Key takeaways

All 15 FDA-approved antibody-drug conjugates as of 2 July 2026 use first-generation stochastic conjugation 

Four lysine, eleven interchain-cysteine — producing heterogeneous DAR 0–8 mixtures. Yet the entire next-generation pipeline is moving toward site-specific, homogeneous DAR2. Southeast Asian entrants should begin where the field is heading, not where it started.

The region's structural advantage is that its path-dependency cost is zero. 

A team starting an ADC programme in 2026 in Singapore, Bangkok, Jakarta or Kuala Lumpur has no legacy stochastic platform, no sunk redox infrastructure, and no analytical methods or regulatory dossiers written around heterogeneity to protect. It can design its control strategy around homogeneity from day one.

This is a leapfrog, not a gamble. 

With AstraZeneca building the world's first end-to-end ADC site in Singapore, ASEAN's capacity-to-capability shift under way, more than 200 ADCs in clinical development, and bispecific and dual-payload formats leading the frontier, the timing to enter directly at the modern node is defensible.

1.  A US$1.5 billion signal in Tuas South

On 7 November 2024, AstraZeneca broke ground in Tuas South, Singapore, on a US$1.5 billion antibody-drug conjugate manufacturing facility — the company's first end-to-end ADC production site anywhere in the world, integrating antibody production, drug-linker synthesis, conjugation and fill-finish at commercial scale. The 58-acre site, more than 2.5 million square feet and supported by the Singapore Economic Development Board, is targeted for operational readiness in 2029, will employ more than 800 skilled specialists across engineering, quality, technical services and supply chain, and is designed to emit zero carbon from its first day of operations.

The choice of Singapore is itself the message. AstraZeneca did not select a location with a deep ADC manufacturing history — there was none. It selected a jurisdiction with regulatory credibility, complex-manufacturing talent, and a policy environment willing to co-invest in a modality the region has not previously made at commercial scale. For Southeast Asian organisations weighing a move into ADCs, that reframes the central question. It is not whether to enter, but at which technology node to enter.

2.  From capacity to capability

The regional backdrop has shifted decisively. As Serena Choo, Cytiva's Bioprocess and Genomic Medicine Sales Director for ASEAN, argued in July 2026, the region is past the point where simply building more capacity will guarantee competitiveness. The advantage now goes to manufacturers that can adapt facilities, transfer technology, and scale complex modalities with confidence.

The evidence is concrete across four markets:

• Singapore. Sanofi's Modulus facility in Tuas Biomedical Park — an S$800 million investment, the only such modular plant Sanofi operates outside France — can house the equivalent of 34 standardised, interconnected production modules, make up to four vaccines or biopharmaceuticals simultaneously, and switch between platforms in days rather than weeks. Singapore hosts more than 60 biopharmaceutical manufacturing plants, with biopharma activities generating over S$20 billion in annual output. ADCs are explicitly named among the emerging modalities the EDB is cultivating.

• Malaysia. At BIO Asia–Taiwan 2026, Malaysian leaders positioned the country as a bridge between Asian innovation and global markets. The New Industrial Master Plan 2030 and the 13th Malaysia Plan earmark biologics as a key growth segment, and established players such as Duopharma Biotech, Inno Biologics and Pharmaniaga provide an antibody-manufacturing base.

• Thailand. The Board of Investment's A1+ tier offers up to ten years of corporate income tax exemption with no cap for biotechnology projects involving technology transfer. Siam Bioscience, the country's most advanced biologics manufacturer, has publicly flagged interest in new modalities including bispecific antibodies and ADCs.

• Indonesia. Bio Farma, with more than 130 years of history, and partners including Etana Biotechnologies and PT Fapon Bioindustries are building biologics and single-use capability under a healthcare-localisation agenda.

The ecosystem infrastructure has matured in parallel. ADC Congress Asia 2026, co-located with the 13th Biologics Manufacturing Asia, convened in Singapore in March 2026, bringing ADC research and manufacturing decision-makers together in-region. The how of ADC capability is now a live question for dozens of ASEAN institutions.

