The meta-analysis collected findings from 11 studies, from which researchers determined statistical heterogeneity regarding the incidence of GVHD between patients receiving only HSC transplantation or only killer cell therapy, and patients receiving HSC transplantation in addition to killer cell therapy.
Combining hematopoietic stem cell (HSC) transplantation with killer cell therapy may be an effective way to reduce the risk of graft-versus-host disease (GVHD) in patients with leukemia, researchers said, based on findings from their meta-analysis.
The meta-analysis collected findings from 11 studies, from which researchers determined statistical heterogeneity regarding the incidence of GVHD between patients receiving only HSC transplantation or only killer cell therapy, and patients receiving HSC transplantation in addition to killer cell therapy (Chi2 = 21.38, I2 = 67%, P =.003). Compared with HSC transplantation or killer cell therapy alone, the combination yielded a significantly lower incidence of GVHD (Z = 3.87, P =.0001).
Meanwhile, the researchers found that the combination of treatment did not seem to have a significant impact of overall survival (OS) rates (Z = 1.53; P = .13) or recurrence rates (Z = 1.93; P = .05).
“The results revealed that HSC transplantation combined with killer cell can effectively reduce the incidence of stem cell GVHD in leukemia patients, the prognosis of transplantation was ideal, and it had no obvious effect on the OS and recurrence rates,” wrote the researchers.
“However, the meta-analysis in this work still had limitations due to various confounding influence factors. The literatures selected were case-control studies. Therefore, there was survival bias itself, and many other indicators may not have been included in the study, which reduces the combined effect size notably,” they said.
The analysis also showed no heterogeneity in leukemia-free survival between the 2 groups, with no significant difference in survival rates (Z = 1.52, P =.13)
Among the 11 studies, published between 2012 and 2018, 7 compared HSC transplantation alone with combination treatment and 4 compared killer cell therapy alone with combination treatment.
Nine of the studies were randomized controlled trials while 2 were retrospective analyses, which the researchers noted introduced bias to the study.
“Overall, however, the results of this study were affected slightly,” they noted. “Studies on a single sample can be volatile. [A] meta-analysis was used to carry out [a] quantitative synthesis of all the included literatures in the study, which can not only avoid the differences of different studies due to the sampling from different populations, but also give different weights to the results regarding sample size of each study, so as to increase the sample size and improve the credibility of conclusion.”
The researchers suggested that future studies include larger sample sizes to prevent bias.
Reference: Zhang Y, Song Y, Ni Q, et al. Systematic review and meta-analysis: transplanted hematopoietic stem cells and killer cells on leukemia. Ann Palliat Med. 2021;10(7):7872-7883. doi:10.21037/apm-21-1359