HER2-Positive Gastric Cancer Market Size & Forecast 2035

HER2-Positive Gastric Cancer Market Size & Forecast 2035

The global HER2-positive gastric cancer market was valued at US$1.31 billion in 2025 and is projected to reach US$2.05 billion by 2035, growing at a CAGR of 4.6% during 2026-2035. HER2-directed antibody-drug conjugates, first-line HER2 and PD-1 combinations, biomarker-guided treatment selection, and next-generation bispecific antibodies are expanding the commercial scope of HER2-positive gastric and gastroesophageal junction cancer.

Treatment standards have changed rapidly. FDA granted traditional approval in March 2025 for pembrolizumab with trastuzumab and fluoropyrimidine/platinum chemotherapy for first-line treatment of locally advanced unresectable or metastatic HER2-positive gastric or gastroesophageal junction adenocarcinoma with PD-L1 CPS ≥1. In KEYNOTE-811, median overall survival reached 20.1 months with pembrolizumab-based treatment versus 15.7 months in the control arm, while objective response was 73% versus 58%.

Second-line treatment is also advancing. DESTINY-Gastric04 showed median overall survival of 14.7 months with trastuzumab deruxtecan versus 11.4 months with ramucirumab plus paclitaxel, strengthening HER2-directed ADCs as a major growth platform.

HER2-Positive Gastric Cancer Market Highlights

• 2025 Market Size: US$1.31 Billion
• 2035 Market Size: US$2.05 Billion
• CAGR, 2026-2035: 4.6%
• Largest Region: North America
• Fastest-Growing Region: Asia-Pacific
• Leading Therapy Platform: HER2-Targeted Therapy
• Largest Stage Segment: Stage IV
• Targeted Therapy Share: 38.6% of 2025 market revenue
• Stage IV Share: 41.2% of 2025 market revenue
• Key Growth Areas: HER2-directed ADCs, HER2/PD-1 combinations, bispecific HER2 antibodies, HER2 retesting, molecular profiling, liquid biopsy, perioperative HER2 therapy and resistance-directed combination treatment.

HER2-Positive Gastric Cancer Market Overview

HER2-positive gastric cancer is a molecularly defined subset of gastric and gastroesophageal junction adenocarcinoma characterized by HER2 protein overexpression or gene amplification. Published clinical literature reports HER2 overexpression in 10%-30% of gastric and gastroesophageal junction adenocarcinomas, although prevalence varies by tumor location, histology, geography, and testing method.

The market has evolved from a trastuzumab-centered treatment model into a multi-platform HER2 oncology market. Current treatment strategies include trastuzumab, trastuzumab deruxtecan, checkpoint inhibitors combined with HER2-targeted therapy, chemotherapy backbones, and investigational bispecific antibodies. HER2 status can also change after treatment, making repeat biopsy and molecular reassessment increasingly relevant when patients progress.

The underlying gastric cancer burden remains large. IARC recorded 980,286 new stomach cancer cases and 641,554 deaths worldwide in 2024. Asia accounted for more than two-thirds of new cases, giving the region the largest underlying patient population for HER2 testing and targeted treatment.

White-Space Opportunities in the HER2-Positive Gastric Cancer Market

First-Line HER2 and PD-1 Combination Therapy

The first-line market has shifted beyond trastuzumab and chemotherapy alone. Pembrolizumab plus trastuzumab and chemotherapy is approved in the United States for eligible HER2-positive, PD-L1 CPS ≥1 advanced gastric or GEJ adenocarcinoma.

KEYNOTE-811 enrolled 698 patients, including 594 patients with PD-L1 CPS ≥1. Among the PD-L1-positive population, median progression-free survival reached 10.9 months versus 7.3 months, median overall survival reached 20.1 months versus 15.7 months, and objective response reached 73% versus 58%.

These results increase demand for coordinated HER2 and PD-L1 testing and support higher treatment intensity in the first-line setting.

