What is Dr. Zubair Khalid's research focus?

Dr. Zubair Khalid specializes in molecular virology, mRNA vaccine development, and computational biology, with a focus on avian pathogens like IBDV and Avian Reovirus.

Where is Dr. Zubair Khalid currently working?

Dr. Zubair Khalid is a Postdoctoral Research Associate at the University of Maryland (UMD), specifically within the Department of Animal and Avian Sciences.

FDA Center for Biologics: Roles, Regulations, and Review Processes

By Dr. Zubair Khalid, DVM, MS, PhD · 2026-08-11

Introduction to the FDA Center for Biologics (CBER)

What is CBER?

The FDA Center for Biologics Evaluation and Research (CBER) is the agency component responsible for regulating biological products intended for human use. Unlike conventional small-molecule drugs, biologics are derived from living systems—cells, tissues, viruses, or recombinant organisms—and their inherent complexity demands a distinct regulatory framework. CBER's mission centers on ensuring that these products are safe, pure, potent, and effective, while also advancing public health through the regulation of blood, vaccines, allergenic products, and cellular and gene therapies.

CBER operates under the authority of the Public Health Service (PHS) Act, specifically Section 351, which requires that biological products receive a license before they can be introduced into interstate commerce. This statutory foundation differs from the Federal Food, Drug, and Cosmetic (FD&C) Act that governs most conventional drugs and devices. The practical consequence is that biologics must demonstrate not only safety and efficacy but also manufacturing consistency sufficient to guarantee product identity, strength, quality, and purity—a standard that places extraordinary weight on the Chemistry, Manufacturing, and Controls (CMC) package.

The center employs a workforce of scientists, physicians, and regulatory reviewers who collectively evaluate products spanning from seasonal influenza vaccines to lentiviral gene therapies. CBER also maintains research laboratories that conduct both regulatory science and applied product testing, giving the center a hands-on role in method development and lot release that has no direct analogue in the small-molecule drug center.

CBER vs. CDER: Key Differences

The FDA Center for Drug Evaluation and Research (CDER) regulates conventional drugs, including small molecules and well-characterized therapeutic proteins that are now reviewed under the biologics pathway. CBER and CDER differ in several fundamental respects:

Aspect	CBER	CDER
Statutory authority	PHS Act Section 351	FD&C Act
Primary product types	Vaccines, blood products, cell and gene therapies, tissues	Small molecules, most therapeutic proteins, antibiotics
Manufacturing emphasis	Lot-by-lot release, live biological systems	Chemical synthesis, batch consistency
Review culture	Heavy emphasis on CMC and product characterization	Emphasis on clinical efficacy and safety endpoints
Post-market tools	Lot release, VAERS, establishment inspections	REMS, post-marketing requirements

A notable historical shift occurred in 2003 when review of most therapeutic proteins (e.g., monoclonal antibodies, cytokines) moved from CBER to CDER. Today, CBER retains jurisdiction over vaccines, blood components and derivatives, allergenic extracts, cellular therapies, gene therapies, xenotransplantation products, and human tissues. Understanding which center has jurisdiction over your product is not merely administrative—it determines the entire regulatory pathway, the review division you will interact with, and the CMC expectations you must meet.

Regulatory Scope and Product Jurisdiction

Vaccines and Allergenics

CBER regulates all preventive vaccines licensed in the United States, including viral, bacterial, toxoid, conjugate, recombinant protein, and nucleic acid-based vaccines. This jurisdiction extends from initial IND submission through BLA approval and into post-market lot release. The center also regulates allergenic extracts used for diagnosis and immunotherapy, including standardized pollen, venom, and mold extracts.

