Telix Pharmaceuticals Limited (ASX: TLX) has welcomed the successful preclinical development of radiolabelled olaratumab, an antibody licensed from Eli Lilly and company.
Telix has demonstrated proof-of-concept (PoC) of using olaratumab to selectively deliver both diagnostic and therapeutic radiation to tumours as a radiopharmaceutical moiety and has produced a candidate for clinical translation. Telix will now progress to first-in-human clinical studies based on these highly encouraging results.
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. 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) 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.
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,” Telix Chief Scientist, Dr Michael Wheatcroft, said.
“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.”
About Soft Tissue Sarcoma (STS)
Soft tissue sarcoma is a complex disease that encompasses a diverse group of relatively rare cancers, with more than 50 histological subtypes. In the United States, it is estimated that 13,040 new cases and 5,150 deaths were caused by STS in 2019, representing 0.75% of overall cancer incidence and 0.84% of overall cancer mortality.
In Europe, nearly 23,600 new STS cases rose annually, and the crude incidence rate was 4.7 per 100,000. Approximately 39,900 new STS cases occurred nationwide in China in 2019, accounting for 1.05% of overall cancer incidence. The crude incidence rate was 2.91/100,000 and generally increased with age. Standard treatment for soft tissue sarcoma includes surgery, radiation therapy and/or chemotherapy. For patients with advanced, unresectable, or metastatic disease, treatment typically involves chemotherapy with single agents (e.g., doxorubicin) or anthracycline-based combination regimens. However, the prognosis for these patients remains poor, with treated patients with metastatic disease having a median overall survival of around 12–18 months.
About olaratumab
Olaratumab (previously marketed under the brand name, Lartruvo) was originally developed as a monoclonal antibody targeting PDGFRα. Olaratumab was granted “Accelerated Approval” in the U.S. and “Conditional Approval” in the EU based on Phase II trial data which showed a 1-year survival benefit in patients with STS, when given in combination with standard chemotherapy.
Olaratumab was voluntarily withdrawn from the market by Lilly following the failure of the Phase III ANNOUNCE clinical trial, in which olaratumab did not improve survival for patients.
