Low Volume Aseptic Filling of Monoclonal Antibodies

The basic idea of targeted drug therapy was already described in the late 19th century by Paul Ehrlich referred as "magic bullet". This idea is already reality today and there are many therapies targeted against a specific disease or pathogen. A special form of this is the therapy of monoclonal antibodies. Monoclonal antibodies are protein drugs which are specifically directed against a distinct marker (antigen). Due to this selectivity, side effects, which are often caused by an effect far away from the desired target, can be reduced to a minimum. The field of application of antibody therapy is endless and includes cancer therapy as well as autoimmune diseases, infectious diseases, asthma, etc. A new, rapidly growing field of application is the therapy of eye diseases using monoclonal antibodies which have to be injected directly into the eye. The human eye is very sensitive to the amount of fluid to be administered and for this reason the volume to be injected is limited to 50 - 100 µL. This volume must be filled before application under strict safety regulations (sterility, particle count etc.) before it can be made available to the patient. The aim of this PhD thesis was to investigate the entire process of aseptic filling < 200 µL and to close the gap to accurate and precise standard filling volumes in the higher volume range.
During the filling process there are four critical process steps, which were investigated in detail in this thesis. The process under investigation starts with the accuracy of aseptic filling of filling volumes < 200 µL, and the influence of physical forces on the sensitive antibody. Subsequently, a system is required that can reliably detect the small filled volumes and act as a control system. The last process step is the particle analysis in the small volumes and the associated methods which are developed for filling volumes in the milliliter range.
In a first study a new and patented filling technology was used, which is more accurate and precise in filling small volumes in direct comparison to traditional filling systems. This technology is based on the principle of linear peristalsis, which was characterized and further developed for the desired volume range. It was shown that linear peristaltic covers a volume range of 12 - 450 µL while maintaining the same accuracy and precision. Furthermore, continuous operation for eight hours is possible without any occurence of material fatigue. In the second part of the work, the influence of linear peristaltic on monoclonal antibody solutions was investigated and compared with traditional filling systems. The background of the study is that not only the accuracy of a filling system is crucial for its applicability, but also the ability not to negatively influence the quality of the drug. Monoclonal antibodies belong to the group of protein drugs and are therefore very sensitive in their handling. Special product and process knowledge is required to fill these dosage forms safely for the patient. Within the study two different models were developed to quantify the influence on the protein and to estimate the future impact. These models can be applied to other areas (e.g. mixing) in the future after further development. After filling or simultaneously during filling, the filling volume is gravimetrically controlled. This technology is unsuitable for filling volumes because its susceptibility to interferences (e.g. vibrations or unidirectional air flow onto the load cell) is too high. In a further study, new sensors were investigated which can be used in the range 10 - 150 µL for fill volume control. In the last chapter of the work, the particle analysis of subvisible particles was investigated, analogy to the last step during aseptic production. The pharmacopoeia describes two methods, of which the light obscuration method is used as standard. This method requires test quantities in the milliliter range and thus poses a great challenge for the analysis of volumes of < 200 µL. In order to better understand the applicability of this method for the smallest volume range and to reduce the sample volume as much as possible, the method was analyzed in its individual sequences and a preview of novel technologies was given.
The work carried out here represents a holistic view of the aseptic filling process. Due to the shown successes it is possible to continue some of the projects in the future and to extend them to new fields of application.