A new generation of bispecific antibodies shrank tumors in preclinical studies while sparing the healthy tissues that often suffer from cancer treatment, pointing toward a safer and more precise way to target cancer-driving pathways.
Study: Tumor-targeted bispecific antibodies effectively inhibit oncogenic pathways while minimizing toxicity. Image credit: Krot_Studio/Shutterstock.com
A recent preclinical study published in Science Advances reports the development and validation of a new antibody-based approach to develop more targeted cancer treatments. Researchers designed bispecific antibodies (bsAbs) that simultaneously bind to tumor-associated markers and to proteins that promote cancer cell growth.
This helps selectively target cancer cells while largely sparing normal cells. If found effective in further trials, the treatment could help reduce side effects. However, these findings remain preclinical and have not yet been tested in humans.
Bispecific Antibodies Aim To Reduce Toxicity
Most cancer treatments block specific biological pathways that help cancer cells grow. The problem is that normal cells also use similar pathways to perform bodily functions. As a result, treatments that are designed to attack cancer cells also harm normal cells, leading to side effects. For example, drugs that block the Wnt pathway can cause digestive problems and increase the risk of bone fractures.
These side effects can affect a person’s quality of life and may also make it more difficult to combine different anticancer drugs into one treatment regimen. Another challenge is that many cancer-related targets are also present in healthy tissues, which is why finding targets that can be safely attacked without harming normal organs becomes challenging.
Testing Targeted Antibodies Across Cancer Models
In the present study, researchers designed bsAbs with two arms. The high-affinity arm was attached to tumor-related markers, including trophoblast cell surface antigen 2 (TROP2) and carcinoembryonic antigen-related cell adhesion molecule 6 (CEACAM6). The lower-affinity arm targeted different proteins that help cancer cells grow and survive.
The team developed distinct bsAb templates for proteins such as frizzled (FZD), epidermal growth factor receptor (EGFR), and fibroblast growth factor receptor 1 (FGFR1). Simultaneous binding to dual targets improved selective binding to cancer cells while minimizing toxicity in healthy tissues.
The team analyzed large datasets to identify suitable tumor-related markers. These contained information on gene activity in tumor tissues and healthy tissues. The researchers used molecular techniques such as single-cell ribonucleic acid sequencing (scRNA-seq) and bulk RNA-seq to identify markers that were abundant in cancer cells but scarce in normal cell populations and were most closely associated with treatment-related toxicities.
In laboratory-grown organoids created from human pancreatic and colon tissues, the team examined how well these new antibodies attached to cells and affected cancer-related gene activity and biological pathways. They also tested the bsAbs in multiple pancreatic ductal adenocarcinoma (PDAC) cell lines, organoids, and mouse models using a range of antibody concentrations and dosing schedules.
Lastly, they evaluated the efficacy of the bispecific antibodies in mice carrying human tumors. The researchers conducted pharmacokinetic studies to measure how long the antibodies remained in the bloodstream and monitored tumor growth, body weight, and tissue toxicity during treatment.
Bispecific Design Preserves Efficacy While Limiting Toxicity
The bsAbs effectively blocked key biological pathways associated with tumor growth and cancer cell survival. Not only was the treatment effective, but it also caused far fewer side effects than conventional pathway inhibitors. In fact, these antibodies achieved half-maximal inhibitory concentration (IC50) values below 1.0 nM, indicating strong in vitro potency.
In the laboratory models of pancreatic cancer, the bispecific antibodies effectively inhibited the Wnt signaling pathway. As a result, tumor cells grew more slowly. The researchers also noted substantial suppression of tumor growth and marked reductions in tumor volume during laboratory tests and animal studies.
Two markers primarily contributed to tumor selectivity, TROP2 and CEACAM6. These markers were abundant in cancer cells but showed minimal expression in the intestinal and bone stem-cell populations associated with Wnt inhibitor toxicity. This is especially beneficial since conventional Wnt-targeting drugs often damage these tissues.
The researchers found the safety results to be especially encouraging. A conventional FZD inhibitor caused severe gastrointestinal damage and considerable weight loss in mice at relatively low doses of only 2.0 mg/kg. In contrast, an attenuated anti-FZD antibody design and tumor-targeted bispecific antibodies showed substantially improved tolerability at higher doses, with only minor intestinal changes observed in some high-dose experiments.
In mice treated with the bispecific antibodies, tumor size was reduced considerably. However, the weight of these animals largely remained the same. Researchers observed no major abnormalities in the kidneys, liver, lungs, heart, or intestines. Applying a similar strategy to EGFR and FGFR1 proteins also yielded promising results in laboratory models designed to assess toxicity-related cell types.
Unlike the FZD-targeting approach, which was evaluated extensively in animal models, the EGFR and FGFR1 programs primarily served as in vitro proof-of-concept demonstrations of the broader platform strategy.
The researchers also found that the tumor-targeted antibodies could act through multiple mechanisms, including enhanced receptor binding, receptor internalization, and sequestration of signaling receptors within cells, helping to suppress cancer-promoting pathways even when the antibody's inhibitory arm was only weakly active on its own.
Toward Safer Inhibitors Of Cancer Pathways
The study findings suggest that researchers may be able to make cancer treatments more accurate and safer using bispecific antibodies. By binding to tumor-associated markers and blocking proteins that promote cancer cell growth, this approach could enhance treatment specificity while reducing off-target effects.
The bsAb approach was effective across multiple targets in slowing tumor growth while causing fewer side effects than conventional pathway inhibitors in preclinical models. However, these findings are preliminary. Future studies are required to determine the optimal dose and confirm long-term safety and effectiveness for broader use in humans.
If validated in future clinical studies, such treatments could advance precision medicine and provide a general framework for designing therapies that selectively inhibit cancer-driving pathways while minimizing toxicity to healthy tissues.
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Journal Reference
Yvonne T. Kschonsak et al. (2026). Tumor-targeted bispecific antibodies effectively inhibit oncogenic pathways while minimizing toxicity. Science Advances, 12, eadx3959. DOI: 10.1126/sciadv.adx3959. https://www.science.org/doi/10.1126/sciadv.adx3959
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