**4. Conclusions**

BsAbs represent a highly promising and emerging therapeutic area. Due to structural and biological differences from monospecific Abs, development of a bioassay strategy for the BsAb poses unique challenges and considerations. We reviewed currently available bioanalytical technological platforms, bioassays, and relevant case studies for BsAbs to provide insight into designing a BsAb release and characterization strategy. Understanding and developing good bioassays are critical for the overall control strategy of BsAbs to measure biological activities, and they will continue to evolve for both BsAb molecules and analytical technologies available.

**Funding:** This research received no external funding.

**Institutional Review Board Statement:** Not applicable.

**Informed Consent Statement:** Not applicable.

**Data Availability Statement:** No new data were created or analyzed in this study. Data sharing is not applicable to this article.

**Acknowledgments:** The authors acknowledge editorial service by Eileen Y. Ivasauskas and review by Dayue Chen for the manuscript.

**Conflicts of Interest:** The authors declare no conflict of interest.

#### **References**

