Telix heads to the US, as RayzeBio runs into problems

Radiopharmaceuticals are still hot, but questions remain about this approach, particularly around their supply. This hasn’t stopped one contender, Telix, from heading to the US. The group, which is currently listed on its home Australian exchange, is planning a US$200m float on Nasdaq, it said yesterday.

Meanwhile, RayzeBio, which Bristol Myers Squibb bought for $4.1bn last year, has had to pause the phase 3 Action-1 trial of its RYZ101 because of a shortage of actinium-225, highlighting the need to secure its own means of producing this radioisotope.

This will add to existing questions about the actinium supply chain; demand for assets using this isotope has grown recently, bolstered by hopes that actinium-based therapies could be more potent and precise than those employing lutetium, like Novartis’s approved drug Pluvicto.

Pluvicto has had its own supply chain issues, although these have now been ironed out; despite this, recent sales fell short of expectations.

Nasdaq beckons for Telix

Telix already has a marketed PSMA imaging agent, Illuccix, but its lead therapeutic contender is TLX591, a PSMA-directed radioconjugate comprising an antibody – rather than a small molecule like Pluvicto – and a lutetium payload.

The company reckons that an antibody-delivered therapy will be internalised more effectively than one using a small molecule, ultimately leading to a prolonged treatment effect. Data from the phase 3 Prostact-Global study of TLX591 in metastatic castration-resistant prostate cancer are due in the first half of 2025.

Telix also has alpha-emitting projects in earlier development. In addition, the company’s Nasdaq listing application noted the group’s investments in manufacturing, which it describes as an “essential foundation for long-term commercial success”.

ITM raise

Meanwhile, another radiopharmaceuticals player, Germany’s ITM (Isotope Technologies Munich), raised €188m in equity today. That group made much of its prowess in radioisotope supply; its lead therapeutic candidate is the lutetium-based ITM-11, but it is also working on actinium-labelled projects.

Investors in both Telix and ITM might be hoping for a big pharma buyout, given the continued interest in radiopharmaceuticals.

However, Bristol's RayzeBio division could provide a cautionary tale for would-be suitors. If there was already criticism that Bristol might have overpaid this will only have increased after news of the clinical trial pause, along with the fact that RayzeBio previously warned of potential supply issues back in 2023.

RayzeBio told ApexOnco that it was hoping to re-initiate new patient enrolment into the Action-1 study in the third quarter. One of its suppliers is based in Russia, and while RayzeBio wouldn't comment on third-party relationships it said its own on-site production of actinium-225 should start adding to clinical supply by the first quarter of 2025.

While Telix noted that its isotope suppliers were “predominantly” based in Canada or Europe, it admitted that radioactive raw materials were sourced from the likes of Russia, Brazil, Turkey and South Africa, which are more prone to political instability.

With questions remaining around radiopharmaceutical supply chains it’s possible that excitement around these therapies could outpace the practical realities.

This story has been updated to add comments from RayzeBio.