HER2-low Cancers Market Set to Register Immense Growth at a CAGR of 9.4% During the Study Period (2020-2034) | DelveInsight

The future of the HER2-low cancer treatment market is poised for significant transformation, driven by the approval of ENHERTU and the advancement of other innovative antibody-drug conjugates (ADCs)  like DATROWAY, TRODELVY, ifinatamab deruxtecan, BB-1701, and Disitamab vedotin. These ADCs are designed to target HER2-low-expressing cancer cells, with major development ongoing in Breast Cancer.

LAS VEGAS, June 19, 2025 /PRNewswire/ -- DelveInsight's HER2-low Cancers Market Size, Target Population, Competitive Landscape & Market Forecast report includes a comprehensive understanding of current treatment practices, emerging HER2-low cancer therapies, market share of individual therapies, and current and forecasted HER2-low cancers market size from 2020 to 2034, segmented into 7MM [the United States, the EU4 (Germany, France, Italy, and Spain), the United Kingdom, and Japan].

Key Takeaways from the HER2-low Cancers Market Report

• HER2-low cancer refers to tumors with low HER2 protein expression that do not meet the criteria for HER2-positive classification. The prevalence of HER2-low expression varies across cancers, occurring in approximately 63% of breast cancers, 42% of biliary tract cancers, 38% of urothelial carcinomas, and 35% of gastric cancers.
• As per DelveInsight's analysis, the total market size of HER2-low cancers in the 7MM was USD 3.2 billion in 2024 and is projected to grow during the forecast period (2025-2034), driven by ENHERTU's usage and strong uptake in this cancer type.
• Of the target indications, breast cancer and gastric cancer are anticipated to generate the most revenue by 2034 due to the highest level of clinical development and authorization of HER2-low cancer therapies.
• Among all therapies, ENHERTU is expected to capture the highest market share, due to its proven clinical efficacy, strong safety, and first-mover advantage in treating HER2-low cancers.
• Based on Delveinsight's assessment in 2024, the 7MM had approximately 360,000 target pool cases of HER2-low cancers. These cases are projected to increase during the forecast period (2025–2034) due to recent clinical advances recognizing HER2-low as a distinct category, thereby expanding the treatable patient population
• There are no HER2-targeting therapies currently in the pipeline for first-line treatment; all available options are focused on the relapsed or refractory setting.
• The HER2-low breast cancer pipeline is becoming increasingly competitive, as ENHERTU has dramatically shifted market dynamics. Its approval for HER2-low breast cancer has significantly transformed the market trajectory, leading to a doubling of overall sales in 2023.
• Leading HER2-low cancer companies, such as AstraZeneca, Daiichi Sankyo, RemeGen, Pfizer (Seagen), Gilead Sciences, Merck, Bliss Biopharmaceutical (Hangzhou), Zymeworks, Jazz Pharmaceuticals, ALX Oncology, Dragonfly Therapeutics, Mersana Therapeutics, and others, are developing novel HER2-low cancer therapies that can be available in the HER2-low cancer market in the coming years. 
• Some of the key HER2-low cancer therapies in the pipeline include DATROWAY (datopotamab deruxtecan/Dato-DXd), AIDIXI (disitamab vedotin), TRODELVY (sacituzumab govitecan), Ifinatamab deruxtecan (I-DXd)/MK-2400, BB-1701, ZIIHERA (zanidatamab), DF1001, Emiltatug ledadotin (XMT-1660), and others.

Discover which therapies are expected to grab the HER2-low cancers market share @ HER2-low Cancers Market Report

HER2-low Cancers Market Dynamics

The HER2-low cancer market has recently garnered significant attention, primarily due to the advancements in targeted therapies for cancers with low expression of the HER2 protein. While HER2-positive cancers, such as breast and gastric cancers, have long been the focus of targeted treatments like trastuzumab (HERCEPTIN), HER2-low cancers represent a distinct subset that requires different therapeutic strategies. These cancers exhibit a lower level of HER2 expression, making them more challenging to treat with traditional HER2-targeted therapies. However, recent breakthroughs in ADCs and novel monoclonal antibodies are starting to offer new avenues for patients with this subgroup.

As researchers continue to explore HER2-low cancers, one of the key dynamics driving the market is the recognition that these tumors can benefit from a broader range of treatments. In particular, ADCs are showing promise as they allow for more precise delivery of chemotherapy agents directly to tumor cells. This approach offers hope for patients whose cancers were previously thought to be less amenable to targeted therapies. The approval of drugs like ENHERTU for HER2-low breast cancer has created a significant shift in the oncology treatment landscape, leading to a surge of interest from pharmaceutical companies developing similar therapies.

