Hematopoietic stem cell transplant in adults with acute lymphoblastic leukemia: the present state

Efficacy and Safety of Total Body Irradiation Versus Chemotherapy Conditioning for Hematopoietic Stem Cell Transplant in Adult Acute Lymphoblastic Leukemia: A Systematic Review and Meta-Analysis

Hematopoietic stem cell transplantation (HSCT) is a potentially curative option for adults with acute lymphoblastic leukemia (ALL) who have achieved remission. This systematic review and meta-analysis compare the efficacy of total body irradiation (TBI) versus chemotherapy (CHT) based regimens for conditioning in adult ALL patients being prepared for HSCT. A comprehensive literature search was conducted in MEDLINE, Embase, the Cochrane Library, and relevant trial registries from their inception to August 2024. The inclusion criteria encompassed all randomized controlled trials (RCTs) and cohort studies that compared TBI with CHT as conditioning regimens prior to HSCT in adult patients with ALL. The primary outcomes assessed were overall survival (OS) and event-free survival (EFS). All statistical analyses were carried out using RevMan version 5.4, using a random-effects model. This meta-analysis includes 20 cohort studies and one RCT. The relative risk (RR) for OS was 1.37 (95% CI: 1.20-1.57), while the RR for EFS was 1.28 (95% CI: 1.15-1.43), highlighting the superior efficacy of TBI-based regimens in this patient population. TBI was also superior in terms of relapse rate (RR 0.71). The 2 regimens were comparable in terms of nonrelapse mortality, acute graft-versus-host disease (GVHD), and chronic GVHD. When used for conditioning prior to HSCT, TBI-based conditioning regimens demonstrate superior OS, EFS, and relapse outcomes compared to CHT-based regimens.

CD7 CAR T bridging to allo-HSCT in R/R T-ALL: A case report

BACKGROUND

Refractory/relapsed T-cell acute lymphoblastic leukemia (R/R T-ALL) is a hematological malignancy with a poor prognosis. The current treatment strategy has not benefited most patients, and the treatment methods are still being explored.

CASE PRESENTATION

An 8-year-old boy with R/R T-ALL achieved CR after multiple chemotherapies, followed by the first allo-HSCT. Unfortunately, 1 year and 3 months later, he relapsed. After recurrence, the patient underwent multiple chemotherapies, but the NOTCH1 gene and MRD were still positive. FCM and immunohistochemistry revealed abnormally high expression of CD7, so we considered bridging the second allo-HSCT after CD7 CAR T-cells treatment. The patient has low toxic and side effects and is still in CR, findings from this case report have more important therapeutic significance for R/R T-ALL.

CONCLUSION

In conclusion, CD7 CAR T-cells bridging to allo-HSCT is a safe and effective approach for R/R T-ALL, resulting in durable CR and longer survival.

Haploidentical Versus Matched Sibling Donor Hematopoietic Stem Cell Transplantation for Adult Patients With Relapsed/Refractory Acute Lymphoblastic Leukemia: A Study From the Acute Leukemia Working Party of the European Society for Blood and Marrow Transplantation

The results of haploidentical stem cell transplantation (haploHCT) for patients with acute lymphoblastic leukemia (ALL) transplanted in active disease remain largely unknown. We retrospectively analyzed adult patients with R/R ALL who underwent haploHCT or matched sibling donor (MSD-HCT) as a first transplantation between 2012 and 2020. The analysis comprised 274 patients, 94 had a haploHCT, and 180 had an MSD-HCT. The median follow-up was 32 months. The median age was 33 (range 18-76) and 37 (18-76) years in the haplo- and MSD-HCT groups, respectively. Post-transplant cyclophosphamide (PTCy) was used in 88% of haploHCT and in 4% of the MSD-HCT group. Graft-versus-host disease grade III-IV was higher in haploHCT than in the MSD-HCT group (18% versus 9%; P = 0.042). The 2-year chronic (c) graft-versus-host disease rates were 17% versus 33% (hazard ratio [HR] = 0.56; P = 0.14), respectively. By multivariate analysis, relapse incidence, and leukemia-free survival were not significatively different between the transplant groups, while nonrelapse mortality (NRM) was significantly higher (25% versus 18% at 2 years; HR = 2.03; P = 0.042) and overall survival (OS) lower (22% versus 38% at 2 years; HR = 1.72; P = 0.009) in the haploHCT group compared with the MSD-HCT group. We conclude that the 2-year OS of R/R ALL patients undergoing MSD transplants is significantly better than in haploHCT with a higher NRM in the latter.

