Stem Cell Transplantation for Relapsed or Refractory Pediatric Solid Tumors

Abstract

Refractory or recurrent pediatric solid tumors continue to have a poor prognosis despite all the progress made in recent decades. Autologous and allogeneic (haploidentical) stem cell transplantation in combination with intensive chemotherapy are potentially curative therapeutic approaches. These therapeutic options have been retrospectively investigated in the presented studies using nephroblastoma and neuroblastoma as examples. It could be shown that both procedures can be performed with low toxicity and without transplantation-related mortality and thereby raising the chances of long-term survival significantly compared to other therapy options. In particular, haploidentical stem cell transplantation offers the possibility of a "salvage therapy" for patients with severe, refractory, or recurrent disease, even when all other therapy options (including autologous stem cell transplantation) have been exhausted. The low rate of side effects combined with a long-term survival rate of approximately 25% offer these patients with otherwise unfavorable prognosis a last chance for a tumor-free life. Additionally, the results of the studies provide a good starting point for modern therapeutic concepts such as immune or cell therapies. Due to the rarity of these tumors, systematic studies with large numbers of patients are not possible to conduct. Especially for haploidentical stem cell transplantation in neuroblastomas, the literature often comprises only individual case reports or very small cohorts. At the time of its publication, the presented study comprises the largest systematically evaluated cohort on this topic. Hopefully, both studies thus contributed to improving the prognosis of these difficult to treat patient groups. The results of these studies suggest that these therapeutic concepts are very likely to be transferable to other solid tumors in terms of feasibility, toxicity, and transplantation-related mortality and thus offer a promising alternative to palliative treatment for all children with refractory or recurrent solid tumors.