Y-Mabs falls to Serb

Y-Mabs is the latest company to demonstrate that having an approved product isn’t a guarantee of success: on Tuesday, the group agreed to be acquired by the speciality pharma player Serb Pharmaceuticals.

For a relatively undemanding $412m up front, Serb, whose current oncology presence is largely peripheral, will gain Y-Mabs’ anti-GD2 MAb Danyelza. The drug got FDA accelerated approval in 2020 for relapsed/refractory high-risk neuroblastoma, a rare childhood cancer. Serb will also pick up Y-Mabs’ portfolio of radiopharmaceuticals, although based on the evidence so far these look in need of refinement.

The $8.60 per-share price tag represents a 105% premium to Y-Mabs’ closing share price on 4 August, the day before the deal was announced. However, it’s a long way off the $16 per share at which Y-Mabs floated in 2018. 

Chequered history

Danyelza, which competes with United Therapeutics' Unituxin, sold $88m in 2024. However, it hasn’t been plain sailing for Y-Mabs: the company’s second paediatric cancer hopeful, the B7-H3-targeting omburtamab, was knocked back by the FDA in 2022.

Since then, the group has undergone various restructurings, and in January “realigned” again to focus on two business units: Danyelza and radiopharmaceuticals. The latter uses the company’s modular SADA PRIT technology, but there are question marks about its utility.

Y-Mabs reported early data with its lead radioconjugate, GD2-SADA, in May, concluding that the project was safe and well tolerated, but that it hadn’t reached the optimal therapeutic index. The company is now testing what it hopes is an improved molecule.

One question is how much Serb will want to invest in the radiopharmaceutical platform, given that group’s expertise lies elsewhere. Serb’s existing oncology products are Xermelo, for carcinoid syndrome diarrhoea caused by neuroendocrine tumours; Vistoguard, for fluorouracil or capecitabine overdose; and Voraxaze, for delayed methotrexate clearance.

Danyelza will therefore allow the company to move into true cancer therapy, for what looks like a reasonable price. 

Y-Mabs’ clinical-stage pipeline

Note: AA=accelerated approval. Source: OncologyPipeline.