HER2, or human epidermal growth factor receptor 2, is a protein found on the surface of cells. In some breast cancers, the HER2 gene is amplified, causing cells to produce excessive amounts of the receptor. This abnormal signaling can stimulate continuous cell division and tumor growth. HER2-positive disease was once associated with particularly aggressive clinical behavior, but targeted medicines have transformed its treatment. Drugs such as trastuzumab and pertuzumab block HER2-related signaling and can recruit immune cells to destroy cancer cells. Zanidatamab belongs to the same broad family of HER2-directed therapies, but its molecular design is intended to engage two separate regions of HER2 simultaneously.

Zanidatamab is a biparatopic antibody, meaning that it binds to two distinct epitopes, or molecular sites, on the HER2 receptor. This dual engagement may interfere with HER2 biology more extensively than an antibody that attaches to only one site. The antibody can promote receptor clustering at the cell surface, a process that may encourage the cancer cell to internalize and remove HER2 from its membrane. It can also inhibit downstream growth signals and stimulate antibody-dependent cellular cytotoxicity, in which immune cells recognize the antibody-coated tumor cell and help destroy it. These mechanisms are being investigated as a way to produce deeper tumor responses while addressing some forms of resistance to established HER2 therapies.

The NeoZanHER study focuses on early-stage disease, a setting in which treatment is often given before surgery. This approach is known as neoadjuvant therapy. Rather than treating an unseen residual risk after an operation, clinicians can observe how a tumor responds while it remains in the breast and lymph nodes. Imaging can show changes in tumor size, while tissue removed during surgery can reveal whether invasive cancer remains. When no invasive cancer is detected in the breast and sampled lymph nodes at surgery, the result is called a pathologic complete response. In HER2-positive breast cancer, this measure is widely used as an early indicator of treatment activity and may help guide the intensity of subsequent therapy.

The trial’s single-arm design means that participants receive the investigational treatment without being randomly assigned to a comparison group within the study. This structure can provide an early view of feasibility, safety and antitumor activity, particularly when researchers are evaluating a treatment strategy in a defined patient population. However, a single-arm phase 2 trial cannot establish superiority over standard therapy on its own. Any apparent benefit must be interpreted alongside historical results, differences in patient selection and the length of follow-up. Randomized trials remain essential for determining whether a new regimen improves long-term outcomes such as recurrence-free survival and overall survival.

The open-label nature of NeoZanHER means that both investigators and participants know which treatment is being administered. While this design can simplify clinical management and allow researchers to document treatment effects in real time, it can also introduce sources of bias in subjective assessments. For this reason, the most informative endpoints are generally those supported by pathology, imaging protocols, laboratory measurements and carefully defined safety criteria. In a neoadjuvant trial, researchers may also examine biomarkers in tumor tissue and blood to understand why some cancers respond while others continue to grow despite HER2 blockade.

The biological question behind the study is particularly important because HER2-positive breast cancer is not a single uniform disease. Tumors can differ in the level of HER2 expression, the presence of hormone receptors, their immune-cell environment and the genetic pathways that operate downstream of HER2. Some tumors may initially shrink but retain microscopic resistant cells capable of causing relapse later. A dual-epitope antibody such as zanidatamab could, in theory, provide broader receptor suppression and more effective immune engagement, but the clinical value of that strategy depends on measurable patient outcomes and a manageable safety profile. The study therefore matters not simply because it tests a new drug, but because it explores whether molecular precision can translate into better preoperative cancer control.

The timing of the research also reflects a major shift in breast cancer treatment. Modern care increasingly combines surgery, chemotherapy, targeted antibodies, antibody-drug conjugates and immunotherapy according to tumor biology. In this landscape, a response achieved before surgery can influence decisions after surgery. Patients with a strong response may be managed differently from those with residual disease, who may require additional treatment aimed at eliminating resistant cancer cells. This response-adapted model seeks to avoid both undertreatment and unnecessary exposure to toxic therapies, although its success depends on reliable biomarkers and evidence that early response accurately predicts long-term protection from relapse.

The NeoZanHER report is therefore likely to be followed closely by oncologists and researchers seeking alternatives or refinements to established HER2-directed regimens. The citation identifies the work as a phase 2, single-arm, open-label trial, but the bibliographic information alone does not provide the study’s participant number, treatment schedule, response rates, adverse-event profile or survival results. Those details are essential for judging the clinical significance of the findings. Until they are examined in the full publication and confirmed in larger comparative studies, zanidatamab should be viewed as an investigational approach in this setting rather than a replacement for standard treatment.

What makes the study newsworthy is the possibility that a carefully engineered antibody could reshape the earliest stage of treatment for a biologically aggressive cancer. If future evidence shows that dual-site HER2 targeting produces high rates of complete tumor eradication before surgery without adding unacceptable heart, blood or infusion-related complications, it could become part of a more personalized treatment strategy. For now, NeoZanHER represents an important test of that hypothesis: whether attacking the same cancer receptor through complementary molecular mechanisms can deliver a deeper and more durable response when treatment begins at the moment the disease is still potentially curable.

Subject of Research: Zanidatamab as neoadjuvant therapy for patients with early-stage HER2-positive breast cancer.

Article Title: Zanidatamab in patients with early stage HER2-positive breast cancer: the NeoZanHER phase 2 single-arm open-label trial.

