Telix Completes Acquisition of Atlab for Prostate Cancer Program

Telix Pharmaceuticals Limited recently announced completion of the acquisition of Atlab Pharma SAS. The option to acquire Atlab for the consideration of $10 million (in cash or shares, at Telix’s election) was previously disclosed in Telix’s IPO prospectus. As part of the acquisition, Telix has renegotiated Atlab’s material background intellectual property licenses, notably with BZL Biologics LLC. BZL is the holder of a portfolio of patents originating from Professor Neil Bander’s laboratory at Weill Cornell Medical Centre (WCMC, NY). The complete transaction details can be found in the Company’s ASX disclosures.

Telix CEO Dr. Christian Behrenbruch stated, “Telix has built on the Atlab/BZL experience to develop TLX591, an engineered and optimized form of ¹⁷⁷Lu-labelled huJ591. The result is a best-in-class anti-PSMA therapeutic that clearly rivals the performance of small molecule anti-PSMA agents, such as PSMA-I&T and PSMA-617. We believe that this transaction also has the potential to give Telix a significant edge in the combination use of PSMA-targeting therapeutics with androgen-targeting drugs such as Zytiga and Xtandi.”

Atlab President, Dr. Jean-Marc Le Doussal added, “We are delighted to become part of Telix and to contribute to the future success of TLX591. Together with our colleagues at BZL we bring a considerable depth of knowledge around antibody-based PSMA therapeutics, built on a decade of clinical collaboration with the University of Nantes and WCMC.”

PSMA is a cell surface antigen that is has relatively little expression in normal tissues and represents a validated and highly promising target for a range of therapeutic strategies, particularly radiopharmaceuticals. PSMA expression has been detected in a limited range of normal tissues, including benign prostatic epithelium, renal proximal tubules, small bowel, and the brain (a subset of astrocytes). However, these tissues generally express PSMA at levels 2 to 3 orders of magnitude lower than that observed in prostate cancer.

Antibody-directed cytotoxicity (whether via targeted radiation or other therapeutic strategies) offers several advantages over small molecule or peptide-based delivery approaches. Normal tissues that express PSMA are highly polarized to the apical/luminal aspect of the benign prostatic glands, renal tubules, and small bowel, basement membrane and epithelial tight junctions, and therefore form substantial barriers to circulating antibodies. PSMA expression by astrocytes is similarly sequestered behind the blood-brain barrier. Consequently, antibodies to PSMA are functionally tumor-specific, whereas small molecule PSMA ligands excreted via the renal tubular lumen are not. As a result, small molecule and peptide therapies targeting PSMA have shown significant off-target effects not seen with antibodies, which may limit their utility outside of the salvage (“end of life”) patient population.

The huJ591 (humanized) mAb is the most clinically-advanced anti-PSMA antibody, with experience in several hundred patients for imaging and therapy, both as a “naked” antibody and with a wide range of diagnostic and therapeutic payloads. Almost 200 patients have been treated with ¹⁷⁷Lu-huJ591 at different dosing levels and in combination with other standard care therapies, including androgen deprivation therapy in the metastatic castrate-resistant prostate cancer (mCRPC) setting. In over a dozen clinical trials, huJ591 has demonstrated excellent immunogenicity, safety, tolerability and efficacy, including with repeat dosing.

TLX591 is a “best-in-class” anti-PSMA radiopharmaceutical based on a re-engineered and optimized form of the huJ591 antibody. Telix has engineered the biological properties and production characteristics of huJ591 to deliver enhanced clinical performance and lower manufacturing cost. TLX591 combines the superior therapeutic efficacy of antibody-based pharmaceuticals with the hematologic toxicity profile of rapidly-clearing small molecules targeting PSMA. TLX591, like huJ591, does not target normal tissue PSMA expression or demonstrate the typical exocrine gland uptake that may limit the utility of small molecule PSMA radiopharmaceuticals outside of the salvage (or “end of life”) therapy setting.

 Telix Pharmaceuticals Limited is a global biopharmaceutical company focused on the development of diagnostic and therapeutic products based on targeted radiopharmaceuticals or “molecularly-targeted radiation” (MTR). The company is headquartered in Melbourne with international operations in Brussels (EU), Kyoto (JP) and Indianapolis (US). Telix is developing a portfolio of clinical-stage oncology products that address significant unmet medical need in renal, prostate, and brain (glioblastoma) cancer. For more information, visit www.telixpharma.com.