Eleven secondary cancers after hematopoietic stem cell transplantation using a total body irradiation-based regimen in 370 consecutive pediatric and adult patients

The impacts of total body irradiation on umbilical cord blood hematopoietic stem cell transplantation

Background

Umbilical cord blood hematopoietic stem cells are commonly used for hematopoietic system reconstitution in recipients after umbilical cord blood transplantation (UCBT). However, the optimal conditioning regimen for UCBT remains a topic of debate. The exact impact of total body irradiation (TBI) as a part of conditioning regimens remains unknown.

Objectives

The aim of this study was to evaluate the impacts of TBI on UCBT outcomes.

Design

This was a multi-institution retrospective study.

Methods

A retrospective analysis was conducted on the outcomes of 136 patients receiving UCBT. Sixty-nine patients received myeloablative conditioning (MAC), in which 33 underwent TBI and 36 did not, and 67 patients received reduced-intensity conditioning (RIC), in which 43 underwent TBI and 24 did not. Univariate and multivariate analyses were conducted to compare the outcomes and the post-transplant complications between patients who did and did not undergo TBI in the MAC subgroup and RIC subgroup, respectively.

Results

In the RIC subgroup, patients who underwent TBI had superior overall survival (adjusted hazard ratio [aHR] = 0.25, 95% confidence interval [CI]: 0.09-0.66, p = 0.005) and progression-free survival (aHR = 0.26, 95% CI: 0.10-0.66, p = 0.005). However, in the MAC subgroup, there were no statistically significant differences between those receiving and not receiving TBI.

Conclusion

In the setting of RIC in UCBT, TBI utilization can improve overall survival and progression-free survival. However, TBI does not show superiority in the MAC setting.

Effective T-cell replete haploidentical stem cell transplantation for pediatric patients with high-risk hematologic disorders

OBJECTIVES

Patients with high-risk hematologic diseases require intensive modalities, including high-dose chemotherapy and allogeneic hematopoietic stem cell transplantation (allo-HSCT). Haploidentical T-cell-replete transplantation is a logical choice because of the limited availability of matched sibling donors and the prolonged time needed to identify matched unrelated donors in Thailand.

METHODS

The clinical outcomes data of 43 patients undergoing allo-HSCT were reviewed. All patients had high-risk hematologic malignancies, were younger than 20 years, and were in complete cytological remission at the time of allo-HSCT. We used two different conditioning regimens: total body irradiation (TBI) combined with cyclophosphamide, fludarabine, and melphalan (n = 23) and thiotepa combined with fludarabine and busulfan (n = 20). All patients received a graft-versus-host disease prophylaxis regimen consisting of cyclophosphamide, mycophenolate mofetil, and a calcineurin inhibitor or sirolimus.

RESULTS

There was no difference in engraftment between patients receiving either of the regimens. After a median follow-up of 35.8 (range, 0.6-106.2) months, the overall survival (OS) and event-free survival (EFS) rates were 62.4% and 54.7%, respectively. OS and EFS were comparable between the respective regimens.

CONCLUSIONS

We conclude that thiotepa-based conditioning has similar efficacy and tolerability as TBI-based conditioning for haploidentical HSCT with post-transplant cyclophosphamide.

Non-genotoxic conditioning facilitates hematopoietic stem cell gene therapy for hemophilia A using bioengineered factor VIII

Hematopoietic stem and progenitor cell (HSPC) lentiviral gene therapy is a promising strategy toward a lifelong cure for hemophilia A (HA). The primary risks associated with this approach center on the requirement for pre-transplantation conditioning necessary to make space for, and provide immune suppression against, stem cells and blood coagulation factor VIII, respectively. Traditional conditioning agents utilize genotoxic mechanisms of action, such as DNA alkylation, that increase risk of sterility, infection, and developing secondary malignancies. In the current study, we describe a non-genotoxic conditioning protocol using an immunotoxin targeting CD117 (c-kit) to achieve endogenous hematopoietic stem cell depletion and a cocktail of monoclonal antibodies to provide transient immune suppression against the transgene product in a murine HA gene therapy model. This strategy provides high-level engraftment of hematopoietic stem cells genetically modified ex vivo using recombinant lentiviral vector (LV) encoding a bioengineered high-expression factor VIII variant, termed ET3. Factor VIII procoagulant activity levels were durably elevated into the normal range and phenotypic correction achieved. Furthermore, no immunological rejection or development of anti-ET3 immunity was observed. These preclinical data support clinical translation of non-genotoxic antibody-based conditioning in HSPC LV gene therapy for HA.

Malignancy post-hematopoietic stem cell transplant in patients with primary immunodeficiency

INTRODUCTION

Hematopoietic cell transplantation (HCT) is a curative treatment for an expanding number of primary immunodeficiencies (PIDs). Malignancies are more common in patients with PID than in the general population, and this review will discuss whether a successful HCT is expected to abolish or alter this risk. Second malignancy post HCT for a malignant disease is well known to occur, but generally less expected in patients transplanted for PID.

AREAS COVERED

This article reviews recently published literature focusing on the pattern of malignancy in children with PID, incidence, and risk factors for developing malignancy post-HCT for PID and possible strategies to reduce the risks.

