Flexible, Modular Tech Platform Overcomes Conventional ADC Toxicity and Resistance Limits

Antibody-drug conjugates (ADCs) are now one of the hottest R&D arenas in global pharma, and Chinese ADC technologies are rapidly winning international recognition. Since 2021, domestic companies have signed a string of increasingly large ADC partnerships with multinationals. From 2022 to 2023 China ranked first worldwide in the number of ADC assets out-licensed. According to Frost & Sullivan, as of August 2024 Chinese firms have concluded 34 ADC license-out deals with a combined potential value exceeding US$46 billion.

By combining the specificity of an antibody with the potent cytotoxic activity of a small-molecule payload, ADCs deliver targeted killing of tumor cells and thereby enable precision therapy. Compared with administering cytotoxins directly, ADC treatment offers superior efficacy and markedly reduced side effects.

The ADC market is vast and expanding rapidly. Frost & Sullivan project that the global market will surge from US$7.9 billion in 2022 to US$64.7 billion in 2030, representing a CAGR of 30.0 percent—far out-pacing the broader biologics sector. ADCs’ share of total biologics is expected to climb from 2.2 percent in 2022 to 8.3 percent by 2030.

As research into antibodies, linkers and payloads has deepened and been iteratively optimized, ADC technology has now reached its fourth generation. Today, ADC therapeutics are widely used in the clinic and in trials, forming a cornerstone of solid-tumor treatment and a key future growth driver. Yet the discontinuation of more than 150 ADC candidates to date underscores the field’s central challenge: dose-dependent toxicity that rises in step with exposure and can prevent an efficacious dose from being reached at the maximum tolerated dose (MTD). Safety concerns remain the single most important limiting factor for ADC therapies.

Moreover, because most current ADCs rely on payloads with just three mechanisms of action—microtubule inhibitors, topoisomerase I inhibitors, or DNA-binding agents—tumours that become resistant to one ADC are frequently cross-resistant to others carrying the same warhead, representing a second major hurdle in ADC development.

After two decades at the bench in the ADC field, Dr. Yin Mao has watched first-hand as the leading technology platforms bumped up against their intrinsic limits. Drawing on that experience he has built a flexible, modular ADC platform designed to tackle safety and resistance problems at their technological roots with the team.

To turn that vision into reality, Dr. Yin founded PrimeLink Bio in July 2021. The company’s core technology philosophy—“tailoring optimal ADC structures for specific targets”—drives an iterative cycle of conceptual design and technical validation. Guided by the conviction that “to do the job well you must first sharpen the tools,” after nearly two years of intensive work, Dr. Yin Mao led the team to develop a highly hydrophilic ADC technology platform. It compensates for the poor pharmacokinetic properties caused by the hydrophobicity of the payload conjugated to the ADC, thereby improving the conjugate’s stability in systemic circulation and addressing ADC safety issues to some extent. The platform’s excellent hydrophilicity also counteracts the disruptive effects of payload hydrophobicity on the ADC’s physicochemical properties, broadening the range of usable toxin molecules and helping to overcome potential ADC resistance.

The highly hydrophilic ADC architecture endows PrimeLink Bio’s platform with exceptional compatibility and flexibility, enabling modular design of ADC structures. Leveraging this platform, PrimeLink Bio has advanced three programs to PCC stage; the lead candidate has already demonstrated superior efficacy and safety in pre-clinical studies, positioning it as a potential best-in-class therapy.

PrimeLink Bio’s flexible and modular technology platform

Meanwhile, PrimeLink Bio has continued to draw strong interest from top-tier investors and leading pharmaceutical companies. In September 2024 the company closed a new RMB 80 million financing round, bringing total funds raised to RMB 150 million. Backers include Vertex Ventures, Fosun Pharma, Fosun Healthcare Fund and KaiTai Capital. Recognized for its technological innovation, translational progress, market prospects and research team, PrimeLink Bio was named among the “Top 100 Chinese Innovative Pharma Discoverers 2022-2023” by Pharma Executive China.