HER2-Directed ADCs Expand the Second-Line Market

Trastuzumab deruxtecan has established antibody-drug conjugates as a major HER2-positive gastric cancer treatment platform. DESTINY-Gastric04 enrolled 494 patients and demonstrated median overall survival of 14.7 months with trastuzumab deruxtecan versus 11.4 months with ramucirumab plus paclitaxel. The hazard ratio for death was 0.70.

The treatment has also expanded geographically. In January 2026, China approved ENHERTU for second-line treatment of HER2-positive metastatic gastric or GEJ adenocarcinoma, while Japan expanded access in March 2026.

Bispecific HER2 Antibodies Could Reshape First-Line Competition

Zanidatamab is emerging as an important investigational competitor. Phase III HERIZON-GEA-01 evaluated zanidatamab with chemotherapy, with or without tislelizumab, against trastuzumab plus chemotherapy in first-line HER2-positive advanced gastroesophageal adenocarcinoma.

Median progression-free survival reached 12.4 months with zanidatamab-based therapy versus 8.1 months with trastuzumab plus chemotherapy in reported results. The program was under FDA Real-Time Oncology Review in 2026.

Successful regulatory expansion would create direct competition between established trastuzumab-based regimens and next-generation HER2 bispecific antibodies.

HER2 Reassessment Creates a Diagnostic Opportunity

HER2 expression is heterogeneous and can change under treatment pressure. A 2025 multicenter study of 398 patients with locally advanced gastric cancer found HER2 expression changed after neoadjuvant treatment in more than 40% of cases. HER2 expression decreased in 26.0% and increased in 17.3%.

Repeat tissue testing, digital pathology, next-generation sequencing and liquid biopsy can therefore become more important as the number of HER2-directed treatment choices expands.

Asia Offers the Largest Patient-Burden Opportunity

Asia recorded 694,188 new stomach cancer cases in 2024, representing 70.8% of global incidence.

The region combines high disease burden with growing access to HER2 testing and new targeted drugs. Japan recorded 142,506 new stomach cancer cases in 2024, while China recorded 358,672 cases in the 2022 IARC dataset.

HER2-Positive Gastric Cancer Market Key Takeaways

• The global market is projected to increase from US$1.31 billion in 2025 to US$2.05 billion by 2035, growing at a CAGR of 4.6% during 2026-2035.
• Targeted therapy accounted for 38.6% of market revenue in 2025, supported by trastuzumab and the growing use of HER2-directed ADCs.
• Stage IV disease represented 41.2% of the market in 2025, reflecting high systemic-treatment intensity and demand for multiple lines of HER2-directed therapy.
• HER2 and PD-1 combination therapy has strengthened first-line treatment, with KEYNOTE-811 showing median overall survival of 20.1 months in patients with PD-L1 CPS> 1 compared with 15.7 months for the control regimen.
• HER2-directed ADCs are moving toward a stronger second-line position, supported by the survival advantage demonstrated in DESTINY-Gastric04 and new access in major Asian markets.
• Asia-Pacific provides the largest underlying patient pool, with Asia representing 70.8% of global stomach cancer incidence in 2024.
• HER2 heterogeneity and treatment-driven biomarker changes are increasing the importance of repeat testing, creating opportunities for pathology laboratories, molecular diagnostics, and liquid-biopsy platforms.

HER2-Positive Gastric Cancer Market Industry Trends and Strategic Insights

HER2 Treatment Is Moving Toward Multi-Biomarker Selection

HER2 status alone no longer defines the entire first-line treatment pathway. PD-L1 expression now influences eligibility for pembrolizumab-containing HER2 therapy in the United States.

The FDA-approved first-line KEYNOTE-811 regimen applies to HER2-positive tumors with PD-L1 CPS ≥1, making combined HER2 and PD-L1 testing an important part of treatment selection.

