Byondis Announces First Patient Dosed in Phase 1 Clinical Trial of Novel SIRPα-Directed Monoclonal Antibody BYON4228 in Patients With Advanced or Metastatic Solid Tumors

Two-Part Dose Escalation and Expansion Trial Will Evaluate Efficacy and Safety of BYON4228 Alone and in Combination with Pembrolizumab

Byondis B.V., an independent clinical stage biopharmaceutical company creating innovative targeted medicines for patients with cancer, announces the first patient dosed in its Phase 1 dose escalation and expansion BYON4228.002 clinical trial to evaluate the safety, pharmacokinetics, pharmacodynamics and efficacy of novel SIRPα-directed monoclonal antibody (mAb) BYON4228 alone and in combination with pembrolizumab in patients with advanced or metastatic solid tumors.

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Louis Denis, MD, Chief Medical Officer, Byondis

BYON4228 is a potential best-in-class novel mAb that targets and blocks the CD47-SIRPα axis, responsible for tumors’ ability to escape from recognition and destruction by the immune system. By targeting SIRPα and not CD47, BYON4228 offers selective targeting of myeloid cells and avoids disruption of other biologically meaningful CD47-dependent interactions. In preclinical studies, BYON4228 was found to potentiate the tumor killing capacity of tumor-targeting mAbs tested without the toxicity associated with CD47 agents.

“Building on strong preclinical data, we believe that there is broad potential for BYON4228 alone and in combination with tumor-targeting mAbs, checkpoint inhibitors and antibody drug conjugates and other modalities across hematological and solid tumors,” said Louis Denis, MD, Chief Medical Officer, Byondis. “We look forward to evaluating the results of this trial to support the clinical development of BYON4228 alone and in combination with other agents and to bring a new therapeutic option to patients with high unmet medical need.”

Part 1 of the BYON4228.002 trial will evaluate the safety of BYON4228 alone and in combination to determine the maximum tolerated dose (MTD), or optimal biological dose (OBD) if the MTD is not reached, and recommended combination dose regimen(s) for expansion (RDE(s)). The second part of the trial will evaluate the objective tumor response rate (ORR). The secondary objectives of this trial are safety, pharmacokinetics, immunogenicity and preliminary efficacy. The trial will be conducted at multiple sites across Europe, including the United Kingdom, Belgium and Spain.

About BYON4228

BYON4228 is a novel monoclonal antibody (mAb) from Byondis’ next generation immuno-oncology (IO) program that targets and blocks the CD47-SIRPα axis, responsible for tumors’ ability to escape from recognition and destruction by the immune system. BYON4228 is currently being studied in two Phase 1 Clinical Trials evaluating BYON4228 alone and in combination with Rituximab in patients with Relapsed/Refractory CD20 positive B-cell Non-Hodgkin's Lymphoma (NHL) (NCT05737628) and BYON4228 alone and in combination with pembrolizumab in patients with advanced or metastatic solid tumors (NCT06932952).

About Byondis

Driven to improve patients’ lives, Byondis is an independent clinical stage fully integrated biopharmaceutical research and development company creating innovative targeted medicines for cancer. The company is developing new biological entities (NBEs) with a focus on antibody-drug conjugates and antibody-based therapeutics.

Byondis’ broad development portfolio comprises preclinical and early-stage clinical programs. The product candidates combine Byondis’ expertise in linker-drug (LD) technology, antibody-drug conjugation, targeted cytotoxic therapy, immunology, and monoclonal antibody (mAb) development. Byondis’ expertise covers all preclinical R&D from early lead finding to production of clinical batches of the selected product candidates, which are all done in-house.

The company’s headquarters and state-of-the-art R&D and GMP manufacturing facilities are based in Nijmegen, the Netherlands. For more information visit www.byondis.com.

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