Summary of Key Points
Astellas successfully demonstrated the commercial potential of the CLDN18.2 target in the treatment of digestive tract tumors with its first monoclonal antibody, Vyloy. However, with the emergence of new technologies such as bispecific antibodies and ADCs (Antibody-Drug Conjugates), the market has shifted from a blue ocean to a red ocean. To maintain its leading position, Astellas has expanded its product portfolio by acquiring and collaborating on bispecific antibody and ADC therapies, aiming to address various patient groups, treatment stages, and indications, and thus build a comprehensive product ecosystem. In the highly competitive ADC field, Chinese pharmaceutical companies have already submitted their marketing applications, posing a challenge to Astellas' lead. Ultimately, the winner in the CLDN18.2 era will be the one that can provide the greatest clinical value.
Detailed Analysis
1. Astellas Made a Wise Bet: Unleashing the Potential of CLDN18.2
CLDN18.2 is a marker on the surface of cancer cells that is particularly abundant in digestive tract tumors such as gastric and pancreatic cancer. In 2016, Astellas spent up to $1.6 billion to acquire a small German company that developed the monoclonal antibody Vyloy targeting this target. At that time, the efficacy of this target had not yet been proven, and Vyloy was only in phase II clinical trials, leading many to question the wisdom of this investment.
However, Vyloy was later approved in Japan, Europe, and the United States, and its sales soared to 63.1 billion yen (over 3 billion RMB) in fiscal year 2025, a more than four-fold increase, making it Astellas' fastest-growing oncology drug. This not only confirmed the efficacy of CLDN18.2 but also established it as a standard target for precision therapy in gastric cancer—doctors now check for this marker before deciding whether to use such drugs. Astellas' bold move has opened up a new market with potential worth tens of billions.
2. Vyloy Has Its Limitations
Despite its success, Vyloy has significant drawbacks:
- Narrow Patient Pool: It is only effective in patients with high expression of CLDN18.2; low-expression patients do not respond well to the drug.
- Significant Side Effects: It must be used in combination with chemotherapy, which can cause gastrointestinal side effects such as nausea and vomiting.
- Competition: Seeing Vyloy's success, other companies have entered the market, developing more advanced therapies using bispecific antibodies and ADCs. More than a dozen products are now in phase III clinical trials or have submitted marketing applications.
Astellas realized that it could not rely solely on Vyloy to stay ahead and needed to develop additional products to overcome these limitations.
3. A Comprehensive Product Portfolio
Astellas' strategy is to address these shortcomings with a range of products:
- Bispecific Antibody ASP2138: Targets both CLDN18.2 and CD3 on immune cells, enabling the activation of immune cells to attack cancer cells even in patients with low expression of the target. Clinical trials have shown an effective rate of 62.5% in first-line treatment for gastric cancer, and it is progressing rapidly compared to similar drugs.
- ADC Drug XNW27011: Designed as a precision therapy, this drug combines chemotherapy with an antibody that targets CLDN18.2, resulting in fewer side effects. It has shown an effective rate of 65.4% in patients who have failed multiple treatments and extended the progression-free period by 11.7 months; it is also effective even in those who have previously received Vyloy.
- Expansion of Indications: Astellas is exploring additional indications, such as pancreatic cancer (where 60% of patients express CLDN18.2). Although Vyloy was not successful in this setting, bispecific antibodies and ADCs are still being tested. The company is also investigating pre- and post-surgical treatments to benefit more patients earlier.
4. ADCs Become the Main Battlefield
The ADC field within the CLDN18.2 ecosystem is the most competitive. Astellas' ADC drug, introduced in 2025 for $1.34 billion, is still in phase II clinical trials, while Chinese companies have taken the lead:
- Innovent Biologics' IBI343 and China BioPharmaceutical's LM-302 submitted their marketing applications in June, becoming some of the first CLDN18.2 ADCs to enter global review.
- Other companies like BeiGene, Junshi Biosciences, and Hengrui Medicine also have ADCs in phase III clinical trials, each with unique advantages (e.g., LM-302 is being tested for first-line treatment, and BeiGene's ADC has fewer side effects; Hengrui's drug is undergoing multi-center trials, making it more attractive for international markets).
Astellas is still catching up in the ADC arena, and it remains to be seen who will emerge as the winner.
5. The Ultimate Competition: Patient Outcomes
Astellas' story reflects the reality of the innovative pharmaceutical industry—the first to enter a new market may not be the last to succeed. The competition in the CLDN18.2 field boils down to clinical value:
- Who can reach the widest range of patients (including those with low expression of the target)?
- Who can extend patients' lives (e.g., by reducing progression-free periods)?
- Who can provide better patient comfort (e.g., with fewer side effects)?
Astellas is using a comprehensive product portfolio to address these challenges, but differentiated innovations from later entrants (such as more advanced ADC technologies) could also change the landscape. Ultimately, the company that truly addresses patients' needs will define the new era of CLDN18.2 therapy.
The battle continues, and every clinical trial result and drug launch will influence the final outcome. For patients, this is good news, as it means more options and better treatment outcomes. The competition in innovative pharmaceuticals always aims to benefit patients.