cell and gene therapy

This is the first in a series of blogs discussing E&L assessment in the production of CGTs. These articles come ahead of a Q&A session which you can watch on demand here. The second is comparing C&GT with mAb and a 3rd looking at simulation studies. So make sure to catch up on those.

Cell and gene therapy is a rapidly evolving area of medicine. Currently, there are almost 300 C&GTs in various stages of clinical development, with candidates covering more than 100 diseases with nearly half of the candidates within oncology. C&GT involves the transfer of genetic material, via a vector (virus), into human cells which are then re-introduced to the patient. For example, CAR T cell therapy – a new gene is introduced into that patient’s immune cells (T-cell), which then targets the cancer cells.

Treatment involves either patients (autologous) or donor (allogenic) cells. These can be either stem or immunomodulatory cells. C&GTs aim to treat diseases where treatments are either non-existent or ineffective. The concept is to target the exact cause of the disease so that the person should no longer have recurring symptoms—ideally after a single treatment.

As the number of C&GTs enter pre-approval registration, there has correspondingly been an increase in extractable and leachable scrutiny. Extractables and leachables (E&L) testing is an important step in ensuring the safety of C&GT products. This is an area of expertise which Hall Analytical has amassed a great deal of knowledge over the years. The following process can be used to ensure the proper assessment of these products.

E&L Testing

Step 1 – Information gathering

Before commencing with any study, it is important to gather as much pertinent information as possible. This involves reviewing process & clinical information, supplier data (e.g. biocompaitibility, BPOG, USP <665>, etc) and data generated for other projects using the same materials.

Step 2 – Paper-based assessment

The next stage is to perform a gap analysis. This can be performed informally through a review of current knowledge or formally through a paper-based risk assessment. This is an important step before designing experimental studies to ensure study design is appropriate for the project needs.

Step 3 – Experimental study

Extractable studies are performed for a number of different reasons, the most common being used to characterize a material or simulate in-use conditions.

Material characterization studies are used to determine what might come out of material under exaggerated conditions; a type of study that helps to identify substances of concern, supporting material selection/rejection at an early stage of a project

Simulation studies are used to provide an understanding of the substances which are most likely to migrate under normal in-use conditions.

The aim of these studies is to detect, identify and quantify organic and inorganic chemical substances that migrate from components, under the extraction conditions, above an analytical evaluation threshold (which can be determined from, for example, the threshold of toxicological concern defined by ICH M7).

Note: often it is not possible to perform leachables studies on C&GT product  due to lack of samples of the final product especially as the batch sizes are often small. Therefore, it is important that extractable studies are robust and well designed such that there can be confidence in conclusions made from extractable data.

Table 1 details the example extraction conditions which might be used depending on the project requirements.

Parameter Simulation Characterization
Solvent based on formulation or manufacturing solutions e.g. aqueous based, X% DMSO(aq) High organic e.g. propane-2-ol
Temperature Container Closure System – Accelerated conditions to model long term storage
Process Materials – Representative worst case e.g. RT, 40°C, etc..
Exaggerated temperature conditions
Extraction Time Container Closure System – Accelerated time conditions to model long term storage
Process Materials – Representative worst case e.g. hours, days, etc..
Extraction Method Incubation Incubation

Once we have generated our analytical sample the following techniques are used to analysis a wide range of extractable compounds which typically migrate from polymeric materials.

Compound Class Instrument
Volatile Headspace GC-MS
Volatile – Semi-Volatile Direct Injection GC-MS
Semi-Volatile – Non-Volatile High Res LC-MS
Inorganic ICP-MS

Step 4 – Data evaluation

Finally, the data are evaluated. A toxicological assessment should be performed for analytes detected above the analytical evaluation threshold.

Get Involved

Not only is an E&L assessment critical to the production of safe cell and gene therapies, but it is also a regulatory expectation. With our experience in these assessments and cutting-edge lab facilities, we are the perfect partner to work with you in the development of therapies.

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