Small Batch, High Risk: QA Strategies for Precision Medicine Production

Traditional pharmaceutical manufacturing has historically been associated with scale.

Large batches are manufactured, tested and released for thousands or millions of patients.

Precision medicine is helping to change that model.

Some emerging therapies target increasingly defined patient populations. Others, particularly advanced therapies, may involve extremely small manufacturing campaigns or even patient-specific material.

That shift has major implications for Quality Assurance.

When batch sizes decrease, the value and importance of every individual unit can increase dramatically.

In the most personalised manufacturing models, losing a batch may not simply represent lost inventory. It can potentially mean losing a treatment intended for one specific patient.

Small Batches Do Not Mean Small Quality Systems

There can be a temptation to assume that smaller production volumes require simpler controls.

In reality, the opposite may be true.

Small-batch and precision medicines can involve:

• complex biological materials;
• highly specialised manufacturing steps;
• short shelf lives;
• manual interventions;
• limited opportunities for repeat testing;
• challenging analytical methods;
• temperature-sensitive supply chains; and
• patient-specific traceability requirements.

Quality systems therefore need to be flexible enough for low-volume manufacture without becoming less rigorous.

ICH Q10 specifically advocates applying Pharmaceutical Quality System elements in a manner appropriate and proportionate to different lifecycle stages and product circumstances.

Proportionate does not mean reduced oversight. It means designing controls around the actual risks associated with the product and process.

Traceability Becomes Mission Critical

In patient-specific manufacturing, identity is fundamental.

The organisation must maintain confidence that starting material, manufacturing records, test results, final product and the intended patient remain correctly connected.

Processes involving cellular material may therefore require particularly robust chain-of-identity and traceability controls.

A label mix-up in conventional manufacturing can already represent a serious quality defect.

In an autologous therapy, confusing material from two patients could have significantly greater consequences.

QA strategies should consider barcode systems, electronic verification, segregation controls, access restrictions and independent checks at critical stages.

The principle is straightforward: as personalisation increases, traceability must become increasingly difficult to break.

Sampling Strategies Need Reconsideration

Traditional statistical approaches can become challenging when batches contain very few units.

Destructive sampling is particularly problematic.

If a batch contains thousands of units, sacrificing several for quality-control testing may have limited impact on supply.

If only a handful of doses exist, every sample taken represents a significant percentage of the available medicine.

This means precision manufacturing requires strong process understanding.

Rather than depending disproportionately on end-product testing, organisations may need greater confidence from:

• raw-material controls;
• validated manufacturing processes;
• in-process controls;
• environmental monitoring;
• process analytical technologies where appropriate; and
• robust analytical strategies.

The concept aligns with the wider movement towards building quality into processes rather than attempting to test quality into the finished product.

Potency Presents a Particular Challenge

For complex biological and cell and gene therapy products, potency can be considerably more difficult to characterise than for conventional small-molecule medicines.

FDA’s guidance work in this area illustrates the importance of considering potency as an overall assurance strategy rather than simply a final test.

Its draft guidance on potency assurance for cellular and gene therapy products describes a science- and risk-based approach involving manufacturing-process design, process control, material controls, in-process testing and lot-release potency assays.

The implication for QA is significant.

Quality assurance increasingly requires an understanding of how manufacturing controls collectively provide confidence in the biological performance of the final medicine.

Raw Materials Can Introduce Significant Variability

Precision medicines frequently rely on biological or otherwise complex starting materials.

Variability can enter the process before manufacturing formally begins.

Supplier controls and incoming-material strategies therefore become particularly important.

FDA has highlighted issues including adventitious-agent transmission, lot-to-lot consistency and identity when human- and animal-derived materials are used in cell and gene therapy manufacturing.

QA teams need visibility beyond certificates of analysis.

Material qualification may require detailed understanding of source, supplier controls, testing strategies, transport conditions and the potential impact of variability on critical quality attributes.

Contamination Control Cannot Be an Afterthought

Many precision medicines are biologically derived and may require aseptic or highly controlled manufacturing environments.

EU GMP Annex 1 places significant emphasis on contamination-control strategy and the application of quality risk management to sterile manufacturing.

For small-batch production, this can create difficult operational decisions.

Frequent product changes, short campaigns and manual processing may increase opportunities for contamination or mix-up.

Facility design, closed processing, single-use technologies, procedural controls, cleaning strategies and environmental monitoring therefore need to be considered as one integrated contamination-control system.

Every Manufacturing Change Matters

Another challenge arises as precision-medicine processes develop rapidly.

New equipment may become available. Raw-material suppliers may change. Analytical methods improve. Processes evolve as manufacturing experience grows.

Changes that improve manufacturability still require rigorous assessment.

ICH Q5E establishes the principle that changes to biotechnology manufacturing should be evaluated to determine whether differences adversely affect product quality, safety or efficacy.

For emerging products where historical manufacturing data may be limited, knowledge management becomes particularly important.

Every batch generates valuable information.

Deviations, process parameters, analytical results and stability observations should therefore contribute to an increasingly detailed understanding of the product and process.

Analytical Strategy Must Evolve With the Product

Advanced medicines can require equally advanced analytical controls.

ICH Q14 provides a framework for science- and risk-based analytical procedure development, including analytical target profiles, knowledge management, risk management, robustness and lifecycle management.

That lifecycle approach is particularly relevant to precision medicines because analytical methods may continue evolving alongside rapidly developing manufacturing technology.

Rather than seeing validation as a single endpoint, QA needs to ensure analytical procedures remain suitable as knowledge increases.

QA Needs New Combinations of Expertise

Precision manufacturing is expanding what organisations require from their Quality Assurance functions.

Traditional GMP knowledge remains essential, but increasingly it must be combined with expertise in areas such as:

• biotechnology;
• advanced analytics;
• digital traceability;
• aseptic manufacturing;
• supplier quality;
• risk management;
• data integrity; and
• lifecycle management.

FDA’s cellular and gene therapy guidance programme continues to evolve rapidly. In 2026 alone, the agency has published additional guidance relating to CMC flexibilities and development of human cellular and gene therapy products, illustrating how quickly expectations and manufacturing approaches in this field continue to develop.

Precision Requires Quality by Design

Small batches challenge many assumptions created by high-volume pharmaceutical production.

Testing opportunities may be limited. Manufacturing timelines may be compressed. Each unit can be extraordinarily valuable.

That makes strong QA more important, not less.

The organisations best positioned for the next generation of precision medicines will be those that build quality into process design, understand where variability originates, maintain exceptional traceability and use risk management to focus controls where failure would matter most.

As pharmaceutical manufacturing becomes more personalised, the definition of a “batch” may continue to change.

The fundamental responsibility of Quality Assurance will not: ensuring that every medicine released is produced with the level of control necessary to protect the patient receiving it.