When Bridging Studies Are Needed in Chinese Clinical Trials

Introduction

Bridging studies play a critical role in global clinical development by determining whether foreign clinical data can be applied to the Chinese population. For decades, sponsors faced mandatory bridging studies in China, often delaying patient access to innovative therapies. However, regulatory reforms under the National Medical Products Administration (NMPA) and China’s adoption of International Council for Harmonisation (ICH) E5 and E17 guidelines have reshaped the requirements for bridging studies. Today, bridging studies are required selectively, primarily when ethnic sensitivity or regional factors affect drug response, safety, or pharmacokinetics. This article provides a regulatory perspective on bridging studies in China, explaining when they are required, how they are designed, and what strategies sponsors can adopt to streamline global development plans.

Background and Regulatory Framework

Historical Requirement for Bridging Studies

Before 2015, China’s regulatory authority (CFDA) often required foreign-developed drugs to undergo local bridging studies regardless of existing global data. This created significant delays, sometimes adding years to drug approval timelines. The intent was to ensure safety and efficacy in the Chinese population, but the approach lacked flexibility.

Reforms Under the NMPA

Since 2015, the NMPA has adopted a risk-based approach, guided by ICH E5 (Ethnic Factors in the Acceptability of Foreign Clinical Data). Bridging studies are now required only when differences in genetics, diet, environment, or medical practice may affect drug response. The NMPA also accepts multinational trial data if Chinese patients are adequately represented, reducing the need for separate bridging studies.

Case Example: Oncology Drug Bridging

A U.S.-developed oncology drug once required a full bridging study in China. After reforms, the NMPA accepted multinational Phase III trial data that included Chinese patients, eliminating the need for a separate study. This reduced the drug lag by nearly two years.

Core Clinical Trial Insights

When Are Bridging Studies Required?

Bridging studies are required if:
Genetic differences affect pharmacokinetics or pharmacodynamics (e.g., CYP450 metabolism variations).
Environmental or dietary factors influence drug response.
Local medical practices differ significantly from those in foreign studies.
There is limited representation of Chinese patients in global trials.
Bioequivalence data for generics must be confirmed in Chinese subjects.
These criteria ensure drug safety and efficacy for the Chinese population.

Study Designs for Bridging

Bridging studies may take several forms:
Phase I PK/PD studies in healthy Chinese volunteers.
Phase II or III efficacy studies in Chinese patients for specific indications.
Bioequivalence (BE) studies for generic drugs.
Subpopulation analyses in multinational trials.
Study design depends on the type of drug, therapeutic area, and availability of global data.

Ethnic Sensitivity and Pharmacogenomics

Ethnic sensitivity is a central factor in bridging decisions. Differences in drug metabolism, such as higher prevalence of CYP2C19 poor metabolizers among Chinese patients, may warrant bridging studies. The NMPA requires pharmacogenomic data to assess whether foreign clinical data can be extrapolated.

Acceptance of Multinational Trial Data

The NMPA increasingly accepts multinational trial data if Chinese patients are adequately included. This aligns with ICH E17 guidelines on multinational clinical trials (MRCTs). For example, including 300–500 Chinese patients in a global Phase III trial may eliminate the need for separate bridging.

Challenges in Bridging Study Implementation

Sponsors must navigate ethical approval processes, site readiness, and patient recruitment. Bridging studies can be delayed by competition at Tier-1 hospitals and limited infrastructure in Tier-2 hospitals. CRO partnerships are essential for smooth execution and compliance.

Therapeutic Area Variability

Oncology, cardiovascular, and central nervous system drugs often face bridging requirements due to variability in response. In contrast, bridging studies are less common for antibiotics or drugs with well-characterized mechanisms and low variability.

Best Practices & Preventive Measures

Sponsors should design global trials to include adequate Chinese representation, reducing the need for bridging. Early engagement with the NMPA helps clarify bridging expectations and avoid delays. Using PK/PD modeling and simulation can also support waivers by demonstrating equivalence across populations. CRO partnerships enhance trial execution and regulatory compliance.

Scientific & Regulatory Evidence

NMPA guidance is based on ICH E5 and E17, WHO GCP, and domestic regulations. Comparative evidence with FDA and EMA demonstrates increasing convergence, though China emphasizes ethnic sensitivity more strongly. The 2019 Drug Administration Law further supports flexible acceptance of multinational data while ensuring safety and efficacy in Chinese patients.

Special Considerations

Bridging studies are especially important in rare diseases, where Chinese patient representation in global trials is limited. Pediatric bridging may also be required due to age-related differences in metabolism and treatment practices. Sponsors must also comply with Human Genetic Resources Administration of China (HGRAC) regulations when genetic samples are involved.

When Sponsors Should Seek Regulatory Advice

Sponsors should consult the NMPA early during global development planning to determine whether bridging studies will be required. Pre-IND consultations can clarify expectations for ethnic sensitivity assessments, study design, and patient enrollment. Regulatory advice is also critical when planning MRCTs to ensure adequate Chinese representation.

Case Studies

Case Study 1: Cardiovascular Drug Bridging Study

A cardiovascular drug developed in Europe faced a bridging requirement in China due to genetic differences in metabolism. A Phase I PK study in healthy Chinese volunteers demonstrated comparable exposure, allowing the drug to proceed without a full Phase III trial, reducing development timelines.

Case Study 2: Rare Disease Trial Bridging Waiver

A rare disease therapy conducted a multinational Phase III trial with 500 Chinese patients included. The NMPA waived the bridging requirement, accepting global data for NDA submission. This expedited approval by over one year, demonstrating the value of early Chinese patient inclusion.

FAQs

1. What are bridging studies in China?

They are studies that assess whether foreign clinical data can be applied to Chinese patients, considering genetic, environmental, and cultural factors.

2. Are bridging studies always required in China?

No. Since NMPA reforms, bridging studies are required only when ethnic or environmental differences may affect drug safety or efficacy.

3. How can sponsors avoid bridging studies?

By including adequate numbers of Chinese patients in multinational trials and providing pharmacogenomic data to demonstrate equivalence.

4. What types of drugs often require bridging studies?

Oncology, cardiovascular, and CNS drugs often require bridging due to genetic variability in response.

5. How do NMPA bridging requirements compare globally?

They are aligned with ICH E5/E17, similar to FDA and EMA expectations, but with stronger emphasis on ethnic sensitivity.

6. What role do CROs play in bridging studies?

CROs support site selection, ethics approvals, and patient recruitment, ensuring bridging studies are executed efficiently and compliantly.

Conclusion & Call-to-Action

Bridging studies in China have evolved from rigid requirements under the CFDA to a flexible, risk-based framework under the NMPA. Today, sponsors must assess ethnic sensitivity, patient representation, and therapeutic area factors to determine whether bridging is necessary. By including Chinese patients in global trials, engaging the NMPA early, and leveraging CRO expertise, sponsors can streamline development and reduce delays. Organizations planning global submissions should integrate bridging strategies into feasibility planning to ensure compliance and accelerate patient access in China.