EXPERT OPINION

Survival post HCT for PID has improved dramatically in the last 20 years and the genomic revolution has led to an expanding number of indications. To improve long-term quality of life attention needs to focus on late effects, including the possibility of malignancy occurring more frequently than expected in the general population, understand the risks and improve the process of transplantation in order to minimize them. Further studies are needed.

Once-a-day fractionated total-body irradiation: A regimen tailored to local logistics in allogeneic stem cell transplantation for acute lymphoblastic leukemia

Aim

The objective of the study was to estimate the cumulative incidence (CI) of relapse, relapse-free survival (RFS) and overall survival (OS) in ALL patients after a once-a-day fractionated TBI (F-TBI) regimen with 9.9 Gy. The secondary objectives were evaluation of short and long-term toxicity and non-relapse mortality (NRM).

Background

Total body irradiation (TBI), as a part of the conditioning regimen before allogeneic stem cell transplantation (ASCT) for acute lymphoblastic leukemia (ALL), allows disease control by eradicating residual blast cells in the transplant recipient.

Materials and methods

Retrospective study conducted in patients with ALL who received between March 2003 and December 2013 a conditioning regimen with F-TBI and chemotherapy. Irradiation was delivered with 3.3 Gy once-a-day for three consecutive days.

Results

Eighty-seven patients were included. The median age was 19 years (range: 5-49 years). The 3-year CI of relapse was 30%. The estimated 3-year RFS and OS were 54% and 58%, respectively. Cumulative incidence of acute graft-versus-host disease (aGVHD) grade II-IV and chronic GVHD (cGVHD) was 31% and 40%, respectively. Interstitial pneumonitis was observed in 2 patients. The 3-year CI of NRM was 16%. In multivariate analysis, cGVHD was associated with a lower CI of relapse (RR = 0.26, 95% CI: 0.07-0.95, p = 0.04). High-risk cytogenetics was associated with a lower RFS (RR = 2, 95 CI: 1.04-3.84, p = 0.03). Grade II-IV aGVHD was an independent predictor of higher CI of NRM (RR = 6.7, 95% CI: 1.4-31.7, p = 0.02).

Conclusions

Once-a-day F-TBI regimen is effective, safe and practical in patients who underwent ASCT for ALL.

Current Status and Perspectives of Irradiation-Based Conditioning Regimens for Patients with Acute Leukemia Undergoing Hematopoietic Stem Cell Transplantation

Acute myeloid leukemia and acute lymphoblastic leukemia are the most common indications for allogeneic hematopoietic stem cell transplantation. Total body irradiation (TBI) is an important part of conditioning regimens. TBI-based regimens offer advantages in sanctuary sites but are associated with significant risks of early and late side effects, including pulmonary toxicity, growth retardation, and second malignancy. TBI is also associated with technical problems, such as dose heterogeneity. With evolving techniques in radiation oncology, it is possible to focus the dose to the entire skeleton while sparing the rest of the body. This technique is called total marrow irradiation (TMI). TMI is able to deliver the same or higher doses to bone marrow while reducing toxicity. With the success of TMI, we are moving toward ultra-personalized conditioning. We review the clinical role of the irradiation-based regimens currently in clinical use, emphasizing on their strengths and limitations. Novel technologies with targeted irradiation accompanied by the modern imaging techniques and increased knowledge of the disease process can help us achieve our goal of maximum response with minimum toxicity.

National Institutes of Health Hematopoietic Cell Transplantation Late Effects Initiative: The Subsequent Neoplasms Working Group Report

Subsequent neoplasms (SN) after hematopoietic cell transplantation (HCT) cause significant patient morbidity and mortality. Risks for specific SN types vary substantially, with particularly elevated risks for post-transplantation lymphoproliferative disorders, myelodysplastic syndrome/acute myeloid leukemia, and squamous cell malignancies. This document provides an overview of the current state of knowledge regarding SN after HCT and recommends priorities and approaches to overcome challenges and gaps in understanding. Numerous factors have been suggested to affect risk, including patient-related (eg, age), primary disease-related (eg, disease type, pre-HCT therapies), and HCT-related characteristics (eg, type and intensity of conditioning regimen, stem cell source, development of graft-versus-host disease). However, gaps in understanding remain for each of these risk factors, particularly for patients receiving HCT in the current era because of substantial advances in clinical transplantation practices. Additionally, the influence of nontransplantation-related risk factors (eg, germline genetic susceptibility, oncogenic viruses, lifestyle factors) is poorly understood. Clarification of the magnitude of SN risks and identification of etiologic factors will require large-scale, long-term, systematic follow-up of HCT survivors with detailed clinical data. Most investigations of the mechanisms of SN pathogenesis after HCT have focused on immune drivers. Expansion of our understanding in this area will require interdisciplinary laboratory collaborations utilizing measures of immune function and availability of archival tissue from SN diagnoses. Consensus-based recommendations for optimal preventive, screening, and therapeutic approaches have been developed for certain SN after HCT, whereas for other SN, general population guidelines are recommended. Further evidence is needed to specifically tailor preventive, screening, and therapeutic guidelines for SN after HCT, particularly for unique patient populations. Accomplishment of this broad research agenda will require increased investment in systematic data collection with engagement from patients, clinicians, and interdisciplinary scientists to reduce the burden of SN in the rapidly growing population of HCT survivors.