Table 4. Specificity of IMMU-132 anti-tumor activity in vitro using flow cytometry with phospho-H2AX (anti-histone)-stained cells.a.
| Treatment | Median fluorescence intensity | |
|---|---|---|
| HCC1806(Trop-2+) | HCC1395(Trop-2−) | |
| Cell alone | 4.25 | 5.54 |
| Cell + anti-rH2AX-AF488 | 168 | 122 |
| Cell + IMMU-132 + anti-rH2AX-AF488 | 546 | 123 |
| Cell + hA20-SN38 + anti-rH2AX-AF488 | 167 | 123 |
a
HCC1806 (Trop-2+) or HCC1395 (Trop-2−) were incubated at 4°C with IMMU-132 or a non-binding control conjugate (anti-CD20-SN-38) for 30 min, washed and incubated overnight at 37°C in fresh drug-free media. Cells were harvested, fixed, and permeabilized, then stained with the fluorescently-conjugated anti-histone antibody (rH2AX-AF488) for detection of double-stranded DNA breaks. The median fluorescence intensity (MFI) is given for (a) background staining of the cells alone (no anti-histone antibody), (b) the background level of dsDNA breaks for the cells that had no prior exposure to the conjugates, and (c) after exposed to IMMU-132 or hA20-SN-38 conjugates.