Astellas Pharma's Vyloy (zolbetuximab), the first Claudin 18.2-targeted therapy for gastric cancer, has been approved in Korea, offering a new treatment option for patients with advanced gastric cancer. However, challenges in the reimbursement process for the companion diagnostic device (CDx) may delay patient access to this promising drug.
Clinical Significance of Vyloy
Vyloy, an immunoglobulin monoclonal antibody, targets Claudin 18.2, a protein expressed in gastric cancer cells. Approved by the Ministry of Food and Drug Safety (MFDS) in September, Vyloy is intended for first-line treatment in combination with fluoropyrimidine-based and platinum-based chemotherapy for patients with CLDN18.2-positive, HER2-negative, unresectable, locally advanced, or metastatic gastric adenocarcinoma or gastroesophageal junction adenocarcinoma.
Professor Lee Keun-wook of Seoul National University Bundang Hospital highlighted the potential of Vyloy to transform gastric cancer treatment in Korea, where treatment options have been limited. Data from a phase 3 trial indicated that Vyloy approximately doubled the median overall survival (mOS) compared to placebo in the Korean subgroup. He noted that the current five-year relative survival rate for patients with metastatic gastric cancer in Korea is only 6.6 percent.
Reimbursement Challenges
Despite the clinical value and Astellas Pharma Korea's efforts to expedite its introduction, Vyloy faces hurdles in securing reimbursement. A key issue is the reimbursement of the companion diagnostic device (CDx), Roche Diagnostics' VENTANA CLDN18(43-14A) RxDx Assay, used to diagnose Claudin 18.2 expression. While the MFDS approved the CDx simultaneously with Vyloy, HIRA is reviewing whether the CDx requires evaluation as a new medical technology.
If the Claudin 18.2 CDx is subject to new medical technology evaluation, the subsequent review process by the National Evidence-based Healthcare Collaborating Agency (NECA) and HIRA could significantly delay Vyloy's launch, even on an unreimbursed basis. Experts in pathology and oncology argue that the CDx should not be classified as a new medical technology, as it utilizes immunohistochemical testing (IHC), a well-established method, despite the novelty of the Claudin 18.2 biomarker.
Expert Opinions and Policy Implications
Dr. Rha Sun-young, chairwoman of the Korean Cancer Association (KCA) and professor of medical oncology at Severance Hospital, warned that evaluating the companion diagnostic technology for zolbetuximab as a new medical technology could delay the domestic introduction of the treatment by up to a year. She emphasized the structural limitations of the current system, which does not adequately support the synchronized introduction of targeted antitumor drugs and their companion diagnostics. The KCA plans to advocate for policy improvements to address these issues.
The decision on whether the CDx is subject to new medical technology evaluation will be made at the next meeting of a subcommittee of the Expert Evaluation Committee. The outcome of this decision will significantly impact the timeline for Vyloy's availability to Korean patients.
