Long-term outcome of reduced-intensity allogeneic hematopoietic SCT in patients with AML in CR

Comparison of Melphalan Dose in Patients with Myelodysplastic Syndrome Undergoing Allogeneic Transplantation with Reduced-Intensity Conditioning

The present study compared lower-dose melphalan (80 mg/m2, FM80) and higher-dose melphalan (140 mg/m2, FM140) when administering reduced-intensity conditioning with fludarabine in adult patients with myelodysplastic syndrome (MDS) undergoing allogeneic hematopoietic stem cell transplantation (allo-HSCT). We retrospectively analyzed nationwide registry data (2006 to 2019) and compared transplant outcomes between the 2 groups. Ninety-two patients (median age, 61 [interquartile range, 56 to 65] years) were assigned to the FM80 and FM140 groups by propensity score matching. The 3-year overall survival (OS) rate in the FM140 group (63.9%; 95% confidence interval [CI], 52.9% to 73.0%) was significantly higher than that in the FM80 group (54.2%; 95% CI, 37.1% to 52.1%) (P = .038). The FM140 group had a nonsignificantly (P = .095) lower 3-year cumulative incidence of relapse (15.5%; 95% CI, 8.9% to 23.8% versus 26.0%; 95% CI, 17.3% to 35.5%). The 3-year cumulative incidences of nonrelapse mortality were 22.3% (95% CI, 14.1% to 31.8%) and 23.7% (95% CI, 15.4% to 33.2%) in the FM80 and FM140 groups, respectively (P = .49). The beneficial effect of FM140 was more evident in patients with a poor cytogenetic risk. Our findings suggest the superiority of FM140 in patients with MDS undergoing allo-HSCT, especially in high-risk patients.

One-Year Survival and Prognosticators of Adults With Acute Leukemia at the Uganda Cancer Institute

PURPOSE

Acute leukemias are associated with substantial morbidity and mortality, particularly in the adult population. Despite an increasing burden of acute leukemia in developing countries, there are limited data on clinical outcomes and prognostic factors in this setting. In this study, we aimed to describe the clinical characteristics, survival, and prognostic factors of adults with acute leukemia at the Uganda Cancer Institute (UCI).

METHODS

A retrospective cohort study was conducted between January 2009 and December 2018, reviewing data of patients 18 years or older with a cytopathologic diagnosis of acute leukemia at UCI. Data were extracted on clinical and laboratory characteristics, response to treatment, and survival. Cox-proportional hazards regression and survival analysis were performed to determine survival rates and associated factors. P < .05 was considered statistically significant.

RESULTS

In total, 233 participants were enrolled. Most (59.2%. n = 138) participants were male, with a median age of 32 years (IQR, 23-48 years), and 136 (58.4%) had AML. Overall, the 1-year survival was 16.5%, with a median survival time of 47 (IQR, 21-219) days. Predictors of mortality were being a female (adjusted hazard ratio [aHR], 2.8; 95% CI, 1.2 to 6.7; P = .022) and overweight (aHR, 4.2; 95% CI, 1.3 to 13.4; P = .015). Among the patients who had AML, the predictors were poor Eastern Cooperative Oncology Group (ECOG; aHR, 3.1; 95% CI, 1.6 to 6.2; P = .001) and HIV (aHR, 6.0; 95% CI, 1.7 to 20.5; P = .004). Among the patients who had ALL, the predictors were poor ECOG (aHR, 2.3; 95% CI, 1.3 to 4.1; P = .006).

CONCLUSION

Patients with acute leukemia in Uganda have poor overall survival. Prospective studies are recommended to better understand causes of early mortality.

Systematic review of epigenetic targets in acute myeloid leukemia

Acute myeloid leukemia (AML), although genetically and morphologically distinct from other B and T cell ALL subtypes, has one of the most rapidly progressing course and worse outcomes. The current diagnostic classification of AML offers best curative intent, the outcomes are not usually those that are expected at the start of therapy. This is partly attributed to the complex mechanism of leukemogenesis and resistance to chemotherapy. The underlying genetic mechanism of resistance is as complex as is the disease etiopathogenesis. Recent advances in therapy of drug resistant AML highlight the role of epigenetic targets. New FDA approved targeted therapy has also provided some evidence at improving outcomes in clinical trials. This review provides a detailed review of FDA approved targets and ongoing clinical trials for targeting CRISPER, CAR-T and other intestinal modalities for approach to epigenetictargets. However, this group of epigenetic targeted therapy needs more validation to prove its clinical efficacy. A systematic review of all published research on these targets, investigational agents and FDA approved targeted therapy summarizes this evidence. It also takes us through a brief review of mechanism of action and targets for therapy.

