Telix Pharmaceuticals Limited received a Complete Response Letter (CRL) from the U.S. FDA regarding its application for TLX250-CDx (Zircaix), a novel PET imaging agent designed to diagnose clear cell renal cell carcinoma (ccRCC), the most common and aggressive subtype of kidney cancer. The regulatory setback sent shares tumbling 20.7% to $14.60 in early trading, leading ASX 200 losses.
Manufacturing and Quality Control Concerns
The FDA identified deficiencies in the chemistry, manufacturing and controls package for TLX250-CDx, requesting additional data regarding the scaled-up manufacturing process intended for commercial use. The regulatory agency also documented "notices of deficiency" issued to two third-party manufacturing and supply chain partners that will require remediation before Telix can resubmit its biologics license application.
The FDA specifically asked Telix to provide more data demonstrating that the product used in clinical trials is similar to the one planned for commercial production. These manufacturing concerns must be addressed before the company can proceed with its regulatory submission.
Breakthrough Therapy Status Maintained
Despite the regulatory hurdle, TLX250-CDx retains its Breakthrough Therapy and Priority Review designations, indicating the FDA's recognition of the product's potential to address an important unmet medical need. If eventually approved, TLX250-CDx would become the first commercially available imaging agent to accurately and non-invasively diagnose and characterize clear cell renal cell carcinoma.
"TLX250-CDx breaks new ground as a highly novel biologic-based PET imaging agent using a first-in-class isotope," said Telix managing director and CEO Christian Behrenbruch. "Like many radiopharmaceuticals, it has a complex supply chain, and as the field advances this creates new challenges around the regulatory framework applied to these products."
Company Response and Next Steps
Telix plans to request a meeting with the FDA "as soon as practicable" to address the identified deficiencies and determine an appropriate timeframe for resubmission. The company expressed confidence that the FDA's concerns are "readily addressable" and can be resolved within a reasonable timeframe.
Behrenbruch noted that the company believes "the outstanding matters are resolvable and that we can address the remaining FDA requests within a reasonable time frame."
Financial Impact and Market Access
The CRL does not impact Telix's stated revenue guidance for 2025, as the company had not included sales from TLX250-CDx in its projections. In the interim, Telix will continue providing TLX250-CDx to patients through the FDA's expanded access program, pending further regulatory discussions.
The stock decline reflects investor concerns about the regulatory delay, with Telix shares now down 22.3% over the past 12 months. The company closed Wednesday's regular trading at $12.10, down $0.44 or 3.51%, before dropping an additional $2.20 or 18.18% in after-hours trading following the CRL announcement.
