TABLE 2.
Immunohematology testing assessing level of interference from isatuximab and daratumumab. Table shows the results of standard IATs performed independently in three different IHLs with plasma samples spiked with different concentrations of isatuximab or daratumumab and as well as with RBCs treated with 0.2 M DTT
| Blood bank | Anti‐CD38 mAb | Concentration | IAT Method | Agglutination grade | DTT 0.2 M a |
|---|---|---|---|---|---|
| IHL1 | Isatuximab | 50, 150, 300, 600, and 1000 μg/ml | Gel |
W+: 17% 1+: 47% 2+: 36% |
Negative |
| Daratumumab | 50, 150, 300, 600, and 1000 μg/ml | Gel |
1+: 19% 2+: 81% |
Negative | |
| IHL2 | Isatuximab | 0.1, 0.5, 1.0, 5.0, 10, and 200 μg/ml | Tube PEG |
0: 7% W+: 17% 1+: 74% 2+: 2% |
Negative a |
| IHL3 | Isatuximab | 0.1, 1, 10, 108, 297, 372, 487, 601, and 945 μg/ml | Gel |
1+: 94% 2+: 6% |
Negative |
| Daratumumab | 0.1, 1, 10, 18, 313, 574, 745, and 915 μg/ml | Gel |
1+: 56% 2+: 44% |
Negative | |
| Isatuximab | 0.1, 1, 10, 108, 297, 372, 487, 601, and 945 μg/ml | Tube PEG |
0: 52% W+: 46% 1+: 2% |
Negative | |
| Daratumumab | 0.1, 1, 10, 18, 313, 574, 745, and 915 μg/ml | Tube PEG |
0: 17% W+: 74% 1+: 9% |
Negative | |
| Isatuximab | 0.1, 1, 10, 108, 297, 372, 487, 601, and 945 μg/ml | Tube LISS |
0: 72% W+: 28% |
Not tested | |
| Daratumumab | 0.1, 1, 10, 18, 313, 574, 745, and 915 μg/ml | Tube LISS |
0: 31% W+: 69% |
Not tested | |
| Isatuximab | 0.1, 1, 10, 108, 297, 372, 487, 601, and 945 μg/ml | Solid phase |
0: 78% 1+: 15% 2+: 7% |
Not tested | |
| Daratumumab | 0.1, 1, 10, 18, 313, 574, 745, and 915 μg/ml | Solid phase |
0: 11% 1+: 26% 2+: 52% 3+: 11% |
Not tested |
Abbreviations: DTT, dithiothreitol; IAT, indirect antiglobulin test; IHL, immunohematology laboratory; mAb, monoclonal antibody; RBC, red blood cell.
DTT testing was only performed for selected concentrations. Similar results obtained with DTT 0.01 M at IHL2.