3.  The technology fork — and why DAR is where generations divide

An ADC's clinical behaviour is shaped by four coupled choices: the antibody, the payload, the linker, and the conjugation strategy. It is the last of these that sets the drug-to-antibody ratio (DAR) distribution, and DAR is where the generational divide sits.

First-generation, stochastic conjugation

Stochastic methods attach payloads to naturally occurring residues. Lysine conjugation targets the ε-amino groups of surface lysines: a typical IgG contains approximately 80 to 90 lysine residues, of which 30 to 40 are solvent-accessible and reactive, and peptide-mapping work has found 78 of 80 putative lysine sites conjugated to some degree. One widely cited study reported that N-hydroxysuccinimide-ester modification produced a population with DARs ranging from 0 to 6, in which at least 40 of 86 lysines were modified — a mixture potentially containing over 4.5 million distinct molecular species. Interchain-cysteine conjugation, used for brentuximab vedotin and many others, partially reduces the four IgG1 interchain disulfides to generate up to eight sites, giving a narrower but still heterogeneous DAR 0–8 distribution.

These approaches are clinically mature and carry the strongest regulatory precedent — all 15 FDA-approved ADCs use them, with zero site-specific products approved to date. But they produce three well-documented liabilities: positional heterogeneity, meaning regioisomers even at a fixed DAR; batch-to-batch variability that complicates the CMC control strategy, comparability and characterisation; and, for maleimide-thiol linkages, retro-Michael deconjugation in plasma, where the thiosuccinimide can eliminate, losing the drug-linker, which may then transfer to circulating thiols such as serum albumin.

Second-generation, site-specific conjugation

Site-specific methods install payloads at defined positions — via engineered cysteines, unnatural amino acids, peptide tags, or enzymatic and glycan-mediated chemistry — to produce homogeneous DAR2 or DAR4 products. Here the literature is careful, and so should we be. Site-specific methods reliably improve product consistency and DAR homogeneity and, in the words of the 2026 Pharmaceutics review, in selected studies and specific payload contexts have been associated with improved plasma stability, pharmacokinetic consistency, or therapeutic performance.

They are not universally superior. They add upfront burden in antibody engineering, expression and process development, and at least one head-to-head study found the therapeutic-index benefit genuine but context-dependent. The review's bottom line is that conjugation strategy should be selected according to the scientific, manufacturing and regulatory requirements of each programme rather than on the basis of a presumed technological hierarchy.

That balanced conclusion is precisely why the Southeast Asia case is interesting.

Left panel adapted from J. Chromatogr. A 2026, doi: 10.1016/j.chroma.2026.466966; right panel adapted from Antibodies 2020, 9(2), 16. Both under CC BY.

4.  For late entrants, path-dependency cost is zero

The technology-neutral verdict implicitly assumes an incumbent who must weigh the switching cost of abandoning a working stochastic platform. Western ADC developers spent roughly two decades building institutional capital around stochastic conjugation: validated redox and partial-reduction unit operations, analytical methods tuned to heterogeneous DAR mixtures, regulatory dossiers written around that heterogeneity, and process teams whose expertise is embedded in it. Every one of those assets becomes a switching cost when moving to site-specific chemistry. That is path dependency.

A team starting an ADC programme in 2026 in Singapore, Bangkok, Jakarta or Kuala Lumpur has none of it. No installed base of stochastic process knowledge to protect. No legacy analytical methods to revalidate. No sunk capital in partial-reduction infrastructure. It can design the control strategy around homogeneity from day one — and a single dominant DAR2 species is inherently easier to characterise, to demonstrate comparability for, and to defend to regulators than a distribution of millions. For a late mover, “no legacy” is not a gap to close; it is the advantage. This is the leapfrog, in the same sense that markets which never built copper telephone networks went straight to mobile.

The market backdrop makes the timing defensible rather than speculative. The ADC field reached roughly US$13.5 billion in 2025 across 15 approved products, with 2026 estimates in the US$15–17 billion range; longer-range analyst forecasts diverge widely, spanning roughly US$32 billion to US$71 billion for 2030–2033, so any single number should be treated with caution. On the pipeline side, the Beacon database tracked 2,334 distinct antibody-based drug conjugates globally as of January 2026, with 130 new candidates entering clinical development in 2025 — a 49 percent year-on-year increase. More than 200 candidates are in active clinical development across more than 50 target antigens. Development has broadened well beyond HER2 and TROP2 into EGFR, CLDN18.2, B7-H3 and c-MET, and bispecific and dual-payload ADCs are now the leading frontier: the c-MET × EGFR bispecific pair alone had 24 candidates in early 2026, nine of them in the clinic. These are formats for which DAR control is not a refinement but a design prerequisite.