The growing understanding of HER2-low cancers has also influenced diagnostic practices, with an emphasis on accurate biomarker testing. Companies are now focusing on developing more sensitive and specific assays to detect low levels of HER2 expression, ensuring that patients are correctly identified for targeted treatment options. This has led to the rise of precision medicine in oncology, where treatments are tailored not only to the type of cancer but also to the molecular characteristics of the tumor. The better the diagnostics, the more likely it is that patients will receive appropriate therapies, boosting market potential.

Additionally, market dynamics are shaped by the competitive landscape, with several big pharmaceutical companies investing heavily in the development of new agents for HER2-low cancers. The approval of HER2-targeted treatments for low-expressing cancers is expected to trigger a surge in demand, especially in indications such as breast and gastric cancers. However, challenges remain, including the cost of these novel therapies, their accessibility in different healthcare settings, and the need for continued clinical validation. As these therapies advance through the pipeline, the future market for HER2-low cancer treatments looks promising, but it will require a combination of scientific innovation, regulatory support, and healthcare infrastructure to realize its full potential.

HER2-low Cancers Treatment Market 

HER2-low cancers, which are marked by low levels of the HER2 protein, pose distinct treatment challenges. Recent research has focused on targeted therapies for such cancers, especially breast cancers. Treatment options for HER2-low cancers, including gastric, endometrial, and other cancers, are evolving as research continues to explore the role of HER2 in these diseases. Traditional therapies, such as monoclonal antibodies and small molecular Tyrosine Kinase Inhibitors (TKIs), have shown limited effectiveness in breast cancers with HER2-low expression. For years, HER2-low breast cancer has been treated similarly to HER2-negative breast cancer, including HR+/HER2− and TNBC cases.

For gastric cancer, particularly adenocarcinoma of the stomach and gastroesophageal junction, recent research has highlighted the potential of ENHERTU, an antibody-drug conjugate. ENHERTU has shown promising results in patients with HER2-low expression (IHC 1+ or 2+/ISH−). In January 2025, ENHERTU was approved by the US FDA for treating adult patients with unresectable or metastatic HR-positive, HER2-low, or HER2-ultralow (IHC 0 with membrane staining) breast cancer, who have progressed on one or more endocrine therapies in the metastatic setting, based on an FDA-approved test.

For HR-negative/HER2-low breast cancer, treatment usually begins with first-line chemotherapy, potentially combined with immunotherapy for PD-L1-positive patients, followed by sequential chemotherapy treatments. For HR-positive breast cancer, due to its progression-free survival advantage over chemotherapy, PARP inhibitors (PARPi) are considered for patients with a germline BRCA mutation.

Learn more about the FDA-approved HER2-low cancer therapies @ HER2-low Cancer Treatment Drugs

HER2-low Cancers Pipeline Therapies and Key Companies

Currently, the clinical development landscape includes late and mid-stage assets. Consequently, our forecast considers the potential impact of Pfizer's Disitamab vedotin, Immutep's Eftilagimod alpha (IMP321), AstraZeneca and Daiichi Sankyo's DATROWAY, Gilead Sciences' TRODELVY, Duality Biologics and BioNTech's DB-1303/BNT323, Daiichi Sankyo and Merck's Ifinatamab deruxtecan, Bliss Biopharmaceutical's BB-1701, and Dragonfly Therapeutics' DF1001.

Dato-DXd is an experimental TROP2-targeted ADC, developed using Daiichi Sankyo's proprietary DXd ADC Technology. It is one of six DXd ADCs in their oncology pipeline and a key program in AstraZeneca's ADC scientific platform. In collaboration with Sapporo Medical University, Dato-DXd is designed with topoisomerase I inhibitor payloads linked via tetrapeptide-based cleavable linkers. 

The drug is currently in Phase III trials for inoperable or metastatic HR-positive, HER2-low or negative breast cancer (IHC 0, IHC 1+, or IHC 2+/ISH-) that has previously been treated with endocrine therapy and at least one systemic therapy. AstraZeneca expects Phase I results from the TROPION-PanTumor01 trial (NCT03401385) to be available in the latter half of 2025, as reported in their 2024 clinical trial appendix.

In February 2025, Daiichi Sankyo presented data from the Phase III TROPION-Breast01 DATROWAY trial for HR+/HER2-low breast cancer at the ESMO Virtual Meeting. While overall survival did not reach statistical significance, Dato-DXd showed a manageable safety profile and continued to favor the investigator's choice of chemotherapy on secondary efficacy endpoints.

