Developability assessment at early-stage discovery to enable development of antibody-derived therapeutics

Abstract

Developability refers to the likelihood that an antibody candidate will become a manufacturable, safe and efficacious drug. Although the safety and efficacy of a drug candidate will be well considered by sponsors and regulatory agencies, developability in the narrow sense can be defined as the likelihood that an antibody candidate will go smoothly through the chemistry, manufacturing and control (CMC) process at a reasonable cost and within a reasonable timeline. Developability in this sense is the focus of this review. To lower the risk that an antibody candidate with poor developability will move to the CMC stage, the candidate's developability-related properties should be screened, assessed and optimized as early as possible. Assessment of developability at the early discovery stage should be performed in a rapid and high-throughput manner while consuming small amounts of testing materials. In addition to monoclonal antibodies, bispecific antibodies, multispecific antibodies and antibody-drug conjugates, as the derivatives of monoclonal antibodies, should also be assessed for developability. Moreover, we propose that the criterion of developability is relative: expected clinical indication, and the dosage and administration route of the antibody could affect this criterion. We also recommend a general screening process during the early discovery stage of antibody-derived therapeutics. With the advance of artificial intelligence-aided prediction of protein structures and features, computational tools can be used to predict, screen and optimize the developability of antibody candidates and greatly reduce the risk of moving a suboptimal candidate to the development stage.

Keywords: antibody; antibody-drug conjugate; bispecific; developability; discovery.

Figure 1

Key factors affecting developability assessment. Four key attributes of developability (homogeneity, stability, solubility and specificity) are determined by antibody structure and alteration. These attributes and the usage of antibody candidates are used to determine the developability criteria.

Figure 2

Considerations of developability-related measurements at the different stages from target evaluation to IND filing.

Figure 3

Structures of an IgG mAb and basic building blocks for bsAbs or msAbs. Structure of the IgG mAb (PDB code 5DK3) was created with PyMol. BsAbs or msAbs can be assembled from the five antigen-binding domains: VHH, Fv, scFv, Fab and scFab, and these five building blocks can also be assembled with heterodimeric or homodimeric Fc to form Fc-containing bsAbs or msAbs. The red mark in the Fc domain represents the mutations facilitating heterodimerization.

Figure 4

Different purposes and tests at the discovery and development stages.

Figure 5

A panel of tests for developability assessment at the discovery and CMC stages. (A) Analytical methods generally used for developability assessment at the discovery and CMC stages. (B) Typical forced stress study plans at the discovery and CMC stages. ^a. In the discovery stage, low pH is for Asp isomerization susceptibility testing, whereas high pH is for deamidation susceptibility testing; ^b. 0.05% and 1% H₂O₂ treatment at 25°C; ^c. Low pH: pH 3.5 incubation; High pH: pH 9.0 incubation; ^d. 3 or 5 freezing (at −70°C) and thawing (at 25°C) cycles; ^e. An antibody is exposed to bright light of 5 000 lx for 4 h and 24 h; ^f. Thermal stress under 2°C–8°C, 25°C and 40°C.

Figure 6

Concentration of the approved antibodies based on disease indications (A) and administration routes (B): 129 antibodies approved by the agencies of the United States, Europe, China and Japan are included in the data analysis. Biosimilar or withdrawn products are excluded. (A) Concentration of approved antibodies grouped based on disease indications. In the boxplots, the concentration for each indication with median (the centre line) and interquartile (25% and 75%) ranges are shown. ^# Two outliers found in the upper and lower whiskers (outside 1.5 interquartile ranges) are excluded: anti-PD-L1 antibodies Envafolimab (200 mg/mL) and Atezolizumab (60 mg/mL). (B) Concentration of approved antibodies based on administration routes. The concentration for IV and SC injection with median (the centre line) are shown. IV, intravenous; SC, subcutaneous; IVI, intravitreal; IM, intramuscular.