Is there an optimal conditioning for older patients with AML receiving allogeneic hematopoietic cell transplantation?

The optimal conditioning regimen for older patients with acute myeloid leukemia (AML) remains unclear. In this study, we compared outcomes of AML patients >60 years of age undergoing allogenic hematopoietic stem cell transplantation at our institution. All 404 consecutively treated patients received 1 of the following conditioning regimens: (1) fludarabine+melphalan 100 mg/m2 (FM100), (2) fludarabine+melphalan 140 mg/m2 (FM140), (3) fludarabine+IV busulfan AUC ≥ 5000/d × 4 d (Bu≥20000), and (4) fludarabine+IV busulfan AUC 4000/d × 4 d (Bu16000). A propensity score analysis (PSA) was used to compare outcomes between these 4 groups. Among the 4 conditioning regimens, the FM100 group had a significantly better long-term survival with 5-year progression-free survival of 49% vs 30%, 34%, and 23%, respectively. The benefit of the FM100 regimen resulted primarily from the lower nonrelapse mortality associated with this regimen, an effect more pronounced in patients with lower performance status. The PSA confirmed that FM100 was associated with better posttransplantation survival, whereas no significant differences were seen between the other regimen groups. In summary, older patients with AML benefited from a reduced-intensity conditioning regimen with lower melphalan doses (FM100), which was associated with better survival, even though it was primarily used in patients who could not receive a more intense conditioning regimen.

A novel immature natural killer cell subpopulation predicts relapse after cord blood transplantation

Natural killer (NK) cells are highly heterogeneous, with vast phenotypic and functional diversity at the single-cell level. They are involved in the innate immune response against malignant and virus-infected cells. To understand the effect of NK diversity during immune recovery on the antitumor response after cord blood transplantation (CBT), we used high-dimensional mass cytometry and the metrics of NK cell diversity to study the NK cell repertoire in serial samples from 43 CBT recipients. A higher-diversity index based on single-cell combinatorial phenotypes was significantly associated with a lower risk for relapse after CBT (P = .005). Cytomegalovirus reactivation was a major factor in the development of a more diverse NK repertoire after CBT. Notably, we identified a group of patients whose CB-derived NK cells after transplantation possessed an immature phenotype (CB-NKim), characterized by poor effector function and a low diversity index. Frequencies of CB-NKim of 11.8% or higher during the early post-CBT recovery phase were highly predictive for relapse (area under the curve [AUC], 0.979), a finding that was validated in a second independent cohort of patients (n = 25; AUC, 0.977). Moreover, we showed that the maturation, diversity, and acquisition of effector function by CB-NKim early after CBT were driven by interleukin 15. Our data indicate that the diversity of the NK cell repertoire after CBT contributes importantly to the risk for subsequent relapse. We suggest that the use of diversity metrics and high-dimensional mass cytometry may be useful tools in predicting clinical outcomes and informing the design of therapeutic strategies to prevent relapse after CBT.

Pilot study using post-transplant cyclophosphamide (PTCy), tacrolimus and mycophenolate GVHD prophylaxis for older patients receiving 10/10 HLA-matched unrelated donor hematopoietic stem cell transplantation

Allogeneic SCT for older patients remains challenging at least in part due to graft-versus-host disease (GVHD) and higher non-relapse mortality (NRM). We conducted a prospective pilot study primarily for older patients undergoing matched unrelated donor (MUD) SCT using a reduced-intensity (RIC) melphalan-based conditioning and post-transplant cyclophosphamide (PTCy)-based GVHD prophylaxis with tacrolimus and mycophenolate mofetil. Twenty-two patients (median age 64, IQR 58, 66) underwent RIC MUD SCT for high-risk hematological malignancies including AML/MDS (73%), CML/MPD (18%), and other (10%). Two (9%) patients had early death; the rest (100%) engrafted. After a median follow-up of 17 months, 11 patients were alive and disease-free with an estimated 2-year progression-free (PFS) and overall (OS) survival of 48%. The cumulative incidences of grades 2-4 and 3-4 acute GVHD (aGVHD) at day + 100 and 2-years were 32 and 4%, and 59 and 24%, respectively. No cases of chronic GVHD (cGVHD) were noted. However, late acute GVHD was observed in 6 (27%) patients. In conclusion, RIC MUD SCT with melphalan-based conditioning and PTCy-based GVHD-based prophylaxis for older patients appears effective in controlling relapse. While cGVHD was not seen and early aGVHD appears controllable, a significant proportion developed late aGVHD responsible for higher NRM seen in these patients.

