Table 3 Highlights of neutralizing antibody assay validation characteristics

Intra-assay precision (%CV of endpoint log₁₀ titer)

6.1%

Inter-assay precision (%CV of endpoint log₁₀ titer)

9.3%

Sensitivity (based on affinity-purified polyclonal antibody)

58.3 ng/mL (in well concentration)

Drug interference

PC antibody was detected in the presence of ≤1.0 μg/mL

Matrix selectivity (recovery) with PCs

All unspiked samples generated signal below the cut point showing negative result; 100% of the ALL lots had recovery of neutralizing antibodies between 70% and 130%

Stability (PC)

21-h ambient temperature

5 freeze/thaw cycles at −70 °C

5 freeze/thaw cycles at −20 °C

Stability (cell passage numbers)

≤ 22 passages