Cracking Industry Bottlenecks: The Core Strengths of Our Platform Technology

Dr. Yin has navigated the entire ADC development journey—from early-stage drug discovery through clinical batch release—and has successfully led two ADC programs from discovery into the clinic.

He deliberately chose to build an advanced technology platform before developing the product pipeline, convinced that only superior technology can truly empower ADC innovation. Dr. Yin’s insistence on a state-of-the-art technology platform stems from years of hands-on experience in ADC research. He has witnessed a widespread pitfall in the field: the same ADC structure is applied to diverse targets. While this “one-size-fits-all” approach may deliver successes on a handful of targets, it inevitably fails on many others.

Therefore, Dr. Yin advocates the philosophy of “tailoring ADC structure for specific targets”. Building on this vision, PrimeLink Bio has developed a highly hydrophilic, modular ADC technology platform that delivers the following advantages:

1. Modular Design: Any ADC component—payload, drug-release mechanism, DAR value, bioconjugation method, etc.—can be swapped out rapidly and easily. Through PrimeLink Bio’s cascade screening platform, the optimal ADC candidate is identified for the selected target.

2. Highly Hydrophilic: The platform’s high hydrophilicity counteracts the physicochemical disruption caused by hydrophobic payloads and simultaneously improves ADC pharmacokinetics.

3. Precisely Controlled DAR: DAR can be accurately adjusted between 2 and 24, enabling the selection of the ideal DAR for every ADC and markedly widening the therapeutic window.

4. Highly Compatible system: The platform accommodates diverse antibodies and payloads of high hydrophobicity.

5. Much Broader Therapeutic Window: The Core pipeline candidate has demonstrated outstanding safety and tolerability in non-human-primate toxicology studies, achieving a therapeutic index >19—far surpassing current technologies.

PrimeLink Bio’s technology platform strategy: tailor ADC structure for specific targets

Differentiated Pipeline Layout

As the ADC field heats up, target homogeneity has intensified, with most players clustering around HER2, TROP2, CLDN18.2 and other “hot” targets. PrimeLink Bio does not reflexively chase these crowded targets; instead we size the market and map the competitive landscape to pinpoint where our differentiated advantage truly lies.

After weighing all these factors, PrimeLin Bio’s pipeline spans not only single-target ADCs but also next-generation formats such as bispecific-antibody ADCs and dual-payload ADCs. Over the next two years our lead assets, PLB-002 and PLB-001, will advance into the clinic. CMC activities for PLB-002 are already in full swing, with an IND filing in Q3 2025.

PrimeLink Bio’s Pipeline

The core pipeline PLB-002 addresses a highly differentiated target in ovarian cancer, a setting with serious unmet medical need; only two other same-target ADCs have entered the clinic, both still in Phase I worldwide. Although sharing the same target, the ADC candidate screened through PrimeLink Bio’s cascade screening platform has demonstrated compelling best-in-class potential in pre-clinical studies: tumor-growth inhibition and PK profiles both outperformed the benchmark ADC in animal models, and an outstanding safety margin (therapeutic index >19) was confirmed in non-human-primate toxicology. Because ADC toxicity is driven primarily by the payload, PLB-002 has already shown the potential to be better tolerated than other ADCs carrying the same cytotoxin.

PLB-002’s and BMK ADC’s OVCAR3 CDX Model

PLB-002’s and BMK ADC’s PDX Model

PLB-002’s and BMK ADC’s PK

PrimeLink Bio consistently follows a “steady and solid, yet innovation-seeking” development strategy, with the ultimate goal of delivering Best-in-Class and First-in-Class ADC therapeutics. To that end, we maintain an active and open stance toward any partnership—be it on individual programs or the technology platform itself—whenever collaboration can create a clear 1 + 1 > 2 value.