the overall survival was 49.6% in the HDM/TBI+, 51.7% in the HDM/TBI-, and 47.3% in the LDM/TBI + groups (p = .67). The relapse rate and non-relapse mortality were comparable among the three groups. Multivariate analysis revealed that conditioning regimen was not associated with overall survival, relapse, and non-relapse mortality; however, central nervous system complication was less frequent with LDM/TBI + than with HDM/TBI+. Our findings suggest reduced-intensity conditioning with LDM/TBI + might be a reasonable option, especially in vulnerable ALL patients, with similar transplant outcomes to HDM with or without TBI.

Risk Stratification and Prognosticators of Acute Myeloid Leukemia with Myelodysplasia-Related Changes in Patients Undergoing Allogeneic Stem Cell Transplantation: A Retrospective Study of the Adult Acute Myeloid Leukemia Working Group of the Japan Society for Hematopoietic Cell Transplantation

Although the prognosis of acute myeloid leukemia with myelodysplasia-related changes (AML-MRC) is worse than that of AML not otherwise specified (AML-NOS), transplantation outcomes and prognosticators of AML-MRC patients undergoing allogeneic stem cell transplantation (allo-SCT) remain unclear. Transplantation outcomes of AML-MRC (n = 4091) were compared with those of AML-NOS (n = 3964) in patients who underwent allo-SCT between 2003 and 2016 using a nationwide registration database. The 3-year overall survival (OS; 35.5% versus 50.6%) was lower and the relapse (42.3% versus 32.1%) and nonrelapse mortality (26.3% versus 22.0%) rates were higher in the AML-MRC group than in the AML-NOS group. Based on the hierarchical AML-MRC classification, myelodysplasia as the sole criterion was associated with better OS compared with AML-NOS, whereas monosomal or complex karyotype and -5/del(5q) were associated with poor OS. A history of myelodysplastic syndrome and -7/del(7q) did not affect OS. Accordingly, AML-MRC with complex karyotype or -5/del(5q) and that with monosomal karyotype were classified as intermediate and high risks, respectively, whereas the remaining cases were classified as low risk. The 3-year OS rates were 50.7%, 36.9%, and 13.8% in the low-, intermediate-, and high-risk groups, respectively (P < .001). Risk classification, older age, and low performance status score were significant risk factors for survival in AML-MRC, independently of the disease status. Grades I to II acute graft-versus-host disease significantly reduced the 3-year relapse (24.7% versus 31.6%), leading to better survival (hazard ratio, .64). Our prognostic risk stratification can potentially aid in elucidating the diverse transplantation outcomes in patients with AML-MRC.

Prognostic impact of melphalan dose and total body irradiation use in patients with acute myeloid leukemia undergoing allogeneic stem cell transplantation with reduced-intensity conditioning

To evaluate the prognostic impact of melphalan dose and total body irradiation (TBI) use in acute myeloid leukemia patients undergoing reduced-intensity allogeneic transplantation, we retrospectively compared outcomes of patients receiving a higher-dose (120-140 mg/m², n = 379) or lower-dose melphalan (80-110 mg/m², n = 128) with or without TBI of ≤4 Gy. At 3 years, overall survival was 48.9% in the higher-dose group versus 40.3% in the lower-dose group (p = .013). This survival benefit was attributed to lower tumor-related mortality (23.9% vs. 31.7%; p = .049). Non-relapse mortality did not differ (24.8% vs. 23.5%, p = .59). The beneficial effect of a higher-dose melphalan was more evident when combined with TBI in younger patients, those not in complete remission, and those with good performance status. Our findings support the use of a higher-dose melphalan in combination with TBI for reduced-intensity conditioning in physically fit patients.