Isolated Renal Relapse in a Post-Allogenic Transplant Adult Patient With Acute Lymphoblastic Leukemia

Acute lymphoblastic leukemia (ALL) is an aggressive hematological neoplasm typically more common in children than adults. More prolonged remissions and a potential cure can be achieved if allogeneic hematopoietic stem cell transplantation (allo-HSCT) is performed. Outcomes after allo-HSCT vary significantly among patients, and multiple factors contribute to these outcomes. Isolated extramedullary relapse (iEMR) after allo-HSCT is rare. We present the case of a 43-year-old man who was diagnosed with Philadelphia chromosome-negative (Ph-neg), B-cell ALL and underwent haploidentical allo-HSCT because of high-risk features at diagnosis. One year later, he was admitted to the hospital with facial and peripheral edema, proteinuria, elevated serum creatinine levels, and hypertension. Renal biopsy was performed immediately. Renal infiltration of TdT+ leukemic cells was detected by immunohistochemistry. Bone marrow aspiration, lumbar puncture, and computed tomography (CT) scans were performed to identify other sites of possible relapse. No other sites were identified, and an extramedullary isolated renal relapse was diagnosed. Intensive re-induction with chemotherapy was not possible because of the coronavirus disease 2019 (COVID-19) infection. Six weeks later, a medullary relapse was noted. Medullary infiltration of B-cell ALL after allo-HSCT has a historically poor prognosis; however, iEMR appears to have a better overall prognosis. The optimal treatment for renal iEMR is still a matter of debate.

Pretransplant Consolidation Therapies Improve the Outcome of Myeloablative Allogeneic Transplantation in Adults with Ph-negative Acute Lymphoblastic Leukemia

BACKROUND AND AIM

The benefit of pre-transplant consolidation in patients with acute lymphoblastic leukemia (ALL) who achieved first complete remission (CR1) has not yet been clearly demonstrated. Here, we aimed to investigate the relationship between the treatments received before transplantation and transplant outcome in Ph-ALL patients who underwent myeloablative allo-HSCT in CR1.

PATIENTS AND METHODS

A total of 55, 32 (58.2%) men and 23 (41.8%) women, who underwent allo-HSCT with the diagnosis of Ph-ALL were evaluated retrospectively. All patients underwent to allo-HSCT with myeloablative conditioning regimen in the 1st CR from the available donor.

RESULTS

In patients who received >2 consolidation, the 2-year and 3-year OS was 69% and 65%, respectively, while the 2-year and 3-year OS was 39% and 26%, respectively, in those who received < 2 consolidation (P =.03). RFS was similar in both groups (P = .8). One year- NRM was found 28% in patients who received ≥ 2 consolidations, and 37% in patients who received <2 consolidation (P =.06). L-asparaginase, high dose methotrexate, and cranial treatments given before transplantation had no effect on transplant outcomes (P > .05).

CONCLUSION

Contrary to the belief that pre-transplant consolidation is not beneficial in ALL patients who proceed with allo-HCST in CR1, our results showed that consolidation treatments reduce NRM and improve the survival.

