ADC “Biological Missile”Production Code Series VI | Single-use Fluid Management Solutions from Conjugation to Filling

ADC drugs, with their "biological missile"-like precision therapeutic mechanism, have become a focal point in the global innovative drug sector. However, transitioning from clinical development to commercial production presents common challenges in process robustness, regulatory compliance, and supply chain security. Particularly in fluid process steps involving highly potent toxins, stringent requirements are imposed on consumables regarding chemical compatibility, containment, and sterility assurance.

BioLink, building on its deep expertise in both upstream and downstream biopharmaceutical processes, has launched a domestic single-use fluid process solution covering the entire workflow from conjugation reaction to final filling. This solution focuses on addressing actual fluid management pain points in ADC production, aiming to provide pharmaceutical companies with compliant, stable, and traceable process support.

Figure 1: BioLink Single-use ADC Bioprocess Platform

Core Challenges in ADC Bioprocess Fluid Management

In the industrialization of ADC drugs, process and production personnel typically face the following fluid management difficulties:

• Fluid dynamics risks in process scale-up: From lab scale to commercial production, bioreactor volumes increase tenfold or more. Relying solely on geometric similarity for scale-up can easily lead to mixing inhomogeneity, creating localized high-concentration zones (Hot Spot) that trigger antibody aggregation or broadening of the DAR distribution.

• Solvent compatibility: Conjugation reactions involve high concentrations of organic solvents such as DMSO and DMAC, posing challenges to the chemical resistance of contact materials.

• High-potency containment risks: Cytotoxic payloads fall under OEB-4/5 highly active substances. Any open operation or non-contained transfer presents risks of personnel exposure and cross-contamination, imposing physical isolation requirements on hardware containment levels.

• Sterility assurance and regulatory requirements: With the release of the Draft Annex on Sterile Medicinal Products to China's GMP (2010 Revision), PUPSIT (Pre-Use, Post-Sterilization Integrity Testing) for sterilizing filters has become a mandatory regulatory requirement. Furthermore, particle and visible particulate control in the formulation filling stage directly impacts product qualification rates and quality.

• High-value drug substance hold-up: ADC drug substance is extremely valuable. Controlling dead volume in the fluid pathway is not only a cost consideration but also a key factor in optimizing process yield.

BioLink's Full-Process Single-use Fluid Management Solution for ADC

01 Conjugation Reaction: Safeguarding the "Lifeline" of DAR Value

Scale-up with Scientific Evidence

The core challenge in scaling up conjugation reactions is not simply volume multiplication but shifts in fluid dynamics parameters: extended mixing time, altered local shear rate distribution, and reduced jacketed heat-transfer area per unit volume upon scale-up. Insufficient mixing can cause localized high toxin (Drug-Linker) concentration upon addition, leading to broadened DAR distribution, antibody aggregation, or increased side reactions.

Scaling up based solely on empirical geometric ratios or maintaining constant power input per unit volume (P/V) is often insufficient to demonstrate equivalence across scales. BioLink's BioHub^® Single-use Conjugation Mixing System employs Computational Fluid Dynamics (CFD) simulation to perform 3D flow-field analysis for each size (2 L to 1000 L):

• Simulates velocity vector fields, turbulent dissipation rates, and shear stress spatial distribution to identify dead zones;

• Uses mixing time (time to reach 95% homogeneity) and P/V as scale-up matching criteria to verify flow-field similarity across scales;

• CFD results provide a theoretical basis for scale-up reports, supporting regulatory audit requirements for scale-down model equivalence.

Built on this theoretical foundation, the BioHub^® BM/DS Single-use Magnetic Mixing Systems feature a low-shear impeller + standardized height-to-diameter ratio tank design:

Figure 2: BioHub^® Single-use Magnetic Mixing System (Round Tank)

1. Jacket with precise temperature control (±0.5°C), real-time pH and conductivity monitoring, locking in the conjugation reaction endpoint;

2. Paired with FirmaX^® S32 Multilayer Co-extruded Film Conjugation Mixing Bags, validated for chemical compatibility with DMSO/DMAC and other solvents, with E&L studies. Available in custom sizes, tubing, and connectors, manufactured in ISO Class 7 cleanrooms with 100% integrity testing;

3. Offers a full range from 2 L (R&D) → 50 L (pilot) → 200 L / 500 L / 1000 L (commercial) conjugation solutions, maximizing batch-to-batch reproducibility of DAR values.

Figure 3: BioHub^® Single-use Mixing Bag

Core Value

BioLink's conjugation system is more than just a "bag + tank" — with CFD fluid simulation as the scale-up basis, your conjugation process has a scientifically defensible justification from lab to commercial scale.