Article References: Valero, V., Pohlmann, P.R., Mouabbi, J. et al. “Zanidatamab in patients with early stage HER2-positive breast cancer: the NeoZanHER phase 2 single-arm open-label trial.” Nature Communications (2026). https://doi.org/10.1038/s41467-026-76662-6

Image Credits: AI Generated

DOI: 10.1038/s41467-026-76662-6

Keywords: zanidatamab, HER2-positive breast cancer, early-stage breast cancer, neoadjuvant therapy, targeted therapy, biparatopic antibody, NeoZanHER, oncology, precision medicine, clinical trial

The study focused on adults with head and neck squamous cell carcinomas, a group of cancers that begins in the flat, surface-forming cells lining structures such as the mouth, throat, larynx and related regions. These tumors can be biologically aggressive and may require complex surgery followed by radiation, chemotherapy or additional systemic treatment. Although immunotherapy has transformed the management of recurrent and metastatic head and neck cancer, its role before surgery—and the potential value of pairing it with chemotherapy—has remained an area of active investigation.

Researchers reviewed the medical records of 86 adults treated within the Mount Sinai Health System between July 2024 and March 2026. All patients received treatment before surgery, during a period that traditionally may involve several weeks of waiting between the decision to operate and the operation itself. Fifty-eight patients received a combination of chemotherapy and immunotherapy, while 28 received immunotherapy alone. Most participants received two cycles of their assigned treatment before undergoing tumor removal.

The investigators evaluated the tumors after surgery, when pathologists could directly measure the amount of living cancer left behind. This approach, known as a pathologic response assessment, provides a more precise view of how effectively treatment damaged or eliminated the tumor than imaging alone. Scans can show that a mass has become smaller, but they cannot always distinguish between viable cancer, scar tissue, inflammation or treatment-related changes. Examination of the surgical specimen allows pathologists to determine whether cancer cells remain and, if so, how extensive the residual disease is.

Approximately two-thirds of the patients who received chemotherapy plus immunotherapy had either no detectable viable cancer or only a very small amount remaining in the resected tumor. By contrast, only one of the 28 patients treated with immunotherapy alone reached a similarly favorable response category. The findings indicate that adding chemotherapy was associated with a considerably greater reduction in tumor viability before surgery. The study describes this difference as statistically significant, although its retrospective design means that the results cannot by themselves establish that the treatment combination caused every observed benefit.

The biological rationale for the combination is based on the different ways the two treatment classes attack cancer. Chemotherapy can directly damage DNA, interfere with cell division and kill rapidly proliferating tumor cells. It may also alter the tumor microenvironment by releasing tumor-associated antigens and inflammatory signals, potentially making malignant cells more visible to the immune system. Immunotherapy, including immune checkpoint inhibitors, does not generally kill cancer cells directly. Instead, it can block inhibitory signals that restrain T cells, allowing the immune system to recognize and attack tumor cells more effectively. In theory, chemotherapy may therefore provide immunotherapy with a more exposed and vulnerable target.

Treating patients before surgery can also offer an important biological advantage. A tumor remains in place during neoadjuvant therapy, giving immune cells an opportunity to encounter a larger supply of cancer-related antigens. The resulting immune response may reach not only the primary tumor but also microscopic cancer deposits that are too small to be detected by imaging. At the same time, the pathologic response observed at surgery may help physicians estimate how sensitive an individual’s cancer is to treatment. Patients whose tumors are nearly eradicated could ultimately require a different intensity or duration of postoperative therapy than those whose tumors show substantial resistance.

The researchers previously reported that this type of combined preoperative treatment could be administered safely in appropriately selected patients. The new analysis adds evidence that the approach may also produce a stronger antitumor effect than immunotherapy alone. However, the comparison was not a randomized clinical trial. Treatment decisions may have been influenced by tumor characteristics, patient health, biomarkers, disease stage or physician judgment, and those factors could also affect the observed outcomes. The sample was relatively small, came from a single health system and included patients treated over a limited period, so the results require confirmation in larger, prospective studies.

The findings are nevertheless important because they challenge the idea that immunotherapy alone is sufficient for every patient receiving treatment before surgery. They also suggest that the weeks before an operation need not be a passive interval. Instead of waiting without active cancer therapy, selected patients may be able to receive treatment intended to shrink or biologically weaken the tumor before surgeons remove it. This strategy could make it possible to tailor subsequent care according to the amount of residual disease, intensifying treatment for patients with resistant tumors while potentially reducing unnecessary exposure for those with exceptionally strong responses.

Whether a dramatic pathologic response translates into longer survival or fewer recurrences remains unknown. In other solid tumors, including some lung, colorectal and breast cancers, major responses to neoadjuvant therapy have been linked to improved long-term outcomes, but the same relationship has not yet been fully established in head and neck cancer. Future trials will need to determine which patients benefit most from the combination, whether specific immune or molecular biomarkers can predict response, and how preoperative treatment should be integrated with surgery, radiation and postoperative systemic therapy. For now, the Mount Sinai study provides an early real-world signal that chemotherapy and immunotherapy together may destroy substantially more head and neck cancer before surgery than immunotherapy alone.

Subject of Research: Preoperative chemotherapy and immunotherapy for head and neck squamous cell carcinoma

Article Title: Pathologic Response After Neoadjuvant Chemo-Immunotherapy in Head and Neck Squamous Cell Carcinomas

Web References: https://jamanetwork.com/journals/jamaotolaryngology/fullarticle/10.1001/jamaoto.2026.2259

References: Roof S, Gomez E, et al. “Pathologic Response After Neoadjuvant Chemo-Immunotherapy in Head and Neck Squamous Cell Carcinomas.” JAMA Otolaryngology–Head & Neck Surgery. DOI: 10.1001/jamaoto.2026.2259

Keywords: head and neck cancer, head and neck squamous cell carcinoma, neoadjuvant therapy, chemotherapy, immunotherapy, cancer surgery, pathologic response, tumor regression, immune checkpoint inhibitors, oncology