Telix partners with Regeneron on radiopharmaceutical therapies in USD 2.1b potential deal

Australia-based Telix Pharmaceuticals Ltd (ASX: TLX, Nasdaq: TLX) and US firm Regeneron Pharmaceuticals, Inc. (Nasdaq: REGN) announced a strategic collaboration to jointly develop and commercialize next-generation antibody-based radiopharmaceutical therapies across multiple solid tumor indications. The agreement pairs Telix’s radiopharmaceutical development platform and global manufacturing infrastructure with Regeneron’s antibody discovery technologies, including its VelocImmune and VelociSuite platforms, to generate a pipeline of radiolabeled biologics. Specific tumor targets have not been disclosed.

Deal specifics

Under the deal terms, Telix will receive an upfront payment of USD 40 million from Regeneron for access to its radiopharmaceutical manufacturing platform across four initial therapeutic programs. Should Telix elect to opt out of co-funding on any individual program, it becomes eligible to receive up to USD 535 million in development and commercial milestone payments per program, plus low double-digit royalties on net sales, with an aggregate milestone ceiling of USD 2.1 billion across all programs. Where Telix remains in the co-funding model, the two companies will share equally in global development costs and commercialization profits on a 50/50 basis, with Telix retaining the option to co-promote certain products.

The collaboration covers four initial therapeutic programs, with Regeneron holding the option to expand to four additional programs subject to further upfront payments. The parties will also jointly develop radio-diagnostic assets to support patient selection and treatment response monitoring, with Telix leading commercialization of those diagnostics and Regeneron receiving a defined percentage of profits. The exact percentage was not disclosed.

The structure gives Telix a per-program election right at a defined decision point: co-fund and share in global profits equally, or opt out and revert to a milestone-plus-royalty economics model. This optionality allows Telix to allocate capital selectively depending on program progression and resource constraints, while preserving upside participation across the portfolio. The agreement is global in scope, with no geographic carve-outs or territorial allocations disclosed. No equity investment by either party in the other was announced in connection with the transaction.

The drug programs will combine Regeneron’s antibody targeting components, drawn from its portfolio of antibodies generated through VelocImmune mice, with Telix’s radiolabeling and manufacturing capabilities. The modality class is antibody-based radiopharmaceutical therapy, in which a tumor-antigen-binding antibody serves as the targeting vehicle for a therapeutic radionuclide payload. The collaboration also encompasses potential bispecific antibody formats, given Regeneron’s established expertise in that area. Regeneron noted in its public commentary that it intends to explore these agents as monotherapy and in rational combination with its immunotherapy platform, citing lung cancer as one area of interest where its PD-1 inhibitor is already in use. The specific antigens, antibody names, and radionuclide payloads for the collaboration programs have not been publicly identified.

The theranostic component of the agreement, pairing matched diagnostic and therapeutic agents using the same antibody targeting vector, supports patient stratification and dosimetry assessment ahead of and during treatment. Telix will lead commercialization of the diagnostic assets developed under the collaboration.

Strategic implications

Regeneron’s entry into radiopharmaceutical oncology drug development marks a modality expansion for a company whose oncology portfolio has been anchored in antibody-based immunotherapy. The company indicated it views targeted radiopharmaceuticals as a frontier in oncology and has framed the collaboration as an opportunity to apply its antibody discovery engine to a delivery modality it has not previously pursued commercially.

For Telix, the arrangement provides validation of its radiopharmaceutical manufacturing infrastructure as a platform asset capable of attracting large-scale co-development partnerships. Telix’s existing commercial radiopharmaceutical portfolio includes Illuccix kit for the preparation of Ga-68 Glu-urea-Lys(ahx)-hbed-CC injection (also known as 68Ga-PSMA-11 injection), approved by the US FDA as a prostate cancer imaging agent. In addition, the firm announced on April 9, 2026, that the US FDA has accepted an NDA filing for TLX101-Px (Pixclara, Floretyrosine F 18 or 18F-FET), an investigational PET agent for the imaging of glioma (brain cancer).