Autologous stem cell transplantation in the treatment of adults with acute myeloid leukaemia

Auto-hematopoietic stem cell transplantation or chemotherapy? Meta-analysis of clinical choice for AML

For patients with acute myeloid leukemia (AML) who are not candidates for allogeneic stem cell transplantation (SCT) or do not have a human leukocyte antigen (HLA)-matched donor, it is unclear whether autologous SCT (ASCT) has a better prognosis after the first complete response (CR1) compared to further chemotherapy treatment. A meta-analysis evaluating ASCT compared to further chemotherapy for AML patients in CR1 was performed. The Medline, Embase, Cochrane Controlled Trials Registry, Cochrane Library, Web of Science, and National Knowledge Infrastructure of China databases were searched for relevant literature as of May 26, 2023. Eligible studies included prospectively enrolled adults with AML and randomized first-time respondent patients who did not have a matched sibling donor. Fourteen randomized controlled trials were identified and included 4281 participants, of which 1499 patients received ASCT and 2782 underwent chemotherapy and continued follow-up. In patients with AML in CR1, a lower relapse rate was associated with ASCT compared to chemotherapy [odds ratio (OR) = 0.49, 95% confidence interval (CI) = 0.41-0.57]. Significant disease-free survival (DFS; OR = 1.37, 95% CI = 1.02-1.84) and relapse-free survival (RFS; OR = 2.78, 95% CI = 1.28-6.02) ASCT benefits were documented, and there was no difference in the overall survival (OS) when the studies were pooled (OR = 1.12, 95% CI = 0.85-1.48). The study results indicated that after the first remission, AML patients receiving autologous stem cell transplantation had higher DFS and RFS, similar OS, and lower relapse compared to patients undergoing chemotherapy treatment. This indicated that autologous stem cell transplantation may have a better prognosis.

TCF-1 Is Required for CD4 T Cell Persistence Functions during AlloImmunity

The transcription factor T cell factor-1 (TCF-1) is encoded by Tcf7 and plays a significant role in regulating immune responses to cancer and pathogens. TCF-1 plays a central role in CD4 T cell development; however, the biological function of TCF-1 on mature peripheral CD4 T cell-mediated alloimmunity is currently unknown. This report reveals that TCF-1 is critical for mature CD4 T cell stemness and their persistence functions. Our data show that mature CD4 T cells from TCF-1 cKO mice did not cause graft versus host disease (GvHD) during allogeneic CD4 T cell transplantation, and donor CD4 T cells did not cause GvHD damage to target organs. For the first time, we showed that TCF-1 regulates CD4 T cell stemness by regulating CD28 expression, which is required for CD4 stemness. Our data showed that TCF-1 regulates CD4 effector and central memory formation. For the first time, we provide evidence that TCF-1 differentially regulates key chemokine and cytokine receptors critical for CD4 T cell migration and inflammation during alloimmunity. Our transcriptomic data uncovered that TCF-1 regulates critical pathways during normal state and alloimmunity. Knowledge acquired from these discoveries will enable us to develop a target-specific approach for treating CD4 T cell-mediated diseases.

