Use of alternative donors for allogeneic stem cell transplantation

Novel genetic therapeutic approaches for modulating the severity of β-thalassemia (Review)

Thalassemia is a genetic haematological disorder that arises due to defects in the α and β-globin genes. Worldwide, 0.3-0.4 million children are born with haemoglobinopathies per year. Thalassemic patients, as well as their families, face various serious clinical, socio-economic, and psychosocial challenges throughout their life. Different therapies are available in clinical practice to minimize the suffering of thalassemic patients to some extent and potentially cure the disease. Predominantly, patients undergo transfusion therapy to maintain their haemoglobin levels. Due to multiple transfusions, the iron levels in their bodies are elevated. Iron overload results in damage to body organs, resulting in heart failure, liver function failure or endocrine failure, all of which are commonly observed. Certain drugs have been developed to enhance the expression of the γ-gene, which ultimately results in augmentation of fetal haemoglobin (HbF) levels and total haemoglobin levels in the body. However, its effectiveness is dependent on the genetic makeup of the individual patient. At present, allogeneic haematopoietic Stem Cell Transplantation (HSCT) is the only practically available option with a high curative rate. However, the outcome of HSCT is strongly influenced by factors such as age at transplantation, irregular iron chelation history before transplantation, histocompatibility, and source of stem cells. Gene therapy using the lentiglobin vector is the most recent method for cure without any mortality, graft rejection and clonal dominance issues. However, delayed platelet engraftment is being reported in some patients. Genome editing is a novel approach which may be used to treat patients with thalassemia; it makes use of targeted nucleases to correct the mutations in specific DNA sequences and modify the sequence to the normal wild-type sequence. To edit the genome at the required sites, CRISPR/Cas9 is an efficient and accurate tool that is used in various genetic engineering programs. Genome editing mediated by CRISPR/Cas9 has the ability to restore the normal β-globin function with minimal side effects. Using CRISPR/Cas9, expression of BCL11A can be downregulated along with increased production of HbF. However, these genome editing tools are still under in-vitro trials. CRISPR/Cas9 has can be used for precise transcriptional regulation, genome modification and epigenetic editing. Additional research is required in this regard, as CRISPR/Cas9 may potentially exhibit off-target activity and there are legal and ethical considerations regarding its use.

Post transplant cyclophosphamide based haplo-identical transplant versus umbilical cord blood transplant; a meta-analysis

OBJECTIVES

Both haplo-identical transplant (haplo) and umbilical cord transplant (UC) are valuable graft options for patients without available matched relative. Previous studies showed inconsistent outcomes comparing Post transplant Cyclophosphamide based haplo (PTCy-haplo) and UC; therefore, we attempt to compare the studies by mean of meta-analysis.

METHODS

We searched for titles of articles in MEDLINE (PubMed), Cochrane library, EMBASE database and Google scholar that compared transplantation with PTCy-haplo versus UC. We conducted a random-effect meta-analysis of seven studies involving a total of 3434 participants and reported the pooled odd ratios (OR) of acute graft-versus-host disease (aGVHD), chronic graft-versus-host disease (cGVHD), relapse and overall survival (OS) between PTCy-haplo and UC groups.

RESULTS

We found a significantly decreased risk of aGVHD and relapse in the PTCy-haplo group compared to the UC group with a pooled OR of 0.78, 95% Confidence Interval (CI) 0.67-0.92, I2=0%, and 0.74, 95% CI 0.57-0.97, I2=23.9% respectively. We also found a significantly increased rate of cGVHD and OS with a pooled OR of 1.41, 95% CI 1.02-1.95, I2=56.8%, and 1.77, 95% CI 1.1-2.87, I2=82.5%, respectively.

CONCLUSION

Our meta-analysis of clinical trials demonstrated superior outcome from PTCy-haplo group compared to the UC group in terms of decreased rate of aGVHD and relapse as well as the increased rate of OS but inferior in terms of increased cGVHD risk compared to UC transplant.

Impact of cumulative steroid dose on infectious diseases after allogenic hematopoietic stem cell transplantation

BACKGROUND

Systemic steroid is used to treat various transplant-related complications after allogenic hematopoietic stem cell transplantation (allo-HSCT). However, measures to evaluate its impact on infections are still limited. Hence, we examined the cumulative steroid dose used within 30 days after transplant as a predictor of future risk of infections.

