Lonza has signed a definitive agreement to acquire five US manufacturing sites from Merck KGaA, Darmstadt, Germany, adding capacity in antibody–drug conjugate (ADC) manufacturing, viral vector production, high-potency active pharmaceutical ingredient (HPAPI) payload synthesis, and lipid nanoparticle (LNP) formulation.
Key Insights: As large CDMOs consolidate end-to-end bioconjugation, viral vector, and LNP manufacturing under one quality system, independent analytical testing providers become a critical safeguard for defensible release documentation and regulatory submissions. QA programs supporting ADC substance or drug product development should verify that testing providers hold ISO/IEC 17025 accreditation or demonstrate CGMP compliance, and confirm those providers have no manufacturing affiliation with the CDMO handling the same drug substance.
What the Five Acquired Sites Add for ADC Manufacturing
Each site addresses a distinct advanced modality platform, expanding Lonza’s US network from four to nine CDMO locations:
| Platform | Acquired site | Pre-close status | Post-acquisition scope |
| Bioconjugates/ADCs | St. Louis, MO | Operating under Merck KGaA | End-to-end ADC manufacturing within Lonza network |
| HPAPI¹ payload-linkers | Madison/Verona, WI | Operating under Merck KGaA | High-potency payload-linker synthesis for ADC programs |
| Viral vectors | Carlsbad, CA | Operating under Merck KGaA | Viral vectors with aseptic fill-finish |
| LNPs and liposomes | Indianapolis, IN | Operating under Merck KGaA | LNPs, liposomes, PEGylated proteins with fill-finish |
¹ HPAPI: high-potency active pharmaceutical ingredient
The acquisition adds approximately 1,100 employees, bringing Lonza’s US workforce to more than 6,000 at closing. The network is projected to contribute around CHF 250 million in full-year 2028 sales, with margins expected to reach Lonza’s group level by the mid-2030s.
Lonza will fund the transaction from existing credit facilities with an enterprise valuation in the low- to mid-triple-digit millions Swiss francs, while maintaining its BBB+ credit rating. The deal closes in mid-2027 pending customary regulatory conditions; all five sites operate independently under Merck KGaA until then.
One carve-out applies: Merck KGaA’s BioReliance® contract testing services, covering analytical safety and characterization testing for biologics, stay within Merck KGaA’s Life Science portfolio and are not part of this transaction.
Does CDMO Consolidation Affect Analytical Testing Independence?
When a single organization handles both drug substance manufacturing and analytical release testing, QA teams risk documentation gaps that complicate regulatory submissions. With five sites moving into Lonza’s network, the case for independent testing providers is concrete.
The ADC programs require a testing panel that goes well beyond standard biologics release work. Key analytical requirements include:
- DAR determination: Drug-to-antibody ratio quantitation by HIC-HPLC, UV, or LC-MS
- Free drug quantitation: Detection and measurement of unconjugated cytotoxic payload
- Conjugation site mapping: Payload attachment site characterization by LC-MS/MS
- Cytotoxicity assays: Cell-based potency testing for ADC efficacy and safety
- HPAPI impurity profiling: High-potency impurity detection in multi-matrix environments
Procurement leads evaluating ADC and biopharmaceutical testing labs need to confirm that independent providers hold appropriate CGMP compliance or ISO/IEC 17025 accreditation and can demonstrate multi-matrix, high-potency containment capability.
Merck KGaA’s exit from US CDMO manufacturing reflects active portfolio pruning toward its life science services and pharmaceutical pipeline, including its agreement to acquire siRNA developer Silence Therapeutics in an approximately $1.3 billion all-cash deal. Wolfgang Wienand, CEO of Lonza, stated: “With high demand for bioconjugates and viral vectors, the acquired sites will strengthen our ability to support customers from innovation to launch and commercial supply.”
For programs involving viral vectors or LNPs, confirming that an independent testing provider has completed regulatory inspections in your target market is as important as capacity. QA teams assessing viral vector or LNP testing providers can explore how advanced biologic programs shape analytical testing requirements, alongside a searchable directory of accredited biotechnology and life science testing labs.
Preparing ADC Testing Programs for a Consolidated Manufacturing Landscape
Lonza’s acquisition of five Merck KGaA CDMO sites adds US manufacturing capacity across ADC bioconjugation, viral vector production, HPAPI payload synthesis, and LNP formulation, with the deal expected to close in mid-2027. BioReliance® testing services remain with Merck KGaA, keeping analytical safety testing for these modalities under separate ownership. This separation makes now the right time for QA teams to verify that independent testing providers hold ISO/IEC 17025 accreditation or demonstrate CGMP compliance appropriate to the ADC program’s regulatory pathway.
If you’re looking for accredited contract labs that deliver DAR characterization, viral vector safety testing, and advanced biologic release testing, submit a free lab request and get started.
The original press release can be found here.
This article was created with the assistance of Generative AI and has undergone editorial review before publishing.