ADCs Are Raising the Clinical Standard After Trastuzumab

Trastuzumab deruxtecan combines HER2 targeting with delivery of a cytotoxic payload and has produced superior survival compared with ramucirumab plus paclitaxel in previously treated HER2-positive advanced gastric and GEJ adenocarcinoma.

The ADC platform is now being studied in earlier treatment settings, expanding its potential beyond patients who have already progressed after trastuzumab.

HER2 Bispecific Antibodies Are Moving into Phase III Competition

HERIZON-GEA-01 represents a major test of whether a next-generation HER2 bispecific antibody can outperform trastuzumab-based first-line treatment. Zanidatamab-based regimens achieved median progression-free survival of 12.4 months in reported Phase III results, compared with 8.1 months for the trastuzumab-based control.

HER2 Retesting Is Becoming More Relevant

Loss or gain of HER2 expression following chemotherapy or targeted treatment can affect subsequent therapy selection. The observed post-neoadjuvant changes in HER2 expression strengthen the case for reassessment at progression or after major treatment transitions.

Treatment Development Is Expanding Toward Resectable Disease

HER2-directed treatment is no longer limited to metastatic disease research. Early clinical programs are examining HER2-targeted ADCs in neoadjuvant settings.

The NeoART study is evaluating trastuzumab deruxtecan with fluorouracil and folinic acid in resectable HER2-positive esophagogastric adenocarcinoma. Early Phase Ib/II findings showed successful resection in five of the first six treated patients, including two pathological complete responses.

HER2-Positive Gastric Cancer Market Scope

The segment structure maintains continuity with the existing HER2-positive gastric cancer report while incorporating the treatment developments that have gained commercial relevance through 2025 and 2026.

HER2-Positive Gastric Cancer Market Disruption Analysis

Trastuzumab Is No Longer the Only HER2 Platform

Trastuzumab established HER2-directed therapy as a treatment standard in advanced gastric cancer. The competitive environment now includes HER2-directed ADCs, checkpoint inhibitor combinations and bispecific antibodies.

This shift means new therapies must demonstrate differentiation not only against chemotherapy but against established HER2-targeted treatment sequences.

Second-Line Treatment Is Moving Toward HER2 ADCs

DESTINY-Gastric04 directly compared trastuzumab deruxtecan with ramucirumab plus paclitaxel. The improvement in median overall survival from 11.4 to 14.7 months strengthens the role of ADC treatment after progression on trastuzumab-based therapy.

The result also raises the development standard for future second-line HER2-targeted drugs.

Bispecific Antibodies Could Challenge the First-Line Trastuzumab Backbone

Zanidatamab binds two separate HER2 epitopes and is being developed as an alternative HER2 antibody platform. Phase III HERIZON-GEA-01 has generated positive progression-free survival results against trastuzumab plus chemotherapy.

A successful regulatory outcome could alter first-line procurement, treatment sequencing and competitive positioning across HER2-positive gastroesophageal cancer.

Biomarker Instability Creates a Need for Dynamic Testing

HER2 expression can differ between primary and metastatic lesions and can change after systemic treatment. Clinical evidence showing treatment-associated shifts in HER2 status supports a move from one-time diagnostic testing toward repeated molecular assessment.

This expands the addressable market for HER2 IHC, ISH, next-generation sequencing and circulating-tumor DNA technologies.

HER2-Positive Gastric Cancer Market Dynamics

Driver: Large Global Gastric Cancer Burden

IARC recorded 980,286 new stomach cancer cases in 2024, with Asia accounting for 694,188 cases. Gastric cancer caused 641,554 deaths globally during the same year.

Because HER2 overexpression is reported in 10%-30% of gastric and GEJ adenocarcinomas, the global disease burden creates a substantial population requiring HER2 testing and potential HER2-directed treatment.

Driver: First-Line Combination Therapy

Pembrolizumab plus trastuzumab and chemotherapy improved response, progression-free survival, and overall survival in eligible PD-L1-positive HER2-positive advanced gastric and GEJ adenocarcinoma.

