Slow platelet recovery after PBPC transplantation from unrelated donors

Efficacy and safety of thrombopoietin receptor agonists in the treatment of thrombocytopenia after hematopoietic stem cell transplantation: a meta-analysis and systematic review

Thrombocytopenia is a tough complication after hematopoietic stem cell transplantation (HSCT) with elusive pathogenesis and lack of well-established therapies. Thrombopoietin receptor agonists (TPO-RAs) have been used for thrombocytopenia post HSCT in recent years, but the outcomes remain debatable. We conducted this meta-analysis and systematic-review to evaluate the efficacy and safety of TPO-RAs for platelet recovery after HSCT. We searched PubMed, EMBASE, and Cochrane databases for studies on the application of TPO-RAs (eltrombopag and romiplostim) in the settings of primary or secondary thrombocytopenia after HSCT by 17 March 2021. Efficacy outcomes included response rate and survival rate, and adverse events were also evaluated. A total of 19 studies involving 378 patients were included. The pooled response rate was 73% (95%CI: 68-78%), which was significantly higher than recombinant human thrombopoietin (rhTPO) (27.8%). The pooled survival rate was 66% (95%CI: 54-77%), and infection was found to be the main cause of death. In addition, the pooled rate of adverse events was 3% (95%CI: 1-7%), with no severe adverse events reported. TPO-RAs could effectively and safely promote the recovery of platelets in patients after HSCT.

A phase I/II trial of intrabone marrow cord blood transplantation and comparison of the hematological recovery with the Japanese nationwide database

Intrabone marrow cord blood transplantation (IB-CBT) was proposed as a promising treatment modality to improve hematological recovery. However, clinical advantages of IB-CBT over conventional IV CBT have been unclear. We conducted a prospective single-center trial of IB-CBT to evaluate its safety and superiority in terms of hematological recovery. Fifteen adults with hematological malignancies were enrolled. A thawed and unwashed single cord blood unit was injected into the bilateral superior-posterior iliac crests under local anesthesia. Engraftments of neutrophils and platelets were achieved in 13 cases, with medians of 17 and 45 days, respectively. For the control, we extracted data from the Japanese nationwide database and compared the hematological recovery of contemporaneously transplanted 1135 CBT cases. Multivariate analysis revealed that IB-CBT enhanced platelet recovery (hazard ratio, 2.13; P=0.007), but neutrophil recovery did not differ significantly (hazard ratio, 1.70; P=0.19). Better donor chimerism was seen in the bone marrow of the ilium than of the sternum on day 14, suggesting that the local hematopoiesis at the injected site was established earlier than that at the remote bone marrow site. Collectively, IB-CBT was well tolerated and may enhance local engraftment, which promotes prompter platelet recovery than does IV-CBT.

Intrabone transplant of cord blood stem cells establishes a local engraftment store: a functional PET/FDG study

BACKGROUND

Despite advancements in comprehension of molecular mechanisms governing bone marrow (BM) homing of hematopoietic stem cells, cord blood transplant (CBT) suffers from a slow rate of hematopoietic recovery. Intrabone (i.b.) injection has been proposed as a method able to improve speed of BM engraftment with respect to conventional i.v. protocols. However, the mechanisms underlying this benefit are largely unknown.

AIM

To verify whether i.b.-CBT determines a local engraftment able to predict the reconstitution of recipient hematopoiesis.

DESIGN AND METHODS

Twenty-one patients with hematologic malignancies received i.b. injection into both iliac crests of 3.2 ± 0.68 ∗ 107/kg cord blood cells. One month following i.b.-CBT, PET-CT imaging was performed. Maximal standardized uptake values (SUVs) were assessed in BM of both iliac crests and in all lumbar vertebrae.

RESULTS

Maximal SUV within iliac crests was higher than in lumbar vertebrae (4.1 ± 1.7 versus 3.2 ± 0.7, resp., P = 0.01). However, metabolic activity in these two different BM districts was significantly correlated (r = 0.7, P < 0.001). Moreover, FDG uptake values within the injection site closely predicted platelet recovery 100 days after i.b.-CBT (r = 0.72, P < 0.01).

CONCLUSIONS

The metabolic activity of injected BM predicts the subsequent rate of hematopoietic recovery after i.b.-CBT, suggesting a pivotal role of the local engraftment in the reconstitution of recipient hematopoiesis.