TCF-1 regulates NKG2D expression on CD8 T cells during anti-tumor responses

Cancer immunotherapy relies on improving T cell effector functions against malignancies, but despite the identification of several key transcription factors (TFs), the biological functions of these TFs are not entirely understood. We developed and utilized a novel, clinically relevant murine model to dissect the functional properties of crucial T cell transcription factors during anti-tumor responses. Our data showed that the loss of TCF-1 in CD8 T cells also leads to loss of key stimulatory molecules such as CD28. Our data showed that TCF-1 suppresses surface NKG2D expression on naïve and activated CD8 T cells via key transcriptional factors Eomes and T-bet. Using both in vitro and in vivo models, we uncovered how TCF-1 regulates critical molecules responsible for peripheral CD8 T cell effector functions. Finally, our unique genetic and molecular approaches suggested that TCF-1 also differentially regulates essential kinases. These kinases, including LCK, LAT, ITK, PLC-γ1, P65, ERKI/II, and JAK/STATs, are required for peripheral CD8 T cell persistent function during alloimmunity. Overall, our molecular and bioinformatics data demonstrate the mechanism by which TCF-1 modulated several critical aspects of T cell function during CD8 T cell response to cancer. Summary Figure: TCF-1 is required for persistent function of CD8 T cells but dispensable for anti-tumor response. Here, we have utilized a novel mouse model that lacks TCF-1 specifically on CD8 T cells for an allogeneic transplant model. We uncovered a molecular mechanism of how TCF-1 regulates key signaling pathways at both transcriptomic and protein levels. These key molecules included LCK, LAT, ITK, PLC-γ1, p65, ERK I/II, and JAK/STAT signaling. Next, we showed that the lack of TCF-1 impacted phenotype, proinflammatory cytokine production, chemokine expression, and T cell activation. We provided clinical evidence for how these changes impact GVHD target organs (skin, small intestine, and liver). Finally, we provided evidence that TCF-1 regulates NKG2D expression on mouse naïve and activated CD8 T cells. We have shown that CD8 T cells from TCF-1 cKO mice mediate cytolytic functions via NKG2D.

Human Wnt/β-Catenin Regulates Alloimmune Signaling during Allogeneic Transplantation

Allogeneic hematopoietic stem cell transplantation (allo-HSCT) is one of the most widely applied forms of adoptive immunotherapy for the treatment of hematological malignancies. Detrimental graft-versus-host disease (GVHD), but also beneficial graft-versus-leukemia (GVL) effects occurring after allo-HSCT are largely mediated by alloantigen-reactive donor T cells in the graft. Separating GVHD from GVL effects is a formidable challenge, and a greater understanding of donor T cell biology is required to accomplish the uncoupling of GVHD from GVL. Here, we evaluated the role of β-catenin in this process. Using a unique mouse model of transgenic overexpression of human β-catenin (Cat-Tg) in an allo-HSCT model, we show here that T cells from Cat-Tg mice did not cause GVHD, and surprisingly, Cat-Tg T cells maintained the GVL effect. Donor T cells from Cat-Tg mice exhibited significantly lower inflammatory cytokine production and reduced donor T cell proliferation, while upregulating cytotoxic mediators that resulted in enhanced cytotoxicity. RNA sequencing revealed changes in the expression of 1169 genes for CD4, and 1006 genes for CD8⁺ T cells involved in essential aspects of immune response and GVHD pathophysiology. Altogether, our data suggest that β-catenin is a druggable target for developing therapeutic strategies to reduce GVHD while preserving the beneficial GVL effects following allo-HSCT treatment.

Targeting SLP76:ITK interaction separates GVHD from GVL in allo-HSCT

Allogeneic hematopoietic stem cell transplantation (allo-HSCT) is a curative therapy for hematological malignancies, due to graft-versus-leukemia (GVL) activity mediated by alloreactive donor T cells. However, graft-versus-host disease (GVHD) is also mediated by these cells. Here, we assessed the effect of attenuating TCR-mediated SLP76:ITK interaction in GVL vs. GVHD effects after allo-HSCT. CD8+ and CD4+ donor T cells from mice expressing a Y145F mutation in SLP-76 did not cause GVHD but preserved GVL effects against B-ALL cells. SLP76Y145FKI CD8+ and CD4+ donor T cells also showed less inflammatory cytokine production and migration to GVHD target organs. We developed a novel peptide to specifically inhibit SLP76:ITK interactions, resulting in decreased phosphorylation of PLCγ1 and ERK, decreased cytokine production in human T cells, and separation of GVHD from GVL effects. Altogether, our data suggest that inhibiting SLP76:ITK interaction could be a therapeutic strategy to separate GVHD from GVL effects after allo-HSCT treatment.