TRODELVY is a first-in-class TROP-2-targeting ADC designed with a proprietary hydrolyzable linker and SN-38, a topoisomerase I inhibitor payload. This combination delivers potent activity to TROP-2-expressing cells and the surrounding microenvironment. It is currently undergoing Phase III trials for HR-positive/HER-negative (HER2 IHC0 or HER2-low [IHC 1+, IHC 2+/ISH–]) inoperable, locally advanced, or metastatic breast cancer after endocrine therapy. Its patent is set to expire in the US by 2028 and in Europe by 2029.

BNT323/DB-1303 is a third-generation ADC targeting HER2, built on DualityBio's proprietary Duality Immune Toxin Antibody Conjugates (DITAC) platform. This candidate has shown antitumor activity in HER2-positive and HER2-low tumor models, as well as in multiple solid tumors, including breast, gastric, endometrial, biliary tract cancers, and other advanced solid tumors. BNT323/DB-1303 is currently being evaluated in a Phase I/II study (NCT05150691) for advanced/metastatic solid tumors and in a pivotal Phase III study (NCT06018337) for HR-positive and HER2-low, metastatic breast cancer that has progressed on hormone and/or CDK4/6 therapy.

The anticipated launch of these emerging therapies are poised to transform the HER2-low cancers market landscape in the coming years. As these cutting-edge therapies continue to mature and gain regulatory approval, they are expected to reshape the HER2-low cancers market landscape, offering new standards of care and unlocking opportunities for medical innovation and economic growth.

To know more about HER2-low cancer drug clinical trials, visit @ HER2-low Cancer Drugs 

Recent Developments in the HER2-low Cancer Market

• In January 2025, the US FDA approved ENHERTU for adults with unresectable or metastatic HR+, HER2-low or HER2-ultralow breast cancer, based on DESTINY-Breast06 Phase III results following progression on one or more endocrine therapies.
• In January 2025, the US FDA granted FTD to emiltatug ledadotin, B7-H4 ADC, for advanced or metastatic HER2-low or HER2-negative breast cancer, including triple-negative cases previously treated with a topoisomerase-1 inhibitor ADC, based on promising results from a Phase I trial.
• As per BioNTech's Q4 2024 annual presentation, published in March 2025, the company plans to prioritize the advancement of DB-1303 for BLA submission in 2025 as a second-line or subsequent therapy in HER2-expressing advanced endometrial cancer.
• According to Pfizer's presentation, the launch of disitamab vedotin for second-line HER2+/low metastatic urothelial carcinoma is expected in 2026. 

HER2-low Cancers Overview

HER2 is a transmembrane tyrosine kinase receptor encoded by the ERBB2 gene, playing a crucial role in cell growth, differentiation, and survival. It is part of the epidermal growth factor receptor family and is typically analyzed using molecular techniques. HER2 protein overexpression is assessed through immunohistochemistry (IHC), while gene amplification is determined using fluorescence in situ hybridization (FISH). A HER2-low status is defined as an IHC score of 1+ or 2+, with no gene amplification detected by FISH. HER2/neu primarily activates the MAPK and PI3K pathways, contributing to malignant transformation when overexpressed or amplified. This receptor is found in several cancers, including breast, colorectal, ovarian, endometrial, bladder, gastric, and biliary tract cancers, with breast cancer being the most prevalent.

HER2-low Cancers Epidemiology Segmentation

In the 7MM, in 2024, among all the HER2-low cancer indications, breast cancer accounted for the highest number of incident cases, while ovarian cancer occupied the bottom of the ladder. The HER2-low cancers market report proffers epidemiological analysis for the study period 2020–2034 in the 7MM, segmented into:

• Total Targeted Patient Pool of Selected Indications for HER2-low Cancers
• Treatment Eligible Pool of Selected Indications for HER2-low Cancers
• Total Incident Cases of HER2-low Breast Cancers
• Age-specific Cases of HER2-low Breast Cancers
• Stage-specific Cases of HER2-low Breast Cancers

Scope of the HER2-low Cancers Market Report

• HER2-low Cancers Therapeutic Assessment: HER2-low Cancers current marketed and emerging therapies
• HER2-low Cancers Market Dynamics: Conjoint analysis of approved and emerging HER2-low Cancers Drugs
• Competitive Intelligence Analysis: SWOT analysis and Market entry strategies
• Unmet Needs, KOL's views, Analyst's views, Cost assumptions, HER2-low Cancers Market Access and Reimbursement

Discover more about HER2-low cancer drugs in development @ HER2-low Cancers Clinical Trials

Table of Contents

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