02 Contained Transfer: SynaLinX^® Platinum Cured Silicone Tubing

SynaLinX^® Platinum Cured Silicone Tubing is supported by comprehensive validation data, passing full biocompatibility tests including USP Class VI cytotoxicity and ISO 10993 sensitization, and comes with a BPOG detailed extractables study to help users expedite regulatory filings.

Figure 4: SynaLinX^® Platinum Cured Silicone Tubing

Given the characteristics and requirements of ADC production processes, high-concentration organic solvents such as DMSO, DMAC, and DMF are commonly used. SynaLinX^® Platinum Cured Silicone Tubing has undergone relevant validation testing, with results showing stable use for up to 30 days in related organic solvents at concentrations of 35% and below, while also meeting short-term transfer needs at 100% high concentrations, safeguarding ADC drug production.

Table 1: Chemical Compatibility Testing of BioHub^® Single-use Mixing/Storage Bag Film, Tubing, and Connectors

Description of Table 1 Results

R — No significant interaction or negligible interaction after 30 days of contact testing;
R₁ — No significant interaction or negligible interaction after 7 days of contact testing;
R₂ — No significant interaction or negligible interaction after 1 day of contact testing;
NR — Interaction present;
LR — Restricted use after 30 days of contact at room temperature; users are advised to test before use;
— — Not tested.

03 Drug Substance Hold and Cryopreservation

ADC drug substance is highly sensitive to storage conditions. Mechanical stress and ice crystal compression during freeze-thaw cycles can cause stress fractures of flexible linkers, leading to free toxin release and a reduced drug-to-antibody ratio, directly impacting drug safety and efficacy. Moreover, ordinary packaging with poor barrier properties allows ingress of moisture and oxygen, accelerating oxidative degradation. BioLink's single-use drug substance freezing bags feature a ULDPE liquid-contact layer and an EVOH barrier layer, with low extractables/leachables, capable of withstanding repeated freeze-thaw cycles from –80°C to room temperature. Paired with rigid outer shells, they effectively prevent low-temperature brittleness and mechanical puncture. The single-use, discard-after-use design eliminates cleaning validation burdens of stainless steel vessels and eliminates batch-to-batch cross-contamination risks.

Figure 5: BioHub^® Plastic Freeze-thaw Box

04 Formulation Sterilizing Filtration: Compliant PUPSIT System

To meet sterilizing filtration regulatory requirements of EMA, PIC/S, MFDS, PMDA, and others, BioLink offers single-use PUPSIT assemblies. These assemblies integrate redundant sterilizing filters, high-precision single-use pressure sensors, and custom flow paths, supporting on-line integrity testing after irradiation sterilization and prior to filtration. BioLink provides 100% customized solutions based on process characteristics and diverse considerations. After assembly, 100% integrity testing ensures the entire PUPSIT system is leak-free, giving users peace of mind.

Figure 6: PUPSIT Design Options

The pressure monitoring system data is compliant with 21 CFR Part 11 electronic records and electronic signatures requirements, ensuring data integrity and traceability, helping pharmaceutical companies pass both domestic and international regulatory audits.

Figure 7: BioHub^® PAT Pressure Monitoring Recorder

[Knowledge Tip] Why PUPSIT?

PUPSIT (Pre-Use, Post-Sterilization Integrity Testing) is designed to address the risk of "flawed filter masking." Sterilization processes (moist heat/irradiation) may cause membrane pore enlargement or seal damage. If testing is performed only after use, the product may block damaged sites and produce a false pass. PUPSIT confirms filter integrity before drug-liquid contact, making it a critical element of sterile process risk control and a clearly recommended practice in EU GMP Annex 1.

05 Terminal Filling: Ultra-Clean WFI-Washed Filling Bags

Formulation filling is the critical step that determines final product quality. BioLink's BioHub^® Sterile Filling Bags are manufactured in Grade B+A environments and feature a unique ultra-clean WFI-washing process:

• Particle control: Multi-stage washing with Water for Injection (WFI), high-pressure purging, and precision drying significantly reduce insoluble particulates and visible foreign matter to levels superior to industry standards.

• Low-residue design: A boat-shaped bottom and an inclined configuration, combined with multiple filling needle setups, maximize the draining of high-value ADC drug solution, minimizing product loss.

• Customization services: One-to-one flow-path customization based on customers' existing filling line equipment to ensure seamless integration.

Figure 8: BioHub^® Single-use Filling Bag

Conclusion

BioLink has deep roots in the bioprocess field. We understand the complexities of ADC drug development and are committed to delivering a fully validated, domestic single-use fluid process platform.

From conjugation and formulation in Grade C environments to sterile filling in Grade B+A environments, BioLink ensures the stability and compliance of every batch of consumables through standardized manufacturing environments and a rigorous quality control system. We hope this integrated solution helps domestic pharmaceutical companies break through technical barriers, achieve a smooth transition from R&D to commercialization of ADC drugs, and jointly drive the high-quality development of China's biopharmaceutical industry.