Recent progress in managing graft-versus-host disease and viral infections following allogeneic stem cell transplantation

Multidisciplinary recommendations for the management of CAR-T recipients in the post-COVID-19 pandemic era

The outbreak of coronavirus disease 2019 (COVID-19) posed an unprecedented challenge on public health systems. Despite the measures put in place to contain it, COVID-19 is likely to continue experiencing sporadic outbreaks for some time, and individuals will remain susceptible to recurrent infections. Chimeric antigen receptor (CAR)-T recipients are characterized by durable B-cell aplasia, hypogammaglobulinemia and loss of T-cell diversity, which lead to an increased proportion of severe/critical cases and a high mortality rate after COVID-19 infection. Thus, treatment decisions have become much more complex and require greater caution when considering CAR T-cell immunotherapy. Hence, we reviewed the current understanding of COVID-19 and reported clinical experience in the management of COVID-19 and CAR-T therapy. After a panel discussion, we proposed a rational procedure pertaining to CAR-T recipients with the aim of maximizing the benefit of CAR-T therapy in the post COVID-19 pandemic era.

Allogeneic clonal mesenchymal stem cell therapy for refractory graft-versus-host disease to standard treatment: a phase I study

Severe graft-versus-host disease (GVHD) is an often lethal complication of allogeneic hematopoietic stem cell transplantation (HSCT). The safety of clinical-grade mesenchymal stem cells (MSCs) has been validated, but mixed results have been obtained due to heterogeneity of the MSCs. In this phase I study, the safety of bone marrow-derived homogeneous clonal MSCs (cMSCs) isolated by a new subfractionation culturing method was evaluated. cMSCs were produced in a GMP facility and intravenously administered to patients who had refractory GVHD to standard treatment resulting after allogeneic HSCT for hematologic malignancies. After administration of a single dose (1×10⁶ cells/kg), 11 patients were evaluated for cMSC treatment safety and efficacy. During the trial, nine patients had 85 total adverse events and the rate of serious adverse events was 27.3% (3/11 patients). The only one adverse drug reaction related to cMSC administration was grade 2 myalgia in one patient. Treatment response was observed in four patients: one with acute GVHD (partial response) and three with chronic GVHD. The other chronic patients maintained stable disease during the observation period. This study demonstrates single cMSC infusion to have an acceptable safety profile and promising efficacy, suggesting that we can proceed with the next stage of the clinical trial.

Blocking TWEAK-Fn14 interaction inhibits hematopoietic stem cell transplantation-induced intestinal cell death and reduces GVHD

Inhibition of the tumor necrosis factor (TNF)-like weak inducer of apoptosis (TWEAK)/fibroblast growth factor-inducible 14 (Fn14) system reduces intestinal cell death and disease development in several models of colitis. In view of the crucial role of TNF and intestinal cell death in graft-versus-host disease (GVHD) and the ability of TWEAK to enhance TNF-induced cell death, we tested here the therapeutic potential of Fn14 blockade on allogeneic hematopoietic cell transplantation (allo-HCT)-induced intestinal GVHD. An Fn14-specific blocking human immunoglobulin G1 antibody variant with compromised antibody-dependent cellular cytotoxicity (ADCC) activity strongly inhibited the severity of murine allo-HCT-induced GVHD. Treatment of the allo-HCT recipients with this monoclonal antibody reduced cell death of gastrointestinal cells but neither affected organ infiltration by donor T cells nor cytokine production. Fn14 blockade also inhibited intestinal cell death in mice challenged with TNF. This suggests that the protective effect of Fn14 blockade in allo-HCT is based on the protection of intestinal cells from TNF-induced apoptosis and not due to immune suppression. Importantly, Fn14 blockade showed no negative effect on graft-versus-leukemia/lymphoma (GVL) activity. Thus, ADCC-defective Fn14-blocking antibodies are not only possible novel GVL effect-sparing therapeutics for the treatment of GVHD but might also be useful for the treatment of other inflammatory bowel diseases where TNF-induced cell death is of relevance.

Caspase-8 polymorphisms result in reduced Alemtuzumab-induced T-cell apoptosis and worse survival after transplantation

Allo-SCT using unrelated donors is a curative treatment for patients with hematological disorders. The best donor is one matched for 10/10 HLA alleles, however studies have shown an additional survival benefit when considering other genetic factors. It has been shown that a six-nucleotide insertion/deletion polymorphism in the CASP8 gene promoter results in reduced susceptibility of T lymphocytes to undergo apoptosis. In 186 SCT recipients, we found a significantly better OS in those who received a transplant from a WT/WT donor compared with donors with a deletion (3 years: 52 vs 34%; P=0.03; multivariate analysis; RR 0.61; 95% CI 0.38-0.98, P=0.04). This was more marked when both the patient and the donor had a deletion (3 years OS: 62% compared with 36%, P=0.01). As the majority of these patients received Alemtuzumab during conditioning, we went on to analyze the in vitro effect of the polymorphism on Alemtuzumab-induced apoptosis. We showed statistically significantly higher percentages of apoptotic naïve CD4 (P<0.0005) and CD8 (P<0.0005) T cells in WT/WT donors in comparison with donors with a deletion. These data imply an unrecognized role for the CASP8 promoter polymorphism on survival following unrelated SCT particularly in the context of T-cell depletion with Alemtuzumab.