This increases the value of first-line therapy and expands demand for coordinated HER2 and PD-L1 diagnostic testing.

Driver: Expansion of Antibody-Drug Conjugates

Trastuzumab deruxtecan demonstrated superior overall survival in DESTINY-Gastric04 and has gained broader access in major markets. China and Japan expanded second-line access during 2026.

Continued evaluation in first-line and earlier disease creates additional long-term market potential.

Driver: Growing Precision-Oncology Infrastructure

HER2 testing is required before HER2-directed treatment, while PD-L1 testing can determine eligibility for first-line pembrolizumab combinations. Tumor heterogeneity and changing HER2 expression are also increasing demand for repeat assessment.

Driver: Next-Generation HER2 Pipeline

Zanidatamab and HLX22 illustrate the shift toward HER2 therapies designed to provide greater receptor engagement or overcome resistance.

A global Phase III study of HLX22 combined with trastuzumab and chemotherapy is targeting around 550 patients. Earlier Phase II findings reported a progression-free survival hazard ratio of 0.20 for the HLX22 combination versus trastuzumab plus chemotherapy.

Restraint: HER2 Heterogeneity

Gastric cancer frequently shows heterogeneous HER2 expression within and between tumor sites. A patient can therefore have HER2-positive and HER2-negative tumor populations simultaneously, reducing the effectiveness of HER2-directed therapy and complicating diagnostic classification.

Restraint: Loss of HER2 Expression After Treatment

HER2 status can change after chemotherapy and HER2-directed therapy. In the 398-patient multicenter study, HER2 expression decreased in 26.0% of patients following neoadjuvant treatment.

This can reduce the addressable population for later-line HER2 therapy unless patients are reassessed.

Restraint: ADC Safety Monitoring

Trastuzumab deruxtecan carries a recognized risk of interstitial lung disease and pneumonitis. Although most events in DESTINY-Gastric04 were low grade, monitoring and early management remain important components of treatment delivery.

HER2-Positive Gastric Cancer Market Segment Analysis

By Therapy

Targeted Therapy Holds the Largest Market Share

Targeted therapy accounted for 38.6% of HER2-positive gastric cancer market revenue in 2025, making it the leading therapy segment.

The segment is supported by the central role of HER2-directed treatment. Trastuzumab remains an established first-line HER2 backbone, while trastuzumab deruxtecan has strengthened the second-line ADC market. Zanidatamab, HLX22, and other next-generation HER2 agents could broaden the targeted-therapy segment further if ongoing clinical programs translate into regulatory approvals.

Targeted therapy is also becoming more closely integrated with immunotherapy. Instead of competing as entirely separate treatment categories, HER2-targeted antibodies and PD-1 inhibitors are increasingly used together.

Immunotherapy Is Expanding Through HER2 Combination Regimens

Immunotherapy is one of the fastest-developing treatment categories in HER2-positive advanced gastric cancer.

Pembrolizumab combined with trastuzumab and chemotherapy is approved for eligible PD-L1 CPS ≥1 tumors. In KEYNOTE-811, the pembrolizumab combination produced a 73% objective response rate, compared with 58% for trastuzumab and chemotherapy alone.

Tislelizumab is also being investigated with zanidatamab and chemotherapy in HERIZON-GEA-01, supporting further convergence between HER2-directed treatment and checkpoint inhibition.

Chemotherapy Remains the Core Combination Backbone

Fluoropyrimidine and platinum chemotherapy remains important in first-line HER2-positive advanced gastric cancer, but its role is increasingly as a backbone for HER2 antibodies and immunotherapy rather than as a stand-alone treatment strategy.

In later lines, paclitaxel-based regimens remain relevant, although HER2-directed ADCs are increasing competitive pressure on conventional chemotherapy combinations.