Vaccine regulation presents unique challenges because these products are administered to healthy individuals, often children, and the benefit-risk calculus is fundamentally different from therapeutics. CBER therefore demands exceptional purity and safety data. For example, a recombinant protein vaccine must demonstrate removal of host-cell proteins to levels typically below 100 ppm, residual host-cell DNA below 10 ng per dose, and endotoxin levels below the established pyrogen threshold of 5 EU/kg/hour. These numeric specifications are not advisory—they are established during licensure and become part of the product's approved specifications.

Blood and Blood Components

CBER regulates blood and blood components intended for transfusion, including red blood cells, platelets, plasma, and cryoprecipitate. The center also oversees plasma-derived products such as albumin, immune globulins, and clotting factor concentrates. This regulatory authority extends to blood collection establishments, processing facilities, and transfusion services.

The regulatory framework for blood products emphasizes donor screening, infectious disease testing, and component manufacturing standards. For example, platelet products must be stored at 20–24°C with continuous gentle agitation, and their shelf life is limited to 5–7 days depending on the storage system and bacterial screening methods employed. Pathogen-reduced plasma products must demonstrate log reduction of enveloped viruses (typically ≥4 logs for HIV, HBV, and HCV) while maintaining coagulation factor activity within acceptable ranges, usually ≥70% of baseline for Factor VIII.

Gene and Cell Therapies

CBER's Office of Tissues and Advanced Therapies (OTAT) regulates gene therapies, cell therapies, and therapeutic vaccines. This includes chimeric antigen receptor (CAR) T-cell products, gene-editing therapies using CRISPR-Cas9 or other nucleases, oncolytic viruses, and stem cell-derived products.

Gene therapy products face particularly rigorous scrutiny because of their potential for long-term persistence, off-target effects, and germline transmission. For adeno-associated virus (AAV) vectors, CBER expects comprehensive characterization including vector genome titer (typically reported in vector genomes/mL), capsid protein identity, empty-to-full capsid ratios (often required to be below 20% empty), and residual host-cell DNA quantification. Integration-site analysis using techniques such as linear amplification-mediated PCR (LAM-PCR) or targeted amplicon sequencing is required for integrating vectors like lentivirus or retrovirus.

Tissue and Tissue-Based Products

CBER regulates human cells, tissues, and cellular and tissue-based products (HCT/Ps) under 21 CFR Part 1271. This regulatory framework is risk-based, with a tiered approach: minimally manipulated tissues intended for homologous use are regulated solely under Section 361 of the PHS Act, requiring registration and listing but not premarket approval. More complex products—those that are more than minimally manipulated, non-homologous, or combined with drugs or devices—require a BLA or an Investigational Device Exemption (IDE) pathway.

Examples of Section 361 products include banked bone, skin, and corneal tissue. Products requiring a BLA include cultured epithelial autografts, cartilage repair products, and any cell product that is expanded, activated, or genetically modified. The distinction between 361 and 351 products is a frequent source of regulatory confusion and a common pitfall in product development.

CBER's Organizational Structure and Divisions

Office of Vaccines Research and Review

The Office of Vaccines Research and Review (OVRR) is responsible for evaluating vaccine candidates from IND through licensure and post-market. OVRR is organized into divisions focused on specific vaccine categories, including viral vaccines, bacterial vaccines, and combination products. The office also houses the Laboratory of Respiratory Viruses and the Laboratory of Bacterial Toxins, which conduct regulatory research and provide scientific expertise.

OVRR reviewers evaluate clinical trial designs, immunogenicity endpoints, and safety databases. For efficacy trials, CBER typically requires demonstration of a clinically meaningful endpoint—for example, prevention of confirmed disease, not merely seroconversion. The office also evaluates adjuvant systems, requiring detailed characterization of the adjuvant's mechanism of action, toxicity profile, and impact on the immune response.

Office of Blood Research and Review

The Office of Blood Research and Review (OBRR) oversees blood collection, processing, and transfusion medicine. OBRR reviews BLA submissions for plasma-derived products, evaluates new blood collection devices, and establishes standards for donor eligibility and infectious disease testing.

