Biosion has dosed the first patient in an investigator-initiated Phase Ia/Ib trial of BSI-082, a fully human anti-SIRPα monoclonal antibody, aimed at treating advanced solid tumours.

The open-label study involves dose escalation and expansion phases. In Phase Ia, researchers will determine the recommended dose for expansion as a monotherapy.

In Phase Ib, BSI-082 will be combined with trastuzumab deruxtecan (T-DXd) for human epidermal growth factor receptor 2 (HER2) positive solid tumours.

The trial is being carried out at the Mays Cancer Center, part of the University of Texas at San Antonio’s Health Science Center and is sponsored by the centre.

John Sarantopoulosis theprincipal investigator at the Mays Cancer Center.

This milestone follows Biosion’s recent partnership with Aclaris Therapeutics for its immunology portfolio.

BSI-082 is developed to target the cluster of differentiation 47-signal regulatory protein alpha (CD47-SIRPα) pathway, which is utilised by tumour cells to evade macrophage-mediated phagocytosis.

The antibody was designed using Biosion’s H³ Antibody Discovery Platform to address challenges encountered with previous candidates in this class.

BSI-082 does not bind to SIRPγ, preserving T-cell function and avoiding inhibition of adaptive immunity.

Biosion founder and CEO Mingjiu Chen said: “The initiation of this trial by a premier institution like the Mays Cancer Center serves as powerful validation of BSI-082's scientific rationale and therapeutic potential.

“BSI-082's unique profile—specifically its ability to potently block the 'don't eat me' signal without compromising patient safety—positions it as an ideal combination partner for standard-of-care therapies, particularly antibody-drug conjugates (ADCs).

“We are honoured to support Dr Sarantopoulos and his team in this study, which represents a key step in our strategy to maximise the value of our oncology assets through high-quality clinical partnerships.”