Telix TLX250-CDx Shows Strong Potential in Imaging Metastatic Triple-Negative Breast Cancer

The Phase 2 OPALESCENCE study, conducted at the Institut de Cancérologie de l’Ouest (ICO) in St Herblain, France, has demonstrated the safety and diagnostic power of TLX250-CDx PET/CT imaging in women with metastatic triple-negative breast cancer (mTNBC).

Triple-negative breast cancer (TNBC) accounts for 10–15% of all breast cancers and lacks common hormonal and HER2 markers, making it difficult to treat and associated with a poorer prognosis.

In this pilot study of 12 patients, investigators confirmed expression of carbonic anhydrase IX (CAIX) in TNBC and effective tumor targeting using TLX250-CDx. Overall imaging sensitivity was 87.5%, with 100% sensitivity for breast, skin, and adrenal lesions. Sensitivity for nodal and bone metastases reached 88.0% and 91.9%, respectively. TLX250-CDx PET/CT identified all brain metastases, confirmed by MRI—while standard FDG PET/CT detected only one-third. Total tumor volume analysis showed comparable measurements between both PET/CT modalities, and no safety issues were observed following TLX250-CDx administration.

The authors concluded that TLX250-CDx immuno-PET “is a sensitive imaging method and offers promise for novel theranostics in mTNBC patients.”

This publication builds on earlier presentations at the European Association of Nuclear Medicine Congress (2022) and the San Antonio Breast Cancer Symposium (2023), further supporting the role of CAIX-targeted imaging in this aggressive cancer subtype.

According to Principal Investigator Dr. Caroline Rousseau, “TLX250-CDx has already shown high sensitivity and specificity in clear cell renal cell carcinoma. Now it has demonstrated potential in metastatic triple-negative breast cancer, identifying lesions that may resist treatment due to hypoxia in patients with limited options.”

Dr. David N. Cade, Group Chief Medical Officer at Telix stated, “We are encouraged by this data in triple-negative breast cancer, an area of significant unmet need. Proof of concept for CAIX-targeted imaging supports the expansion of this pan-tumor program to new indications and potential radiotherapeutic applications using lutetium-177 and actinium-225.”

Telix Pharmaceuticals supplied and authorized ICO’s use of TLX250-CDx for the study. The agent is currently investigational and has not received marketing authorization.