Actithera Secures $75.5M Series A Funding, Joining the Burgeoning Radiopharmaceutical Market

Actithera, a startup specializing in next-generation radiopharmaceuticals, has successfully closed an oversubscribed Series A financing round, raising $75.5 million. The Massachusetts-based company aims to advance its innovative radiotherapy platform, which employs covalent chemistry to enhance tumor targeting and drug retention.

Funding Details and Investor Lineup

The Series A round was co-led by M Ventures, Actithera's founding investor, alongside new lead investors Sofinnova Partners, 4BIO Capital, and Hadean Ventures. Additional participants included second founding investor Arkin Bio Ventures II, as well as Surveyor Capital and Bioqube Ventures.

Andreas Goutopoulos, CEO and founder of Actithera, emphasized the potential of their technology: "Our covalent chemistry approach leads to extended retention of radioconjugates inside tumors, potentially offering patients more convenient dosing schedules and enhanced efficacy and safety."

Innovative Radiopharmaceutical Technology

Actithera's radiopharmaceutical assets are designed to form irreversible bonds with their targets, maximizing treatment specificity and allowing for longer drug retention within tumors. The company's platform is isotope-agnostic, capable of carrying both alpha- and beta-emitting payloads.

The primary focus of Actithera's development efforts is a radioligand therapy targeting the fibroblast activation protein (FAP). This protein, expressed on cells forming connective tissue, can support tumor growth in cancer. Actithera aims to eliminate these proteins and cancer-associated fibroblasts through what Goutopoulos describes as "a cross-fire effect that kills nearby tumor cells."

Market Context and Industry Trends

Actithera's entry into the radiopharmaceutical space comes at a time of significant industry interest and investment. Major pharmaceutical companies have been actively expanding their presence in this field through acquisitions and collaborations.

Novartis currently leads the market with two commercial radiotherapies: Lutathera for gastroenteropancreatic neuroendocrine tumors and Pluvicto for metastatic castration-resistant prostate cancer. These drugs combined earned over $2.1 billion in 2025, with Pluvicto alone generating more than $1.3 billion.

Other industry giants have made notable moves in the radiopharmaceutical sector:

• Eli Lilly acquired Point Biopharma for $1.4 billion in October 2023 and subsequently entered collaborations with Aktis Oncology and Radionetics Oncology, worth potential combined values of $2.24 billion.
• AstraZeneca purchased Fusion Pharmaceuticals for $2.4 billion in March 2024.
• Bristol Myers Squibb acquired RayzeBio for $4.1 billion in December 2023.

As the radiopharmaceutical market continues to expand, Actithera's innovative approach and substantial funding position the company as a potential key player in this rapidly evolving field.