Table 4.
Samalizumab bound to CD200+ CLL cells by cohort
| Samalizumab Cohort | CLL cells bound by samalizumab (%) | Density of bound samalizumab (MFI) | ||
|---|---|---|---|---|
| Pre-dose | Day 1 | Pre-dose | Day 1 | |
| 50 mg/m2 (n = 4) | 0.3–0.7 | 1.1–3.3 | 1.9–3.1 | 3.3–4.1 |
| 100 mg/m2 (n = 5) | 0.2–2.4 | 0.2–9.5 | 3.5–5.6 | 5.0–11.1 |
| 200 mg/m2 (n = 2) | 0.3–0.7 | 27.8–29.6 | 3.2–3.3 | 16.6–19.3 |
| 300 mg/m2 (n = 2) | 0.5–0.7 | 5–28.6 | 1.7–3.0 | 5.6–16.8 |
| 400 mg/m2 (n = 3) | 1.1–5.7 | 1.7–71.3 | 1.7–3.4 | 4.6–26.6 |
| 500 mg/m2 (n = 5) | 0.5–2.1 | 1–47.0 | 1–3.7 | 1.9–17.6 |
Binding of samalizumab to CD200 on circulating CLL cells was evaluated by multi-parametric flow cytometry using a fluorescently-labeled monoclonal antibody specific for samalizumab (7B8) together with a second anti-CD200 antibody (IB2) specific for an epitope of CD200 distinct from the binding site of samalizumab