Extended CCR5 Blockade for Graft-versus-Host Disease Prophylaxis Improves Outcomes of Reduced-Intensity Unrelated Donor Hematopoietic Cell Transplantation: A Phase II Clinical Trial

Graft-versus-host disease (GVHD) remains the most common treatment-related complication after allogeneic hematopoietic cell transplantation (allo-HCT). Lymphocyte migration plays a critical role in the pathogenesis of GVHD. A previous phase I/II trial demonstrated that CCR5 blockade with maraviroc in the first 30days after allo-HCT resulted in a low incidence of early acute GVHD, primarily in visceral organs, but with no impact on late acute or chronic GVHD. We conducted a phase II trial to examine the efficacy of an extended course of maraviroc, administered through post-transplantation day +90 in addition to standard prophylaxis in 37 recipients of reduced-intensity-conditioned unrelated donor allo-HCT performed to treat hematologic malignancies. Extended maraviroc treatment was safe and feasible. The primary study endpoint, day +180 rate of grade II-IV acute GVHD, was 22 ± 7%, liver GVHD was not observed, and gut GVHD was uncommon. The day +180 rate of grade III-IV acute GVHD was 5 ± 4%. The 1-year rate of moderate to severe chronic GVHD was 8 ± 5% and that of disease relapse was 30 ± 8%. Overall survival at 1 year was 70 ± 8%. Compared with the previously studied short course of maraviroc, the extended course resulted in a significantly higher GVHD-free, relapse-free survival (adjusted hazard ratio [HR], .45; 95% confidence interval [CI], .25 to .82; P = .009) and overall survival (adjusted HR, .48; 95% CI, .24 to .96; P = .037). A combined analysis of both trials showed that high maraviroc trough concentrations on the day of hematopoietic cell infusion were associated with lower rates of acute GVHD. An extended course of maraviroc after reduced-intensity-conditioned unrelated donor allo-HCT is safe and effective in preventing acute and chronic GVHD and is associated with favorable survival.

Advancements in the management of medically less-fit and older adults with newly diagnosed acute myeloid leukemia

INTRODUCTION

Treating acute myeloid leukemia (AML) in older adults remains daunting. The unique biology often renders conventional chemotherapies less effective. Accurately predicting the toxicities of treatment is another unresolved challenge. Treatment planning thus requires a good knowledge of the current trial data and familiarity with clinical tools, including formal fitness and geriatric assessments. Both obstacles - disease biology and patient fitness - might be easier overcome with specific, AML cell-targeted agents rather than traditional cytotoxic chemotherapy. This may be the future of AML therapy, but it is not our current state.

AREAS COVERED

Herein, the authors appraise the data supporting a standard induction approach, including an outline of how to predict treatment-related mortality and a review of the most up-to-date methods of geriatric assessment. They also discuss treatment expectations with less-intense therapies and highlight novel agents in development. Finally, they provide a basic approach to choosing treatment intensity.

EXPERT OPINION

In an older and/or medically less-fit patient, treatment choice should begin with a thorough disease assessment, a formal evaluation of patient fitness and frailty. There should also be a clear communication with the patient and patient's family about the risks and anticipated benefits of either an intense or nonintense treatment approach.

Myelodysplastic Syndromes: Updates and Nuances

Myelodysplastic syndrome (MDS) is a heterogeneous, clonal stem cell disorder of the blood and marrow typically diagnosed based on the presence of persistent cytopenia(s), dysplastic cells, and genetic markers. Common issues that arise in the clinical management include difficulty confirming MDS diagnosis, lack of a standard approach with novel agents in MDS, and few prospective long-term, randomized controlled MDS clinical studies to guide allogeneic blood and marrow transplant. With the recent genetic characterization of MDS, certain aspects of these issues will be better addressed by integrating genetic data into clinical study design and clinical practice.

