A prospective multicenter phase II study of intrabone marrow transplantation of unwashed cord blood using reduced-intensity conditioning

Umbilical cord blood derived cellular therapy: advances in clinical development

While cord blood (CB) is primarily utilized in allogeneic hematopoietic cell transplantation (HCT), the development of novel cell therapy products from CB is a growing and developing field. Compared to adult blood, CB is characterized by a higher percentage of hematopoietic stem cells (HSCs) and progenitor cells, less mature immune cells that retain a high capacity of proliferation, and stronger immune tolerance that requires less stringent HLA-matching when used in the allogenic setting. Given that CB is an FDA regulated product and along with its unique cellular composition, CB lends itself as a readily available and safe starting material for the development of off-the-shelf cell therapies. Moreover, non-hematologic cells such as mesenchymal stem cell (MSCs) residing in CB or CB tissue also have potential in regenerative medicine and inflammatory and autoimmune conditions. In this review, we will focus on recent clinical development on CB-derived cellular therapies in the field of oncology, including T-cell therapies such as chimeric antigen receptor (CAR) T-cells, regulatory T-cells, and virus-specific T-cells; NK-cell therapies, such as NK cell engagers and CAR NK-cells; CB-HCT and various modifications; as well as applications of MSCs in HCT.

Magnetically empowered bone marrow cells as a micro-living motor can improve early hematopoietic reconstitution

BACKGROUND AIMS

Bone marrow-derived hematopoietic stem cell transplantation/hematopoietic progenitor cell transplantation (HSCT/HPCT) is widely used and one of the most useful treatments in clinical practice. However, the homing rate of hematopoietic stem cells/hematopoietic progenitor cells (HSCs/HPCs) by routine cell transfusion is quite low, influencing hematopoietic reconstitution after HSCT/HPCT.

METHODS

The authors developed a micro-living motor (MLM) strategy to increase the number of magnetically empowered bone marrow cells (ME-BMCs) homing to the bone marrow of recipient mice.

RESULTS

In the in vitro study, migration and retention of ME-BMCs were greatly improved in comparison with non-magnetized bone marrow cells, and the biological characteristics of ME-BMCs were well maintained. Differentially expressed gene analysis indicated that ME-BMCs might function through gene regulation. In the in vivo study, faster hematopoietic reconstitution was observed in ME-BMC mice, which demonstrated a better survival rate and milder symptoms of acute graft-versus-host disease after transplantation of allogeneic ME-BMCs.

CONCLUSIONS

This study demonstrated that ME-BMCs serving as MLMs facilitated the homing of HSCs/HPCs and eventually contributed to earlier hematopoietic reconstitution in recipients. These data might provide useful information for other kinds of cell therapies.

Phase I study of intra-osseous co-transplantation of a single-unit cord blood and mesenchymal stromal cells with reduced intensity conditioning regimens

Cord blood (CB) is a valuable graft source for patients undergoing allogeneic hematopoietic cell transplant (HCT) who lack human leukocyte antigen (HLA)-matched donors. However, single-unit CB-HCT is limited by the insufficient cell dose and slow engraftment. To overcome these limitations, we combined a single-unit CB with third-party healthy donors' bone marrow (BM) derived mesenchymal stromal cells (MSCs) to improve engraftment and injected intra-osseously (IO) to enhance homing. In this phase I clinical trial, six patients with high-risk hematologic malignancies were enrolled and received allogeneic HCT using reduced intensity conditioning regimens. The primary objective was to determine the engraftment rate at day 42. The median age of enrolled patients was 68 years, and only one patient was in complete remission at the time of HCT. The median CB total nucleated cell dose was 3.2x10⁷/kg. No serious adverse events were reported. Two patients had early deaths due to persistent disease and multi-drug resistant bacterial infection, respectively. Of the remaining four evaluable patients, all had successful neutrophil engraftment in a median of 17.5 days. No grade 3 or higher acute graft-versus-host disease (GvHD) was observed, and only one patient developed moderate-extensive chronic GvHD. In conclusion, IO co-transplantation of a single-unit CB and MSCs was feasible and resulted in a reasonable engraftment rate in these very high-risk patients.

