On December 6, 2023 Telix Pharmaceuticals Limited (ASX: TLX, Telix, the Company) reported positive topline results from the Phase II OPALESCENCE investigator-initiated trial (IIT) of its carbonic anhydrase IX (CAIX)-targeting positron emission tomography (PET) imaging candidate, TLX250-CDx (89Zr-DFO-girentuximab), in patients with triple negative breast cancer (TNBC) (Press release, Telix Pharmaceuticals, DEC 6, 2023, View Source [SID1234638204]). Results will be presented today at the 2023 San Antonio Breast Cancer Symposium (SABCS).

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The pilot prospective study of twelve (12) metastatic patients demonstrated the expression of CAIX in TNBC and effective targeting with radiolabelled girentuximab:

Expression and targeting of CAIX in lesions in the breast, skin, adrenal gland and brain was 100%
Expression in nodes and bone was 88.0% and 91.9%, respectively
TLX250-CDx was found to be safe and well tolerated by patients.
The OPALESCENCE study (ClinicalTrials.gov ID NCT04758780) was undertaken by Dr. Caroline Rousseau at the Institut de Cancérologie de l’Ouest (ICO) in St Herblain (France). The primary objective was to evaluate how CAIX-targeted imaging with PET can be utilised for the diagnosis and staging of TNBC and to develop a deeper understanding of CAIX as a potential therapeutic target in this patient population where there is significant unmet medical need.

Results demonstrate the ability of TLX250-CDx to detect lesions that may resist chemotherapy and have a more aggressive profile resulting from hypoxia. The theranostic potential for girentuximab in this poor prognosis disease supports Telix’s goal to expand its CAIX program into other indications beyond renal (kidney) cancer, including future applications for lutetium-177 (177Lu) and actinium-225 (225Ac) based therapies.

Principal Investigator for the OPALESCENCE study, Dr. Caroline Rousseau stated, "We are pleased to present encouraging topline results from this study of Telix’s investigational CAIX targeting imaging agent in TNBC at SABCS, the largest and most prestigious scientific gathering on breast cancer research worldwide. Telix’s imaging agent TLX250-CDx, which has shown high sensitivity and specificity in clinical trials for the detection of clear cell renal cell carcinoma,[1] has now also exhibited potential utility in this most aggressive form of breast cancer, which is often metastatic and drug-resistant, with limited therapeutic options."

Dr. Christian Behrenbruch, Managing Director and Group CEO added, "Identifying new targets and treatment strategies for TNBC is a severe unmet need where only 20 percent of diagnosed patients are currently eligible for PD-L1-targeted therapies,[2] the standard of care, with the remainder reliant on toxic chemotherapeutic regimens. This topline imaging data may demonstrate proof of concept for future therapeutic applications of radiolabelled girentuximab based on a "theranostic" approach. Telix looks forward to continuing to support the development of its CAIX-targeting antibody-based program for patients with TNBC and other solid tumours, with the ultimate aim to establish CAIX as pan-cancer therapeutic target."

About Triple Negative Breast Cancer

Breast cancer is the most common cancer in women and the second most common cancer overall.[3] In 2020, over 2.2 million women were diagnosed with breast cancer and 685,000 died from their disease.[4] 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.