Improvements in allogeneic hematopoietic cell transplantation outcomes for adults with ALL over the past 3 decades

Allogeneic hematopoietic cell transplantation (allo-HCT) is a promising treatment for adult acute lymphoblastic leukemia (ALL), an intractable hematological malignancy. The trends in allo-HCT outcomes over the past 30 years were examined to verify the efficacy of evolving treatment methods and to identify further challenges. We analyzed data from a registry database that included 8467 adult ALL patients who underwent their first allo-HCT between 1990 and 2019. The period was divided into three 10-year intervals for analysis. Five-year overall survival improved from 48.2% to 70.2% in the first complete remission (CR1), from 25.6% to 44.1% in subsequent CR, and from 10.0% to 22.7% in non-CR. Nonrelapse mortality improved over the 3 decades in each disease stage. However, the relapse rate only improved in CR1 every decade (26.3% to 15.9% in CR1, 33.4% to 32.8% in subsequent CR, and 53.6% to 54.8% in non-CR). Although there were continual improvements in adjusted survival for Philadelphia chromosome (Ph)-positive patients, the improvement was inadequate for Ph⁻ patients with t(4;11), t(8;14), t(14;18), or hypodiploidy. Allo-HCT outcomes for adults with ALL have improved over the past 30 years. Improved outcomes in the future will require more effective prevention of relapse in patients with ALL not in CR1 and in those with high-risk chromosomal abnormalities.

Endocan in Acute Leukemia: Current Knowledge and Future Perspectives

Endocan is a soluble dermatan sulfate proteoglycan expressed by endothelial cells and detected in serum/plasma. Its expression is increased in tumors/tumor vessels in several human malignancies, and high expression (high serum/plasma levels or tumor levels) has an adverse prognostic impact in several malignancies. The p14 endocan degradation product can also be detected in serum/plasma, but previous clinical studies as well as previously unpublished results presented in this review suggest that endocan and p14 endocan fragment levels reflect different biological characteristics, and the endocan levels seem to reflect the disease heterogeneity in acute leukemia better than the p14 fragment levels. Furthermore, decreased systemic endocan levels in previously immunocompetent sepsis patients are associated with later severe respiratory complications, but it is not known whether this is true also for immunocompromised acute leukemia patients. Finally, endocan is associated with increased early nonrelapse mortality in (acute leukemia) patients receiving allogeneic stem cell transplantation, and this adverse prognostic impact seems to be independent of the adverse impact of excessive fluid overload. Systemic endocan levels may also become important to predict cytokine release syndrome after immunotherapy/haploidentical transplantation, and in the long-term follow-up of acute leukemia survivors with regard to cardiovascular risk. Therapeutic targeting of endocan is now possible, and the possible role of endocan in acute leukemia should be further investigated to clarify whether the therapeutic strategy should also be considered.

CAR-T after Stem Cell Transplantation in B-Cell Lymphoproliferative Disorders: Are They Really Autologous or Allogenic Cell Therapies?

Allogenic hematopoietic stem cell transplantation (allo-HSCT) is one of the standard treatments for B-cell lymphoproliferative disorders; however, deep relapses are common after an allo-HSCT, and it is associated with poor prognosis. A successful approach to overcome these relapses is to exploit the body's own immune system with chimeric antigen receptor (CAR) T-cells. These two approaches are potentially combinatorial for treating R/R B-cell lymphoproliferative disorders. Several clinical trials have described different scenarios in which allo-HSCT and CAR-T are successively combined. Further, for all transplanted patients, assessment of chimerism is important to evaluate the engraftment success. Nonetheless, for those patients who previously received an allo-HSCT there is no monitorization of chimerism before manufacturing CAR T-cells. In this review, we focus on allo-HSCT and CAR-T treatments and the different sources of T-cells for manufacturing CAR T-cells.