Market range: Mordor Intelligence (CC BY 4.0) and Grand View Research. Approved-product count: Pharmaceutics 2026, 18(7), 852

5.  Three practical entry routes for ASEAN organisations

Route A — the academic and translational route. 

Groups at institutions such as A*STAR, EDDC, NUS, NTU, Chulalongkorn, Siriraj or Universiti Malaya often already hold candidate antibodies. Glycan-mediated remodelling is attractive here because the N297 Fc glycosylation site is single and absolutely conserved across IgG, so conjugation requires no antibody re-engineering. The existing antibody can be used as it is.

Route B — the CDMO differentiation route. 

Rather than competing on commodity monoclonal antibody capacity against far larger players, a regional CDMO can offer site-specific conjugation as a differentiated, higher-value service. This meets the capability-not-capacity thesis head-on.

Route C — the capability-extension route. 

Biosimilar and vaccine organisations already possess antibody expression and fill-finish capability. Adding a defined, enzyme-driven conjugation step is a considerably smaller leap than building an ADC capability from zero.

6.  The minimum viable technical stack

Regardless of route, a first site-specific ADC programme needs three things. It is worth understanding why each matters, independent of any supplier.

A compliant conjugation enzyme, treated as a defined critical raw material. 

Because the enzyme acts directly on the drug substance, its quality attributes propagate into the product. The specifications that matter are purity, host-cell protein, host-cell DNA, endotoxin and sterility — and, critically for glycan and glutamine chemistries, the absence of contaminating exo-glycosidase and proteolytic activity, which would otherwise degrade the antibody or the remodelled glycan. GMP-grade documentation and traceability determine whether the material can be used beyond bench research.

The right analytical readouts. 

Hydrophobic-interaction chromatography resolves the DAR distribution; intact-mass LC-MS confirms site-specificity and detects unconjugated DAR0 or partially conjugated DAR1 species. Together they operationalise the principle that DAR is a distribution, not a number — you cannot control what you cannot see.

An application-support system. 

Conjugation chemistry is unforgiving of small process errors. Access to protocols, troubleshooting and reference data materially shortens the path from first experiment to a defensible process.

7.  Product section — to be completed

The technical stack above is described in vendor-neutral terms on purpose, because the argument stands on its own: Southeast Asia's structural advantage is real whether or not any particular supplier is involved. But the argument only becomes actionable when the critical raw material at its centre — the conjugation enzyme — is available at the right grade, with the right documentation, and backed by the right technical support. This is where Hzymes Biotech's enzyme portfolio fits into the picture.

An enzyme toolbox for site-specific conjugation

The Hzymes enzyme toolbox offers three site-specific conjugation routes: glycan remodelling (Endo S2, Cat. No. HBP000133) facilitates preservation of native glycosylation; the glutamine Q295 route (mTGase, Cat. No. HBP000136) targets specific residues; and Sortase A (Cat. No. HBP000122) is suitable for gentle ligation via the LPXTG tag. These three routes are complementary in terms of substrate selectivity, reaction site, and operating conditions, allowing selection of the appropriate strategy for different target molecules. 

EndoS2-pro — the glycan remodelling route (Route A)

Key Features of Endo S2 Pro

Source and engineering: tag‑free, AI‑engineered enzyme derived from Streptococcus pyogenes serotype M49, with independent intellectual property.

Substrate specificity: It specifically cleaves the β (1‑4) glycosidic bond between the first and second N‑acetylglucosamine (GlcNAc) residues in the N‑glycan of the IgG Fc region.

Broad substrate range: Unlike Endo S, which acts only on complex‑type glycans, EndoS2 has a broader substrate spectrum, showing activity on complex‑type, hybrid‑type, and high‑mannose N‑glycans.

