Regeneron Pharmaceuticals plans to expand its pipeline into radiopharmaceutical therapies through an up to $4.3 billion collaboration with Telix Pharmaceuticals to co-develop and co-commercialize precision oncology treatments and companion diagnostics.

The companies have agreed to partner on next-generation radiopharmaceutical therapies aimed at up to eight solid tumor targets from Regeneron’s portfolio of antibodies, generated from VelocImmune^® technology, which uses the company’s own mouse platform engineered with a genetically humanized immune system.

Regeneron and Telix also said they plan to develop radio-diagnostics designed to support patient selection and treatment response assessment.

The collaboration is intended to combine the biologics expertise of Tarrytown, NY-based Regeneron, including bispecific antibody discovery, with the radiopharmaceutical development platform, global manufacturing capabilities, and supply chain infrastructure of Telix, which is headquartered in Melbourne, Australia.

“Regeneron is excited to enter the targeted radiopharmaceuticals space and explore the utility of these agents either as monotherapy or rationally combined with our immunotherapy platform, particularly in areas of high unmet patient need such as lung cancer, where our PD-1 inhibitor is a global standard of care,” Israel Lowy, MD, PhD, Regeneron’s senior vice president and clinical development unit head, oncology, said in a statement.

Lowy referred to Libtayo^® (cemiplimab-rwlc), a programmed death receptor-1 blocking antibody approved for multiple oncology indications including forms of non-small cell lung cancer (NSCLC), as well as cutaneous squamous cell carcinoma, and basal cell carcinoma. Libtayo finished 2025 with $1.453 billion in worldwide net product sales, up 19% from $1.217 billion in 2024. Figures include $425 million in Q4 2025 global net product sales, up 16% from $367 million in the year-ago quarter.

‘An ideal partner’

“In our view, the deal with Regeneron validates Telix’s differentiated capabilities in radiopharmaceutical development and handling of complex supply chain logistics,” Andy T. Hsieh, PhD, a partner and biotechnology analyst with William Blair, wrote Monday in a research note. “Furthermore, given Regeneron’s track record of developing successful commercial therapeutics, we believe it is an ideal partner in bringing forth antibody-based theranostic assets.”

Telix investors appeared to somewhat agree with that analysis. The company’s ordinary shares traded on the Australian Stock Exchange climbed nearly 8% from A$14.64 ($10.34) to A$15.77 ($11.13). Telix’s American depositary shares traded on NASDAQ rose about 7%, from $10.56 to $11.24.

Hsieh reiterated William Blair’s “Outperform” rating for Telix shares based on several potential value-creating inflection points, including:

• Continuing gains in market share gains within the prostate-specific membrane antigen (PSMA) positron emission tomography (PET) diagnostic imaging market, based on rising sales and price stability as payers have offered clarity on reimbursement—factors he said enable Telix to expand its precision medicine franchise “from a position of strength.”
• Therapeutic franchise potential, as supported by recent positive preliminary data from part 1 of the ongoing Phase III ProstACT GLOBAL trial (NCT06520345) assessing TLX591 in metastatic androgen pathway modulation resistant prostate cancer.
• Potential approvals of two PET imaging agents—TLX250-CDx (Zircaix^®, ⁸⁹Zr-DFO-girentuximab), designed to non-invasively detect and characterize clear cell renal cell carcinoma (ccRCC); and TLX101-Px (Pixclara^®, Floretyrosine F 18 or ¹⁸F-FET), designed to image glioma. Both could “meaningfully” contribute to Telix’s profit-and-loss statement next year, the analyst predicted.

The FDA rejected both Zircaix and Pixclara last year via separate complete response letters. The agency held in April 2025 that Zircaix required additional confirmatory clinical evidence, which the company agreed to provide. On Friday, Telix said the FDA accepted its resubmitted New Drug Application (NDA) for Pixcara, assigning a target decision date of September 12 under the Prescription Drug User Fee Act (PDUFA).

In August 2025, the FDA rejected Zircaix via complete response letter, alleging deficiencies relating to its chemistry, manufacturing, and controls (CMC) package—deficiencies the company said were “readily addressable.”

“We look forward to additional updates pertaining to efficacy parameters, such as progression-free survival, an approvable endpoint, likely later this year,” Hsieh added.

Growth through acquisitions

Telix has built up its radiopharma infrastructure in recent years through acquisitions, spending $13.6 million to purchase IsoTherapeutics, a contract development and manufacturing organization (CDMO) focused on providing services to Telix and other radiopharmaceutical companies—followed by an up to $82 million buyout of radioisotope production technology firm ARTMS, which stands for alternative radioisotope technologies for medical science.

In September 2024, Telix expanded its manufacturing footprint by acquiring RLS Radiopharmacies for up to $250 million, part of an investment strategy focused around creating vertically integrated supply chain, manufacturing, and distribution.

The global radiopharmaceuticals market is predicted to grow at a compound annual growth rate of 10.1%, more than doubling from $14.2 billion this year to $31 billion in 2032, then soaring again to $54.6 billion by 2040, according to a Roots Analysis report issued in January.

Telix briefly pursued a U.S. initial public offering, which it withdrew in June 2024. The company cited market conditions as biotech IPOs met with chilly receptions on Wall Street and asserted that the offering was not predicated on the need to raise capital.

Regeneron has agreed to pay Telix $40 million in upfront cash for access to its radiopharmaceutical manufacturing platform for four initial therapeutic programs, with Regeneron holding an option to expand the collaboration to include four additional programs with additional upfront payments.

Telix and Regeneron have agreed to share equally their global commercialization costs and potential profits, with Telix retaining the option to co-promote certain potential products. However, if Telix were instead to opt out of the co-funding model for any of the original four programs, it would then be eligible to receive up to $535 million in development and commercial milestone payments, plus low double-digit royalties on future net sales, for that program.

If Telix opts out of co-funding for all four, company could achieve $2.14 billion in payments tied to achieving milestones.

For the diagnostics to be covered by the collaboration, Telix and Regeneron have agreed to jointly develop diagnostic assets, with Telix leading commercialization and Regeneron receiving a set percentage of profits.

“The collaboration with Regeneron reflects a highly complementary set of capabilities and a unique opportunity to explore what true ‘next gen’ biologics-based radiopharmaceuticals can potentially do for patients,” added Christian Behrenbruch, DPhil, managing director and group CEO at Telix. “We are well positioned to work toward the shared goal of advancing next-generation precision radiopharmaceuticals for patients with hard-to-treat cancers.”

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