Targeting Interleukin-2-Inducible T-Cell Kinase (ITK) Differentiates GVL and GVHD in Allo-HSCT

Allogeneic hematopoietic stem cell transplantation is a potentially curative procedure for many malignant diseases. Donor T cells prevent disease recurrence via graft-versus-leukemia (GVL) effect. Donor T cells also contribute to graft-versus-host disease (GVHD), a debilitating and potentially fatal complication. Novel treatment strategies are needed which allow preservation of GVL effects without causing GVHD. Using murine models, we show that targeting IL-2-inducible T cell kinase (ITK) in donor T cells reduces GVHD while preserving GVL effects. Both CD8⁺ and CD4⁺ donor T cells from Itk^-/- mice produce less inflammatory cytokines and show decrease migration to GVHD target organs such as the liver and small intestine, while maintaining GVL efficacy against primary B-cell acute lymphoblastic leukemia (B-ALL). Itk^-/- T cells exhibit reduced expression of IRF4 and decreased JAK/STAT signaling activity but upregulating expression of Eomesodermin (Eomes) and preserve cytotoxicity, necessary for GVL effect. Transcriptome analysis indicates that ITK signaling controls chemokine receptor expression during alloactivation, which in turn affects the ability of donor T cells to migrate to GVHD target organs. Our data suggest that inhibiting ITK could be a therapeutic strategy to reduce GVHD while preserving the beneficial GVL effects following allo-HSCT treatment.

NKG2D expression by CD8+ T cells contributes to GVHD and GVT effects in a murine model of allogeneic HSCT

In allogeneic hematopoietic stem cell transplantation (HSCT), controlling graft-versus-host disease (GVHD) while maintaining graft-versus-tumor (GVT) responses is of critical importance. Using a mouse model of allogeneic HSCT, we hereby demonstrate that NKG2D expression by CD8(+) T cells plays a major role in mediating GVHD and GVT effects by promoting the survival and cytotoxic function of CD8(+) T cells. The expression of NKG2D ligands was not induced persistently on normal tissues of allogeneic HSCT-recipient mice treated with anti-NKG2D antibody, suggesting that transient NKG2D blockade might be sufficient to attenuate GVHD and allow CD8(+) T cells to regain their GVT function. Indeed, short-term treatment with anti-NKG2D antibody restored GVT effects while maintaining an attenuated GVHD state. NKG2D expression was also detected on CD8(+) T cells from allogeneic HSCT patients and trended to be higher in those with active GVHD. Together, these data support a novel role for NKG2D expression by CD8(+) T cells during allogeneic HSCT, which could be potentially therapeutically exploited to separate GVHD from GVT effects.

[Current indications of allogeneic stem cell transplant in adults with acute myeloid leukemia]

Allogeneic stem cell transplantation (SCT) is an increasingly important therapeutic option for the treatment of adult patients with acute myeloid leukemia. Here we review the current indications of SCT in this disease. While patients with favorable cytogenetics should receive consolidation chemotherapy, patients with unfavorable karyotype are prime candidates for SCT or new approaches to SCT (which should be done in first complete remission). Patients with intermediate prognoses should also receive SCT in first complete remission. In the absence of a suitable matched related donor, most patients will be able to find an alternative donor to proceed to a potentially curative allogeneic transplantation. The use of reduced-intensity conditioning regimens before SCT has allowed patients in the sixth or seventh decades of life to be routinely transplanted. Despite major differences among transplant centers in the intensity and composition of the conditioning regimen and immunosuppression, choice of graft source, postgraft immune-modulation, and supportive care, there has been a dramatic improvement in terms of tolerance. Although it is presumed to be a curative strategy, major complications of SCT remain graft-versus-host disease, delayed immune recovery, multiple comorbidities, and relapse after transplant.