Core Advantages

High transglycosylation activity: Endo S2 exhibits both high glycosidase and transglycosylation activities

Site specificity: EndoS2‑pro catalyses with high selectivity at the glycosylation site (Asn297) in the antibody Fc region, without affecting Fab glycosylation. This ensures precise and homogeneous modification.

Enhanced product homogeneity: Leveraging its efficient transglycosylation activity, the enzyme allows “trimming” and “rebuilding” of antibody glycans, yielding highly homogeneous glycoforms.

One‑pot reaction feasibility: Benefiting from its dual glycosidase and transglycosylase activities, EndoS2‑pro enables simultaneous deglycosylation and transglycosylation in a one‑pot process, simplifying the workflow.

LC-MS Results of Endo S2-pro mediated Trastuzumab Conjugation with LacNAc-oxa: 

Conclusion:

1. EndoS2-pro can completely hydrolyze antibody glycans, no native IgG was detected after hydrolyzation.

2. High transglycosylation efficiency with LacNAc (~100%), DAR0 and DAR2 signals were not detected.

3. Endo S2‑pro exhibits performance equivalent to Endo S2 WT.

Evaluation results of Endo S2 Pro from our customers

mTGase — the glutamine/Q295 route (Routes B and C)

Hzymes mTGase from Streptoverticillium mobaraense, expressed in E. coli with a C-terminal 6×His tag, enabling site-specific conjugation at antibody Q295 following PNGase F deglycosylation mTGase-mediated antibody conjugation centers on the enzymatic formation of a stable amide bond between a specific site on the antibody (e.g., the heavy chain Q295 residue) and a linker bearing reactive groups.   

Key Features and Advantages

Site‑specificity: mTGase precisely recognizes and modifies the Q295 glutamine residue in the Fc region of antibodies, enabling site‑specific conjugation.

No antibody engineering required: This technology can be directly applied to native antibodies without the need for genetic engineering.

DAR Confirmation of ADCs by LC-MS

Data confirmed that after conjugation, only DAR2 signals were detected, there were no DAR0 and DAR1 signals

Sortase A and PNGase F — supporting enzymes

Sortase A is a highly specific cross-linking enzyme derived from Gram-positive bacteria that catalyzes transpeptidation by cleaving between threonine and glycine in a C-terminal LPXTG recognition motif and joining it to the amino group of an N-terminal glycine of another molecule.

PNGase F is a recombinant glycosidase cloned from Elizabethkingia miricola and overexpressed in E. coli. PNGase F catalyzes the cleavage of N-linked oligosaccharides between the innermost GlcNAc and asparagine residues of high mannose, hybrid and complex oligosaccharides from N-linked glycoproteins (see figure). PNGase F will not remove oligosaccharides containing Alpha-(1,3)-linked core fucose commonly found on plant glycoproteins.:  

Why these specifications matter for your programme

EndoS2-pro

 Independent intellectual property rights,

v  Meet GMP requirements,

v  A well-developed application system can provide technical support for customers,

v  Capable of large-batch production and lower prices.

mTGase

v  Meet GMP requirements,

v  A well-developed application system can provide technical support for customers,

v  Capable of large-batch production and lower prices.

Working with the Hzymes application team

The Hzymes application team provides technical support for protocol optimisation and troubleshooting across the conjugation-enzyme portfolio. For enquiries, requests for samples, application notes or  protocols may be directed to the Southeast Asia region                                                                                                       

None of these changes the fundamental point of the first four-fifths of this article. Southeast Asia's opportunity in ADCs is not to catch up along the path the West already walked — it is to skip the first steps of that path entirely. AstraZeneca chose Singapore to build the world's first end-to-end ADC site not because the region has a long ADC history, but because it does not: there is nothing to unlearn. For the CDMOs, biotechs, national institutes and academic groups now weighing their first move, the most durable decision available is also the simplest to state. Start at the modern node. Start at DAR2.