OBRR also manages the lot release program for blood products, which involves reviewing manufacturer's test results and performing independent testing on selected lots. For example, each lot of intravenous immune globulin (IVIG) must meet specifications for IgG content (typically ≥95% of total protein), antibody titers against specific pathogens, and Fc function as measured by Fcγ receptor binding assays.

Office of Tissues and Advanced Therapies

The Office of Tissues and Advanced Therapies (OTAT) is the newest and fastest-growing division within CBER. OTAT regulates gene therapies, cell therapies, therapeutic vaccines, and certain medical devices used in their administration. The office is organized into divisions covering cellular therapies, gene therapies, and devices.

OTAT reviewers are often the most specialized within CBER, with expertise in molecular biology, virology, immunology, and bioengineering. They evaluate vector design, manufacturing processes, potency assays, and clinical protocols. For gene therapy products, OTAT requires detailed information on vector integration sites, off-target editing frequencies (for nuclease-based approaches), and biodistribution studies in animal models before first-in-human trials.

The Regulatory Review Process for Biologics

Investigational New Drug (IND) Application

Before any clinical trial of a biologic can begin in the United States, the sponsor must submit an IND to CBER. The IND must contain preclinical data sufficient to support the proposed clinical investigation, including pharmacology and toxicology studies in relevant animal models, as well as complete manufacturing information.

The IND process begins with a pre-IND meeting, which is strongly recommended but not required. During this meeting, sponsors present their development plan, proposed manufacturing approach, and clinical trial design to CBER reviewers. The feedback received can substantially de-risk the development program by identifying potential issues before significant resources are committed.

The IND itself must include:

Form FDA 1571 (IND application form)
Table of contents and introductory statement
General investigational plan
Investigator's brochure
Clinical protocol(s)
Chemistry, Manufacturing, and Controls (CMC) information
Pharmacology and toxicology data
Previous human experience with the product

CBER has 30 calendar days to review an IND and place it on clinical hold if safety concerns exist. If no hold is issued, the trial may proceed. Common reasons for clinical hold include inadequate preclinical toxicology data, poorly designed dosing regimens, or insufficient product characterization.

Biologics License Application (BLA)

The Biologics License Application (BLA) is the formal request for permission to introduce a biological product into interstate commerce. The BLA must contain full reports of safety and effectiveness, a complete description of the manufacturing process, and proposed product labeling.

The BLA submission is governed by 21 CFR Part 601 and must include:

Form FDA 356h (application form)
Cover letter and administrative information
Comprehensive summary of the application
Chemistry, Manufacturing, and Controls (CMC) information
Nonclinical pharmacology and toxicology data
Human pharmacokinetics and bioavailability data
Clinical microbiology data (for anti-infectives)
Clinical safety and efficacy data
Statistical analysis plans and results
Case report forms and tabulations
Proposed labeling and package insert

The BLA review process involves a multidisciplinary team including medical officers, pharmacologists, statisticians, and CMC reviewers. The review timeline is governed by the Prescription Drug User Fee Act (PDUFA), which sets performance goals for FDA review. Standard review is 10 months from the 60-day filing date; priority review is 6 months.

Priority Review and Accelerated Approval

CBER offers several expedited pathways for products addressing unmet medical needs. Priority review designation shortens the review timeline from 10 to 6 months and is granted when a product provides a significant improvement in safety or effectiveness over existing therapies.

Accelerated approval allows CBER to approve a biologic based on a surrogate endpoint reasonably likely to predict clinical benefit. This pathway is particularly relevant for gene therapies and cell therapies where long-term clinical outcomes may take years to assess. For example, a gene therapy for hemophilia might be approved based on factor VIII expression levels rather than bleeding episodes, provided the surrogate is reasonably likely to predict clinical benefit.

Breakthrough therapy designation provides intensive FDA guidance and organizational commitment, including rolling review of BLA sections. This designation is available for products that demonstrate substantial improvement over existing therapies on a clinically significant endpoint.

