Companion diagnostics platforms

01Overview and value chain

Markers: [EC: IVDR 2017/746 | OECD: Biotech-health | Regulator: FDA (USA), EMA (European Union), NMPA (China)]

Companion diagnostics platforms are tissue-based immunohistochemistry (IHC) and fluorescence in-situ hybridization (FISH) assay systems that determine whether a specific patient’s tumor expresses the biomarker a targeted therapy requires, sold and regulated as a companion diagnostic (CDx) approved alongside a specific drug label. Ventana Medical Systems, operating globally as Roche Tissue Diagnostics, recently received EU IVDR approval for its VENTANA MMR RxDx panel companion diagnostic across multiple cancer types and therapies. Agilent’s Dako PD-L1 IHC 22C3 pharmDx assay — paired with Merck’s Keytruda (pembrolizumab) — has received a string of 2026 FDA approvals expanding its use into esophageal squamous cell carcinoma, triple-negative breast cancer, cervical cancer, gastric/gastroesophageal junction adenocarcinoma and epithelial ovarian/fallopian tube/primary peritoneal carcinoma. Myriad Genetics’ MyChoice CDx received FDA approval as the companion diagnostic for Zejula (niraparib) in ovarian cancer, and the company continues expanding its Precise MRD test to colorectal, renal and breast cancers. In China, 3D Medicines develops companion diagnostics and genomic testing paired with domestic and global oncology drug approvals. In India, MedGenome offers oncology companion-diagnostic and precision-oncology testing including a CNS tumor methylation classifier and its TumourTrack Advance panel.

The key directions of companion diagnostics platforms are:

1. IHC/FISH tissue-based CDx (IHC/FISH Companion Diagnostics): immunohistochemistry and FISH assays run on a tumor tissue biopsy to determine drug eligibility — Ventana/Roche Tissue Diagnostics, Agilent Dako.
2. PD-L1 testing platforms (PD-L1 Testing Platforms): IHC assays specifically quantifying PD-L1 expression to determine checkpoint-inhibitor eligibility across an expanding list of cancer types — Agilent Dako’s 22C3 pharmDx.
3. Hereditary-cancer and biomarker CDx (Hereditary Cancer CDx): germline and homologous-recombination-deficiency testing tied to PARP-inhibitor and other targeted-therapy eligibility — Myriad Genetics.
4. Regional precision-oncology CDx platforms (Tissue-Based Precision Oncology): domestic tissue-based genomic and IHC testing paired with local oncology drug approvals — 3D Medicines, MedGenome.

Sectoral value chain

[biomarker/assay development] ──> [co-development with drug sponsor] ──> [regulatory approval (paired with drug label)]
                                                    │
                                       (tissue biopsy testing at diagnosis)
                                                    │
                                                    ▼
[label expansion to new indications] <─── [treatment eligibility decision] <─────┘

Value chain levels

Cross-cutting technologies of the sector:

• Immunohistochemistry (IHC) staining (IHC/FISH Companion Diagnostics): antibody-based staining of tumor tissue sections visualizes protein expression (PD-L1, HER2) directly under a microscope, the workhorse technology of tissue-based CDx.
• PD-L1 quantification scoring (PD-L1 Testing Platforms): standardized scoring systems (Tumor Proportion Score, Combined Positive Score) applied to IHC-stained tissue determine checkpoint-inhibitor eligibility across an expanding list of approved indications.
• Homologous-recombination-deficiency (HRD) testing (Hereditary Cancer CDx): germline and tumor genomic testing identifies patients whose DNA-repair deficiency predicts response to PARP inhibitors and related targeted therapies.

02US

The US anchors the deepest companion-diagnostics platform bench, spanning IHC/FISH tissue testing and hereditary-cancer CDx, with an accelerating cadence of label-expansion approvals.

Ventana, Agilent Dako, Myriad Genetics, FDA

• Ventana Medical Systems (Roche Tissue Diagnostics): its VENTANA MMR RxDx panel companion diagnostic recently received EU IVDR approval across multiple cancer types and therapies, extending its global tissue-diagnostics platform.
• Agilent Dako: its PD-L1 IHC 22C3 pharmDx assay has received a string of 2026 FDA approvals expanding use into esophageal squamous cell carcinoma, triple-negative breast cancer, cervical cancer, gastric/gastroesophageal junction adenocarcinoma and epithelial ovarian/fallopian tube/primary peritoneal carcinoma, each tied to Merck’s Keytruda label.
• Myriad Genetics: its MyChoice CDx received FDA approval as the companion diagnostic for Zejula (niraparib) in ovarian cancer, and the company continues expanding its Precise MRD test into colorectal, renal and breast cancer.
• FDA framework: companion diagnostics are approved via FDA PMA as a device explicitly tied to a specific drug’s label, with expansion into new cancer types and treatment lines requiring a fresh approval for each indication.

