New Canadian Real-World Evidence at ESMO 2026 Highlights Integration of CLDN18.2 Testing and Targeted Treatment in Clinical Practice

- Canadian patient support program data demonstrate the importance of timely biomarker testing on access to targeted therapy for eligible patients with advanced gastric or gastroesophageal junction cancer -

MARKHAM, ON, Oct. 26, 2026 /CNW/ -- Astellas Pharma Canada, Inc. today announced the presentation of new Canadian real-world evidence describing the implementation of biomarker testing and targeted treatment delivery for adults with CLDN 18.2-positive, HER2-negative locally advanced unresectable or metastatic gastric or gastroesophageal junction (GEJ) cancer. The data demonstrate the value of a national testing pathway through validated centres that enabled timely access to CLDN 18.2 biomarker testing and targeted treatment with zolbetuximab in combination with chemotherapy.¹

The Canadian real-world evidence study analyzed data from a nationwide patient support program (PSP) and was presented at the European Society for Medical Oncology (ESMO) Congress 2026 in Madrid, Spain. Its presentation brings Canadian-generated evidence to one of the world's leading oncology congresses and serves as an opportunity to contribute Canadian experience to the global scientific discussion. It is among the 21 Astellas abstracts presented at ESMO 2026, reflecting the breadth and strategic focus of the company's oncology portfolio and its commitment to shaping cancer care in hard-to-treat areas where significant unmet need remains.

The Canadian experience reflects a coordinated effort to translate biomarker science into practice. ¹ With the leadership of Canadian health care professionals, Astellas supported efforts to establish CLDN18.2 testing pathways and connect biomarker results with access to CLDN18.2-targeted treatment.^{1, 2} This groundwork helps move CLDN18.2 testing and targeted treatment toward integration into routine care while generating practical insights that help address emerging questions around patient management, disease monitoring and the future of biomarker-guided care

Dr. Hatim Karachiwala, Medical Oncologist, Arthur J.E. Child Comprehensive Cancer Centre
"For the first time, we're seeing how CLDN18.2 testing and zolbetuximab are being integrated into real-world care across Canada. The strong interest in this approach reflects the need for more personalized treatment options for people living with advanced gastric and gastroesophageal junction cancers. These findings also reinforce the importance of making biomarker testing a routine part of the treatment journey, so that eligible patients can be identified and considered for targeted therapies as early as possible. As the treatment landscape continues to evolve, collaboration will be key to ensuring patients can access the right testing and the right treatment at the right time."

Between May 20, 2025, and January 31, 2026, 63 patients received at least one cycle of zolbetuximab plus chemotherapy. Patients were enrolled in the PSP across eight provinces. Among those who received treatment, the median age was 64 years, with 47.6% diagnosed with gastric cancer and 52.4% diagnosed with GEJ cancer. Zolbetuximab was used irrespective of PD-L1 CPS, consistent with the Health Canada-authorized indication.¹

As of March 31, 2026, 1,576 samples had been tested for CLDN18.2 at 13 validated centres across Canada through the PSP. The mean turnaround time from access to pathologist sign-out was 6.1 days, and the median CLDN18.2 positivity rate was 41.0%. Together, these findings provide an early view of a PSP-supported testing pathway across participating Canadian centres--including its geographic reach, testing volume, turnaround time and identification of CLDN 18.2-positive samples--during the period between regulatory authorization and public reimbursement.¹

Pierre Olivier Fiset, Pathologist, McGill University Health Centre
"Precision oncology depends on more than identifying a promising biomarker. It requires a reliable and high-quality testing pathway that can deliver clear, timely, consistently interpreted results to treating teams. Collaboration among pathologists, oncologists, laboratories and program partners helped establish CLDN18.2 testing across validated Canadian centres. This experience provides an important foundation for integrating a new biomarker into routine practice and treatment decisions."

October 2026 marks 10 years since Astellas announced its agreement to acquire Ganymed Pharmaceuticals, adding the antibody program that would become zolbetuximab to its oncology pipeline. Since that initial investment, Astellas has continued to advance the science of CLDN18.2 through clinical development, biomarker research and evidence generation.

Graham Watson, Interim General Manager, Astellas Pharma Canada, Inc.
"Astellas is proud to have supported Canadian health care professionals in establishing the infrastructure, access pathways, clinical collaboration and real-world evidence needed to advance CLDN18.2 testing and targeted treatment. A decade after our initial investment in CLDN18.2 innovation, we continue to advance multiple approaches across our portfolio, deepen our understanding of the target and explore new ways to improve outcomes for patients with CLDN18.2-positive cancers. Through ongoing clinical research, biomarker science and real-world evidence generation, we are working with the Canadian oncology community to help address evolving questions around patient identification, testing, treatment sequencing and implementation across care settings."

