Depletion of αβ+ T cells for a haploidentical hematopoietic stem cell transplantation in children

Immunological recovery following HLA-matched CD3+ TCR αß+/CD19+ depleted hematopoietic stem cell transplantation in children

BACKGROUND

Allogeneic hematopoietic stem cell transplantation (HSCT) is a potentially curative option for children with both malignant and nonmalignant diseases. T-cell depletion techniques may result in reduced transplant-related mortality compared with unmanipulated grafts due to a lower incidence of GvHD.

METHODS

Immune recovery and outcome were analyzed in a cohort of 23 patients with malignant and nonmalignant diseases who received CD3+TCRαβ+ T- and B-cell-depleted allografts from matched donors after reduced-intensity or myeloablative conditioning. The median number of CD34+, CD3+TCRαβ+, and CD19+B-cells infused was 12.7 × 10⁶ /kg, 16.8 × 10³ /kg, and 96 × 10³ /kg bodyweight.

RESULTS

With a median follow-up of 36 (range 1-73) months, overall survival and disease-free survival at 3 years were 65.2% and 60.8%. Eight patients died, six due to the underlying disease and two of extended visceral cGvHD. Immune reconstitution, disease-free, and overall survivals were similar compared with a historical cohort of 23 patients transplanted with matched unmanipulated bone marrow. A significant lower rate of higher grade (III-IV) aGvHD was observed in the manipulated HSCT group (8.7% vs. 26%; p = 0.001), whereas the incidence of cGvHD was equal.

CONCLUSIONS

Our data suggest that this graft manipulation strategy could be a safe and effective alternative to conventional HSCT techniques in matched donors.

Improved outcomes using unmanipulated haploidentical hematopoietic stem cells combined with third-party umbilical cord blood transplantation for non-malignant diseases in children: The experience of a single center

BACKGROUND

Unmanipulated haploid HSCT for SAA has resulted in improved outcomes over recent years. However, studies related to unmanipulated haploid HSCs combined with tp-UCB transplantation for other types of NMD are rare. Accordingly, we present the outcomes of 109 pediatric patients with life-threatening NMD undergoing unmanipulated haploid HSCs combined with tp-UCB transplantation.

PROCEDURE

We retrospectively investigated 109 pediatric patients with life-threatening NMD treated with unmanipulated haploid HSCs combined with tp-UCB transplantation in a single center.

RESULTS

The median days of neutrophil and platelet engraftment were +13 and +22 days, respectively. None of the cases experienced PGF. The incidence rates for grade I-II, III-IV aGVHD and cGVHD were 44.9%, 24.8%, and 9.3%, respectively. The incidence rates of CMV and EBV viremia were 46.7% and 39.4%, respectively. The median follow-up duration was 997 days. In total, 106 patients survived, including 104 cases with FFS and 2 cases with SGF. Three patients died. The 5-year TRM, OS, and FFS were 2.8%, 97.2%, and 96.2%, respectively.

CONCLUSION

The results of unmanipulated haploid HSCs combined with tp-UCB in pediatric patients with life-threatening NMD were promising. However, further research is now needed to determine specific factors that might influence the engraftment of HSCs.

The BTLA and PD-1 signaling pathways independently regulate the proliferation and cytotoxicity of human peripheral blood γδ T cells

Background

B‐ and T‐lymphocyte attenuator (BTLA) and programmed cell death‐1 (PD‐1) inhibit γδ T cell homeostasis and activation. This study aimed to determine whether BTLA and PD‐1 signaling pathways were convergent or independent in human peripheral blood γδ T cells. Herein we demonstrate that the signalings of BTLA and PD‐1 regulated proliferation and cytotoxicity of human γδ T cells, respectively.

Methods

Human peripheral blood γδ T cells were cultured with inactivated Jurkat cells in the presence of interleukin‐2 and zoledronate (Zol) for 14 days. Flow cytometry was performed to evaluate the phenotypes and functions of γδ T cells.

Results

The proliferation of the γδ T cells was increased when PBMCs were cocultured with inactivated herpes virus entry mediator (HVEM)^low Jurkat cells. The cytotoxicity of the expanded γδ T cells was not affected by coculture with inactivated HVEM^low Jurkat cells and was further increased in the presence of anti‐PD‐L1 mAb. These results suggest that the inactivation of the BTLA signaling pathway during expansion could help produce more γδ T cells without compromising γδ T cell function. The inhibition of BTLA or PD‐1 signaling repressed phosphorylation of the src homology region 2‐containing protein tyrosine phosphatase 2 and increased the phosphorylation of protein kinase B in γδ T cells. However, there were no synergistic or additive effects by a combination of BTLA and PD‐1 blockade.

Conclusion

These results suggest that BTLA signaling is crucial in regulating γδ T cell proliferation and function and that the BTLA and PD‐1 signaling pathways act independently on the proliferation and cytotoxicity of human peripheral γδ T cells.

