TNC dose can affect PFS, OS after PBSCT
Burns and his colleagues also conducted a multivariate analysis to see if any other factors affected the relationship between TNC and survival. They controlled for patient age, Karnofsky performance status, and body mass index. And they stratified patients into 4 groups according to TBI and conditioning regimen.
The results showed that patients who received TBI and RIC, as well as a TNC dose less than 8 x 108 cells/kg, had a relative risk of 3.3 for PFS (P=0.026) and a relative risk of 3.4 for OS (P=0.021).
“The association of higher TNC dose with better progression-free and overall survival implies there is a population of nucleated cells which mitigate GVHD but enhance the [graft-vs-leukemia] effect after reduced-intensity TBI conditioning,” Burns said.
“Myeloablative conditioning regimens result in more direct tumor killing. Thus, they rely less on the graft-vs-leukemia effect than the RIC regimens.”
He also noted that the lack of an association between TNC dose and survival rates with non-TBI-based regimens implies there are different mechanisms of tumor kill with TBI and non-TBI-containing regimens.
And a more detailed analysis of cell population subsets in apheresis product may allow researchers to identify cell populations that could improve patient outcomes. 
*Some data in the abstract differ from data presented at the meeting.