About the Canadian Real-World Evidence Study¹
A poster for the abstract, "Real-World Use of Zolbetuximab Plus Chemotherapy in Patients With CLDN18.2-Positive, HER2-Negative, Locally Advanced Unresectable or Metastatic Gastric or Gastroesophageal Junction Cancer in a Canadian Patient Support Program," was presented at the ESMO 2026 Congress on October 25, 2026. The PSP was designed to provide timely access to treatment before public coverage, not to collect detailed research data. The analysis was descriptive, and information was limited; no further data were collected after patients transitioned to public coverage. Findings should therefore be interpreted in the context of these limitations. The study was funded by Astellas Pharma Canada, Inc.

About Zolbetuximab²
Zolbetuximab is a claudin 18.2-directed cytolytic antibody that was investigated in combination with fluoropyrimidine- and platinum-containing chemotherapy for the first-line treatment of adult patients with locally advanced unresectable or metastatic human epidermal growth factor receptor 2 (HER2)-negative gastric or gastroesophageal junction (GEJ) adenocarcinoma whose tumours are claudin (CLDN) 18.2 positive. In both the SPOTLIGHT and GLOW Phase 3 clinical trials, approximately 38 per cent of patients screened had tumours that were CLDN18.2 positive, defined as ≥75 per cent of tumour cells demonstrating moderate to strong membranous CLDN18 immunohistochemical staining, assessed and confirmed using a validated in-vitro companion diagnostic test or medical device.

About Gastric and Gastroesophageal Junction Cancer
Gastric and gastroesophageal junction (G/GEJ) cancers are known to be histologically similar, are recommended to be managed in the same way in treatment guidelines and frequently display aligned responses to treatment.³

Gastric cancer (GC) is the fifth most common cancer and the fourth leading cause of cancer-related deaths worldwide.⁴ In Canada, there were approximately 4,100 new cases in 2025, with an incidence rate of 9.6 per 100,000 people.⁵

GEJ adenocarcinomas start in the first two inches (5 cm) where the esophagus joins the stomach.⁶ GC has a 5-year survival rate of 29 percent in Canada, driving the need for new therapeutic options that can slow disease progression and extend lives. ⁵

About Astellas Pharma Canada, Inc.
Astellas Pharma Canada, Inc. is a Canadian affiliate of Tokyo-based Astellas Pharma Inc., a global life sciences company conducting business in more than 70 countries around the world. Astellas is committed to turning innovative science into VALUE for patients. We provide transformative therapies in disease areas that include oncology, urology, immunology and women's health. Through our research and development programs, we are pioneering new healthcare solutions for diseases with high unmet medical need. Learn more at https://www.astellas.com/ca/

Cautionary Notes
In this press release, statements made with respect to current plans, estimates, strategies and beliefs, and other statements that are not historical facts, are forward-looking statements about the future performance of Astellas. These statements are based on management's current assumptions and beliefs in light of the information currently available to it and involve known and unknown risks and uncertainties. A number of factors could cause actual results to differ materially from those discussed in the forward-looking statements. Information about pharmaceutical products, including products currently in development, included in this press release is not intended to constitute an advertisement or medical advice.

References
1. Karachiwala, H. et al. Real-World Use of Zolbetuximab Plus Chemotherapy (CTx) in Patients With CLDN18.2+, HER2−, Locally Advanced (LA) Unresectable or Metastatic Gastric or Gastroesophageal Junction Cancer (mGC/GEJC) in a Canadian Patient Support Program (PSP). ESMO 2026 Poster 2941P. October 2026.
2. Astellas Pharma Canada, Inc. VYLOY Product Monograph. December 13, 2024.
3. Barra WF, et al. GEJ cancers: gastric or esophageal tumors? Searching for the answer according to molecular identity. Oncotarget. 2017; 8(61):104286–104294.
4. Sung, H.; Ferlay, J.; Siegel, R.L.; Laversanne, M.; Soerjomataram, I.; Jemal, A.; Bray, F. Global Cancer Statistics 2020: GLOBOCAN Estimates of Incidence and Mortality Worldwide for 36 Cancers in 185 Countries. CA Cancer J. Clin. 2021, 71, 209–249.
5. Brenner, D. et al. Canadian Cancer Statistics. Government of Canada. Available at: https://cdn.cancer.ca/-/media/files/research/cancer-statistics/2025-statistics/2025_pdf_final_en.pdf?rev=1af65aa6d2c349a5b7ad7a649786e321&hash=D1906D16B0E39DE1C463D2FD3641EA50. Accessed October 16, 2026.
6. American Cancer Society. About esophagus cancer (03-20-2020). Available at: https://www.cancer.org/content/dam/CRC/PDF/Public/8614.00.pdf.

SOURCE Astellas Pharma Inc.