Myeloablative haploidentical hematopoietic stem cell transplantation using basiliximab for graft-versus-host disease prophylaxis

OBJECTIVES

We retrospectively compared the prophylactic effect of basiliximab and antithymocyte globulin (ATG) after haploidentical hematopoietic stem cell transplantation (HSCT) in patients with leukemia.

METHODS

Haploidentical HSCT using basiliximab for graft-versus-host disease (GVHD) prophylaxis in 10 patients with leukemia was retrospectively compared to ATG for GVHD prophylaxis in 24 patients.

RESULTS

All the patients achieved neutrophil engraftment. One patient in the ATG group did not achieve platelet engraftment. The incidence of grade II-IV and grade III-IV acute GVHD was 30 and 20%, respectively, in the basiliximab group and 16.7 and 4.2%, respectively, in the ATG group (P > 0.05). Extensive cGVHD developed in 40 and 22.2% of patients in the basiliximab group and ATG group, respectively (P > 0.05). Basiliximab resulted in mild infection and a low incidence (10%) of infection-related mortality; ATG resulted in relative severe infection with 29.2% infection-related mortality (P > 0.05). During the follow-up period, 20% of the basiliximab group and 22.7% of the ATG group relapsed (P > 0.05). In the basiliximab group and the ATG group, the 3-year accumulative overall survival rate was, respectively, 80 and 52.5% and the 3-year leukemia-free survival, respectively, was 60 and 49.6% (P > 0.05).

DISCUSSION

The incidences of grade II-IV and grade III-IV aGVHD in the basiliximab group were similar to those in halpoidentical HSCT containing ATG. Compared to the ATG group, the basiliximab group had a lower rate of transplantation-related mortality and better long-term survival, but without statistical significance.

CONCLUSION

The prophylactic regimen of basiliximab with haploidentical HSCT against GVHD seems safe and promising. More studies needed to verify this.

Mouse Flk-1+Sca-1- mesenchymal stem cells: functional plasticity in vitro and immunoregulation in vivo

OBJECTIVES

Mesenchymal stem cells (MSCs) represent a powerful tool in regenerative medicine because of their differentiation and migration capacities. Moreover, the immunomodulatory ability of MSCs may be used to develop therapies for the treatment of autoimmune diseases.

METHODS

In this study, we isolated Flk-1Sca-1 MSCs from bone marrow (bMSCs). Next, we studied their biological characteristics and immunologic functions. We also investigated their effects on graft-versus-host disease (GVHD) associated with allogeneic bone marrow transplantation in mice.

RESULTS

Flk-1Sca-1 bMSCs were able to differentiate into fat and cartilage cells, indicating that the isolated cells had stem cell properties. They could also suppress alloantigen-induced T cell proliferation in vitro in a dose-dependent manner. Infusion of bMSCs into allogeneic bone marrow-transplanted mice alleviated the lethal GVHD that occurred in control recipient mice. There was significantly lower mortality among the recipients of the Flk-1Sca-1 bMSCs that also ameliorated the clinical symptoms and GVHD histopathology. Beneficial effects on GVHD by Flk-1Sca-1 bMSCs were also observed when MSCs were engineered to express anti-inflammatory cytokines IL-4 and IL-10 and decrease expression of proinflammatory cytokines IFN-γ, TNF-α, and IL-2.

CONCLUSION

Flk-1Sca-1 bMSCs have stem cell properties and can efficiently ameliorate the GVHD associated with allogeneic bone marrow transplantation in mice.

Allogeneic hematopoietic stem cell transplantation for patients with acute leukemia

OBJECTIVE

The purposes of this study were to assess the efficacy of allogeneic hematopoietic stem cell transplantation (HSCT) for acute leukemia (AL) and analyze the factors affecting the prognosis of these patients.

METHODS

The clinical and follow-up data of 93 AL patients (median age, 30 years) undergoing allogeneic HSCT in Xiangya Hospital over the past 12 years were collected, and the potential factors affecting the efficacy and prognosis of allogeneic HSCT patients were determined.

RESULTS

Hematopoietic reconstitution was achieved in 90 patients. At the last follow-up, the incidences of severe acute graft versus host disease (aGvHD) and extensive chronic GvHD (cGvHD) were 14.0% and 20.0%, the 3-year cumulative incidence of transplantation related mortality (TRM) and relapse rate were 16.8%±6.1% and 21.3%±6.7%, and the estimated 3-year overall survival (OS) and disease-free survival (DFS) of the patients were 64.6%±5.4% and 56.5%±5.5%, respectively. Univariate analysis indicated that age older than 40 years, HLA mismatch, and severe lung infection within the first 100 days after transplantation were risk factors for severe aGvHD, age older than 40 years, HLA mismatch, severe lung infection within the first 100 days after transplantation, and severe aGvHD were risk factors for TRM, high-risk AL and lack of cGvHD were risk factors for relapse (all P<0.05). Survival estimation showed that HLA mismatch, severe lung infection occurring within the first 100 days post-transplantation, high-risk AL severe aGvHD and lack of cGvHD were risk factors associated with poor prognosis (all P<0.05). Further multivariate analyses revealed that severe lung infection within the first 100 days post-transplantation, severe aGvHD and lack of cGvHD were independent risk factors for unfavorable outcomes (all P<0.05).

CONCLUSIONS

Allogeneic HSCT can improve the DFS of AL patients, and severe lung infection within the first 100 days post-transplantation, severe aGvHD and lack of cGvHD are independent risk factors affecting the prognosis.