Durable outcomes of double cord blood transplantation in adults with acute lymphoblastic leukemia: high-risk features for early and long-term mortality

Comparison of Long-Term Outcomes of Double Unit Cord Blood Versus Haploidentical Donor Transplantation in Adult Patients With Acute Lymphoblastic Leukemia Regarding KIR-Ligand Mismatch

BACKGROUND

Haploidentical donor transplantation (HIDT) or cord blood transplantation (CBT) are common alternatives for patients lacking human-leukocyte antigen (HLA)-matched donors. In addition to the donor source, NK cell alloreactivity due to HLA-mismatch setting may affect outcomes in alternative-donor hematopoietic cell transplantation (HCT). However, a limited number of studies have evaluated their impacts in adult acute lymphoblastic leukemia (ALL).

OBJECTIVES

We aimed to assess the effects of donor source and KIRL-MM on outcomes of alternative-donor HCT, with a special focus on adult ALL.

STUDY DESIGN

We retrospectively compared clinical outcomes between HIDT (n=47) and double unit CBT (DCBT) (n=134). Patients received fludarabine and busulfan-based reduced toxicity conditioning before HIDT, and TBI-based myeloablative conditioning before DCBT. KIR ligands were determined using a web-based calculator. For DCBT, donor KIR ligand groups were defined by the dominant CB unit after engraftment.

RESULTS

After a median follow-up of 39.4 months, DCBT showed higher 3-year non-relapse mortality (NRM) (22.8% vs. 9.0%, p=0.038), whereas the cumulative incidence of relapse (CIR) was significantly higher in HIDT (47.9% vs. 18.9%, p<0.001). Estimated disease-free survival (DFS) was comparable (DCBT 58.5% vs. HIDT 44.3%, p=0.106). GVH direction KIRL-MM showed lower incidence of acute GVHD in both HIDT and DCBT. However, GVH direction KIRL-MM was associated with poorer DFS (37.2% vs. 66.0%, p=0.008) only in the DCBT subgroup, mostly due to specifically higher NRM rate (35.0% vs 18.4%, p=0.057).

CONCLUSION

Our study supports the usefulness of DCBT in the HIDT-dominant era and suggests potential ways to improve survival outcomes of DCBT.

Diagnostic and therapeutic advances in adults with acute lymphoblastic leukemia in the era of gene analysis and targeted immunotherapy

Acute lymphoblastic leukemia (ALL) is one of the most rapidly changing hematological malignancies with advanced understanding of the genetic landscape, detection methods of minimal residual disease (MRD), and the development of immunotherapeutic agents with good clinical outcomes. The annual incidence of adult ALL in Korea is 300-350 patients per year. The WHO classification of ALL was revised in 2022 to reflect the molecular cytogenetic features and suggest new adverse- risk subgroups, such as Ph-like ALL and ETP-ALL. We continue to use traditional adverse-risk features and cytogenetics, with MRD-directed post-remission therapy including allogeneic hematopoietic cell transplantation. However, with the introduction of novel agents, such as ponatinib, blinatumomab, and inotuzumab ozogamicin incorporated into frontline therapy, good MRD responses have been achieved, and overall survival outcomes are improving. Accordingly, some clinical trials have suggested a possible era of chemotherapy-free or transplantation-free approaches in the near future. Nevertheless, relapse of refractory ALL still occurs, and some poor ALL subtypes, such as Ph-like ALL and ETP-ALL, are unsolved problems for which novel agents and treatment strategies are needed. In this review, we summarize the currently applied diagnostic and therapeutic practices in the era of advanced genetic analysis and targeted immunotherapies in United States and Europe and introduce real-world Korean data.

Cytogenetic and molecular characteristics and outcomes of adult patients with early T-cell precursor acute lymphoblastic leukemia

Early T-cell precursor acute lymphoblastic leukemia (ETP-ALL) is a recently identified high-risk subgroup of T-cell ALL in children. However, there have been conflicting reports and limited data have been reported in adult patients. We retrospectively analyzed the cytogenetic and molecular characteristics and long-term survival outcomes of adult patients with ETP-ALL versus non-ETP-ALL. We analyzed 58 patients (median age, 35 years [range, 18-76 years]) with newly diagnosed T-cell ALL who received a uniform remission induction and consolidation chemotherapy with suitable samples for genetic analyses. If a donor was available, all patients were recommended allogeneic hematopoietic cell transplantation (allo-HCT) for post-remission therapy. Out of 58 patients, 21 (36.2%) had ETP-ALL. Patients with ETP-ALL were older and had a higher proportion of complex karyotype than non-ETP-ALL. Additionally, more DNMT3A mutations were detected in ETP-ALL, whereas FBXW7 mutations and CDKN2A/CDKN2B deletions were found nearly exclusively in non-ETP-ALL. The overall complete remission (CR) rates were not different between ETP-ALL (95.2%) and non-ETP-ALL (81.1%) and subsequent allo-HCT proceeding rates in CR1 were 61.9% for ETP-ALL and 43.2% for non-ETP-ALL, respectively. The overall prognosis of patients with T-ALL was poor that estimated 5-year overall survival (OS) was 33.3% for ETP-ALL and 29.5% for non-ETP-ALL. In a subgroup analysis of patients treated with allo-HCT in CR1 (n = 29), 5-year OS was 53.8% for ETP-ALL and 55.4% for non-ETP-ALL. Our data showed molecular characteristics of ETP-ALL and non-ETP-ALL and revealed that intensive chemotherapy followed by allo-HCT for post-remission therapy can contribute to preserved survival outcome of adult patients with ETP-ALL.

Haploidentical versus Double-Cord Blood Stem Cells as a Second Transplantation for Relapsed Acute Myeloid Leukemia

There are limited data on second stem cell transplantation (SCT2) outcomes with alternative donors for relapsed AML after the first stem cell transplantation (SCT1). We analyzed the outcomes of 52 adult AML patients who received SCT2 from haploidentical donors (HIT, N = 32) and double-cord blood (dCBT, N = 20) between 2008 and 2021. The HIT group received T-cell-replete peripheral blood stem cells after reduced-toxicity conditioning with anti-thymocyte globulin (ATG), while the dCBT group received myeloablative conditioning. For a median follow-up of 64.9 months, the HIT group, compared to the dCBT group, had earlier engraftment, superior 2-year overall survival (OS), disease-free survival (DFS), and non-relapse mortality (NRM) with similar relapse. Multivariate analysis demonstrated that HIT was significantly associated with better OS, DFS, and lower NRM than dCBT. Both longer remission duration after SCT1 and complete remission at SCT2 were significantly associated with a lower relapse rate. In addition, bone marrow WT1 measurable residual disease (MRD) positivity was significantly associated with inferior OS and higher relapse. This study suggests that T-cell-replete HIT with ATG-based GVHD prophylaxis may be preferred over dCBT as SCT2 for relapsed AML and that WT1-MRD negativity may be warranted for better SCT2 outcomes.