Allogeneic hematopoietic cell transplant for acute myeloid leukemia: Current state in 2013 and future directions

Acute myeloid leukemia (AML) represents a heterogeneous group of high-grade myeloid neoplasms of the elderly with variable outcomes. Though remission-induction is an important first step in the management of AML, additional treatment strategies are essential to ensure long-term disease-free survival. Recent pivotal advances in understanding the genetics and molecular biology of AML have allowed for a risk-adapted approach in its management based on relapse-risk. Allogeneic hematopoietic cell transplantation (allo-HCT) represents an effective therapeutic strategy in AML providing the possibility of cure with potent graft-versus-leukemia reactions, with a demonstrable survival advantage in younger patients with intermediate- or poor-risk cytogenetics. Herein we review the published data regarding the role of allo-HCT in adults with AML. We searched MEDLINE/PubMed and EMBASE/Ovid. In addition, we searched reference lists of relevant articles, conference proceedings and ongoing trial databases. We discuss the role of allo-HCT in AML patients stratified by cytogenetic- and molecular-risk in first complete remission, as well as allo-HCT as an option in relapsed/refractory AML. Besides the conventional sibling and unrelated donor allografts, we review the available data and recent advances for alternative donor sources such as haploidentical grafts and umbilical cord blood. We also discuss conditioning regimens, including reduced intensity conditioning which has broadened the applicability of allo-HCT. Finally we explore recent advances and future possibilities and directions of allo-HCT in AML. Practical therapeutic recommendations have been made where possible based on available data and expert opinion.

Cloretazine for the treatment of acute myeloid leukemia

Cloretazine is a new sulfonylhydrazine alkylating agent with antileukemic activity. Phase I studies have shown myelosuppression to be the dose limiting toxicity in both solid tumors and leukemias. A large Phase II study of single agent cloretazine (600 mg/m2) confirmed its activity in patients with relapsed acute myeloid leukemia, and in elderly patients with previously untreated acute myeloid leukemia or myelodysplastic syndrome. It also confirmed the limited nonhematological toxicity, even in elderly patients. Cloretazine can be safely combined with cytarabine, and this combination regimen is currently being tested in a large Phase III study in patients with relapsed acute myeloid leukemia. Cloretazine is a promising new antileukemic agent that may be incorporated into an intensive combination regimen.

Unrelated donor allogeneic transplantation after failure of autologous transplantation for acute myelogenous leukemia: a study from the center for international blood and marrow transplantation research

The survival of patients with relapsed acute myelogenous leukemia (AML) after autologous hematopoietic stem cell transplantation (auto-HCT) is very poor. We studied the outcomes of 302 patients who underwent secondary allogeneic hematopoietic cell transplantation (allo-HCT) from an unrelated donor (URD) using either myeloablative (n = 242) or reduced-intensity conditioning (RIC; n = 60) regimens reported to the Center for International Blood and Marrow Transplantation Research. After a median follow-up of 58 months (range, 2 to 160 months), the probability of treatment-related mortality was 44% (95% confidence interval [CI], 38%-50%) at 1-year. The 5-year incidence of relapse was 32% (95% CI, 27%-38%), and that of overall survival was 22% (95% CI, 18%-27%). Multivariate analysis revealed a significantly better overal survival with RIC regimens (hazard ratio [HR], 0.51; 95% CI, 0.35-0.75; P <.001), with Karnofsky Performance Status score ≥90% (HR, 0.62; 95% CI, 0.47-0.82: P = .001) and in cytomegalovirus-negative recipients (HR, 0.64; 95% CI, 0.44-0.94; P = .022). A longer interval (>18 months) from auto-HCT to URD allo-HCT was associated with significantly lower riak of relapse (HR, 0.19; 95% CI, 0.09-0.38; P <.001) and improved leukemia-free survival (HR, 0.53; 95% CI, 0.34-0.84; P = .006). URD allo-HCT after auto-HCT relapse resulted in 20% long-term leukemia-free survival, with the best results seen in patients with a longer interval to secondary URD transplantation, with a Karnofsky Performance Status score ≥90%, in complete remission, and using an RIC regimen. Further efforts to reduce treatment-related mortaility and relapse are still needed.

