FDA, Telix Agree on NDA Resubmission Pathway for Glioma Imaging Agent

Melbourne-based Telix Pharmaceuticals (Telix) announced on Sept. 9, 2025 that it has reached an agreement with FDA on the conditions under which Telix will resubmit a new drug application (NDA) for its investigational agent TLX101-CDx (floretyrosine F18 or ¹⁸F-FET, with the provisional brand name Pixclara) intended for the imaging of glioma, a rare and life-threatening brain cancer (1).

What additional information does FDA want?

In a press release, Telix said it engaged with FDA and received detailed feedback regarding a resubmission package, which Telix said will include an additional, confirmatory efficacy study that analyzes existing data (1). Telix said it believes this study will satisfy FDA’s request for supplemental evidence to bolster the NDA and address matters raised in a complete response letter (CRL) issued for TLX101-CDx.

FDA has acknowledged that glioma imaging is an unmet medical need and that an expedited review is likely upon successful resubmission, according to the press release (1).

While TLX101-CDx has not received a marketing authorization in any jurisdiction, Telix said it remains committed to providing patient access to the imaging agent, through an FDA-approved expanded access program, until regulatory approval is granted in the United States (1).

“As previously advised, Telix had multiple options for delivering additional data requested by FDA in the CRL response,” David N. Cade, MBBS, MBA, Telix Group chief medical officer, said in the press release (1). “This flexibility has enabled us to work with relative speed to reach a mutually agreed path forward for resubmission of the NDA. We remain steadfastly focused on our goal of bringing this important imaging agent to patients in the US to support improved diagnosis and management of glioma.”

How is FDA increasing transparency efforts?

In July 2025, FDA said it would be embracing “radical transparency” by publishing more than 200 CRLs issued between 2020 and 2024 for drug and biologic applications that were not approved during their initial review cycle (2).

At that time, Pharmaceutical Technology® Group explored the lessons learned from the content of those published letters, which collectively underscored various underlying issues that frequently involve the maturity of the chemistry, manufacturing, and controls process, manufacturing consistency, and analytical validation—even for sponsors with strong FDA engagement throughout development (3).

FDA then said on Sept. 4, 2025 that it would further advance its focus on transparency by releasing future CRLs “promptly” after being issued to sponsors, immediately releasing 89 previously unpublished CRLs issued from 2024 to present that dealt with pending or withdrawn applications (4).

What else is Telix working on?

As for Telix, in January 2025 the company announced that it had entered into an asset purchase agreement with ImaginAb, giving Telix a pipeline of next-generation therapeutic candidates, a proprietary and novel biologics technology platform, and a protein engineering and discovery research facility located in California (5).

Telix plans to resubmit the NDA for TLX101-CDx in the fourth quarter of 2025; if the resubmission is successful, FDA will subsequently set a new Prescription Drug User Fee Act goal date (1).

References

1. Telix Pharmaceuticals. Telix and FDA Agree on Resubmission Pathway for TLX101-CDx (Pixclara) US NDA. Press Release. Sept. 9, 2025.
2. FDA. FDA Embraces Radical Transparency by Publishing Complete Response Letters. Press Release. July 10, 2025.
3. Cole, C. Manufacturing and CMC Challenges in Immunotherapy: Lessons from Recent Complete Response Letters. Press Release. July 25, 2025.
4. FDA. FDA Announces Real-Time Release of Complete Response Letters, Posts Previously Unpublished Batch of 89. Press Release. Sept. 4, 2025.
5. Telix Pharmaceuticals. Telix to Acquire Next-Generation Therapeutic Assets and Innovative Biologics Technology Platform. Press Release. Jan. 13, 2025.