Mechanisms of Immune Evasion in Acute Lymphoblastic Leukemia

Acute lymphoblastic leukemia (ALL) results from a clonal expansion of abnormal lymphoid progenitors of B cell (BCP-ALL) or T cell (T-ALL) origin that invade bone marrow, peripheral blood, and extramedullary sites. Leukemic cells, apart from their oncogene-driven ability to proliferate and avoid differentiation, also change the phenotype and function of innate and adaptive immune cells, leading to escape from the immune surveillance. In this review, we provide an overview of the genetic heterogeneity and treatment of BCP- and T-ALL. We outline the interactions of leukemic cells in the bone marrow microenvironment, mainly with mesenchymal stem cells and immune cells. We describe the mechanisms by which ALL cells escape from immune recognition and elimination by the immune system. We focus on the alterations in ALL cells, such as overexpression of ligands for various inhibitory receptors, including anti-phagocytic receptors on macrophages, NK cell inhibitory receptors, as well as T cell immune checkpoints. In addition, we describe how developing leukemia shapes the bone marrow microenvironment and alters the function of immune cells. Finally, we emphasize that an immunosuppressive microenvironment can reduce the efficacy of chemo- and immunotherapy and provide examples of preclinical studies showing strategies for improving ALL treatment by targeting these immunosuppressive interactions.

Long-Term Follow-Up of CD19-CAR T-Cell Therapy in Children and Young Adults With B-ALL

PURPOSE

CD19 chimeric antigen receptor (CD19-CAR) T cells induce high response rates in children and young adults (CAYAs) with B-cell acute lymphoblastic leukemia (B-ALL), but relapse rates are high. The role for allogeneic hematopoietic stem-cell transplant (alloHSCT) following CD19-CAR T-cell therapy to improve long-term outcomes in CAYAs has not been examined.

METHODS

We conducted a phase I trial of autologous CD19.28ζ-CAR T cells in CAYAs with relapsed or refractory B-ALL. Response and long-term clinical outcomes were assessed in relation to disease and treatment variables.

RESULTS

Fifty CAYAs with B-ALL were treated (median age, 13.5 years; range, 4.3-30.4). Thirty-one (62.0%) patients achieved a complete remission (CR), 28 (90.3%) of whom were minimal residual disease-negative by flow cytometry. Utilization of fludarabine/cyclophosphamide-based lymphodepletion was associated with improved CR rates (29/42, 69%) compared with non-fludarabine/cyclophosphamide-based lymphodepletion (2/8, 25%; P = .041). With median follow-up of 4.8 years, median overall survival was 10.5 months (95% CI, 6.3 to 29.2 months). Twenty-one of 28 (75.0%) patients achieving a minimal residual disease-negative CR proceeded to alloHSCT. For those proceeding to alloHSCT, median overall survival was 70.2 months (95% CI, 10.4 months to not estimable). The cumulative incidence of relapse after alloHSCT was 9.5% (95% CI, 1.5 to 26.8) at 24 months; 5-year EFS following alloHSCT was 61.9% (95% CI, 38.1 to 78.8).

CONCLUSION

We provide the longest follow-up in CAYAs with B-ALL after CD19-CAR T-cell therapy reported to date and demonstrate that sequential therapy with CD19.28ζ-CAR T cells followed by alloHSCT can mediate durable disease control in a sizable fraction of CAYAs with relapsed or refractory B-ALL (ClinicalTrials.gov identifier: NCT01593696).

Cytomegalovirus prophylaxis using low-dose valganciclovir in patients with acute leukemia undergoing allogeneic hematopoietic stem-cell transplantation

Background

Letermovir prophylaxis is currently the standard of care for the prevention of cytomegalovirus (CMV) infections in allogeneic hematopoietic stem-cell transplantation (allo-HSCT). However, drug-drug interactions between letermovir and azoles or calcineurin inhibitors and the high financial burden of letermovir remain problematic, especially in resource-limited countries. It has not been clarified whether a lower dose of valganciclovir would constitute an effective strategy for CMV prevention in patients with acute leukemia undergoing allo-HSCT.

Methods

We retrospectively assessed 84 consecutive adult patients with acute leukemia who underwent allo-HSCT. These 84 patients were stratified into a valganciclovir prophylaxis group (n = 20) and a non-valganciclovir prophylaxis group (n = 64).

