Next-Generation Bispecific Nanobody Targeting CD3 Complex and ROR1 for Triple Negative Breast Cancer

VHH-P259 is a humanized nanobody-based bispecific antibody construct designed to simultaneously target the CD3 Complex (T Cell Receptor Complex) and receptor tyrosine kinase-like orphan receptor 1 (ROR1). Currently in the Biological Testing phase, VHH-P259 leverages the specificity of single-domain antibodies to redirect immune effector T cells towards malignant cells expressing ROR1. This innovative approach aims to address the urgent therapeutic needs associated with triple negative breast cancer, an aggressive subtype lacking targeted treatment options. By modulating T-cell activity and precisely targeting tumor-associated antigens, VHH-P259 holds promise as a novel immunotherapeutic candidate.

Licensing Opportunity

VHH-P259 is currently available for out-licensing and collaborative development opportunities. We welcome inquiries from partners seeking innovative immunotherapy assets for triple negative breast cancer.

Development Phase

Modality

VHH-P259 is a codon-optimized, bispecific T-cell engager constructed from two distinct polypeptide chains. One chain comprises a single-domain antibody (VHH) specifically recognizing human ROR1, fused to the N-terminus of a human IgG1 Fc hole fragment. The alternate chain includes an anti-ROR1 VHH linked via a flexible (G4S)3 sequence to an anti-CD3 Fab, further attached to a human IgG1 Fc knob fragment with engineered mutations. Expressed in mammalian cells, this design provides a small molecular size and enhanced tissue penetration, attributes of nanobodies that facilitate efficient tumor access and increased stability—critical for achieving therapeutic benefit in the dense tumor microenvironments characteristic of triple negative breast cancer.

Target

CD3 Complex and ROR1 are pivotal molecular targets in cancer immunotherapy. The CD3 Complex is an essential component of the T-cell receptor, responsible for antigen recognition and initiating T-cell activation. In contrast, ROR1 is a receptor tyrosine kinase-like orphan receptor, overexpressed on various solid tumors including triple negative breast cancer, while exhibiting limited expression in most healthy adult tissues. The selective expression of ROR1 in malignancies makes it an attractive therapeutic target, minimizing off-tumor toxicity. Targeting CD3 Complex with ROR1 allows VHH-P259 to mediate T-cell redirection specifically to ROR1-positive tumor cells, enhancing tumor killing while preserving non-malignant tissue function. This dual-targeting strategy positions VHH-P259 as a strategically valuable asset in immuno-oncology pipelines seeking precision medicine solutions.

Mechanism of Action

VHH-P259 exerts its biological activity by simultaneously binding to ROR1 on tumor cells and the CD3 Complex on T cells. Acting as a T-cell engager, it harnesses the effector function of cytotoxic T lymphocytes, facilitating the formation of immunological synapses that enable direct tumor cell lysis. This dual targeting triggers T-cell activation independent of MHC presentation, promoting targeted cytotoxicity against ROR1-expressing cells within the tumor microenvironment. The modular nanobody platform underlying VHH-P259 also allows for future expansion into antibody-drug conjugates or additional bispecific constructs, offering versatility for adapting therapeutic mechanisms and addressing diverse oncological indications.

Triple Negative Breast Cancer

Triple negative breast cancer (TNBC) is a highly aggressive subtype of breast cancer defined by the absence of estrogen receptor, progesterone receptor, and HER2 amplification. TNBC accounts for a significant proportion of breast cancer diagnoses globally and disproportionately affects younger women and certain ethnic groups. The standard of care for TNBC primarily relies on systemic chemotherapy due to the lack of actionable molecular targets. However, the clinical outcomes remain suboptimal, with high recurrence rates and limited overall survival, attributable to intrinsic resistance to conventional therapies and the heterogeneous biology of TNBC. Novel targeted therapies and immunotherapies are urgently needed to address these unmet clinical demands. VHH-P259 introduces a promising therapeutic avenue by engaging both immune effector cells and tumor-associated antigens, potentially overcoming resistance mechanisms and improving response rates in TNBC treatment.