Biocytogen and Whitehawk Therapeutics Partner to Develop Bispecific Antibody-Drug Conjugates Using Complementary Platform Technologies

Biocytogen and Whitehawk Therapeutics announced a global collaboration to develop bispecific antibody-drug conjugates (BsADCs), combining Biocytogen's proprietary RenLite bispecific antibody discovery platform with Whitehawk's CPT113-based ADC linker-payload and bioconjugation technology.¹ The deal reflects the accelerating convergence of two of the most active engineering strategies in oncology drug development — bispecific antibodies and ADCs — into a single therapeutic format designed to improve tumor selectivity and therapeutic index simultaneously, a direction that has attracted significant capital and partnership activity across the broader bispecific ADC field in 2026.

What are the two platforms being combined, and why does the combination matter?

Biocytogen's RenLite platform generates fully human bispecific antibodies using a common light-chain design — an engineering approach that ensures the two different heavy chains pair with a single shared light chain, addressing one of the most persistent manufacturing challenges in bispecific antibody development: light-chain mispairing, which can produce non-functional or off-target antibody species during expression.¹ Under the agreement, Biocytogen will contribute up to five bispecific antibodies generated through RenLite for evaluation as BsADC backbones.

Whitehawk's ADC platform is built on CPT113, a linker-payload technology licensed from Hangzhou DAC, enhanced with the company's proprietary Carbon Bridge Cysteine Re-pairing (CBCR) bioconjugation process.¹ CBCR is a site-specific conjugation method that re-pairs cysteine residues to create stable carbon-carbon bonds, producing ADCs with uniform drug-to-antibody ratios and improved plasma stability relative to conventional maleimide conjugation — key features for widening the therapeutic window and reducing off-target toxicity.¹ Whitehawk will evaluate each of the five bispecific antibodies in combination with its CPT113 payload and CBCR conjugation to identify BsADC candidates with differentiated tumor-targeting profiles.

"Bispecific antibodies are a promising approach to broadening our targeting strategies, and Biocytogen's established platform provides a robust framework for exploring this modality in combination with our ADC platform," said Dave Lennon, PhD, Chief Executive Officer of Whitehawk Therapeutics. "We are excited about the potential of this collaboration to expand our pipeline opportunities and support our ambition to deliver new ADC INDs in the next 12 to 24 months."¹

Why is the bispecific ADC format attracting so much attention?

Conventional ADCs pair a single-target antibody with a cytotoxic payload, relying on high, homogeneous expression of a single tumor antigen for selective delivery. BsADCs are designed to raise the bar further: by requiring simultaneous binding to two antigens — or by engaging both a tumor antigen and an immune cell receptor — they can improve selectivity through an avidity effect, reduce the risk of antigen escape-driven resistance, and potentially combine tumor-killing and immune-engaging mechanisms in a single molecule.²

As Sabeen Mekan, MD, chief medical officer at Zymeworks, told BioPharm International ahead of the BIO International Convention 2026: "Bispecific, trispecific, and multispecific formats are designed to improve targeting precision and enhance therapeutic activity by engaging multiple epitopes or biological mechanisms simultaneously." The Biocytogen-Whitehawk collaboration is a direct expression of this principle — using bispecific antibody backbones to provide improved antigen discrimination before deploying a potent cytotoxic payload.³

The first globally approved BsADC, iza-bren, was authorized by China's National Medical Products Administration in 2025 for epidermal growth factor receptor-mutant non-small cell lung cancer — a milestone that BioPharm International has noted "could provide insight into how future bispecific ADCs are developed and evaluated worldwide." The Biocytogen-Whitehawk collaboration joins a rapidly expanding cohort of preclinical-stage BsADC programs advancing toward IND, including Sidewinder Therapeutics and Alphamab Oncology's JSKN016, which presented phase 1 data at ASCO 2026.⁴

What are the deal terms and what happens next?

Under the financial terms of the agreement, Biocytogen will receive an upfront payment and is eligible for development, regulatory, and commercial milestone payments, as well as low single-digit royalties on net sales of any approved BsADC products.¹ Additional financial terms were not disclosed. If Whitehawk exercises its option to advance any resulting BsADC candidates, it will hold global rights and full program control over those assets.¹

The collaboration adds BsADC discovery to Whitehawk's existing pipeline, which includes three ADC programs — HWK-007, HWK-016, and HWK-206 — in-licensed from WuXi Biologics under an exclusive global development and commercialization agreement, each engineered to address limitations of earlier-generation ADCs.¹ Whitehawk also holds an option agreement with Hangzhou DAC for access to CPT113 for up to five additional ADC programs beyond those covered by this collaboration, providing capacity for broad BsADC pipeline expansion.¹

"This collaboration further expands the application of Biocytogen's fully human bispecific antibodies in ADC development," said Yuelei Shen, PhD, President and CEO of Biocytogen. "We look forward to supporting the efficient advancement of multiple programs by contributing high-quality antibody molecules and integrated research capabilities."¹

References

1. Biocytogen and Whitehawk Therapeutics Enter Global Collaboration for Bispecific Antibody ADC Development. (2026 Jul 7). Business Wire. https://www.businesswire.com/news/home/20260707551767/en/Biocytogen-and-Whitehawk-Therapeutics-Enter-Global-Collaboration-for-Bispecific-Antibody-ADC-Development
2. Joubert N, Beck A, Dumontet C, Denevault-Sabourin C. (2020 Sep 14). Antibody-drug conjugates: the last decade. Pharmaceuticals (Basel). https://pubmed.ncbi.nlm.nih.gov/32937862/
3. Mekan S. (2026 Jun 25). Novel payloads and multispecific antibodies fuel ADC innovation. Interview by BioPharm International for BIO International Convention 2026. BioPharm International.https://www.biopharminternational.com/view/novel-payloads-and-multispecific-antibodies-fuel-adc-innovation
4. Yao H, Liu J, Zeng Y, et al. (2025 May 28). First-in-human study of JSKN016, a bispecific anti-TROP2/HER3 antibody drug conjugate: antitumor activity in patients with metastatic triple-negative breast cancer and safety results. J Clin Oncol. https://ascopubs.org/doi/10.1200/JCO.2025.43.16_suppl.e13138
5. Marisol F. (2024 Dec 31). The benefit of technological advancements to BsAb development. BioPharm International. https://www.biopharminternational.com/view/benefit-technological-advancements-bsab-development