OPALESCENCE Trial Published in EJNMMI: Confirms Theranostic Potential of TLX250-CDx in Breast Cancer

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12 Nov, 2025, 04:00 CST

MELBOURNE, Australia and INDIANAPOLIS, Nov. 12, 2025 /PRNewswire/ -- Telix Pharmaceuticals Limited (ASX: TLX, NASDAQ: TLX, "Telix") today announces that final positive results from the Phase 2 OPALESCENCE trial^[1] of TLX250-CDx (⁸⁹Zr-girentuximab) in metastatic triple negative breast cancer (mTNBC) have been published in the European Journal of Nuclear Medicine and Molecular Imaging (EJNMMI)^[2].

OPALESCENCE was a prospective, single-center Phase 2 investigator-initiated trial (IIT) conducted at the Institut de Cancérologie de l'Ouest (ICO) in St Herblain, France. The trial evaluated the safety, sensitivity, and diagnostic utility of TLX250-CDx PET/CT^[3] imaging in women with mTNBC.

The pilot prospective study of twelve (12) patients demonstrated the expression of carbonic anhydrase IX (CAIX) in TNBC and effective tumor targeting with TLX250-CDx:

Overall sensitivity was 87.5% with 100% sensitivity for breast, skin, and adrenal gland;
Expression in nodes and bone lesions was 88.0% and 91.9%, respectively;
TLX250-CDx PET/CT detected all brain metastases, confirmed by MRI, whereas FDG PET/CT detected only one-third of brain lesions;
Tumor burden analyzed using total tumor volume (TTV) was equivalent between both PET/CT methods; and
No safety issues were reported after TLX250-CDx administration.

The authors conclude that TLX250-CDx immuno-PET "is a sensitive imaging method and offers promise for novel theranostics for mTNBC patients".

The first peer-reviewed publication about the trial builds on preliminary results presented at the European Association of Nuclear Medicine Annual Congress in 2022^[4] and at the San Antonio Breast Cancer Symposium in 2023^[5], further substantiating the potential of CAIX-targeted PET imaging in this aggressive cancer subtype.

Principal Investigator for the OPALESCENCE study, Dr. Caroline Rousseau stated, "TLX250-CDx has already shown high sensitivity and specificity in clinical trials for the detection of clear cell renal cell carcinoma^[6]. Now it has also exhibited potential utility in metastatic triple negative breast cancer, an aggressive form of breast cancer. These results demonstrate the ability of TLX250-CDx to identify lesions that may be resistant to treatment due to their aggressive profile resulting from hypoxia, in patients with limited options for therapeutic management."

Dr. David N. Cade, Group Chief Medical Officer at Telix, added, "We are encouraged by this data in triple negative breast cancer, which remains an area of significant unmet need. Proof of concept for CAIX-targeted imaging supports the expansion of this potential pan-tumor program into new indications beyond renal cancer, including future applications for lutetium-177 (¹⁷⁷Lu) and actinium-225 (²²⁵Ac) based therapies."

The full paper can be found at: https://link.springer.com/article/10.1007/s00259-025-07619-y

Telix supplied and authorized ICO to use TLX250-CDx during the clinical study. TLX250-CDx has not received a marketing authorization in any jurisdiction.

About Triple Negative Breast Cancer 

Breast cancer is the most common cancer in women and the second most common cancer overall^[7]. In 2022, almost 2.3 million women were diagnosed with breast cancer and 666,000 died from their disease^[8]. Triple negative breast cancer (TNBC) accounts for about 10-15% of all breast cancers with the term triple negative referring to the fact that the cancer cells do not have any of the three markers commonly found on breast cancer cells – the oestrogen and progesterone receptors, and HER2 protein. TNBCs differ from other types of invasive breast cancer in that they grow and spread faster, have limited treatment options, and a poorer prognosis^[9].

About Telix Pharmaceuticals Limited

Telix is a biopharmaceutical company focused on the development and commercialization of therapeutic and diagnostic radiopharmaceuticals and associated medical technologies. Telix is headquartered in Melbourne, Australia, with international operations in the United States, United Kingdom, Brazil, Canada, Europe (Belgium and Switzerland), and Japan. Telix is developing a portfolio of clinical and commercial stage products that aims to address significant unmet medical needs in oncology and rare diseases. Telix is listed on the Australian Securities Exchange (ASX: TLX) and the Nasdaq Global Select Market (NASDAQ: TLX).

Visit www.telixpharma.com for further information about Telix, including details of the latest share price, ASX and U.S. Securities and Exchange Commission (SEC) filings, investor and analyst presentations, news releases, event details and other publications that may be of interest. You can also follow Telix on LinkedIn, X and Facebook

Telix Investor Relations (Global)

Ms. Kyahn Williamson
Telix Pharmaceuticals Limited
SVP Investor Relations and Corporate Communications
Email: [email protected]

Telix Investor Relations (U.S.) 

Annie Kasparian 
Telix Pharmaceuticals Limited 
Director Investor Relations and Corporate Communications 
Email: [email protected]

^[1] ClinicalTrials.gov ID: NCT04758780.

^[2] Rousseau et al. Eur J Nucl Med Mol Imaging. 2025.

^[3] Positron emission tomography/computed tomography.

^[4] Telix ASX disclosure 18 October 2022.

^[5] Telix media release 7 December 2023.

^[6] Telix ASX disclosures 7 November 2022. Shuch et al. Lancet Oncol. 2024.

^[7] World Cancer Research Fund (WCRF): https://www.wcrf.org/dietandcancer/breast-cancer-statistics

^[8] Global Cancer Statistics 2022: GLOBOCAN survey. Published August 2024.

^[9] American Cancer Society: https://www.cancer.org/cancer/types/breast-cancer/about/types-of-breast-cancer/triple-negative.html

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