Published on 20/12/2025
Comprehensive Overview of Regulatory Requirements for Drug-Device Combinations and Companion Diagnostics
Introduction: The Intersection of Drugs, Devices, and Diagnostics
The pharmaceutical and medical device industries have become increasingly integrated, especially with the emergence of combination products and companion diagnostics (CDx). These complex therapeutic systems blend drugs, devices, and diagnostics to improve patient outcomes and enable precision medicine. However, this integration introduces significant regulatory challenges, requiring manufacturers to navigate dual or even triple frameworks across global jurisdictions.
Combination products and CDx are regulated differently across regions. In the U.S., the FDA uses a “primary mode of action” approach, whereas the EU evaluates products under both the Medical Device Regulation (MDR) and pharmaceutical legislation. Regulatory bodies such as EMA, PMDA, and CDSCO are also advancing frameworks for co-development and approval of these hybrid innovations.
Defining Drug-Device Combination Products and Companion Diagnostics
Drug-device combination products are therapeutic products that incorporate both a drug and a medical device. Examples include prefilled syringes, drug-eluting stents, transdermal patches, and autoinjectors.
Companion diagnostics are in vitro diagnostic (IVD) tests used to determine the suitability of a drug for a particular patient. They help identify responders, monitor safety, or guide dosage adjustments—playing
The regulatory status of these products depends on whether the drug or device component is the primary driver of therapeutic action, often referred to as the “Primary Mode of Action (PMOA).” This determination affects the lead review center and approval process.
FDA Regulatory Pathways for Drug-Device and CDx Products
Under 21 CFR Part 3, the FDA classifies and assigns combination products to one of its centers:
- CDER – for drug-led combinations
- CBER – for biologic-led combinations
- CDRH – for device-led combinations
Common submission routes include:
- NDA or BLA with device component – primary drug or biologic action
- PMA or 510(k) with drug information – primary device action
- Single application – where components are physically combined
- Separate but cross-referenced submissions – for co-packaged or cross-labeled products
The FDA also provides guidance on cGMP compliance via 21 CFR Part 4 and mandates Quality System Regulations (QSRs) for the device part. For CDx, the FDA requires a PMA for approval unless exempt under specific circumstances. CDx is typically developed alongside the therapeutic under Investigational New Drug (IND) and Investigational Device Exemption (IDE) regulations.
EMA and EU Regulatory Requirements for Combination Products and CDx
In the European Union, drug-device combination products are regulated under both:
- EU MDR (Regulation 2017/745) – for medical devices
- Directive 2001/83/EC or Regulation (EC) No 726/2004 – for medicinal products
If the device component contains a medicinal substance as an ancillary part, the product is treated as a device but evaluated for the drug component by EMA or national authorities. If the drug is primary, device safety and performance are assessed via a notified body.
As of May 2022, CDx must meet the requirements of EU IVD Regulation (IVDR) and obtain CE marking through notified bodies. Clinical evidence must demonstrate analytical and clinical performance and be aligned with the intended therapeutic use.
Companion Diagnostics: Co-Development and Clinical Integration
For CDx, co-development with the drug product is crucial. Regulatory authorities recommend synchronized clinical trials to validate the diagnostic test’s predictive power alongside therapeutic efficacy. A few core principles include:
- Same patient population in drug and diagnostic trials
- Bridging studies for analytical validity if the test kit changes
- Joint labeling strategy to reflect diagnostic requirement on drug product
In oncology, CDx is essential for drugs like trastuzumab (HER2 testing), osimertinib (EGFR mutation testing), or pembrolizumab (PD-L1 testing). The SOP for clinical trial integration of CDx must define protocols for sample handling, result reporting, and eligibility confirmation.
Global Harmonization and Challenges in Regulatory Submission
Harmonizing combination product and CDx approvals across jurisdictions remains challenging. While the International Medical Device Regulators Forum (IMDRF) and ICH provide some harmonized principles, national-level interpretations differ.
Key challenges include:
- Inconsistent PMOA definitions across agencies
- Divergent labeling requirements and risk classification
- Separate regulatory timelines leading to market access delays
- Complexities in maintaining GMP and QSR simultaneously
China (NMPA) and Japan (PMDA) have their own combination product frameworks, often requiring local clinical trials or bridging studies for approval. India (CDSCO) is evolving its guidance, with draft policies on combination products and IVD/CDx awaiting finalization.
Post-Market Surveillance, Labeling, and Risk Management
Post-approval, companies must manage pharmacovigilance, device vigilance, and adverse event reporting. This includes:
- Combination product vigilance – reporting under both drug and device regulations
- Labeling updates – reflecting device upgrades or drug safety information
- Stability testing and compatibility data – especially for prefilled systems
Risk Management Plans (RMPs) and REMS (Risk Evaluation and Mitigation Strategies) must account for both components. In the EU, a Periodic Safety Update Report (PSUR) is required for both parts if applicable. In the U.S., post-market device modifications may necessitate updated 510(k) or PMA supplements.
Strategic Considerations for Regulatory Success
To successfully navigate drug-device or CDx regulations, manufacturers should:
- Engage early with regulatory bodies via scientific advice or pre-submission meetings
- Design a global regulatory strategy integrating IVD/CDx lifecycle with drug development timelines
- Develop modular submissions to allow phased approvals across regions
- Establish robust quality systems covering both GMP and device QSR
- Train regulatory and clinical staff in device regulations and personalized medicine frameworks
Adopting digital tools such as eCTD publishing software, regulatory intelligence dashboards, and centralized labeling management improves compliance and audit readiness. As regulatory landscapes evolve, proactive monitoring of updates from clinical trials and guidance from WHO or IMDRF can provide early insights for better preparedness.