Reduced-intensity conditioning with fludarabine and busulfan for allogeneic hematopoietic cell transplantation in elderly or infirm patients with advanced myeloid malignancies

Targeted gene therapy into a safe harbor site in human hematopoietic progenitor cells

Directed gene therapy mediated by nucleases has become a new alternative to lead targeted integration of therapeutic genes in specific regions in the genome. In this work, we have compared the efficiency of two nuclease types, TALEN and meganucleases (MN), to introduce an EGFP reporter gene in a specific site in a safe harbor locus on chromosome 21 in an intergenic region, named here SH6. The efficiency of targeted integration mediated by SH6v5-MN and SH6-TALEN in HEK-293H cells was up to 16.3 and 15.0%. A stable expression was observed both in the pool of transfected cells and in established pseudoclones, with no detection of off-target integrations by Southern blot. In human hematopoietic stem and progenitor CD34⁺ cells, the nucleofection process preserved the viability and clonogenic capacity of nucleofected cells, reaching up to 3.1% of specific integration of the transgene in colony forming cells when the SH6-TALEN was used, although no expression of the transgene could be found in these cells. Our results show the possibility to specifically integrate genes at the SH6 locus in CD34⁺ progenitor cells, although further improvements in the efficacy of the procedure are required before this approach could be used for the gene editing of hematopoietic stem cells in patients with hematopoietic diseases.

Reduced intensity conditioning of allogeneic hematopoietic stem cell transplantation for myelodysplastic syndrome and acute myeloid leukemia in patients older than 50 years of age: a systematic review and meta-analysis

PURPOSE

A systematic review and meta-analysis were performed to explore the efficacy and safety of allogeneic hematopoietic stem cell transplantation with a reduced intensity conditioning regimen in elderly patients with myelodysplastic syndrome (MDS) or acute myeloid leukemia (AML).

METHODS

Overall survival (OS) and event-free survival (EFS) were established as the primary endpoints for directly assessing the efficacy, and non-relapse mortality (NRM) for safety. The eligible patients were at or above 50 years of age, and the outcomes of the typical elderly patients (≥60 years) were analyzed individually.

RESULTS

The pooled estimates (95% confidence interval (CI)) for 1-year OS, EFS and NRM were 65 (55-74)  %, 50 (44-55)  % and 26 (21-30)  %, respectively; as for the patients ≥60 years of age, these were 63 (53-72) %, 46 (41-50)  % and 28 (23-32) %, respectively. No significantly statistical difference achieved between MDS and AML patients in 1-year EFS and NRM [relative risk (RR) 0.91, 95% CI 0.80-1.04; P = 0.172 and RR 1.18, 95% CI 0.82-1.69; P = 0.365]. The patients with lower diseases risk had the possibility of higher OS rate at ≥ 3 years than those with higher diseases risk (RR 1.37, 95% CI 0.95-1.97; P = 0.088). The patients had significantly higher 2-year OS and EFS rates in complete remission (CR, CR1 and CR2) at transplantation compared to those with advanced diseases (P < 0.05).

CONCLUSIONS

RIC-alloHSCT is a feasible treatment option for the patients older than 50 year of age with MDS and AML. Advanced diseases status and higher diseases risk may be the poor factors for prognosis.

Personalized fludarabine dosing to reduce nonrelapse mortality in hematopoietic stem-cell transplant recipients receiving reduced intensity conditioning

Patients undergoing hematopoietic cell transplantation (HCT) with reduced intensity conditioning (RIC) commonly receive fludarabine. Higher exposure of F-ara-A, the active component of fludarabine, has been associated with a greater risk of nonrelapse mortality (NRM). We sought to develop a model for fludarabine dosing in adult HCT recipients that would allow for precise dose targeting and predict adverse clinical outcomes. We developed a pharmacokinetic model from 87 adults undergoing allogeneic RIC HCT that predicts F-ara-A population clearance (Clpop) accounting for ideal body weight and renal function. We then applied the developed model to an independent cohort of 240 patients to identify whether model predictions were associated with NRM and acute graft versus host disease (GVHD). Renal mechanisms accounted for 35.6% of total F-ara-A Clpop. In the independent cohort, the hazard ratio of NRM at day 100 was significantly higher in patients with predicted F-ara-A clearance (Clpred) <8.50 L/h (P < 0.01) and area under the curve (AUCpred) >6.00 μg × h/mL (P = 0.01). A lower Clpred was also associated with more NRM at month 6 (P = 0.01) and trended toward significance at 12 months (P = 0.05). In multivariate analysis, low fludarabine clearance trended toward higher risk of acute GVHD (P = 0.05). We developed a model that predicts an individual's systemic F-ara-A exposure accounting for kidney function and weight. This model may provide guidance in dosing especially in overweight individuals and those with altered kidney function.