Haploidentical transplantation in pediatric non-malignant diseases: A retrospective analysis on behalf of the Spanish Group for Hematopoietic Transplantation (GETH)

OBJECTIVE

Describe the GETH haploidentical stem cell transplantation (haplo-HSCT) activity in non-malignant disease (NMDs).

METHODS

We retrospectively analyzed data from children with NMDs who underwent haplo-HSCT.

RESULTS

From January 2001 to December 2016, 26 pediatric patients underwent 31 haplo-HSCT through ex vivo T cell-depleted (TCD) graft platforms or post-transplantation cyclophosphamide (PT-Cy) at 7 Spanish centers. Five cases employed unmanipulated PT-Cy haplo-HSCT, 16 employed highly purified CD34⁺ cells, and 10 employed ex vivo TCD grafts manipulated either with CD3⁺ CD19⁺ depletion, TCRαβ⁺ CD19⁺ selection or naive CD45RA⁺ T-cell depletion. Peripheral blood stem cells were the sole source for patients following TCD haplo-HSCT, and bone marrow was the source for one PT-Cy haplo-HSCT. The most common indications for transplantation were primary immunodeficiency disorders (PIDs), severe aplastic anemia, osteopetrosis, and thalassemia. The 1-year cumulative incidence of graft failure was 27.4%. The 1-year III-IV acute graft-versus-host disease (GvHD) and 1-year chronic GvHD rates were 34.6% and 16.7%, respectively. The 2-year overall survival was 44.9% for PIDs, and the 2-year graft-versus-host disease-free and relapse-free survival rate was 37.6% for the other NMDs. The transplantation-related mortality at day 100 was 30.8%.

CONCLUSION

Although these results are discouraging, improvements will come if procedures are centralized in centers of expertise.

Depletion of αβ+ T and B Cells Using the CliniMACS Prodigy: Results of 10 Graft-Processing Procedures from Haploidentical Donors

Background

Depletion of TCRαβ+ T cells and B cells with the CliniMACS Plus® has been used for haploidentical hematopoietic stem cell transplantation for a decade. The depletion procedure is time and labour demanding and with variable reported efficiencies. Recently, an automated procedure was launched for the CliniMACS Prodigy® (Miltenyi Biotec) but reported data are scarce. Here, we report the results of the first ten TCRαβ+ and B cell depletion procedures for clinical use performed at our centre.

Materials and Methods

All transplants were from a parent to a child. Collection of peripheral blood stem cells was performed after filgrastim mobilisation by use of the Spectra Optia® (TerumoBCT) set on the MNC program. Because of insufficient hematopoietic stem cell mobilisation, 1 donor received additional plerixafor.

Results

We performed ten uncomplicated processes with the CliniMACS Prodigy. We found the results of the depletion procedures satisfactory with a median log reduction of TCRαβ+ cells of -4.21 (range -3.98 to -4.74), resulting in a median number of TCRαβ+ cells in the depleted product of 28.6 × 10³/kg recipient weight (range 14.9-69.7 × 10³/kg). The median CD34 recovery was 83% (range 70-100). To achieve a sufficient number of CD34+ cells, we performed an additional CD34+ enrichment procedure using the CliniMACS Plus for 3 patients. The B cell depletion was slightly less efficient with a median log reduction of -3.72 (range -2.83 to -4.20).

Conclusion

Overall, we found the TCRαβ and CD19 depletion procedure on the CliniMACS Prodigy easy to handle and reliable, providing reproducible good results.

Comparable Outcome with a Faster Engraftment of Optimized Haploidentical Hematopoietic Stem Cell Transplantation Compared with Transplantations from Other Donor Types in Pediatric Acquired Aplastic Anemia

Haploidentical family donors have been used as an alternative source in hematopoietic cell transplantation for patients with severe aplastic anemia. We evaluated and compared the outcomes of transplantation in pediatric acquired severe aplastic anemia based on donor type. Sixty-seven patients who underwent transplantation between 1998 and 2017 were included. Fourteen patients received grafts from matched sibling donors, 21 from suitable unrelated donors, and 32 from haploidentical family donors. Ex vivo CD3⁺ or αβ⁺ T cell-depleted grafts were used for haploidentical transplantation. Sixty-five patients (97.0%) achieved neutrophil engraftment at a median of 11 days. Haploidentical transplantation resulted in significantly faster neutrophil engraftment at a median of 10 days, compared with 14 days in cases of matched sibling donors and 12 days in cases of unrelated donor recipients. Nine patients experienced graft failure, and 5 of 7 who underwent a second transplantation are alive. There was no difference in the incidence of acute or chronic graft-versus-host disease based on donor type. The 5-year overall survival and failure-free survival rates were 93.8% ± 3.0% and 83.3% ± 4.6%, respectively, and there was no significant survival difference based on donor type. The survival outcomes of haploidentical transplantation in patients were comparable with those of matched sibling or unrelated donor transplantation. Optimized haploidentical transplantation using selective T cell depletion and conditioning regimens including low-dose total body irradiation for enhancing engraftment may be a realistic therapeutic option for pediatric patients with severe aplastic anemia.