Table 1.

Selection of human scFvs targeting human GBM tumor spheres

(A)
GBM tissuesTumor sphere formationCD133 epitope expressionTarget tissues for initial selectionTissues used for retest
GBMx-1++80%+
GBMx-2++50%+
GBMx-3++2%+
GBMx-4++0*+
GBMx-5++3%+
GBMx-6++4%+
GBMx-7++15%+
GBMx-8++70%++
GBMx-9++0*
GBMh-1+0*
GBMh-2++12%++
GBMh-3+8%
GBMh-4++3%+
GBMh-5+6%
(B)
H3GC4GB1GB8GH9
Binding to GBM sphere cells100%50–99%Variable*Variable*Variable*
Binding to nonsphere GBM cellsUnchanged (100%)ReducedReduced concurrently with CD133Reduced concurrently with CD133Reduced concurrently with CD133
Relationship to CD133+ cellsCover CD133+Cover CD133+A subset of CD133+A subset of CD133+Costain with CD133+
Target antigenCD166NDNDNDND

NOTE: (A) Tumor sphere formation and CD133 epitope expression. ++, large-sized spheres containing >100 cells per sphere after 14 days of incubation. +, small-sized spheres containing <100 cells per sphere after 14 days of incubation. 0*, expression levels indistinguishable from that of the control (control isotype–matched mouse IgG stain). GBMx-8 and GBMh-2 were used for initial phage antibody library selection. Positive binders were retested on additional GBM tissues as indicated. (B) Summary of binding results for the five unique human scFvs studied. Costaining with CD133 is shown in Fig. 3. Nonsphere GBM cells are derived from sphere cells cultured in differentiation-promoting medium containing serum.

Abbreviations: GBMh, human GBM tissues; GBMx, GBM maintained as xenografts in nude mice; ND, not determined.

  • *Variable binding patterns were shown in Supplementary Table S1.