Autologous Stem Cell Transplantation in elderly Acute Myeloid Leukemia

Treatment outcome in elderly Acute Myeloid Leukemia (AML) is still very disappointing. Although complete remission rate is around 50–60% the 2 years survival is only in the magnitude of 10–20%. This is mainly due to an overrepresentation of adverse prognostic factors present in elderly AML. As relapses emerge from residual disease present after chemotherapy, intensification of treatment could emerge as a rational strategy. Intensification of chemotherapy by increasing the dose of anthracyclines or addition of gemtuzumab ozogamycin (Mylotarg) to standard chemotherapy indeed has proved to be of advantage in elderly AML. In younger AML autologous peripheral blood stem cell transplantation (AuPBSCT) as post remission treatment in comparison to intensive consolidation chemotherapy has been investigated in a few randomized studies. AuPBSCT showed reduced relapse rates with low non-relapse mortality rates. In elderly AML intensification by AuPBSCT also have been performed although randomized studies are lacking. Nevertheless, in the previous years various reports have suggested the potential utility of AuHSCT in AML of the elderly with encouraging results, albeit mostly in highly selected patients. Acceptable toxicity and a relatively low rate of transplant-related mortality has been notified. However relapses occurred which, irrespective of age, still remains the major cause of treatment failure of AuHSCT in AML. In this review we summarize the experience of AuPBSCT in elderly AML.

Clinical activity of laromustine (Onrigin™) in hematologic malignancies

Laromustine (Onrigin™), formerly known as Cloretazine(®) (VNP40101M), belongs to a novel class of alkylating agents--the sulfonylhydrazines--and was selected for clinical development based on its broad anti-tumor activity in preclinical models. Laromustine is metabolized to yield 90CE and methylisocyanate, the former rapidly produces an alkylating, chloroethylating species, similar to the chloroethylating species generated by carmustine. However, several features distinguish laromustine from carmustine and possibly account for their biological differences in vitro and in vivo. The chloroethylating species responsible for laromustine's alkylator effect is relatively specific for guanine and forms a crosslink after incorporation into DNA. Laromustine has significant activity in both older patients with previously untreated acute myeloid leukemia or high-risk myelodysplastic syndrome, including those with very poor-risk disease, and in patients with relapsed disease. Further clinical studies are required with laromustine to evaluate its place as an anticancer agent in other hematological malignancies.

Stem cell transplantation in Europe: trends and prospects

The aim of the present study was to identify trends in numbers of European patients treated with autologous and allogeneic haematopoietic stem cell transplantation (HSCT) as well as to provide anticipated transplant rates for the upcoming years. The following indications were considered: haematological malignancies (acute leukaemias, myeloproliferative disorders, lymphoproliferative disorders and multiple myeloma), solid tumours and non-malignant diseases. Numbers of patients treated from 1990 to 2004 were extracted from the European Group for Blood and Marrow Transplantation database, extrapolated to 2012 using mathematic models and adjusted to the literature study and expert opinion. In Europe, a 13% raise in HSCT utilisation is to be expected from 2005 to 2010, mostly due to the growing application of reduced-intensity conditioning regimens followed by allogeneic HSCT. Growing transplant rates are likely to exert health expenditure budgets and put pressure on health care providers and health insurers in Europe. Therefore, the rapid expansion would ideally imply a simultaneous increase in HSCT budgets.

Is there a plateau in the survival curve after autologous transplantation in patients with intermediate and high-risk acute myeloid leukemia? A 20-year single institution experience

In an attempt to examine whether autologous SCT provides long-term disease control in patients with intermediate and high-risk AML where a suitable donor is not available, we analyzed the outcomes of autologous SCT in patients with intermediate and high-risk AML from 1986 to 2005. No relapses occurred after 2.2 years. The overall survival curve appears to have developed a plateau after 2.2 years. In conclusion, autologous SCT in patients with AML in whom an allogeneic transplantation is not feasible appears to be a safe alternative and a plateau in the survival curve indicates cure in a small proportion of patients.

Can reduced-intensity allogeneic transplantation cure older adults with AML?

