Effectiveness of T-Cell Replete Haploidentical Hematopoietic Stem Cell Transplantation for Refractory/Relapsed B Cell Acute Lymphoblastic Leukemia in Children and Adolescents

Haploidentical hematopoietic stem cell transplantation as promising therapy in the improved survival of pediatric patients with leukemias and myelodysplasias

BACKGROUND

Haploidentical hematopoietic stem cell transplantation (Haplo-HSCT) is often performed in children with hematologic malignancies. Faced with the gap in the literature regarding the approach to experiences related to Haplo-HSCT with pediatric patients with leukemias and myelodysplasias aged up to 18 years, there was an interest in exploring the clinical outcomes of patients undergoing this treatment.

AIM

To identify and summarize the scientific contributions available on Haplo-HSCT performed in the last 10 years in children and adolescents with myeloid and lymphoid leukemias and myelodysplasias, aged up to 18 years.

METHODS

This is a descriptive systematic review. We extracted data including characteristics of participants, health condition, characteristics of the donation, conditioning regimen, recurrent clinical complications and clinical outcomes. The Virtual Health Library Brazil, PubMed, EMBASE, and SciELO platforms were used, finding a total of 1052 studies. After the eligibility criteria and complete reading of the texts, 18 articles were included for analysis.

RESULTS

The total sample of all study cohorts was 1825 patients, mostly male, the highest reported median age was 15.0 years and the lowest was 1.2 years. Acute graft-versus-host disease and chronic graft-versus-host disease were observed in almost all studies. Relapse, graft rejection and delayed immune recovery were identified as major clinical challenges. Pre-transplant minimal positive residual disease was identified in 288 patients. Infections are also among the main clinical complications, viral, bacterial and fungal infections being reported. It is observed that in the 5-year interval, the lowest rates of EFS and overall survival (OS) were 29.5% and 68.0%, respectively. While, the highest rates of EFS and OS, in the same interval, were 80.1% and 81.0%.

CONCLUSION

Haplo-HSCT represents a promising therapy, considering the potential number of possible donors and the conditioning and treatment platforms that can be offered. The results obtained show that this type of transplant has a strong antileukemic effect, with generally favorable OS rates. Overcoming relapse as the first cause of transplant failure is the great clinical challenge.

T-Cell-Replete Haploidentical Hematopoietic Stem Cell Transplantation for a Patient With Tcf3-Hlf-Positive Acute Lymphoblastic Leukemia Extramedullary Relapse After Unrelated Bone Marrow Transplantation

TCF3-HLF-positive B-cell precursor acute lymphoblastic leukemia (BCP-ALL) has an extremely poor prognosis. A 2-year-old boy with TCF3-HLF-positive BCP-ALL had an isolated extramedullary relapse in multiple bones after allogeneic hematopoietic stem cells transplantation (HSCT) from a human leukocyte antigen-matched unrelated donor. In this study, he received a T-cell-replete haploidentical HSCT (TCR-haplo-HSCT) from his father when in nonremission state, which resulted in a sustained complete remission for over 3 years. Immune therapies for patients with an extramedullary relapse of TCF3-HLF-positive BCP-ALL have been attempted; however, long-term efficacies of these therapies remain unknown. Our TCR-haplo-HSCT may be an effective therapeutic option for such patients.

Evaluation of a quantitative PCR-based method for chimerism analysis of Japanese donor/recipient pairs

Chimerism analysis is a surrogate indicator of graft rejection or relapse after allogeneic hematopoietic stem cell transplantation (HSCT). Although short tandem repeat PCR (STR-PCR) is the usual method, limited sensitivity and technical variability are matters of concern. Quantitative PCR-based methods to detect single nucleotide polymorphisms (SNP-qPCR) are more sensitive, but their informativity and quantitative accuracy are highly variable. For accurate and sensitive chimerism analysis, a set of KMR kits (GenDx, Utrecht, Netherlands), based on detection of insertions/deletions (indels) by qPCR, have been developed. Here, we investigated informativity and validated the accuracy of KMR kits in Japanese donor/recipient pairs and virtual samples of DNA mixtures representative of Japanese genetic diversity. We found that at least one recipient-specific marker among 39 KMR-kit markers was informative in all of 65 Japanese donor/recipient pairs. Moreover, the percentage of recipient chimerism estimated by KMRtrack correlated well with ratios of mixed DNA in virtual samples and with the percentage of chimerism in HSCT recipients estimated by STR-PCR/in-house SNP-qPCR. Moreover, KMRtrack showed better sensitivity with high specificity when compared to STR-PCR to detect recipient chimerism. Chimerism analysis with KMR kits can be a standardized, sensitive, and highly informative method to evaluate the graft status of HSCT recipients.