Post-Market Surveillance and Safety Monitoring

Vaccine Adverse Event Reporting System (VAERS)

VAERS is a national early-warning system for vaccine safety, co-managed by CBER and the CDC. Healthcare providers and manufacturers are required to report adverse events following vaccination, and the system receives over 50,000 reports annually. VAERS is a passive surveillance system, meaning it cannot establish causality but can generate signals that trigger further investigation.

When a safety signal is identified, CBER may mandate additional studies, require label changes, or in rare cases, withdraw a product from the market. The center also operates the Vaccine Safety Datalink (VSD), an active surveillance system that monitors vaccine safety in near-real-time using electronic health records from multiple healthcare organizations.

Lot Release and Product Testing

CBER operates a unique lot release program for certain biological products, including vaccines, blood derivatives, and allergenic extracts. Under this program, manufacturers must submit samples and protocols for each production lot to CBER before the lot can be distributed. CBER may perform independent testing on selected lots to verify manufacturer results.

For vaccines, lot release testing typically includes potency assays, sterility testing, and general safety tests. Potency is often measured by in vivo or in vitro assays—for example, a hemagglutination inhibition (HAI) assay for influenza vaccines or a plaque reduction neutralization test (PRNT) for live viral vaccines. The lot release process ensures that each batch meets established specifications, providing an additional layer of quality assurance beyond the manufacturer's own quality control.

Risk Evaluation and Mitigation Strategies (REMS)

For products with serious safety concerns, CBER may require a Risk Evaluation and Mitigation Strategy (REMS). A REMS may include elements such as medication guides, communication plans, and elements to assure safe use (ETASU), which can include restricted distribution, prescriber certification, or patient registries.

For biologics, REMS are most commonly required for products with significant immunogenicity risks or those requiring specialized administration. For example, gene therapies with potential for insertional oncogenesis may require long-term follow-up registries to monitor for late adverse events. The REMS must be designed to ensure that the benefits of the product outweigh its risks while minimizing burden on the healthcare system.

Key Regulations and Guidance Documents

21 CFR Part 600: Biological Products

The core regulations governing biological products are found in 21 CFR Parts 600–680. Part 600 establishes general provisions, including definitions, establishment standards, and inspection requirements. Part 601 covers licensing, including BLA content and review procedures. Parts 606–640 address blood and blood components, while Parts 660–680 cover specific product categories.

Key provisions of 21 CFR Part 600 include:

Section 600.3: Definitions of biological product, manufacturer, and lot
Section 600.10: Establishment standards requiring adequate personnel, facilities, and equipment
Section 600.11: Requirements for the prevention of contamination and cross-contamination
Section 600.12: Record-keeping requirements, including retention of all manufacturing records

These regulations are supplemented by the FDA Regulations for Biologics, which provide additional detail on specific product categories and manufacturing requirements.

ICH Guidelines Relevant to Biologics

The International Council for Harmonisation (ICH) has developed numerous guidelines that CBER adopts and applies to biologics review. Key guidelines include:

ICH Q5A: Viral safety evaluation of biotechnology products, requiring demonstration of viral clearance through dedicated steps such as low-pH incubation (typically pH 3.5–4.0 for 30–60 minutes), solvent-detergent treatment, or nanofiltration with 20 nm filters
ICH Q5B: Analysis of the expression construct in cells used for production of recombinant proteins
ICH Q5C: Stability testing of biotechnological products, requiring real-time, real-condition data for shelf-life determination
ICH Q5D: Derivation and characterization of cell substrates used for production of biotechnological products
ICH Q6B: Specifications for biotechnological products, establishing acceptance criteria for identity, purity, potency, and quantity

These guidelines are harmonized across the US, EU, and Japan, facilitating global development programs. However, CBER may impose additional requirements beyond ICH guidelines, particularly for novel product classes like gene therapies.