Results

Patients in the valganciclovir prophylaxis group had a lower possibility of CMV DNAemia at week 14 after allo-HSCT than those in the non-valganciclovir prophylaxis group (15.0% versus 50.0%; p = 0.012). The cumulative incidence of CMV DNAemia at week 14 was also lower in patients with valganciclovir CMV prophylaxis than in those without (15.0% versus 50.4%; p = 0.006). Multivariate analysis validated these data, showing that a low dose of valganciclovir significantly reduced the risk of CMV DNAemia at week 14 by 88% (hazard ratio: 0.12; 95% confidence interval: 0.04-0.42; p = 0.001). However, these two groups had similar overall survival rates at week 48 (75.0% versus 76.6%; p = 0.805). Four of 20 (20%) patients discontinued valganciclovir prophylaxis because of adverse events.

Conclusion

Low-dose valganciclovir prophylaxis could be an alternative to letermovir to prevent CMV infection in allo-HSCT, especially in resource-limited countries.

Anti-CD19 CAR-T cell therapy bridge to HSCT decreases the relapse rate and improves the long-term survival of R/R B-ALL patients: a systematic review and meta-analysis

Chimeric antigen receptor (CAR) T cell therapy improves the remission rate of refractory/relapsed B-acute lymphoblastic leukemia (R/R B-ALL) patients, but the relapse rate remains high. Recent studies suggest patients who underwent post-chimeric antigen receptor T cell therapy hematopoietic stem cell transplantation (post- HSCT) would achieve durable remission and better survival, but this remains controversial. To this end, we conducted a meta-analysis to assess the role of post-HSCT in R/R B-ALL. The Cochrane Library, Embase, and PubMed were used to identify relevant studies; the latest search update was on July 05, 2020. We used the Cochran Q test and I-squared statistics to test for heterogeneity among the studies analyzed. The fixed model and random model were used to combine results when appropriate. We performed all statistical analyses with Stata 12, and P < 0.05 was considered statistically significant. We included 18 studies with 758 patients in the meta-analysis. Our results indicated that post-HSCT was associated with lower relapse rate (RR: 0.40, 95% CI: 0.32-0.50, P = 0.000), better overall survival (HR: 0.37, 95% CI: 0.19-0.71, P = 0.003), better leukemia-free survival (HR: 0.20, 95% CI: 0.10-0.40, P = 0.000). However, post-HSCT did not influence OS in Caucasians, and CAR-T cells with CD28 co-stimulation factor bridged to HSCT did not influence OS. Post-HSCT decreased the relapse rate and improved the long-term survival of R/R B-ALL patients. R/R B-ALL patients would benefit from post-HSCT after CAR-T cell therapy.

Haematopoietic Stem Cell Transplantation in Adolescents and Young Adults With Acute Lymphoblastic Leukaemia: Special Considerations and Challenges

Adolescents and young adults (AYAs) represent a challenging group of acute lymphoblastic leukaemia (ALL) patients with specific needs. While there is growing evidence from comparative studies that this age group profits from intensified paediatric-based chemotherapy, the impact and optimal implementation of haematopoietic stem cell transplantation (HSCT) in the overall treatment strategy is less clear. Over recent years, improved survival rates after myeloablative allogeneic HSCT for ALL have been reported similarly for AYAs and children despite differences in transplantation practise. Still, AYAs appear to have inferior outcomes and an increased risk of treatment-related morbidity and mortality in comparison with children. To further improve HSCT outcomes and reduce toxicities in AYAs, accurate stratification and evaluation of additional or alternative targeted treatment options are crucial, based on specific molecular and immunological characterisation of ALL and minimal residual disease (MRD) assessment during therapy. Age-specific factors such as increased acute toxicities and poorer adherence to treatment as well as late sequelae might influence treatment decisions. In addition, educational, social, work, emotional, and sexual aspects during this very crucial period of life need to be considered. In this review, we summarise the key findings of recent studies on treatment approach and outcomes in this vulnerable patient group after HSCT, turning our attention to the different approaches applied in paediatric and adult centres. We focus on the specific needs of AYAs with ALL regarding social aspects and supportive care to handle complications as well as fertility issues. Finally, we comment on potential areas of future research and concisely debate the capacity of currently available immunotherapies to reduce toxicity and further improve survival in this challenging patient group.