References

1.   AstraZeneca Singapore — groundbreaking, 800+ jobs, 58 acres, 2029, zero carbon (7 Nov 2024): astrazeneca.com/country-sites/singapore/press-releases/

2.   Singapore EDB — AstraZeneca ADC facility: edb.gov.sg/en/about-edb/media-releases-publications/

3.   AstraZeneca — original US$1.5bn ADC announcement (May 2024): astrazeneca.com/media-centre/press-releases/2024/astrazeneca-to-manufacture-adcs-in-singapore.html

4.   Biospectrum Asia — groundbreaking, 58 acres / 2.5m sq ft, first end-to-end globally: biospectrumasia.com/news/25/25172/

5.   Biopharma APAC — Cytiva, Serena Choo, “From Capacity to Capability“ (17 Jul 2026): biopharmaapac.com/expert-insight/120/8195/

6.   Singapore EDB — Sanofi Modulus, world-first modular facility: edb.gov.sg/en/about-edb/media-releases-publications/

7.   PMLiVE — Sanofi Modulus €558m, ~200 jobs: pmlive.com/pharma_news/

8.   Fierce Pharma — Sanofi Modulus S$800m / US$590m, Tuas: fiercepharma.com/pharma/

9.   Singapore EDB — biotech and pharma industry, 60+ plants: edb.gov.sg/en/our-industries/biotechnology-pharmaceuticals.html

10.  ASEAN Briefing — Singapore biopharma output above S$20bn: aseanbriefing.com/news/

11.  Biopharma APAC — Malaysia as bridge between Asian innovation and global markets, BIO Asia–Taiwan 2026: biopharmaapac.com/news/18/8205/

12.  Duopharma Biotech FY2025 results, NIMP 2030 and RMK-13 context: news.marketersmedia.com/

13.  Iconic — Thailand pharmaceutical industry and BOI A1+ incentives (2026): iconicthai.com/thailand-pharmaceutical-industry/

14.  Siam Bioscience — stated interest in ADCs and bispecifics, BIO convention profile: convention.bio.org/exhibitors/siam-bioscience-co-

15.  Antara News — Fapon and Bio Farma MOU: en.antaranews.com/news/305667/

16.  IMAPAC — ADC Congress Asia 2026 and 13th Biologics Manufacturing Asia, Singapore, 11–12 Mar 2026: eventbrite.sg

17.  Pharmaceutics 2026, 18(7), 852 — ADC conjugation strategies review: doi.org/10.3390/pharmaceutics18070852

18.  ACS Bioconjugate Chemistry — “Site-Specific ADCs: The Nexus“, >4.5m species, 40 of 86 lysines: pubs.acs.org/doi/pdf/10.1021/bc5004982

19.  mAbs 2019 — site-specific ADC heterogeneity root-cause analysis, DAR 0–8: tandfonline.com/doi/full/10.1080/19420862.2019.1624127

20.  BOC Sciences — lysine conjugation, ~80–90 lysines, 30–40 accessible: adc.bocsci.com/services/lysine-conjugation.html

21.  Nature Biotechnology — self-hydrolysing maleimides and retro-Michael, Lyon et al. 2014: nature.com/articles/nbt.2968

22.  ACS Bioconjugate Chemistry — site-specific DGN549, context-dependent therapeutic index: pubs.acs.org/doi/10.1021/acs.bioconjchem.9b00777

23.  MDPI Antibodies / PMC — EndoS2 one-pot glycan remodelling, N297, chemoenzymatic ADCs: pmc.ncbi.nlm.nih.gov/articles/PMC10660516/

24.  ACS Bioconjugate Chemistry — mTGase Q295 conjugation with EndoS2 glycan trimming: pubs.acs.org/doi/10.1021/acs.bioconjchem.4c00013

25.  Vision Lifesciences — ADC market US$13.5bn (2025), 15 approved, 200+ clinical: visionlifesciences.com/insights/

26.  ChemExpress — ADC Landscape Review 2025, Beacon 2,334 tracked, c-MET×EGFR 24 candidates: chemexpress.com/news-and-events/news/191

27.  DIMA Biotechnology — top ADC targets, AACR 2026: dimabio.com/blog/popular-adc-targets-at-aacr-2026

28.  Biopharma PEG — FDA-approved ADCs and pipeline, >200 candidates, >50 antigens: biochempeg.com/article/74.html

29.  PatSnap — ADC manufacturing technology trends 2026: patsnap.com/resources/blog/articles/adc-manufacturing-technology-trends-in-2026/