Haploidentical Transplantation for Older Patients with Acute Myeloid Leukemia and Myelodysplastic Syndrome

Allogeneic stem cell transplantation with HLA-matched donors is increasingly used for older patients with acute myeloid leukemia (AML) and myelodysplastic syndrome (MDS). It remains unclear if haploidentical stem cell transplantation (haploSCT) is a suitable option for older patients with this disease. We analyzed 43 patients with AML/MDS (median age, 61 years) who underwent a haploSCT at our institution. All patients received a fludarabine-melphalan-based reduced-intensity conditioning regimen and post-transplant cyclophosphamide-based graft-versus-host disease (GVHD) prophylaxis. Except for 1 patient who had early death, the remaining 42 patients (98%) engrafted donor cells. The cumulative incidences of grades II to IV and III to IV acute GVHD at 6 months were 35% and 5%, respectively, and chronic GVHD at 2 years was 9%. After a median follow-up of 19 months, 2-year overall survival, progression-free survival (PFS), and relapse incidence were 42%, 42%, and 24%, respectively. Best PFS (74% at 2 years) was seen in patients with intermediate-/good-risk cytogenetics, in first or second remission (hazard ratio, .4; P = .05), and with a younger donor (≤40 years; hazard ratio, .2; P = .01). In conclusion, these data suggest that haploidentical transplantation is safe and effective for older AML/MDS patients. Disease status, cytogenetics, and younger donor age are predictors for improved survival in older patients receiving a haploidentical transplant.

A Chemotherapy-Only Regimen of Busulfan, Melphalan, and Fludarabine, and Rabbit Antithymocyte Globulin Followed by Allogeneic T-Cell Depleted Hematopoietic Stem Cell Transplantations for the Treatment of Myeloid Malignancies

We sought to develop a myeloablative chemotherapeutic regimen to secure consistent engraftment of T-cell depleted (TCD) hematopoietic stem cell transplantations (HSCT) without the need for total body irradiation, thereby reducing toxicity while maintaining low rates of graft-versus-host disease (GVHD) and without increasing relapse. We investigated the myeloablative combination of busulfan (Bu) and melphalan (Mel), with the immunosuppressive agents fludarabine (Flu) and rabbit antithymocyte globulin (r-ATG) as cytoreduction before a TCD HSCT. No post-transplantation immunosuppression was administered. Between April 2001 and May 2008, 102 patients (median age, 55 years) with a diagnosis of primary or secondary myelodysplastic syndrome (MDS) or acute myeloid leukemia (AML) underwent cytoreduction with Bu/Mel/Flu, followed by TCD grafts. TCD was accomplished by CD34⁺-selection followed by E-rosette depletion for peripheral blood stem cell grafts and, for bone marrow grafts, by soybean agglutination followed by E-rosette depletion. Donors included matched and mismatched, related and unrelated donors. Risk stratification was by American Society for Blood and Marrow Transplantation risk categorization for patients with primary disease. For patients with secondary/treatment-related MDS/AML, those in complete remission (CR) 1 or with refractory anemia were classified as intermediate risk, and all other patients were considered high risk. Neutrophil engraftment occurred at a median of 11 days in 100 of 101 evaluable patients. The cumulative incidences of grades II to IV acute and chronic GVHD at 1 year were 8.8% and 5.9%, respectively. Overall- and disease-free survival (DFS) rates at 5 years were 50.0% and 46.1%, respectively, and the cumulative incidences of relapse and treatment-related mortality were 23.5% and 28.4%, respectively. Stratification by risk group demonstrated superior DFS for low-risk patients (61.5% at 5 years) compared with intermediate- or high-risk (34.2% and 40.0%, respectively, P = .021). For patients with AML, those in CR1 had superior 5-year DFS compared with those in ≥CR2 (60% and 30.6%, respectively, P = .01), without a significant difference in incidence of relapse (17.1% and 30.6%, respectively, P = .209). There were no differences in DFS for other patient, donor, or disease characteristics. In summary, cytoreduction with Bu/Mel/Flu and r-ATG secured consistent engraftment of TCD transplantations. The incidences of acute/chronic GVHD and disease relapse were low, with favorable outcomes in this patient population with high-risk myeloid malignancies.