CBER-Specific Guidance Documents

CBER issues product-specific and topic-specific guidance documents that provide the center's current thinking on regulatory issues. These guidances are not legally binding but represent the agency's interpretation of regulations and its expectations for sponsors.

Key CBER guidances include:

Guidance for Industry: Content and Format of Chemistry, Manufacturing and Controls Information for a Biologics License Application — outlines the CMC data expected in a BLA
Guidance for Industry: Preclinical Assessment of Investigational Cellular and Gene Therapy Products — describes the nonclinical studies needed to support IND submission
Guidance for Industry: Characterization of Cell Substrates and Other Biological Materials Used in the Production of Viral Vaccines — addresses cell line characterization requirements
Guidance for Industry: Potency Tests for Cellular and Gene Therapy Products — discusses potency assay development and validation

These documents are essential reading for any sponsor preparing to engage with CBER. The FDA Guidance for Industry Biologics page provides a comprehensive listing of current guidance documents.

Common Pitfalls in Biologics Development and Submission

Incomplete Chemistry, Manufacturing, and Controls (CMC) Data

The most common reason for BLA delays or rejection is inadequate CMC data. Unlike small molecules, where the active pharmaceutical ingredient is a well-defined chemical entity, biologics are complex mixtures whose quality depends on the manufacturing process itself. CBER expects a level of product characterization that many sponsors underestimate.

Common CMC deficiencies include:

Insufficient product characterization: Failure to identify and quantify product-related impurities such as aggregates, fragments, or oxidized variants. For monoclonal antibodies, aggregate levels should typically be below 5% and fragmentation below 10%
Inadequate process validation: Failure to demonstrate consistency across at least three consecutive commercial-scale batches with defined acceptance criteria
Poor assay validation: Potency assays must be validated for accuracy, precision, specificity, and linearity, with acceptance criteria established before the BLA is submitted
Insufficient stability data: Real-time stability data must cover the proposed shelf life; accelerated stability data alone is insufficient

Sponsors should review the FDA Post Approval Changes Guidance Biologics to understand how CMC changes will be evaluated after licensure.

Misunderstanding of Combination Products

Many biologics are combination products—for example, a drug-eluting stent coated with a therapeutic antibody, or a pre-filled syringe containing a vaccine and an adjuvant. The regulatory pathway for combination products depends on the primary mode of action (PMOA), which determines whether CBER, CDER, or CDRH has lead jurisdiction.

A common pitfall is assuming that because a product contains a biologic, CBER automatically has jurisdiction. If the primary mode of action is the device or the drug component, the product may be assigned to a different center. Sponsors should request a formal designation from the FDA's Office of Combination Products early in development to avoid regulatory misclassification.

Inadequate Post-Market Commitments

CBER increasingly requires post-marketing studies to address remaining questions at the time of approval. These may include long-term safety follow-up, immunogenicity monitoring, or additional efficacy studies in specific populations. Sponsors who underestimate the scope of these commitments may face delays in approval or post-market compliance issues.

For gene therapies, CBER typically requires 15-year follow-up for integrating vectors to monitor for delayed adverse events such as insertional oncogenesis. For cell therapies, long-term persistence and ectopic tissue formation must be monitored. These commitments should be planned for during clinical development, not after the BLA is submitted.

Practical Summary: Navigating CBER for Successful Approval

Early and Frequent Communication

The single most important factor in successful CBER interactions is early and frequent communication. CBER offers several formal meeting types:

Pre-IND meeting: Discusses preclinical data requirements and clinical trial design
End-of-Phase 1 meeting: Reviews initial safety data and plans for pivotal trials
Pre-BLA meeting: Discusses the content and format of the BLA submission
Type A, B, and C meetings: Formal meetings with defined timelines and agendas

Sponsors should also take advantage of informal communications, including written correspondence and teleconferences. CBER reviewers are generally accessible and willing to provide feedback on specific questions. The Biologics Regulatory Affairs Course provides additional guidance on effective FDA communication strategies.