A Review of Myeloablative vs Reduced Intensity/Non-Myeloablative Regimens in Allogeneic Hematopoietic Stem Cell Transplantations

Allogeneic hematopoietic stem cell transplantation (Allo-HSCT) is a curative treatment option for both malignant and some benign hematological diseases. During the last decade, many of the newer high-dose regimens in different intensity have been developed specifically for patients with hematologic malignancies and solid tumors. Today there are three main approaches used prior to allogeneic transplantation: Myeloablative (MA), Reduced Intensity Conditioning (RIC) and Non-MA (NMA) regimens. MA regimens cause irreversible cytopenia and there is a requirement for stem cell support. Patients who receive NMA regimen have minimal cytopenia and this type of regimen can be given without stem cell support. RIC regimens do not fit the criteria of MA and NMA: the cytopenia is reversible and the stem cell support is necessary. NMA/RIC for Allo-HSCT has opened a new era for treating elderly patients and those with comorbidities. The RIC conditioning was used for 40% of all Allo-HSCT and this trend continue to increase. In this paper, we will review these regimens in the setting of especially allogeneic HSCT and our aim is to describe the history, features and impact of these conditioning regimens on specific diseases.

Nonmyeloablative Haploidentical Bone Marrow Transplantation with Post-Transplantation Cyclophosphamide for Pediatric and Young Adult Patients with High-Risk Hematologic Malignancies

Lower-intensity conditioning regimens for haploidentical blood or marrow transplantation (BMT) are safe and efficacious for adult patients with hematologic malignancies. We report data for pediatric/young adult patients with high-risk hematologic malignancies (n = 40) treated with nonmyeloablative haploidentical BMT with post-transplantation cyclophosphamide from 2003 to 2015. Patients received a preparative regimen of fludarabine, cyclophosphamide, and total body irradiation. Post-transplantation immunosuppression consisted of cyclophosphamide, mycophenolate mofetil, and tacrolimus. Donor engraftment occurred in 29 of 32 (91%), with median time to engraftment of neutrophils >500/µL of 16 days (range, 13 to 22) and for platelets >20,000/µL without transfusion of 18 days (range, 12 to 62). Cumulative incidences of acute graft-versus-host disease (GVHD) grades II to IV and grades III and IV at day 100 were 33% and 5%, respectively. The cumulative incidence of chronic GVHD was 23%, with 7% moderate-to-severe chronic GVHD, according to National Institutes of Health consensus criteria. Transplantation-related mortality (TRM) at 1 year was 13%. The cumulative incidence of relapse at 2 years was 52%. With a median follow-up of 20 months (range, 3 to 148), 1-year actuarial overall and event-free survival were 56% and 43%, respectively. Thus, we demonstrate excellent rates of engraftment, GVHD, and TRM in pediatric/young adult patients treated with this regimen. This approach is a widely available, safe, and feasible option for pediatric and young adult patients with high-risk hematologic malignancies, including those with a prior history of myeloablative BMT and/or those with comorbidities or organ dysfunction that preclude eligibility for myeloablative BMT.

Precision in donor selection: Identifying ideal stem-cell donors through their T cells

HLA-identical siblings have always been considered ideal donors for allogeneic hematopoietic stem-cell transplantation (allo-HSCT) in the treatment of hematologic cancers. Recent data suggest that we should rethink this paradigm. In "High Graft CD8+ Cell Dose Predicts Improved Survival and Enables Better Donor Selection in Allogeneic Stem-Cell Transplantation With Reduced-Intensity Conditioning," we identified a group of stem-cell donors whose grafts contain an optimal composition of T-cells, leading to a dramatic decrease in disease relapse risk and an improvement in overall survival following allo-HSCT. To demonstrate this, we analyzed the outcomes of 200 patients with hematologic malignancies who underwent allo-HSCT after reduced-intensity conditioning (RIC). The analysis focused on T-cell content of peripheral blood stem-cell grafts. We found that higher graft CD8+ T-cell dose (CD8hi), a trait found only in grafts collected from young donors, was associated with improved survival due to a reduction in the risk for cancer relapse without a significant increase in graft-versus-host disease (GVHD). Though not all young donors mobilized CD8hi grafts, we found that a low CD4:CD8 ratio in the peripheral blood could identify these ideal donors prior to transplant. The likelihood of finding CD8hi donors correlated inversely with age, and elderly RIC transplant recipients had a low chance of receiving an ideal graft from their similarly aged siblings. Here, we examine these findings and their implications on choosing donors according to age and relatedness. We also explore biological mechanisms that determine the CD4:CD8 ratio in healthy donors.