Milestones of Hematopoietic Stem Cell Transplantation - From First Human Studies to Current Developments

Since the early beginnings, in the 1950s, hematopoietic stem cell transplantation (HSCT) has become an established curative treatment for an increasing number of patients with life-threatening hematological, oncological, hereditary, and immunological diseases. This has become possible due to worldwide efforts of preclinical and clinical research focusing on issues of transplant immunology, reduction of transplant-associated morbidity, and mortality and efficient malignant disease eradication. The latter has been accomplished by potent graft-versus-leukemia (GvL) effector cells contained in the stem cell graft. Exciting insights into the genetics of the human leukocyte antigen (HLA) system allowed improved donor selection, including HLA-identical related and unrelated donors. Besides bone marrow, other stem cell sources like granulocyte-colony stimulating-mobilized peripheral blood stem cells and cord blood stem cells have been established in clinical routine. Use of reduced-intensity or non-myeloablative conditioning regimens has been associated with a marked reduction of non-hematological toxicities and eventually, non-relapse mortality allowing older patients and individuals with comorbidities to undergo allogeneic HSCT and to benefit from GvL or antitumor effects. Whereas in the early years, malignant disease eradication by high-dose chemotherapy or radiotherapy was the ultimate goal; nowadays, allogeneic HSCT has been recognized as cellular immunotherapy relying prominently on immune mechanisms and to a lesser extent on non-specific direct cellular toxicity. This chapter will summarize the key milestones of HSCT and introduce current developments.

Acute Myeloid Leukemia: A Concise Review

Acute myeloid leukemia (AML) is a heterogeneous clonal disorder characterized by immature myeloid cell proliferation and bone marrow failure. Cytogenetics and mutation testing remain a critical prognostic tool for post induction treatment. Despite rapid advances in the field including new drug targets and increased understanding of the biology, AML treatment remains unchanged for the past three decades with the majority of patients eventually relapsing and dying of the disease. Allogenic transplant remains the best chance for cure for patients with intermediate or high risk disease. In this review, we discuss the landmark genetic studies that have improved outcome prediction and novel therapies.

Similar transplantation outcomes for acute myeloid leukemia and myelodysplastic syndrome patients with haploidentical versus 10/10 human leukocyte antigen-matched unrelated and related donors

Allogeneic stem cell transplantation for patients with acute myeloid leukemia (AML) and myelodysplastic syndromes (MDS) has been performed primarily with an HLA-matched donor. Outcomes of haploidentical transplantation have recently improved, and a comparison between donor sources in a uniform cohort of patients has not been performed. We evaluated outcomes of 227 patients with AML/MDS treated with melphalan-based conditioning. Donors were matched related (MRD) (n = 87, 38%), matched unrelated (MUD) (n = 108, 48%), or haploidentical (n = 32, 14%). No significant differences were found between haploidentical and MUD transplantation outcomes; however, there was a trend for improved outcomes in the MRD group, with 3-year progression-free survival for patients in remission of 57%, 45%, and 41% for MRD, MUD, and haploidentical recipients, respectively (P = .417). Recovery of T cell subsets was similar for all groups. These results suggest that haploidentical donors can safely extend transplantation for AML/MDS patients without an HLA-matched donor. Prospective studies comparing haploidentical and MUD transplantation are warranted.

Conditioning regimens for hematopoietic cell transplantation: one size does not fit all

An essential component of allogeneic and autologous hematopoietic cell transplantation (HCT) is the conditioning regimen administered before the hematopoietic cell infusion. Early regimens relied on dose intensity, assuming that high-dose chemoradiotherapy would eliminate malignant disease and reinfusion of the graft would then restore hematopoiesis. However, as the contribution of graft-versus-tumor effects to the success of allogeneic HCT was recognized over time, in an effort to exploit these, many investigators lowered the dose of radiation and chemotherapeutic agents in the preparative regimen. This resulted in a major paradigm shift, and consequently, the pool of eligible patients underwent a remarkable expansion. In this article, we provide a review of the definition of high-dose, reduced-intensity, and nonmyeloablative conditioning regimens, the most commonly used agents and combinations, and the evolution of some early regimens. We also provide a brief review of the toxicities associated with these regimens.

