The U.S. Food and Drug Administration (FDA) has asked Telix Pharmaceuticals to provide more detailed data before it can approve the company’s new diagnostic imaging drug for kidney cancer. The request centers on gaps in the company’s submission regarding manufacturing standards and comparability between the drug batches used in clinical trials and those intended for commercial use.
The drug in question, TLX250-CDx (branded as Zircaix), is designed to help doctors detect clear cell renal cell carcinoma, the most common and aggressive form of kidney cancer. While the FDA has acknowledged the clinical value of the agent by granting it Breakthrough Therapy and Priority Review status, approval will now be delayed until Telix Pharmaceuticals addresses the concerns raised.
Market Reaction and Investor Concerns
News of the FDA’s decision sparked immediate volatility in Telix’s share price. On the Australian Securities Exchange, the company’s stock plummeted sharply in early trading, at one point losing nearly a quarter of its value. Although the drop later moderated, the decline still ranked among the steepest in the company’s trading history.
Investors reacted to the uncertainty surrounding the drug’s approval timeline, which could affect Telix’s near-term growth strategy. The company, however, emphasized that its 2025 financial outlook remains unchanged, as Zircaix sales were not included in revenue forecasts for the year. Telix Pharmaceuticals also reiterated its commitment to resolving the regulatory issues quickly, framing the FDA’s request as “readily addressable.”
Path Forward for Telix
The FDA issued what is known as a Complete Response Letter, outlining the areas where additional clarification and supporting data are required. Key points included deficiencies in the quality control and comparability data, as well as issues identified in two third-party manufacturing partners responsible for producing the imaging agent.
Telix has begun working closely with the FDA to determine how best to meet the regulator’s requirements. The company is preparing a comprehensive response and will outline a timeline for resubmitting its application once discussions advance. In the meantime, Telix Pharmaceuticals will continue making Zircaix available through the FDA’s Expanded Access Program, ensuring that eligible patients still have access to the diagnostic tool.
Despite the setback, Telix Pharmaceuticals maintains a strong position in the oncology diagnostics space. Zircaix’s special designations highlight its potential to address an urgent medical need, and the company believes the approval delay is a procedural matter rather than a scientific one. With kidney cancer accounting for a significant burden in global oncology care, the successful launch of Zircaix could offer physicians a powerful new tool for improving early detection and treatment planning.
Sources:
https://www.reuters.com/business/healthcare-pharmaceuticals/us-fda-seeks-more-information-telix-pharmas-diagnostic-drug-kidney-cancer-2025-08-28/
https://www.nasdaq.com/articles/fda-requests-more-data-telixs-kidney-cancer-imaging-drug