Hematopoietic Stem Cells in Regenerative Medicine: Astray or on the Path?

Hematopoietic stem cells (HSCs) are the best characterized adult stem cells and the only stem cell type in routine clinical use. The concept of stem cell transplantation laid the foundations for the development of novel cell therapies within, and even outside, the hematopoietic system. Here, we report on the history of hematopoietic cell transplantation (HCT) and of HSC isolation, we briefly summarize the capabilities of HSCs to reconstitute the entire hemato/lymphoid cell system, and we assess current indications for HCT. We aim to draw the lines between areas where HCT has been firmly established, areas where HCT can in the future be expected to be of clinical benefit using their regenerative functions, and areas where doubts persist. We further review clinical trials for diverse approaches that are based on HCT. Finally, we highlight the advent of genome editing in HSCs and critically view the use of HSCs in non-hematopoietic tissue regeneration.

Expanding transplant options to patients over 50 years. Improved outcome after reduced intensity conditioning mismatched-unrelated donor transplantation for patients with acute myeloid leukemia: a report from the Acute Leukemia Working Party of the EBMT

The outcome of patients undergoing HLA-matched unrelated donor allogeneic hematopoietic cell transplantation following reduced-intensity conditioning or myeloablative regimens is reported to be equivalent; however, it is not known if the intensity of the conditioning impacts outcomes after mismatched unrelated donor transplantation for acute myeloid leukemia. Eight hundred and eighty three patients receiving reduced-intensity conditioning were compared with 1041 myeloablative conditioning regimen recipients in the setting of mismatched unrelated donor transplantation. The donor graft was HLA-matched at 9/10 in 872 (83.8%) and at 8/10 in 169 (16.2%) myeloablative conditioning recipients, while in the reduced-intensity conditioning cohort, 754 (85.4%) and 129 (14.6%) were matched at 9/10 and 8/10 loci, respectively. Myeloablative conditioning regimen recipients were younger, 70% being <50 years of age compared to only 30% in the reduced-intensity conditioning group (P=0.0001). Significantly, more patients had secondary acute myeloid leukemia (P=0.04) and Karnofsky Performance Status score <90% (P=0.02) in the reduced-intensity conditioning group. Patients <50 and ≥50 years were analyzed separately. On multivariate analysis and after adjusting for differences between the two groups, reduced-intensity conditioning in patients age ≥50 years was associated with higher overall survival (HR 0.78; P=0.01), leukemia-free survival (HR 0.82; P=0.05), and decreased non-relapse mortality (HR 0.73; P=0.03). Relapse incidence (HR 0.91; P=0.51) and chronic graft-versus-host disease (HR 1.31; P=0.11) were, however, not significantly different. In patients <50 years old, there were no statistically significant differences in overall survival, leukemia-free survival, relapse incidence, non-relapse mortality, and chronic graft-versus-host-disease between the groups. Our study shows no significant outcome differences in patients younger than 50 years receiving reduced-intensity vs myeloablative conditioning regimens after mismatched unrelated donor transplantation. Furthermore, the data support the superiority of reduced-intensity conditioning regimens in older adults receiving transplants from mismatched unrelated donors.

Hematopoietic stem cell transplantation for patients with AML in first complete remission

Postremission therapy in patients with acute myeloid leukemia (AML) may consist of continuing chemotherapy or transplantation using either autologous or allogeneic stem cells. Patients with favorable subtypes of AML generally receive chemotherapeutic consolidation, although recent studies have also suggested favorable outcome after hematopoietic stem cell transplantation (HSCT). Although allogeneic HSCT (alloHSCT) is considered the preferred type of postremission therapy in poor- and very-poor-risk AML, the place of alloHSCT in intermediate-risk AML is being debated, and autologous HSCT is considered a valuable alternative that may be preferred in patients without minimal residual disease after induction chemotherapy. Here, we review postremission transplantation strategies using either autologous or allogeneic stem cells. Recent developments in the field of alternative donors, including cord blood and haploidentical donors, are highlighted, and we discuss reduced-intensity alloHSCT in older AML recipients who represent the predominant category of patients with AML who have a high risk of relapse in first remission.

