CleanCut GS ADCC+ CHO: Afucosylated Antibody Production with Maintained Productivity

White Paper by Corey Brizzee, PhD, Director of Gene Editing, Demeetra

Why this matters for ADCC-focused antibody development

Afucosylation is a validated strategy for improving Fc-mediated effector function in therapeutic antibodies, particularly when antibody-dependent cellular cytotoxicity (ADCC) is central to the mechanism of action. However, implementation can introduce practical trade-offs, including lower productivity, additional glycan modification steps, or more restrictive commercial licensing structures as programs advance.

Demeetra’s CleanCut GS ADCC+ CHO host was developed to address this gap by enabling afucosylated antibody production in a high-performing CleanCut GS CHO background while maintaining growth, titer, and cell-specific productivity. The platform combines the CleanCut GS CHO foundation with a FUT8 knockout, creating a host designed for ADCC-enhanced antibody production within a standard cell line development workflow.

Summary

  • Afucosylation: Lead CleanCut GS ADCC+ clones produced trastuzumab with approximately 85–89% afucosylation, compared with 3.5% in the CleanCut GS control.
  • Productivity: ADCC+ clones maintained Day 14 Qp at 97.9%, 106.4%, and 101.7% relative to the CleanCut GS control.
  • Titer: Lead clones reached final fed-batch titers of approximately 5.7–5.8 g/L in a 14-day format.
  • ADCC potency: ADCC+ antibodies showed a 2.0–4.8× increase in apparent ADCC potency in a reporter assay.
  • Platform access: CleanCut GS ADCC+ is available through a one-time GMP implementation fee for unlimited product use, or through Demeetra’s CLD services with no royalty obligations on resulting cell lines.

Key takeaway: CleanCut GS ADCC+ CHO demonstrates that afucosylated antibody production can be achieved in a CleanCut GS CHO background while maintaining the productivity profile needed for practical cell line development and commercialization.

What’s new about CleanCut GS ADCC+ CHO?

CleanCut GS ADCC+ is not a new host platform built solely around a FUT8 knockout. Instead, it extends Demeetra’s CleanCut GS CHO foundation—a double glutamine synthetase (GS) knockout CHO-K1 platform engineered using Cas-CLOVER. This foundation is designed to increase the stringency of GS-based selection by eliminating endogenous GS activity from both the primary GS locus and a GS-like secondary locus.

The ADCC+ variant adds a FUT8 knockout to this foundation, enabling production of afucosylated antibodies while preserving the productivity characteristics of the CleanCut GS platform. In the white paper, Harbor-IN was used to stably integrate a trastuzumab expression construct via GS selection, allowing evaluation of afucosylation, productivity, titer, and ADCC activity within a single workflow.

Study highlights

  1. Analytical confirmation of afucosylation
    Reduced and intact LC-MS analysis showed mass shifts consistent with the loss of core fucose from trastuzumab produced by CleanCut GS ADCC+ clones. Lead clones produced trastuzumab with approximately 85–89% afucosylation, compared with 3.5% in the CleanCut GS control.
  2. Productivity maintained in the ADCC+ host
    In a 14-day TubeSpin fed-batch study, FUT8 knockout clones maintained cell-specific productivity levels comparable to those of the CleanCut GS control. Day 14 Qp values reached 111.23, 120.85, and 115.61 pg/cell/day across the tested ADCC+ clones, compared with 113.59 pg/cell/day for the control.
  3. High fed-batch titers retained
    CleanCut GS ADCC+ clones 2C3 and 5A6 reached final titers of 5.8 g/L and 5.7 g/L, respectively, in the same 14-day fed-batch format used for productivity assessment.
  4. Enhanced apparent ADCC potency
    In an ADCC reporter bioassay, afucosylated antibodies generated from CleanCut GS ADCC+ clones showed left-shifted response curves and higher peak signals compared with the fucosylated CleanCut GS trastuzumab control. The reported EC50 values represented a 50–79% reduction, or a 2.0–4.8× increase, in apparent ADCC potency.
  5. Flexible platform access
    For biopharma companies building internal CLD capabilities, CleanCut GS ADCC+ is available under a one-time GMP implementation fee with unlimited product use, no per-program royalties, and no milestone-based access restrictions. For organizations seeking a supported development path, Demeetra offers CLD services using CleanCut GS ADCC+ with no royalty obligations on resulting cell lines.

Demeetra provides gene-edited CHO host platforms, licensing options, and CLD services backed by deep technical expertise.

Contact us to learn how CleanCut GS ADCC+ CHO can support afucosylated antibody development, from platform implementation to fully supported cell line development services.