03CN

China develops domestic companion diagnostics and genomic testing paired with both local and global oncology drug approvals, with 3D Medicines among the active developers.

3D Medicines, NMPA

• 3D Medicines: develops companion diagnostics and genomic testing paired with domestic and global oncology drug approvals, part of China’s growing precision-oncology testing base.
• NMPA framework: companion diagnostics in China require NMPA approval explicitly linked to the paired drug’s label, following the same co-development principle as FDA and EU IVDR pathways.

04EU

Roche, headquartered in Basel, Switzerland, drives global IVDR compliance for its Ventana/Roche Tissue Diagnostics companion-diagnostic platform, anchoring Europe’s regulatory role in this category.

Roche Tissue Diagnostics, IVDR

• Roche (Basel, Switzerland): as Ventana Medical Systems’ parent, Roche recently secured EU IVDR approval for the VENTANA MMR RxDx panel companion diagnostic across multiple cancer types and therapies, illustrating the conformity-assessment bar every companion-diagnostic developer selling into the EU must clear.
• IVDR framework: companion diagnostics sold in the EU require conformity assessment and CE marking under the In Vitro Diagnostic Regulation (IVDR 2017/746), with each drug-paired indication typically requiring its own assessment.

05Leading companies and research institutes

06Tech stack and innovations

The stack pairs tissue-based IHC/FISH staining and scoring technology with a co-development regulatory pathway that ties the diagnostic directly to a specific drug’s approved label.

1. IHC/FISH assay platforms (IHC/FISH Companion Diagnostics):
   • Ventana’s automated staining platforms and Agilent Dako’s Omnis system run standardized IHC/FISH protocols on tumor tissue sections, the technical foundation every tissue-based CDx builds on.
2. PD-L1 scoring systems (PD-L1 Testing Platforms):
   • Agilent Dako’s 22C3 pharmDx assay applies Tumor Proportion Score and Combined Positive Score scoring to determine checkpoint-inhibitor eligibility, with 2026 approvals expanding the assay across esophageal, breast, cervical, gastric and ovarian cancer indications.
3. Hereditary-cancer and HRD testing (Hereditary Cancer CDx):
   • Myriad Genetics’ MyChoice CDx tests tumor and germline DNA for homologous-recombination deficiency, identifying patients likely to respond to PARP inhibitors such as niraparib.
4. Regional precision-oncology testing (Tissue-Based Precision Oncology):
   • 3D Medicines and MedGenome build domestic tissue-based genomic and IHC testing capacity paired with local oncology drug approvals in China and India respectively.

07Value chains and production pipelines

Industrial pipeline of a companion diagnostic (FDA PMA / EU IVDR 2017/746)

┌───────────────────────────┐      ┌───────────────────────────┐
│ 1. Biomarker/assay        │ ───> │ 2. Co-development with   │
│    development             │      │    drug sponsor             │
└───────────────────────────┘      └───────────────────────────┘
                                                   │
                                                   ▼
┌───────────────────────────┐      ┌───────────────────────────┐
│ 4. Tissue biopsy testing  │ <─── │ 3. Regulatory approval    │
└───────────────────────────┘      └───────────────────────────┘
              │
              ▼
┌───────────────────────────┐      ┌───────────────────────────┐
│ 5. Treatment eligibility  │ ───> │ 6. Label expansion        │
│    decision                 │      │                           │
└───────────────────────────┘      └───────────────────────────┘

Stage 1: Biomarker and assay development

The diagnostic developer identifies the tissue biomarker a targeted therapy’s mechanism requires (PD-L1 expression, HRD status, MMR/MSI status) and develops the IHC or FISH assay protocol to detect it reliably on a standard tumor biopsy.

Stage 2: Co-development with drug sponsor

The diagnostic company partners with the pharmaceutical sponsor during the drug’s pivotal clinical trials, validating that the assay result predicts treatment response in the same patient population.

Stage 3: Regulatory approval

The assay receives FDA PMA approval, EU IVDR conformity assessment/CE marking, or NMPA approval explicitly tied to the drug’s approved label, as Agilent Dako’s 22C3 pharmDx and Myriad’s MyChoice CDx have each done repeatedly.

Stage 4: Tissue biopsy testing

A pathology laboratory runs the approved assay on the patient’s tumor tissue biopsy at diagnosis or disease progression, returning a biomarker-positive or -negative result.

Stage 5: Treatment eligibility decision

The treating oncologist uses the CDx result to determine whether the patient qualifies for the paired targeted therapy, directly gating access to drugs like Keytruda or Zejula.

Stage 6: Label expansion

The CDx/drug pair undergoes additional clinical validation and regulatory review to expand into new cancer types or treatment lines, the pattern behind Agilent Dako’s string of 2026 indication approvals and Myriad’s expanding Precise MRD coverage.