Radiation Therapy Holds a Smaller Systemic-Market Share

Radiation therapy is used selectively for localized, perioperative, or palliative disease. Its commercial role within a HER2-specific market is smaller because HER2 status primarily determines systemic targeted therapy rather than radiation eligibility.

By Stage

Stage IV Holds the Largest Market Share

Stage IV disease accounted for 41.2% of HER2-positive gastric cancer market revenue in 2025, making it the largest stage segment.

Advanced and metastatic disease generates higher pharmaceutical spending because patients can receive multiple systemic treatment lines. First-line treatment can include trastuzumab, chemotherapy, and pembrolizumab in eligible patients, followed by HER2-directed ADCs or other subsequent-line regimens.

The increasing number of treatment options also extends the therapeutic journey for patients who maintain sufficient performance status after progression.

Stage III Creates Growing Perioperative Opportunity

Stage III disease can require surgery combined with systemic perioperative treatment. HER2-directed strategies are increasingly being evaluated in resectable and locally advanced disease, which could increase the commercial importance of Stage II and Stage III treatment over the forecast period.

Stage I and Stage II Remain Surgery-Led

Earlier-stage gastric cancer is more commonly managed through surgery with perioperative or adjuvant treatment according to tumor characteristics and clinical risk. HER2-directed treatment has not yet reached the same commercial penetration seen in metastatic disease, leaving room for future perioperative clinical development.

By End User

Hospitals and Specialty Clinics Account for the Largest Treatment Activity

Hospitals and specialty clinics together accounted for 47.1% of market revenue in a 2025 end-user benchmark, reflecting the need for multidisciplinary oncology care, HER2 testing, infusion therapy, chemotherapy administration, and toxicity monitoring.

Large oncology hospitals are particularly important for trastuzumab deruxtecan and complex combination regimens because treatment requires infusion capacity, cardiac assessment for HER2 therapies, pathology support, and monitoring for treatment-related adverse events.

Specialty oncology clinics play a growing role in long-term systemic treatment, while academic centers remain central to clinical trials involving next-generation HER2 antibodies and perioperative strategies.

HER2-Positive Gastric Cancer Market Regional Analysis

North America

North America remains the largest commercial region for HER2-positive gastric cancer treatment. The published regional benchmark reported a 38.4% market revenue share for North America in 2022, supported by advanced molecular diagnostics, high oncology expenditure, and early access to HER2-targeted therapies.

The United States continues to drive regional growth. NCI estimates 31,510 new stomach cancer cases and 10,740 deaths in the United States in 2026. The five-year relative survival rate is 39.8% based on cases diagnosed during 2016-2022.

The U.S. market has also benefited from the March 2025 traditional FDA approval of pembrolizumab plus trastuzumab and chemotherapy for PD-L1-positive, HER2-positive advanced gastric or GEJ adenocarcinoma.

High HER2 and PD-L1 testing rates, access to NGS, and rapid uptake of high-value biologics support North America's revenue leadership even though the region accounts for a smaller share of worldwide gastric cancer incidence than Asia.

Asia-Pacific

Asia-Pacific is the fastest-growing market and carries the world's largest gastric cancer patient burden. Asia recorded 694,188 new stomach cancer cases in 2024, representing 70.8% of global incidence.

The region's commercial position is strengthening as China, Japan, and other major markets broaden access to HER2-directed therapies. Japan recorded 142,506 new stomach cancer cases in 2024, making stomach cancer the country's second most frequently diagnosed cancer in the IARC dataset.

China recorded 358,672 new stomach cancer cases in 2022, giving it one of the world's largest country-level treatment populations. ENHERTU received second-line HER2-positive metastatic gastric cancer approval in China in January 2026 and expanded access in Japan in March 2026.

Greater biomarker testing, oncology infrastructure expansion, and access to HER2-targeted biologics are expected to move Asia-Pacific closer to its underlying share of the global patient population.