Development of nonablative and reduced-intensity conditioning regimens has enabled older or medically infirm patients with myeloid malignancies to be treated with allogeneic hematopoietic cell transplantation (HCT). These regimens rely largely on graft-versus-leukemia effects rather than high-dose therapy to eliminate malignant cells. Studies indicate that there is sustained engraftment with relatively low transplant-related mortality in the small number of patients who have been treated. This review summarizes the outcome in recent studies of patients with myeloid malignancies who received HCT following nonmyeloablative or reduced-intensity conditioning. Comparison of nonmyeloablative with myeloablative transplant shows that the myeloablative patients are about 10-15 years younger. Toxicity is a major problem in the elderly who have comorbid conditions, but otherwise the patient has a similar outcome, again emphasizing the graft-versus-leukemia effect. Comparison of patients receiving related or unrelated grafts following nonmyeloablative conditioning shows that the outcome in these patients is similar. These studies have demonstrated encouraging overall survival and nonrelapse mortalities with evidence for graft-versus-leukemia responses in elderly patients with hematologic malignancies. Relapse and progressive disease continued to be problems, particularly in patients with large tumor burdens at time of HCT. Elimination of tumor burden prior to transplant with immunotherapy such as with radiolabeled anti-CD45 antibody or vaccines may improve outcome further.

HLA-identical sibling allogeneic peripheral blood stem cell transplantation with reduced intensity conditioning compared to autologous peripheral blood stem cell transplantation for elderly patients with de novo acute myeloid leukemia

We conducted a retrospective registry-based analysis to compare the outcome of 361 allogeneic human leukocyte antigen (HLA)-identical peripheral blood stem cell transplants (PBSCT) with reduced intensity conditioning (RIC) to that of 1369 autologous (auto) PBSCT in patients aged 50 years or older with de novo acute myeloid leukemia (AML), performed from 1997 until 2003 and reported to the European Group for Blood and Marrow Transplantation. Median age was 58 and 57 years in the RIC and auto groups, respectively. RIC patients had more advanced disease at the time of transplant. At a median follow-up of 24 months for RIC and 16 months for auto, multivariate analysis showed a lower risk for relapse (RR 0.77, P=0.013) without increased non-relapse mortality (NRM) in RIC patients (RR 1.26, P=0.28). Moreover, leukemia-free survival (RR 1.22, P=0.02) and overall survival (OS) (RR 1.32, P=0.005) were superior in the RIC group. In patients in 1st (CR), fewer relapses were counterbalanced by significantly increased NRM. Therefore, there was no survival advantage in this subgroup. In patients in 2nd or subsequent CR, LFS and OS were superior in the RIC group. RIC transplants show encouraging results in this older patient population with de novo AML.

Autotransplantation versus HLA-matched unrelated donor transplantation for acute myeloid leukaemia: a retrospective analysis from the Center for International Blood and Marrow Transplant Research

Most acute myeloid leukaemia (AML) patients lack human leucocyte antigen-identical sibling donors for transplantation. Autotransplants and unrelated donor (URD) transplants are therapeutic options. To compare autologous versus URD transplantation for AML in first (CR1) or second complete remission (CR2), we studied the outcomes of 668 autotransplants were compared with 476 URD transplants reported to the Center for International Blood and Marrow Transplant Research. Proportional hazards regression adjusted for differences in prognostic variables. In multivariate analyses transplant-related mortality (TRM) was significantly higher and relapse lower with URD transplantation. Adjusted 3-year survival probabilities were: in CR1 57 (53-61)% with autotransplants and 44 (37-51)% URD (P = 0.002), in CR2 46 (39-53)% and 33 (28-38)% respectively (P = 0.006). Adjusted 3-year leukaemia-free survival (LFS) probabilities were: CR1 53 (48-57)% with autotransplants and 43 (36-50)% with URD (P = 0.021), CR2 39 (32-46)% and 33 (27-38)% respectively (P = 0.169). Both autologous and URD transplantation produced prolonged LFS. High TRM offsets the superior antileukaemia effect of URD transplantation. This retrospective, observational database study showed that autotransplantation, in general, offered higher 3-year survival for AML patients in CR1 and CR2. Cytogenetics, however, were known in only two-thirds of patients and treatment bias cannot be eliminated.