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Purging peripheral blood stem cells did not extend survival in high-risk neuroblastoma
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The purging of peripheral blood stem cells did not improve outcomes in children and young adults who underwent myeloablative therapy for high-risk neuroblastoma, according to study results.
In current practice, peripheral blood stem cells (PBSCs) are infused after myeloablative therapy. However, the effect of purging is unclear.
For this reason, Susan G. Kreissman, MD, a professor of pediatrics at Duke University School of Medicine, and colleagues conducted a randomized study to evaluate the effects of tumor-selective PBSC purging in stem-cell transplantation for patients with high-risk neuroblastoma.
Susan G. Kreissman
The analysis included 486 patients aged 30 years and younger who were treated between March 2001 and February 2006. A web-based system randomly assigned patients at diagnosis to receive non-purged (n=243) or immunomagnetically purged (n=243) PBSC.
All patients received six cycles of induction chemotherapy, myeloablative consolidation and radiation therapy to the primary tumor site. EFS served as the primary outcome.
Researchers reported that 372 patients — 180 in the purged group and 192 in the nonpurged group — underwent transplant.
Five-year EFS rates were 40% (95% CI, 33-46) in the purged group and 36% (95% CI, 30-42) in the nonpurged group. Five-year OS rates were 51% (95% CI, 44-57) in the nonpurged group vs. 50% (95% CI, 43-56) in the purged group.
At 5 years, patients with detectable tumor mRNA had lower EFS (29% vs. 51%) and OS (41% vs. 62%) than those with undetectable tumor mRNA, researchers wrote.
Eight deaths occurred during induction in the purged group and seven occurred in the nonpurged group. During consolidation, eight deaths occurred in the purged group and four occurred in the nonpurged group.
More patients in the nonpurged group reported grade ≥3 stomatitis during induction (38.2% vs. 35.9%) and consolidation (75.9% vs. 74%). Researchers reported similar rates of grade ≥3 decreased cardiac function and elevated creatinine during induction between the two arms.
During consolidation, more patients in the purged group reported sinusoidal obstructive syndrome (6.7% vs. 8.9%) and more patients in the nonpurged group reported acute vascular leak (6.2% vs. 4.7%). One patient in the purged group experienced decreased cardiac function during consolidation compared with four in the nonpurged group.
“Immunomagnetic purging of PBSC for autologous stem cell transplantation did not improve outcome, perhaps because of incomplete purging or residual tumor in patients,” Kreissman and colleagues concluded. “Nonpurged PBSC are acceptable for support of myeloablative therapy of high-risk neuroblastoma.”
In an accompanying editorial, Thomas Klingebiel, MD, of the department for children and adolescents of University Hospital at Goethe University Frankfurt in Germany, called Kreissman and colleagues courageous for conducting the trial during a time when the question about the value of purging was “highly controversial.”
“However, the results of this trial do not close this chapter but rather restart the discussion,” Klingebiel wrote. “Their results show that patients with purging did not do better in terms of event-free survival and overall survival than did patients without purging. But this finding is only half true. Patients who proved to still have tumor cells in the graft did significantly worse after myeloablative therapy ... than did those without tumor cells detected.
“This finding does not mean that purging is not needed; on the contrary, this study is an argument for purging stem cells before giving them back to patients despite not showing superiority over the nonpurged group,” Klingebiel wrote. “The purging used in this study was perhaps not effective enough.”
For more information:
- Kreissman SG. Lancet Oncol. 2013;doi:10.1016/S1470-2045(13)70309-7.
- Klingebiel T. Lancet Oncol. 2013;doi:10.1016/S1470-2045(13)70353-X.
Disclosure: This study was funded by the NCI and Alex’s Lemonade Stand Foundation.