Differential CXCR4 expression on hematopoietic progenitor cells versus stem cells directs homing and engraftment

Gene therapy involves a substantial loss of hematopoietic stem and progenitor cells (HSPC) during processing and homing. Intra-BM (i.b.m.) transplantation can reduce homing losses, but prior studies have not yielded promising results. We studied the mechanisms involved in homing and engraftment of i.b.m. transplanted and i.v. transplanted genetically modified (GM) human HSPC. We found that i.b.m. HSPC transplantation improved engraftment of hematopoietic progenitor cells (HPC) but not of long-term repopulating hematopoietic stem cells (HSC). Mechanistically, HPC expressed higher functional levels of CXCR4 than HSC, conferring them a retention and homing advantage when transplanted i.b.m. Removing HPC and transplanting an HSC-enriched population i.b.m. significantly increased long-term engraftment over i.v. transplantation. Transient upregulation of CXCR4 on GM HSC-enriched cells, using a noncytotoxic portion of viral protein R (VPR) fused to CXCR4 delivered as a protein in lentiviral particles, resulted in higher homing and long-term engraftment of GM HSC transplanted either i.v. or i.b.m. compared with standard i.v. transplants. Overall, we show a mechanism for why i.b.m. transplants do not significantly improve long-term engraftment over i.v. transplants. I.b.m. transplantation becomes relevant when an HSC-enriched population is delivered. Alternatively, CXCR4 expression on HSC, when transiently increased using a protein delivery method, improves homing and engraftment specifically of GM HSC.

Intrabone transplantation of CD34+ cells with optimized delivery does not enhance engraftment in a rhesus macaque model

Intrabone (IB) injection of umbilical cord blood has been proposed as a potential mechanism to improve transplant engraftment and prevent graft failure. However, conventional IB techniques produce low retention of transplanted cells in the marrow. To overcome this barrier, we developed an optimized IB (OIB) injection method using low-volume, computer-controlled slow infusion that promotes cellular retention in the marrow. Here, we compare engraftment of CD34+ cells transplanted in a myeloablative rhesus macaque (RM) model using the OIB method compared with IV delivery. RM CD34+ cells obtained by apheresis were split equally for transduction with lentiviral vectors encoding either green fluorescent protein or yellow fluorescent protein reporters. Following conditioning, one marked autologous population of CD34+ cells was injected directly IB using the OIB method and the other was injected via slow IV push into the same animal (n = 3). Daily flow cytometry of blood quantified the proportion of engrafting cells deriving from each source. Marrow retention was examined using positron emission tomography/computed tomography imaging of 89Zirconium (89Zr)-oxine-labeled CD34+ cells. CD34+ cells injected via the OIB method were retained in the marrow and engrafted in all 3 animals. However, OIB-transplanted progenitor cells did not engraft any faster than those delivered IV and contributed significantly less to hematopoiesis than IV-delivered cells at all time points. Rigorous testing of our OIB delivery system in a competitive RM myeloablative transplant model showed no engraftment advantage over conventional IV infusion. Given the increased complexity and potential risks of IB vs IV approaches, our data do not support IB transplantation as a strategy to improve hematopoietic engraftment.

Muscle oxygen extraction and lung function are related to exercise tolerance after allogeneic hematopoietic stem cell transplantation

PURPOSE

This study aimed to investigate the relationship between exercise intolerance, muscle oxidative metabolism, and cardiopulmonary function following allogeneic hematopoietic stem cell transplantation (allo-HSCT) in a sterile isolation room setting.

METHODS

This was a prospective observational cohort study conducted in a single center. Fourteen patients with hematopoietic malignancies who had undergone allo-HSCT were included in this study from June 2015 to April 2020. Patients received donor HSCT after high dose-chemotherapy and total-body irradiation. Physical activity was limited during treatments. Outcome measures included body anthropometric measurements, exercise tolerance tests using the ramp protocol, pulmonary function tests, and near-infrared spectroscopy (NIRS) measurements. Data of pre- and posttransplant measurements were compared using the paired t test or nonparametric Wilcoxon U test. Associations were assessed using the Pearson or nonparametric Spearman correlations.

