Sail through formulation screening on Uncle and Honeybun

Importance of the topic

Biologics such as monoclonal antibodies must remain stable under various stresses and concentrations. High-concentration formulations often exhibit increased viscosity and reduced stability, complicating manufacturability and administration. Early identification of formulation issues through high-throughput, low-volume screening can accelerate developability assessments and reduce risk in drug development.

Objectives and study overview

The study evaluated two complementary platforms—Uncle and Honeybun—for rapid formulation screening of therapeutic antibodies. Objectives included:

• Profiling protein conformational stability, aggregation onset, and particle size using microvolumes.
• Measuring viscosity of high-concentration antibody solutions in parallel.
• Comparing the effects of common excipients (NaCl, sucrose, arginine, and their combinations) on multiple monoclonal antibodies (mAb1, mAb2, trastuzumab, adalimumab) at 1, 10, and 100 mg/mL.

Methodology and instrumentation

Uncle platform:

• Sample volume: 9 µL in sealed multi-well cuvettes.
• Measurements: intrinsic fluorescence, static light scattering (SLS), dynamic light scattering (DLS) over 15–95 °C ramp (0.3 °C/min).
• Outputs: melting temperature (Tm), aggregation onset temperature (Tagg), hydrodynamic diameter, polydispersity index.

Honeybun viscometer:

• Sample volume: 35 µL (default) or 15 µL (low-volume mode).
• Capacity: up to 10 samples in parallel.
• Viscosity range: 0.5–150 cP at 20 °C.

Sample preparation:

• Buffer exchange and concentration performed with automated centrifugal device (“Big Tuna”).
• Antibodies formulated in 10 mM histidine pH 6 with 0.001% PS80 and excipient spikes of 0.9% NaCl, 80 mg/mL sucrose, 10 mg/mL arginine, or both.

Main results and discussion

Thermal stability:

• Sucrose increased Tm of mAb1 from 67 °C (NaCl) to 70 °C; arginine and NaCl showed higher SLS signals, indicating more extensive aggregation.
• Arginine alone yielded the highest Tagg for mAb1 (76 °C), but aggregation magnitude was larger compared to sucrose.
• DLS confirmed monodisperse profiles with sucrose and showed broad, large-particle distributions with arginine or NaCl at 95 °C.
• Across four antibodies and three concentrations, sucrose consistently improved stability for mAb1 and trastuzumab; sucrose plus arginine was optimal for mAb2 and adalimumab at higher concentrations.

Viscosity screening:

• At 100 mg/mL, sucrose-containing formulations exhibited higher viscosity than salt alone.
• Arginine reduced viscosity for mAb2 when combined with sucrose but increased it for mAb1, reflecting protein-specific interactions.
• Honeybun delivered precise viscosity data in minutes using microvolumes, enabling inclusion of viscosity in early-stage screening workflows.

Benefits and practical applications

• Combined use of Uncle and Honeybun allows simultaneous assessment of stability and viscosity from microgram-scale samples.
• High-throughput format accelerates excipient optimization and developability decisions in discovery, process development, and manufacturing.
• Data-driven selection of formulations can improve manufacturability, reduce aggregation risk, and support subcutaneous delivery decisions.

Future trends and applications

• Expansion to other biologics, including gene therapy vectors and fusion proteins.
• Integration with automated liquid-handling for end-to-end formulation screening pipelines.
• Application of machine-learning models to predict stability and viscosity based on high-throughput data.
• Further miniaturization and multiplexing to increase throughput and reduce sample consumption even more.

Conclusion

The combined platforms offer a powerful workflow for rapid, low-volume formulation screening. Intrinsic fluorescence and light-scattering data from Uncle, paired with microvolume viscosity measurements from Honeybun, enable comprehensive developability assessments and informed excipient selection, ultimately accelerating biologics development.

References

1. Jarasch A et al. Developability assessment during the selection of novel therapeutic antibodies. J Pharm Sci. 2015;104(6):1885–1898.
2. Wang W et al. Antibody structure, instability, and formulation. J Pharm Sci. 2007;96(1):1–26.
3. Kamerzell TJ et al. Protein-excipient interactions: Mechanisms and biophysical characterization applied to protein formulation development. Adv Drug Deliv Rev. 2011;63(13):1118–1159.
4. Berteau C et al. Evaluation of the impact of viscosity, injection volume, and injection flow rate on subcutaneous injection tolerance. Med Devices. 2015;8:473–484.
5. Hong T et al. Viscosity control of protein solution by small solutes: A review. Curr Protein Pept Sci. 2017;19(8):746–758.