G-CSF use post peripheral blood stem cell transplant is associated with faster neutrophil engraftment, shorter hospital stay and increased incidence of chronic GVHD

The Effect of Granulocyte Colony-Stimulating Factor (G-CSF) on Early Complications and Graft-Versus-Host Disease (GVHD) in Allogeneic Stem Cell Transplantation (ASCT) Recipients

Objectives Granulocyte colony-stimulating factor (G-CSF) is commonly used to accelerate neutrophil recovery after allogeneic stem cell transplantation (ASCT) in most transplant centers. There was no consensus on the optimal use of G-CSF after ASCT. Although we use G-CSF to minimize morbidity and mortality, G-CSF can increase the risk of graft-versus-host disease (GVHD). In our study, we want to show the effect of prophylactic G-CSF on infection frequency, neutrophil and platelet engraftment, the duration of neutropenia, the development of GVHD, hospitalization time, and transplant-related mortality (TRM) after ASCT. Materials and methods One hundred (71 males and 29 females) patients who did not receive G-CSF and 100 (58 males and 42 females) patients who received prophylactic G-CSF were included in the study. Results Age, diagnosis, the time between diagnosis and transplantation, preparation regimen, donor type, and the number of infused cluster of differentiation (CD) 34+ cells were not different in both groups (p>0.05). The frequency of female patients was higher in the group receiving G-CSF. Febrile neutropenia was more frequent in patients who did not receive G-CSF. Neutrophil engraftment and platelet engraftment were detected longer in patients not receiving G-CSF. The frequency of veno-occlusive disease (VOD) and hyperacute, chronic, and acute GVHD was not different in both groups (p>0.05). One hundred-day TRM and five-year overall survival (OS) were similar in the two groups (p>0.05). Conclusions Our study supports that G-CSF usage does not cause an increase in the frequency of GVHD and has a positive effect on the process by accelerating myeloid engraftment. In light of the data in our study, we can say that the use of G-CSF should be investigated in a randomized controlled clinical trial.

Post-Transplant Administration of G-CSF Impedes Engraftment of Gene Edited Human Hematopoietic Stem Cells by Exacerbating the p53-Mediated DNA Damage Response

Granulocyte colony stimulating factor (G-CSF) is commonly used as adjunct treatment to hasten recovery from neutropenia following chemotherapy and autologous transplantation of hematopoietic stem and progenitor cells (HSPCs) for malignant disorders. However, the utility of G-CSF administration after ex vivo gene therapy procedures targeting human HSPCs has not been thoroughly evaluated. Here, we provide evidence that post-transplant administration of G-CSF impedes engraftment of CRISPR-Cas9 gene edited human HSPCs in xenograft models. G-CSF acts by exacerbating the p53-mediated DNA damage response triggered by Cas9- mediated DNA double-stranded breaks. Transient p53 inhibition in culture attenuates the negative impact of G-CSF on gene edited HSPC function. In contrast, post-transplant administration of G-CSF does not impair the repopulating properties of unmanipulated human HSPCs or HSPCs genetically engineered by transduction with lentiviral vectors. The potential for post-transplant G-CSF administration to aggravate HSPC toxicity associated with CRISPR-Cas9 gene editing should be considered in the design of ex vivo autologous HSPC gene editing clinical trials.

Posttransplant blockade of CXCR4 improves leukemia complete remission rates and donor stem cell engraftment without aggravating GVHD

Allogeneic hematopoietic cell transplantation (allo-HCT) is a promising therapeutic option for hematological malignancies, but relapse resulting predominantly from residual disease in the bone marrow (BM) remains the major cause of treatment failure. Using immunodeficient mice grafted with laboratory-generated human B-ALL, our previous study suggested that leukemia cells within the BM are resistant to graft-versus-leukemia (GVL) effects and that mobilization with CXCR4 antagonists may dislodge leukemia cells from the BM, enabling them to be destroyed by GVL effects. In this study, we extended this approach to patient-derived xenograft (PDX) and murine T-ALL and AML models to determine its clinical relevance and effects on GVHD and donor hematopoietic engraftment. We found that posttransplant treatment with the CXCR4 antagonist AMD3100 significantly improved the eradication of leukemia cells in the BM in PDX mice grafted with B-ALL cells from multiple patients. AMD3100 also significantly improved GVL effects in murine T-ALL and AML models and promoted donor hematopoietic engraftment in mice following nonmyeloablative allo-HCT. Furthermore, posttransplant treatment with AMD3100 had no detectable deleterious effect related to acute or chronic GVHD. These findings provide important preclinical data supporting the initiation of clinical trials exploring combination therapy with CXCR4 antagonists and allo-HCT.

Associations between the Gut Microbiota, Immune Reconstitution, and Outcomes of Allogeneic Hematopoietic Stem Cell Transplantation

Immune reconstitution following allogeneic hematopoietic stem cell transplantation (allo-HSCT) sets the stage for the goal of a successful transplant—the prevention of disease relapse without graft versus host disease (GVHD) and opportunistic infection. In both epidemiologic studies and in controlled animal studies, it is known that the gut microbiome (GM) can profoundly influence normal innate and adaptive immune development and can be altered by microbial transfer and antibiotics. Following allo-HSCT the GM has been shown to influence clinical outcomes but published associations between the GM and immune reconstitution post-allo-HSCT are lacking. In this viewpoint we propose that the extensive knowledge garnered from studying normal immune development can serve as a framework for studying immune development post-allo-HSCT. We summarize existing studies addressing the effect of the GM on immune ontogeny and draw associations with immune reconstitution and the GM post-allo-HSCT.