Table 1.
Selection of human scFvs targeting human GBM tumor spheres. (a) Tumor sphere formation and CD133 epitope expression. (b) Summary of binding results for the five unique human scFvs studied. GBMh: human GBM tissues. GBMx: GBM maintained as xenografts in nude mice. ++: large size spheres containing > 100 cells per sphere after 14 days of incubation. +: small size 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 re-tested on additional GBM tissues as indicated. Co-staining with CD133 is shown in Figure 3. Non-sphere GBM cells are derived from sphere cells cultured in differentiation promoting media containing serum. ND, not determined.
| (a) | ||||
|---|---|---|---|---|
| GBM Tissues | Tumor sphere formation | CD133 epitope expression | Target tissues for initial selection | Tissues used for re-test |
| 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) | |||||
|---|---|---|---|---|---|
| H3 | GC4 | GB1 | GB8 | GH9 | |
| Binding to GBM sphere cells | 100% | 50–99% | Variable# | Variable# | Variable# |
| Binding to non-sphere GBM cells | Unchanged (100%) | Reduced | Reduced concurrently with CD133 | Reduced concurrently with CD133 | Reduced concurrently with CD133 |
| Relationship to CD133+ cells Target antigen | Cover CD133+ CD166 | Cover CD133+ ND | A subset of CD133+ ND | A subset of CD133+ ND | Co-stain w/CD133+ ND |
: variable binding patterns were shown in Table S1.