Nature Cancer | p95HER2 Limits T-DXd Efficacy through an Immunosuppressive Program

This study reveals a novel mechanism by which p95HER2 drives immune escape in HER2+ breast cancer, providing experimental evidence for combination therapeutic strategies to overcome resistance to antibody–drug conjugates, and highlighting the importance of considering p95HER2 expression status when designing anti-tumor immunity models.

 

Literature Overview

The study titled 'p95HER2, a truncated form of the HER2 oncoprotein, drives an immunosuppressive program in HER2+ breast cancer that limits trastuzumab deruxtecan efficacy,' published in Nature Cancer, systematically investigates how p95HER2 induces immunosuppression by modulating the tumor microenvironment, thereby limiting the efficacy of T-DXd. By integrating transgenic models, clinical cohort analyses, and pharmacological intervention experiments, the study reveals the clinical significance of p95HER2 as a key node in treatment resistance.

Background Knowledge

1. HER2+ breast cancer is an aggressive and highly recurrent subtype. Although HER2-targeted antibody therapies have significantly improved patient outcomes, drug resistance remains a major challenge. Current standard treatments such as T-DXd are effective even in patients with low HER2 expression, yet primary or acquired resistance still occurs.
2. Existing research has primarily focused on HER2 expression levels, activation of downstream signaling pathways, and characteristics of the immune microenvironment. However, functional understanding of HER2 isoforms such as p95HER2 remains limited, particularly regarding whether and how p95HER2 influences anti-tumor immune responses.
3. This study identifies that p95HER2 not only mediates antibody escape but also actively shapes an immunosuppressive microenvironment by upregulating PD-L1 and secreting immunosuppressive factors that inhibit T cell infiltration and function—thereby impairing the efficacy of antibody–drug conjugates (ADCs) reliant on immune activation. This mechanism provides a theoretical foundation for co-targeting p95HER2.

 

 

Research Methods and Experiments

The authors used PB2 and EMT6 murine breast cancer models to generate cell lines with inducible expression of either p95HER2 or full-length (FL)-HER2, and assessed differences in tumor growth and immune infiltration in immunocompetent versus immunodeficient mice. Multi-omics analyses (RNA-seq, NanoString, secretome) were performed to identify immune-related pathways specifically regulated by p95HER2. The association between p95HER2 and immune features was validated using the FinHER clinical cohort. Further functional validation and intervention strategies were tested via CRISPR/Cas9-mediated PD-L1 knockout, tyrosine kinase inhibitor (TKI) treatment, and combination therapies.

Key Conclusions and Perspectives

• p95HER2 expression significantly suppresses infiltration of T cells, NK cells, and dendritic cells while promoting accumulation of MDSCs, creating an immunosuppressive microenvironment; this phenotype is evident in immunocompetent but not immunodeficient mice, indicating dependence on the host immune system. [Data discovery] + [Guidance for future animal model development]
• p95HER2 specifically activates the JAK/STAT pathway and induces PD-L1 expression—effects not observed with FL-HER2. This is dependent on cell surface glycosylated p95HER2 and its autocrine signaling. [Data discovery] + [Guidance for future signaling pathway studies]
• In the FinHER cohort, a high p95HER2/total HER2 ratio is significantly associated with low immune scores, T cell exhaustion, and upregulation of the PD-L1 pathway, confirming clinical relevance. [Data discovery] + [Guidance for future biomarker development]
• T-DXd fails in p95HER2+ tumors due to inability to trigger immunogenic cell death; however, efficacy can be restored by combining with neratinib or anti–PD-L1 therapy. [Data discovery] + [Guidance for future combination therapy strategies]
• p95HER2 protein is highly sensitive to irreversible TKIs (e.g., neratinib), undergoing degradation via the ubiquitin-proteasome pathway, suggesting that targeting its stability is a viable therapeutic approach. [Data discovery] + [Guidance for future drug development]

Research Significance and Prospects

This study redefines the role of p95HER2 in HER2+ breast cancer—not merely as a factor enabling antibody escape, but as a master regulator of the immune microenvironment. This suggests that p95HER2 expression should be routinely assessed in clinical practice to predict response to T-DXd.

From a drug development perspective, combining irreversible TKIs or immune checkpoint blockade may overcome resistance, especially in patients with high p95HER2 expression. Furthermore, establishing cell and animal models with stable p95HER2 expression will facilitate systematic evaluation of the immune-dependent efficacy of ADCs.

 

 

Conclusion

This study establishes p95HER2 as a key driver of immune escape in HER2+ breast cancer, demonstrating that it remodels the tumor microenvironment through activation of PD-L1 and secretion of immunosuppressive factors, thereby antagonizing the anti-tumor immune response required for T-DXd efficacy. This mechanism explains why some patients do not respond to ADC therapy and identifies actionable molecular targets. From bench to bedside, assessing p95HER2 expression may become a necessary step in personalized treatment, while combination strategies with neratinib or anti–PD-L1 antibodies have shown promise in mouse models, providing a rationale for future clinical trials. This work not only deepens our understanding of HER2 isoform functions but also underscores the importance of integrating immune perspectives into precision oncology, laying both theoretical and practical foundations for improving outcomes in HER2+ breast cancer patients.

 

Dong Hu, Xiaoshuang Lyu, Zheqi Li, Linda M McAllister-Lucas, and Peter C Lucas. p95HER2, a truncated form of the HER2 oncoprotein, drives an immunosuppressive program in HER2+ breast cancer that limits trastuzumab deruxtecan efficacy. Nature cancer.