Europe

Europe accounted for 14.0% of global stomach cancer incidence in 2024, with 137,501 new cases.

Germany, the United Kingdom, France, Italy and Spain represent important commercial markets due to established pathology infrastructure, access to HER2 testing and use of targeted oncology drugs.

The region has established treatment pathways for trastuzumab and HER2-directed ADCs, while next-generation HER2 and immunotherapy combinations could increase pharmaceutical spending per patient as regulatory access expands.

Latin America

Latin America and the Caribbean recorded 79,706 new stomach cancer cases in 2024, accounting for 8.1% of global incidence.

Brazil represents the largest commercial opportunity in the region, supported by its population, private oncology sector, and growing availability of molecular testing. Access remains uneven between private cancer centers and public health systems, making reimbursement and diagnostic availability important determinants of HER2 treatment uptake.

Middle East and Africa

Africa recorded 33,234 new stomach cancer cases in 2024, representing 3.4% of global incidence.

Commercial development remains concentrated in major tertiary cancer centers. HER2 testing capacity, pathology availability, and affordability of biologic treatment continue to influence treatment penetration.

Gulf countries, Israel, Türkiye and South Africa offer stronger access to advanced targeted therapies than many lower-resource markets, while broader regional growth depends on diagnostic infrastructure and oncology reimbursement.

HER2-Positive Gastric Cancer Country-Level Analysis

United States

The United States is the leading individual commercial market because of early regulatory access, extensive biomarker testing, and high oncology treatment expenditure.

NCI projects 31,510 new stomach cancer cases in 2026, creating a substantial population for HER2 and PD-L1 evaluation.

The U.S. also remains a key regulatory market for first-line HER2/PD-1 combination therapy and emerging bispecific HER2 antibodies.

Japan

Japan recorded 142,506 new stomach cancer cases in 2024, including 98,490 cases in men and 44,016 in women. Gastric cancer caused 51,440 deaths in the country during the same year.

Japan is therefore one of the world's most important HER2-positive gastric cancer markets by addressable patient population. Expanded access to trastuzumab deruxtecan in March 2026 further strengthens the country's importance for HER2-directed ADC adoption.

China

China recorded 358,672 new stomach cancer cases and 260,372 deaths in 2022, with five-year prevalence reaching 523,812 cases.

The country's patient volume gives China significant importance for HER2 testing, clinical development and commercialization. ENHERTU received second-line approval for HER2-positive metastatic gastric cancer in China in January 2026.

Domestic companies are also developing next-generation HER2 products. Shanghai Henlius is conducting the global Phase III HLX22-GC-301 study, strengthening China's role in HER2 drug development as well as treatment consumption.

India

India recorded 68,548 new stomach cancer cases and 45,392 deaths in 2024. Five-year prevalence reached 105,197 cases.

India presents a significant long-term opportunity as HER2 testing and private oncology infrastructure expand. Price sensitivity, access to biologics and diagnostic availability remain major factors affecting commercial penetration.

South Korea

South Korea remains an important gastric cancer treatment market because of its high disease burden, established screening infrastructure and strong adoption of precision oncology.

The country also participates extensively in global gastroesophageal cancer trials, supporting access to new HER2 therapies and accelerating clinical adoption after regulatory approval.

HER2-Positive Gastric Cancer Epidemiology and Biomarker Analysis

HER2-positive gastric cancer represents a molecular subset of a much larger global gastric cancer population. Published studies report HER2 overexpression in 10%-30% of gastric and GEJ adenocarcinomas.

Worldwide stomach cancer incidence reached 980,286 new cases in 2024, while mortality reached 641,554.

Asia accounted for 70.8% of new cases, Europe for 14.0%, Latin America and the Caribbean for 8.1%, Africa for 3.4%, Northern America for 3.3%, and Oceania for 0.38%. These percentages describe stomach cancer incidence and provide a measure of the underlying testing and treatment population; they are not HER2-positive treatment-market revenue shares.