A Review of Infections After Hematopoietic Cell Transplantation Requiring PICU Care: Transplant Timeline Is Key

Despite major advances in antimicrobial prophylaxis and therapy, opportunistic infections remain a major cause of morbidity and mortality after pediatric hematopoietic cell transplant (HCT). Risk factors associated with the development of opportunistic infections include the patient's underlying disease, previous infection history, co-morbidities, source of the donor graft, preparative therapy prior to the graft infusion, immunosuppressive agents, early and late toxicities after transplant, and graft-vs.-host disease (GVHD). Additionally, the risk for and type of infection changes throughout the HCT course and is greatly influenced by the degree and duration of immunosuppression of the HCT recipient. Hematopoietic cell transplant recipients are at high risk for rapid clinical decompensation from infections. The pediatric intensivist must remain abreast of the status of the timeline from HCT to understand the risk for different infections. This review will serve to highlight the infection risks over the year-long course of the HCT process and to provide key clinical considerations for the pediatric intensivist by presenting a series of hypothetical HCT cases.

Comparing the outcomes between TMLI and non-TMLI conditioning regimens for adult high-risk acute lymphoblastic leukemia patients undergoing allogeneic hematopoietic stem cell transplantation: a single-center experience

This study aimed to retrospectively evaluate the outcomes of adult patients with high-risk acute lymphoblastic leukemia (ALL) who received allogeneic hematopoietic stem cell transplantation (allo-HSCT) with either total marrow and lymphoid irradiation (TMLI)-containing or non-TMLI conditioning regimen. Seventy adult patients with high-risk ALL who received allo-HSCT were enrolled in this study and divided into two groups based on the conditioning regimen type (TMLI group: n = 29 and non-TMLI group: n = 41). We noted significant statistical differences in the 1-year estimated cumulative incidence of relapse (25% vs. 46.5%, p = 0.018), the 1-year estimated overall survival (73.1% vs. 52.6%, p = 0.033) and disease-free survival (65.2% vs. 48.2%, p = 0.026) but found no considerable difference in transplant-related mortality (12% vs. 13.4%, p = 0.619) between patients in the TMLI and non-TMLI groups. The TMLI-containing regimen is safe and alternative for patients with high-risk ALL undergoing allo-HSCT.

Haploidentical transplant in adult patients with acute lymphoblastic leukemia in Argentina: a comparison with matched related and unrelated donors

We aimed at analyzing the outcome of allogeneic stem cell transplant (ASCT) in adult patients with acute lymphoblastic leukemia (ALL), comparing Haploidentical (Haplo) with HLA-matched (sibling and unrelated) donors. Between 2008 and 2017, we collected data from 236 patients (median age 31 years; range 16-64; 90% HCT-CI 0-1) who underwent unmanipulated ASCT in first complete remission and subsequent remissions in 15 Argentinian centers. Donors were HLA-matched (n = 175; 74%) and Haplo (n = 61; 26%). Two-year overall survival (OS) was 55% (95% CI 47-63) for the HLA-matched group and 49% (95% CI 34-62) for the Haplo group (p = 0.351). For OS, crude HR, adjusted HR for covariates (HR 1.24; 95% CI 0.77-1.99; p = 0.363) and HR including a propensity score in the model (HR 1.22; 95% CI 0.71-2.08; p = 0.414) showed no impact of donor category on the OS. No difference was found in terms of nonrelapse mortality, relapse, leukemia-free survival, and grade 3-4 acute graft-versus-host disease (GVHD); 2-year incidence of chronic GVHD was higher in HLA-matched vs Haplo group (p = 0.028). Patients with ALL who underwent ASCT were young subjects with low HCT-CI. In this setting, a Haplo donor represents an alternative widely available in the absence of an HLA-matched donor. Relapse remains a challenge for all donor categories.