Strategies to reduce relapse after allogeneic hematopoietic cell transplantation in acute myeloid leukemia

The incidence of acute myeloid leukemia (AML) is expected to increase in conjunction with our ageing population. Although it is proving to be a heterogeneous disease process, the only treatment with proven survival benefit for poor risk AML remains allogeneic hematopoietic cell transplant. Although this is presumed to be a curative strategy, many patients relapse after transplant, prompting us to examine various ways that we can improve outcomes. These efforts involve every step of AML diagnostics and therapy, including the intricate processes of conditioning, graft manipulation and immunomodulation. The hope is that improvement in these steps will ultimately improve survival and decrease relapse rates for AML patients after transplant.

Comparative outcome of reduced intensity and myeloablative conditioning regimen in HLA identical sibling allogeneic hematopoietic stem cell transplantation for acute leukemia patients: a single center experience

Due to the high transplant related morbidity and mortality (TRM), relatively younger acute leukemia patients that have a good performance status and no comorbidity are eligible for myeloablative conditioning (MAC) followed by allogeneic hematopoietic stem cell transplantation (allo-HSCT). The outcomes of 84 consecutive adult patients with ALL (n=38) or AML (n=46) who underwent allo-HSCT from their HLA-identical siblings were evaluated retrospectively. The median age at transplantation was 34 (17-58 years) for the whole patient population. Of these, 24 patients received a MAC and 60 patients received a fludarabine-based reduced intensity conditioning regimen (RIC). After a median follow-up of 32 months (range, 1-119), for the entire group, the 3-year estimated overall survival (OS) was 57.5% and the disease-free survival (DFS) was 51.5%. The OS for ALL and AML patients were 53.9% vs 62.1%: and DFS were 50.5% and 53.4%, respectively. The 3-year estimated OS for RIC and MAC patients were 63.2% and 41.7%; and DFS were 57.1% and 34.7%, respectively. In ALL patients, conditioning regimens (RIC vs MAC) led to similar OS and DFS; however, in AML patients both OS (70.1% vs 21.4%) and DFS (59.3% vs 42.9%) were found to be higher in RIC patients compared to MAC recipients. Overall, the TRM at day 100 was 1.7% and has increased up to 5.1% at 1st year. In multivariate analysis, the diagnosis (p=0.03) and RIC regimen (p=0.027) were the prognostic variables for prolonged OS in all patients; and RIC regimen (p=0.031) was the only prognostic factor for prolonged OS in AML patients. The first complete remission (CR1) was correlated with a prolonged DFS as an independent variable for all patients (p=0.09). Eleven of the RIC patients (18.3%) and 6 of the MAC patients (25%) developed acute graft-versus-host disease (GvHD). Seventeen of the RIC patients (33.3%) and 4 of the MAC patients (16.7%) developed chronic GvHD. In conclusion, RIC conditioning regimens may provide a longer OS and DFS, especially in patients with AML who are in first CR, not eligible for MAC conditioning.

Do different conditioning regimens really make a difference?

Over the past 15 years, the use of reduced-intensity/nonmyeloablative conditioning regimens before allogeneic hematopoietic stem cell transplantation has been increasing. Despite major disparities in the level of myeloablation, intensity of immunosuppression (including great diversity of in vivo T-cell depletion), and postgraft immunomodulation, the different approaches have contributed jointly to a modification of the stage of allogeneic stem cell transplantation: transplantation-related procedure mortality has been decreased dramatically, allowing allogeneic immunotherapy to be used in previously excluded populations, including elderly patients, young but clinically unsuitable patients, patients with lymphoid malignancies or solid tumors, and patients without an HLA-identical related or unrelated donor. Together, these diverse regimens have provided one of the biggest breakthroughs since the birth of allogeneic BM transplantation. However, consensus on how to reach the optimal goal of minimal transplantation-related mortality with maximum graft-versus-tumor effect is far from being reached, and further studies are needed to define optimal conditioning and immunomodulatory regimens that can be integrated to reach this goal. These developments, which will most likely vary according to different clinical situations, have to be compared continuously with advances achieved in traditional allogeneic transplantation and nontransplantation treatments. However, the lack of prospective comparative trials is and will continue to make this task challenging.