Companion Diagnostics Market Report (6th Edition): 2027-2031 Forecast, Technology and Partnering Opportunities by Disease Area, Therapy Class, Technology, Sample Type, Product & Service and Country - Strategic Analysis of 102 Companies with Executive and Consultant Guides

Companion diagnostics are moving from a one-time test at diagnosis to monitoring during treatment. Blood joins tissue, sequencing panels collect claims across many drugs, and AI starts scoring the slides.

Companion diagnostics (CDx) are tests that decide whether a patient should receive a particular drug. They range from immunohistochemistry (IHC) stains on a tumour slide to sequencing panels that test hundreds of genes, and blood tests repeated during treatment. Regulators such as the U.S. FDA and the EU under the IVDR treat them as essential to the safe and effective use of the matched therapy.

The past year has brought several firsts: the first companion diagnostic based on minimal residual disease (MRD) testing, Natera’s Signatera CDx; the first liquid biopsy CDx approved for repeat testing during treatment; and a Phase 3 trial that selects patients with an AI-scored pathology test. The FDA renamed its list of companion diagnostics to cover every regulatory route, and the EU’s IVDR reached its main deadline for companion diagnostics in May 2026.

Market Size and Growth Outlook

This report estimates the global companion diagnostics market at $9.5 billion in 2026, growing at 12.4% a year to $17.1 billion in 2031. Values are at the manufacturer level in constant 2026 U.S. dollars.

Market Size 2026: USD $9.5B Market Size 2031: USD $17.1B CAGR: 12.4%

Key Market Drivers

Comprehensive Panels Replace Single Tests

Sequencing takes most of the growth. NGS-based companion diagnostics grow 17.5% a year, from $3.3 billion to $7.4 billion, and account for 54% of the $7.6 billion of new spending. Comprehensive panels such as FoundationOne CDx, Guardant360, TruSight Oncology Comprehensive, Oncomine and PGDx elio collect claims across many drugs.

This changes the economics from one test per drug to platforms that serve many drugs. Platform owners with large evidence bases and many claims are best placed, and smaller developers increasingly win by partnering with them or by owning a hard-to-copy biomarker.

Blood Joins Tissue

Blood-based companion diagnostics grow 19.4% a year, from $2.4 billion to $5.9 billion, and their share rises from 26% to 35%. Companion diagnostics are moving from a single test at diagnosis to monitoring. The forecast covers the main technologies:

• Next-generation sequencing (NGS)
• PCR and digital PCR
• Immunohistochemistry (IHC)
• In situ hybridization (ISH/FISH)
• Digital pathology and AI

The September 2026 approval of Guardant360 CDx for camizestrant, with repeat testing every three months, and Signatera CDx for adjuvant immunotherapy show where the market is heading. Tissue remains the largest sample type at $10.5 billion in 2031, but its share falls from 71% to 61%.

Antibody-Drug Conjugates Revive Tissue Testing

Antibodies and antibody-drug conjugates (ADCs) grow 15.1% a year to $4.7 billion and supply 31% of the growth. HER2-low and HER2-ultralow, CLDN18.2, c-Met and TROP2 all need protein tests on tissue, so IHC is again a growth area after years in the shadow of sequencing.

AI is becoming part of the test. Roche’s AI-scored TROP2 test is selecting patients in the TROPION-Lung17 Phase 3 trial, Tempus bought Paige, and PathAI works with Roche on AI-scored companion diagnostics. Digital pathology and AI is the fastest-growing technology, rising from $190 million to $599 million at 25.7% a year.

Regulation Diverges

The FDA’s list of authorised companion diagnostics passed 170 entries in 2026 and was renamed in July 2026 to cover 510(k), De Novo and humanitarian routes as well as premarket approval. In Europe, companion diagnostics are Class C devices under the IVDR and need a notified body certificate after consultation with a medicines regulator.

In the U.S., a court set aside the FDA’s rule on laboratory-developed tests in 2025, so laboratories can still offer therapy-selection tests without FDA review. Most drugs in late-stage oncology development now have a diagnostic partner, because a test that predicts treatment success can turn a “failed” drug into a success.

Market Segmentation

The report forecasts the market by disease area, therapy class, technology, sample type, product & service and country.

By Technology:

• NGS grows from 35% to 43% of the market. PCR grows 9.2% a year to $3.8 billion and IHC 9.1% a year to $3.7 billion, while digital pathology and AI is small but the fastest-growing technology.

By Disease Area:

Lung cancer is the largest disease area, growing from $2.6 billion to $4.1 billion, followed by other solid tumours, breast cancer and blood cancers. The fastest growth is outside oncology:

• Neurology, growing 33.2% a year as amyloid blood tests select patients for Alzheimer’s drugs
• Gene therapy and rare disease, growing 20.7% a year
• Cell and gene therapy companion diagnostics, growing 21% a year

By Therapy Class:

• Targeted small molecules remain the largest group at $6.8 billion in 2031, while immunotherapy tests grow 13.4% a year to $4 billion.

By Product & Service:

• Product and service categories include:
• Central laboratory services
• Kits & reagents and instruments
• Pharma development services
• Software & AI

Central laboratory services are the largest category, growing 14.4% a year to $7.2 billion. Kits and reagents grow 9.8% a year to $5.4 billion, pharma development services 14.9% a year to $2.5 billion, and software and AI 26.5% a year to $770 million.

Geographic Trends

The United States accounts for 43% of global revenue, reaching $7.4 billion in 2031. Europe accounts for about a quarter and grows a little more slowly as the IVDR raises the cost of keeping tests on the market. China is the fastest-growing major market, at 15.1% a year, as its drug industry produces more targeted therapies and antibody-drug conjugates.

Competitive Landscape

Roche, through Roche Tissue Diagnostics and Foundation Medicine, is the largest participant, followed by Agilent, Thermo Fisher Scientific, Illumina, QIAGEN, Guardant Health, Labcorp, Myriad Genetics and Abbott. The report profiles 102 companies.

The industry is reorganising around platforms and data. Tempus bought the AI pathology company Paige, SOPHiA GENETICS signed two decentralised CDx programmes with AstraZeneca, and Leica Biosystems expanded its CDx partnerships to compete with Roche and Agilent in tissue testing. Success depends on pharma relationships, regulatory capability and reach into laboratories and hospitals.

Future Outlook

• In the long term, the largest opportunities are in monitoring and in new therapy classes. Repeat blood testing during treatment, AI-scored tissue tests for antibody-drug conjugates and companion diagnostics for gene and cell therapies all expand the market beyond the original one-time test at diagnosis.
• Testing is also moving closer to the patient. Distributable kits with fast turnaround, such as Thermo Fisher’s 24-hour Oncomine Dx Express Test and Labcorp’s PGDx elio, and decentralised CDx programmes let hospitals keep samples and data in house.
• The main risks are the failure or delay of partners’ drugs, price pressure on comprehensive panels as distributable kits spread, the cost and capacity of IVDR certification in Europe, and uncertainty over how regulators will treat AI-based tests.