HER2 prevalence also varies between intestinal and diffuse histology and between proximal and distal tumors. Tumor heterogeneity means a single biopsy can fail to capture every HER2-positive tumor clone, making pathology quality and adequate tissue sampling important for treatment selection.

HER2-Positive Gastric Cancer Market Pipeline Analysis

Zanidatamab

Zanidatamab is one of the most advanced next-generation HER2 programs in first-line gastroesophageal adenocarcinoma.

HERIZON-GEA-01 enrolled more than 900 patients across more than 30 countries. Zanidatamab-based treatment produced median progression-free survival of 12.4 months compared with 8.1 months for trastuzumab plus chemotherapy in reported Phase III results.

The program was under FDA Real-Time Oncology Review during 2026, making it one of the most important near-term competitive developments to monitor.

HLX22

Shanghai Henlius is evaluating HLX22 in combination with trastuzumab and chemotherapy in the global Phase III HLX22-GC-301 trial.

The program targets around 550 patients across countries including China, the United States, Japan, Australia and Argentina. Phase II results reported median progression-free survival not reached with HLX22 plus trastuzumab and chemotherapy, compared with 8.3 months for the control group.

Trastuzumab Deruxtecan in Earlier Lines

Following success in later-line HER2-positive gastric cancer, trastuzumab deruxtecan is being evaluated in earlier treatment settings.

Programs including DESTINY-Gastric05 and ARTEMIDE-Gastric01 are exploring its role in first-line disease and combination treatment, which could expand ADC exposure across a larger patient population.

Perioperative HER2-Directed Therapy

Early-stage development is testing whether HER2-directed ADC treatment can improve outcomes before surgery.

NeoART is evaluating neoadjuvant trastuzumab deruxtecan with fluorouracil and folinic acid in resectable HER2-positive esophagogastric adenocarcinoma. Early data showed no serious adverse events or dose-limiting toxicities during neoadjuvant therapy among the first six treated patients.

HER2-Positive Gastric Cancer Market Company Positioning

AstraZeneca and Daiichi Sankyo

AstraZeneca and Daiichi Sankyo hold a strong position through ENHERTU (trastuzumab deruxtecan).

DESTINY-Gastric04 strengthened the product's clinical positioning by showing a median overall survival advantage of 14.7 months versus 11.4 months against ramucirumab plus paclitaxel.

Expanded access in China and Japan during 2026 increases the product's commercial reach across the world's largest gastric cancer region.

Merck & Co.

Merck competes through KEYTRUDA, which is used with trastuzumab and chemotherapy for eligible PD-L1-positive HER2-positive advanced gastric and GEJ adenocarcinoma.

KEYNOTE-811 demonstrated improvements in overall survival, progression-free survival, and response rate, strengthening Merck's position at the intersection of HER2 targeting and checkpoint inhibition.

Roche/Genentech

Roche and Genentech retain a foundational position through HERCEPTIN (trastuzumab), which established HER2 targeting as a treatment standard in gastric cancer.

Although competition has expanded, trastuzumab remains an important comparator and combination backbone for newer first-line therapies and clinical trials.

Jazz Pharmaceuticals

Jazz Pharmaceuticals is developing zanidatamab for HER2-positive gastroesophageal adenocarcinoma.

Positive Phase III HERIZON-GEA-01 data create a potential opportunity to challenge trastuzumab-based first-line therapy. The program's FDA Real-Time Oncology Review status during 2026 makes it an important near-term regulatory catalyst.

BeOne Medicines

BeOne Medicines contributes to the HERIZON-GEA-01 program through tislelizumab, which is being studied alongside zanidatamab and chemotherapy.

The combination reflects growing competition between HER2-directed treatment and PD-1 inhibition as an integrated first-line platform.

Shanghai Henlius Biotech

Shanghai Henlius is developing HLX22, a novel HER2-targeting monoclonal antibody being evaluated with trastuzumab and chemotherapy.

