In vitro comparison of CD20xCD3 bispecific antibodies against diffuse large B-cell lymphoma (DLBCL) cell lines with different levels of expression of CD20

Abstract

Although CD20xCD3 bispecific antibodies (BsAbs) have demonstrated transformational activity in diffuse large B-cell lymphoma (DLBCL), some patients fail to respond and others relapse. To begin to explore possible limitations, we compared the in vitro activity of four CD20xCD3 biosimilar BsAbs against four DLBCL cell lines with CD20 expression ranging over a 100-fold. All four biosimilar BsAbs demonstrated superior in vitro activity to rituximab, with biosimilar glofitamab consistently being the most potent. Moreover, biosimilar glofitamab and odronextamab retained significant activity in the presence of low-level CD20 expression. Finally, one DLBCL cell line exhibited intrinsic resistance to all four CD20xCD3 BsAbs despite inducing marked T-cell and NK-cell activation.

Keywords: CD20; antibody therapy; bispecific antibodies; lymphoid malignancies.

FIGURE 1

Variable CD20 expression across DLBCL cell lines. (A) QiFi quantification of surface CD20 (mean ± SD) in DLBCL cell lines. N = 3–5. (B) CD20 expression determined by immunoblot in DLBCL whole cell lysates, normalised to alpha‐tubulin (mean ± SD). N = 4. (C) Median fluorescence intensity (mean ± SD) of surface‐bound CD20 antibody biosimilar. Cells were incubated with 10 nM CD20 antibody biosimilar for 1 h at 4°C, then stained with anti‐human IgG‐APC. N = 3.

FIGURE 2

In vitro efficacy of CD20 antibody biosimilars against DLBCL cell lines. DLBCL cells were treated with CD20 monospecific mAb or CD20xCD3 BsAb for 24 h using healthy volunteer PBMCs at an effector: target ratio of 6:1. N = 6–12. (A) B cell depletion (mean ± SD) efficacy of monospecific CD20 mAbs. (B) B cell depletion (mean ± SD) efficacy of CD20xCD3 BsAbs. (C–E) Maximum expression (mean ± SD) of (C) CD69, (D) CD25 and (E) CD107a in effector cell subsets. EP‐B, epcoritamab biosimilar; GL‐B, glofitamab biosimilar; MO‐B, mosunetuzumab biosimilar; OB‐B, obinutuzumab biosimilar; OD‐B, odronextamab biosimilar; RI‐B, rituximab biosimilar.