Robust CMC and Quality Data

Given CBER's emphasis on product quality, sponsors should invest heavily in CMC development. This includes:

Comprehensive product characterization using orthogonal analytical methods
Well-validated potency assays that reflect the product's mechanism of action
Process validation demonstrating consistency across commercial-scale batches
Stability programs that generate real-time data throughout development

The Biologics Development resource provides a detailed overview of CMC expectations for biologics.

Understanding the Review Timeline

The BLA review timeline is governed by PDUFA performance goals. Standard review is 10 months from the 60-day filing date; priority review is 6 months. However, this timeline does not include the time required to respond to FDA information requests, which can add months to the review.

Sponsors should plan for:

Filing review (Day 0–60): FDA determines whether the application is complete enough for substantive review
Mid-cycle review (Month 4–5): FDA provides preliminary feedback and identifies major issues
Late-cycle review (Month 8–9): FDA communicates final review findings
Advisory committee meeting (if required): Typically held 1–2 months before the PDUFA date

The FDA Approval Process for Biologics page provides a detailed breakdown of the review timeline and milestones.

Frequently Asked Questions

What does the FDA Center for Biologics do?

The FDA Center for Biologics Evaluation and Research (CBER) regulates biological products for human use, including vaccines, blood products, gene and cell therapies, allergenic extracts, and human tissues. CBER ensures these products are safe, pure, potent, and effective through premarket review, lot release testing, and post-market surveillance.

What is the difference between CBER and CDER?

CBER regulates vaccines, blood products, cell and gene therapies, and tissues under the PHS Act. CDER regulates conventional drugs and most therapeutic proteins under the FD&C Act. CBER places greater emphasis on manufacturing consistency and lot-by-lot quality, while CDER focuses more on clinical efficacy and safety endpoints.

What is a BLA and when is it required?

A Biologics License Application (BLA) is the submission required to obtain FDA approval to market a biological product in the United States. It is required for any product regulated under PHS Act Section 351, including vaccines, blood derivatives, gene therapies, and cell therapies. The BLA must contain full safety and efficacy data, complete manufacturing information, and proposed labeling.

How long does FDA review take for a BLA?

Standard BLA review takes 10 months from the 60-day filing date. Priority review takes 6 months. These timelines do not include the time required to respond to FDA information requests, which can extend the overall timeline by several months.

What is lot release and why is it important?

Lot release is a CBER program in which manufacturers submit samples and protocols for each production lot of certain biologics (vaccines, blood derivatives, allergenic extracts) before distribution. CBER may perform independent testing to verify manufacturer results. This program provides an additional layer of quality assurance beyond the manufacturer's own quality control.

What are common reasons for BLA rejection?

Common reasons for BLA rejection include inadequate CMC data, insufficient clinical efficacy evidence, unresolved safety concerns, poor trial design, and failure to meet post-market commitments. CMC deficiencies are the most common cause of review delays, while clinical efficacy and safety issues are the most common causes of complete response letters.

Key Takeaways

CBER regulates biologics under the PHS Act, with a focus on manufacturing consistency and product quality that exceeds typical small-molecule drug standards.
Product jurisdiction determines the regulatory pathway; misclassification of a product as a drug rather than a biologic can result in significant development delays.
The IND-to-BLA pathway requires extensive CMC data, with lot release testing and post-market surveillance continuing after approval.
Early and frequent communication with CBER through formal meetings and informal correspondence is the most effective strategy for de-risking development.
CMC deficiencies are the most common cause of BLA delays; invest in comprehensive product characterization and validated potency assays.
Post-market commitments, including long-term follow-up for gene therapies, should be planned during clinical development, not after submission.
Understanding the review timeline and PDUFA performance goals is essential for managing expectations and resource allocation.