RESULTS

NIRS showed reduced muscle consumption and extraction of oxygen in the posttransplant period compared to the pretransplant period (ΔStO_{2 min} pre: -18.6% vs. post: -13.0%, P = 0.04; ΔHHb _max pre: 4.21μmol/l vs. post: 3.31μmol/l: P = 0.048). Exercise tolerance had reduced following allo-HSCT (Peak workload pre: 70.3 W vs. post: 58.0 W: P = 0.014). Furthermore, exercise intolerance was associated with pulmonary function, muscle oxygen consumption, and muscle oxygen extraction (all P <0.05).

CONCLUSION

This analysis revealed that exercise intolerance following allo-HSCT was associated with pulmonary dysfunction and muscle oxidative dysfunction. These findings could help identify the physical function associated with impaired tissue oxygen transport leading to exercise intolerance following allo-HSCT.

A multicenter phase II study of intrabone single-unit cord blood transplantation without antithymocyte globulin

To overcome the delayed or failed engraftment after unrelated cord blood transplantation (CBT), we conducted a multicenter phase II study of intrabone single-unit CBT without antithymocyte globulin (ATG) for adult patients with hematological malignancies (UMIN-CTR, UMIN000020997). Sixty-four patients received an intrabone injection of unwashed (n = 61) or washed (n = 3) cord blood after local anesthesia. All injection-related adverse events were mild and resolved spontaneously. Sixty-two patients were evaluable for the efficacy of intrabone CBT of serological HLA-A, -B, and -DR ≥ 4/6 matched cord blood with a median number of 2.57 × 10⁷/kg cryopreserved total nucleated cells. The probability of survival with neutrophil engraftment on day 28 was 77.4% (95% confidence interval, 67.0-85.8%), which exceeded the threshold value. The cumulative incidences of neutrophils ≥ 0.5 × 10⁹/L on day 60 was 80.6% (68.2-88.6%), with a median time to recovery of 21 days after transplantation. The cumulative incidences of platelets ≥ 20 × 10⁹/L and platelets ≥ 50 × 10⁹/L on day 100 were 75.8% (62.6-84.9%) and 72.6% (59.4-82.1%), respectively, with median time to platelets ≥ 20 × 10⁹/L and platelets ≥ 50 × 10⁹/L of 38 and 45 days after transplantation, respectively. The cumulative incidences of grade II-IV and III-IV acute graft-versus-host disease were 29.0% and 6.5%, respectively. All responded to steroid therapy, and secondary treatments were not required. The present study suggests the efficacy of intrabone single-unit CBT without ATG in terms of early engraftment and controllable acute graft-versus-host disease.

Geriatric nutritional risk index as a useful prognostic factor in second allogeneic hematopoietic stem cell transplantation

Second allogeneic hematopoietic stem cell transplantation (allo-HSCT) has a low survival outcome and a high non-relapse mortality (NRM) rate which is a major obstacle to this treatment. We hypothesized that the status of malnourishment after first allo-HSCT as represented by the geriatric nutritional risk index (GNRI) could be used as a prognostic factor to determine the outcomes of second allo-HSCT. A total of 108 patients with a median age of 42 (range, 17-69) years, who received second allo-HSCT for disease recurrence after first allo-HSCT from our institution, were included in this study. Low GNRI had a significant impact on NRM at 2 years after second allo-HSCT: 56.9% in patients with GNRI ≤ 92 compared with 27.5% in patients with GNRI > 92 (P = 0.002). In multivariate analysis, GNRI of ≤ 92 was the only significant factor for NRM (hazard ratio [HR] 2.29, 95% confidence interval [CI] 1.15-4.56, P = 0.018). High-risk disease status at second allo-HSCT (HR 2.74, 95% CI 1.46-5.14, P = 0.002) and GNRI of ≤ 92 (HR 1.70, 95% CI 1.02-2.82, P = 0.042) were identified as significant factors for overall survival (OS). A score of 1 was assigned to each factor, and the OS rate at 2 years after second allo-HSCT decreased according to the score: 53.0% in patients with score 0, 32.3% with score 1, and 2.5% with score 2 (P < 0.001). In conclusion, GNRI could be a useful predictor for the outcomes of second allo-HSCT. A prospective study in other cohorts is warranted to validate the findings of our study.