Higher tacrolimus concentrations early after transplant reduce the risk of acute GvHD in reduced-intensity allogeneic stem cell transplantation

There is significant variability in the serum concentrations of tacrolimus attained early post transplant due to drug interactions and genomic variation. We evaluated whether tacrolimus concentrations early post transplant correlated with incidence of acute GvHD in 120 consecutive patients allografted with a uniform reduced-intensity conditioning regimen. All patients received standard prophylaxis with oral tacrolimus and IV methotrexate. The primary variable of interest was mean weekly tacrolimus concentrations in the initial 4 weeks post transplant. In multivariate analysis, week 1 tacrolimus concentration was an independent predictor of acute grade 2-4 GvHD (hazard ratio (HR), 0.90; 95% confidence interval (CI), 0.84-0.97; P<0.01). This association was driven by a lower risk of acute grade 2-4 GvHD in patients with week 1 tacrolimus concentrations >12 ng/mL (HR, 0.47; 95% CI, 0.25-0.88; P=0.02). Week 1 tacrolimus concentrations were not associated with chronic GvHD, relapse or overall survival. Lower tacrolimus concentrations at weeks 2, 3 and 4 were not associated with a higher incidence of GvHD. In summary, we found that higher tacrolimus concentrations during the first week after allografting with a reduced-intensity conditioning regimen were associated with significantly reduced risk of acute grade 2-4 GvHD without increasing risk of relapse.

Peripheral blood stem cell graft compared to bone marrow after reduced intensity conditioning regimens for acute leukemia: a report from the ALWP of the EBMT

Increasing numbers of patients are receiving reduced intensity conditioning regimen allogeneic hematopoietic stem cell transplantation. We hypothesized that the use of bone marrow graft might decrease the risk of graft-versus-host disease compared to peripheral blood after reduced intensity conditioning regimens without compromising graft-versus-leukemia effects. Patients who underwent reduced intensity conditioning regimen allogeneic hematopoietic stem cell transplantation from 2000 to 2012 for acute leukemia, and who were reported to the Acute Leukemia Working Party of the European Group for Blood and Marrow Transplantation were included in the study. Eight hundred and thirty-seven patients receiving bone marrow grafts were compared with 9011 peripheral blood transplant recipients after reduced intensity conditioning regimen. Median follow up of surviving patients was 27 months. Cumulative incidence of engraftment (neutrophil ≥0.5×10(9)/L at day 60) was lower in bone marrow recipients: 88% versus 95% (P<0.0001). Grade II to IV acute graft-versus-host disease was lower in bone marrow recipients: 19% versus 24% for peripheral blood (P=0.005). In multivariate analysis, after adjusting for differences between both groups, overall survival [Hazard Ratio (HR) 0.90; P=0.05] and leukemia-free survival (HR 0.88; P=0.01) were higher in patients transplanted with peripheral blood compared to bone marrow grafts. Furthermore, peripheral blood graft was also associated with decreased risk of relapse (HR 0.78; P=0.0001). There was no significant difference in non-relapse mortality between recipients of bone marrow and peripheral blood grafts, and chronic graft-versus-host disease was significantly higher after peripheral blood grafts (HR 1.38; P<0.0001). Despite the limitation of a retrospective registry-based study, we found that peripheral blood grafts after reduced intensity conditioning regimens had better overall and leukemia-free survival than bone marrow grafts. However, there is an increase in chronic graft-versus-host disease after peripheral blood grafts. Long-term follow up is needed to clarify whether chronic graft-versus-host disease might increase the risk of late morbidity and mortality.

Outcome of patients with distinct molecular genotypes and cytogenetically normal AML after allogeneic transplantation

In AML with normal cytogenetics, age, response to induction, and FLT3-ITD allow for an estimate of outcome after allogeneic HSCT in CR1. Neither variation of classical transplant techniques nor development of chronic GVHD outweighs the negative impact of FLT3-ITD.