In April 2022, Telix secured the exclusive worldwide rights to develop and commercialise radiolabelled forms of olaratumab for the diagnosis and treatment of human cancers.^[1] Olaratumab was originally developed as a naked (non-radiolabelled) monoclonal antibody targeting Platelet Derived Growth Factor Receptor Alpha (PDGFRα), a target expressed in multiple tumour types. Olaratumab has a well-established clinical safety profile, a favourable toxicology dataset and advanced manufacturing package in relation to Lilly's development program, which Telix expects to be able to leverage for future development as a radiopharmaceutical drug product.

Telix's initial development PoC has focused on a rare type of cancer known as Soft Tissue Sarcoma (STS). External beam radiation is a key part of the standard of care for STS, which may therefore be a suitable clinical target for novel radionuclide therapy, particularly for alpha-emitting radionuclides. The ability of olaratumab to target PDGFRα in the STS tumour microenvironment makes it a highly novel and high-potential radiopharmaceutical candidate.

Telix has now completed its preclinical evaluation, with results sufficiently encouraging to advance development toward initial human clinical trials, in line with planned R&D expenditure for 2023/24. The agent has been assigned formal candidate status in Telix's development pipeline (to be denoted as TLX300-CDx/TLX300 for the diagnostic/patient selection tool and therapeutic, respectively). Specifically, these studies have shown that olaratumab can be bioconjugated with multiple chelators (including Telix's proprietary DFO-squaramide chelator), radiolabelled with zirconium-89 (⁸⁹Zr) for imaging by Positron Emission Tomography (PET) and used to demonstrate specific delivery of radiation to STS cancer cells to show proof of concept in xenograft tumour mouse models. Furthermore, olaratumab radiolabelled with therapeutic radionuclide payloads has demonstrated in vivo efficacy with significant reduction in tumour volumes in relevant disease models, even after administration of a single dose. The Company is preparing to publish preliminary findings.

Telix Chief Scientist, Dr Michael Wheatcroft stated, "Building on Telix's proven track record in acquiring and developing novel radiopharmaceutical assets, it is extremely pleasing to demonstrate the adaptation of this traditional biologic agent for future potential use as a targeted radiopharmaceutical. TLX300 will initially be evaluated in a first-in-human clinical study that is designed to inform both the potential efficacy (dosimetry) and safety profile of this research candidate as a therapeutic, demonstrating the development advantage of a theranostic approach."