The ongoing global Phase III program gives Henlius a potential position in next-generation HER2 combination therapy.

HER2-Positive Gastric Cancer Market Competitive Landscape

Competition is shifting from a single HER2-antibody market toward several distinct platforms: trastuzumab-based combinations, HER2-directed ADCs, HER2/PD-1 combinations and next-generation HER2 bispecific or complementary antibodies.

AstraZeneca and Daiichi Sankyo have established a strong ADC position through trastuzumab deruxtecan. Merck has expanded checkpoint inhibition into first-line HER2-positive disease through KEYTRUDA. Roche remains important through trastuzumab, while Jazz Pharmaceuticals and Shanghai Henlius represent two major emerging HER2 antibody programs.

Competitive differentiation through 2035 will depend on overall survival, progression-free survival, response durability, ability to overcome HER2 heterogeneity, toxicity, biomarker requirements and positioning across treatment lines.

HER2-Positive Gastric Cancer Market Key Developments

May 2026: Phase III HERIZON-GEA-01 Results Published

Phase III data for zanidatamab-based first-line therapy were published in May 2026. Median progression-free survival reached 12.4 months with zanidatamab-based treatment compared with 8.1 months for trastuzumab plus chemotherapy.

March 2026: Japan Expands ENHERTU Use

Japan expanded access to trastuzumab deruxtecan for second-line HER2-positive metastatic gastric cancer following DESTINY-Gastric04 results.

January 2026: China Approves ENHERTU in Second-Line Disease

China approved trastuzumab deruxtecan as the country's first HER2-directed ADC for second-line HER2-positive metastatic gastric or GEJ adenocarcinoma.

January 2026: Global HLX22 Phase III Development Advances

Shanghai Henlius reported progress in the global Phase III HLX22-GC-301 study evaluating HLX22 plus trastuzumab and chemotherapy in first-line HER2-positive advanced gastric and GEJ cancer.

March 2025: FDA Grants Traditional Approval to KEYTRUDA Combination

FDA granted traditional approval to pembrolizumab with trastuzumab and chemotherapy for first-line treatment of eligible PD-L1 CPS ≥1 HER2-positive locally advanced unresectable or metastatic gastric or GEJ adenocarcinoma.

2025: DESTINY-Gastric04 Establishes Phase III Survival Benefit

DESTINY-Gastric04 showed that trastuzumab deruxtecan improved overall survival compared with ramucirumab plus paclitaxel after progression on trastuzumab-containing therapy.

Key Procurement Priorities and Buyer Evaluation Criteria

Healthcare systems evaluating HER2-positive gastric cancer therapies increasingly consider the complete biomarker and treatment pathway rather than drug acquisition price alone.

HER2 confirmation is the first requirement. Reliable IHC and ISH testing is necessary to identify patients who are candidates for HER2-directed treatment. Tumor heterogeneity also makes specimen quality and repeat testing important when results are borderline or disease progresses.

PD-L1 testing affects first-line treatment selection. The approved pembrolizumab, trastuzumab and chemotherapy regimen requires PD-L1 CPS ≥1 in the United States.

Overall survival and progression-free survival remain central purchasing criteria. Hospitals and payers increasingly compare the magnitude and durability of clinical benefit across trastuzumab-based combinations, ADCs and emerging bispecific antibodies.

Safety monitoring affects total treatment cost. ADCs require monitoring for interstitial lung disease and other treatment-related toxicities, while checkpoint inhibitors require management of immune-mediated adverse events.

Treatment sequencing is becoming more complex. The availability of multiple HER2-directed products requires institutions to determine optimal first-line and second-line pathways and when HER2 should be retested.

Infusion and diagnostic capacity influence adoption. Comprehensive cancer centers with integrated pathology, molecular diagnostics and infusion infrastructure are better positioned to adopt multi-drug biomarker-selected regimens.