METHODS

This study included 226 patients who underwent their first allo-HSCT at Kyoto University Hospital between 2005 and 2015.

RESULTS

Sixty-one patients received transplantation from related donors, 106 received unrelated BMT and 59 received unrelated single-unit CBT. Patients were categorized into three groups according to the cumulative steroid dose in terms of prednisolone: no-steroid group (n = 174), low-dose group (≤7 mg/kg) (n = 22) and high-dose group (>7 mg/kg) (n = 30). In a multivariate analysis, high-dose steroid administration was associated with cytomegalovirus (CMV) antigenemia (HR 1.91, P = 0.037) and bacteremia (HR 2.59, P = 0.053). No impact was found on the occurrence of invasive fungal infection.

CONCLUSION

High-dose cumulative steroid could predict high risks of bacteremia and CMV antigenemia. Additional anti-bacterial agents for fever and regular measurement of CMV antigen are recommended for whom with systemic steroid administration even after neutrophil engraftment.

Pretransplant serum FT3 levels in recipients predict early non-relapse mortality after myeloablative allogeneic haematopoietic cell transplantation from matched sibling donors

OBJECTIVES

Although decreased thyroid function is negatively correlated with clinical outcomes in critically ill patients, its role in allogeneic haematopoietic cell transplantation (allo-HCT) has not been sufficiently described.

METHODS

The associations between pre-conditioning thyroid hormone concentrations and transplant-related complications in 474 adult patients with haematologic malignancies who underwent myeloablative allo-HCT were assessed.

RESULTS

A receiver-operating characteristic curve showed that the baseline serum-free triiodothyronine 3 (FT3) level had an excellent predictive value for non-relapse mortality (NRM) within 100 days in sibling HCT with an area under the curve of 0.73 [95% confidence interval (CI), 0.64-0.82]. With a cut-off value of 4.7 pmol/l, the sensitivity and specificity for early NRM were 68% and 73%, respectively. The cumulative incidences of early NRM within 100 days after sibling HCT were 14% (95% CI, 10-18%) in the low FT3 group and 6% (95% CI, 4-8%) in the high-FT3 group (p = 0.033). In multivariate analysis, a lower FT3 level was significantly associated with high early NRM (HR = 3.19, 95% CI, 1.13-9.03, p = 0.029). The difference was also significant at 3 years after HCT (24% vs. 14%, p = 0.046). Recipients with lower FT3 levels also had a trend towards a lower OS at 3 years after HCT (66% vs. 72%, p = 0.235), although the difference did not reach statistical significance.

CONCLUSION

A low FT3 level before conditioning may be a useful predictive biomarker for higher early NRM among patients undergoing myeloablative sibling transplantation.

Risk Factors for Graft-Versus-Host Disease After Transplantation of Hematopoietic Stem Cells from Unrelated Donors in the China Marrow Donor Program

Background

We identified risk factors for acute and chronic graft-versus-host disease (aGVHD and cGVHD, respectively) in recipients after hematopoietic stem cell transplantation (HSCT) from unrelated donors in the China Marrow Donor Program (CMDP).

Material/Methods

We analyzed follow-up clinical information from 1824 patients who underwent HSCT between 2001 and 2010.

Results

The incidence of aGVHD and cGVHD after transplantation was 49.29% and 27.3%, respectively. aGVHD incidence decreased as HLA matching increased (p<0.001). Incidence of aGVHD and cGVHD was higher in 2 HLA-A locus donor/recipient groups (02: 01/02: 06 and 02: 01/02: 07; p≤0.022). aGVHD incidence was associated with patient age, absence of rabbit anti-thymocyte globulin (ATG) pretreatment, and disease status (p≤0.040). aGVHD appeared to be a risk factor for cGVHD, and total body irradiation (TBI) was also associated with cGVHD. Patients with cGVHD after transplantation had a higher survival rate than patients without cGVHD (p<0.001), which may be due to reduced relapse rates. Survival was also associated with ATG prophylaxis and disease status.

Conclusions

The incidence of GVHD after HSCT from unrelated donors in the Chinese population is similar to the results reported from other countries. A high degree of HLA matching, a conditioning regimen without TBI, and the use of ATG may reduce the incidence of aGVHD.