10 minute read
APIs/HPAPIs
Author: DANNY GALBRAITH
- head of New Services and Technology Management at Merck KGaA, Darmstadt, Germany
How innovation in pharma is enabling RNA therapeutics’ rapid move to the clinic
Clinically signifi cant
Innovation in the biopharmaceutical industry has always been rapid; however, this pace is accelerating with the global call to action to develop therapies to prevent and treat Covid-19. As the industry continues to look to novel modalities as a solution to Covid-19 and other diseases, a new class of therapeutic molecule is capturing attention -- nucleic acid, particularly Ribonucleic Acid (RNA).
These molecules have demonstrated several clinical mechanisms of action in the treatment of a multitude of illnesses. For example, anti-sense or interfering RNA therapies have been used in oncology treatment and the use of the RNA to act as a means of gene delivery is showing promise.
First described in 1961, RNA is the least developed of the biologically active molecules as a therapeutic. Compared with DNA delivered gene vectors, RNA has the advantage of being biologically active in both dividing and non-dividing cells and as such would be the preferred tool to deliver expression of gene encoding proteins. They also have the advantage of no “foreign” genetic materials such as promoters on many DNA vectors. These molecules can be surprisingly easy to manufacture. Producer cells are transfected with an appropriate plasmid DNA and RNA polymerase, and these drive the production of RNA. The purifi cation of the RNA away from the other host and manufacturing materials requires multiple steps but fortunately requires little in the way of the development of novel technologies, allowing a faster path to the clinic. A signifi cant downside to RNA molecules, however, is their fragility in biological systems. The largest challenge with these drugs is the delivery system to achieve adequate survival of the biologically active molecule to the cells where the gene transfer and expression can be delivered. Many innovative compounds are being developed to enable these therapies to move to the clinic safely.
The pharmacokinetics of naked RNA is well understood. With a half-life of around seven hours, this type of molecule is rapidly degraded in the extracellular space by a variety of RNase mediated mechanisms. If the molecule survives to reach a cell it requires to translocate across the plasma membrane into the cytosol where the protein can be translated and initiate its therapeutic target. However, these naked RNA molecules are negatively charged and compose a high molecular weight; both characteristics mean that passive movement across the charged cell membrane is incredibly low. For these reasons naked RNA is no longer considered an option for drug developers.
To combat these challenges, two strategies are used to create RNA therapy and delivery systems for the clinic. Firstly, modifi cations of the RNA molecule can increase stability during transportation to the cell. These modifi cations have included changes to the 5’ cap and 5’ and 3’ UTR regions to enhance stability and modifi cation of the Poly-A tail. These modifi cations can enhance the potency of the molecule as well as reducing degradation. However, modifi cations in the genomic construct alone are seldom enough to improve the pharmacokinetics of the drug. One of the more interesting approaches has been the use of
diff erent formulation strategies to stabilise these products. The challenge of the dense negative charge of these RNA molecules can be overcome with the use of lipids or polymers that are used to encapsulate the RNA strand and mask the charge. Simple or complex polymer compounds such as Diethylaminomethyl dextran or polyethyleneimine have been proposed and some clinical work has been carried out, however safety issues have been described. A great deal of attention has been recently focused on lipidbased compounds such as lipidoids. Cationic lipids would appear to be the ideal polymer as they form a spontaneous, encapsulated complex with the RNA, thereby providing a mask to the charge and a protection to the degradative activity during transport to the cells. Cationic lipids are generally less toxic but do have some safety hurdles to overcome as pro-infl ammatory responses have been identifi ed. A solution to reduce toxicity is to complex neutral lipids with the cationic lipids, as this will also improve stability. These strategies have already shown promise in clinical trials. The chemical fl exibility of lipid compounds has seen innovation with ionizable lipids which switch charge depending on the surrounding pH values. Products are encapsulated at low pH and at physiological pH conditions the compound switches to a neutral charge, thereby reducing toxicity. In combination with glycols these lipid compounds are essential for RNA therapeutics to be viable in clinical trials. These compounds still must be evaluated long term and with multiple dosing regimens with respect to toxicity to understand if these novel lipids may have issues with patient tolerance in a long run. Appropriate testing of other characteristics of these lipids and the compounded end products, such as stability, is also required for safety assurance.
Ultimately the lipids that can target specifi c cell types would be the ideal carrier. If, for example, T cells or tumour cells were able to be selected and RNA coding proteins expressed this would reduce the amount of materials needed to treat a patient and thereby reduce any potential toxicity. Although at early stages, there are some groups investigating the ability of glycan markers on the cell surface to interact with lipids to enhance delivery to a target cell type.
RNA based therapeutics could revolutionise how we deliver therapeutics. In the future it is possible that in place of a monotherapy, a population of diff erent RNA substrates will code and cascade several proteins to trigger pathways to eliminate cancer cells. The primary obstacles of how to deliver these molecules to cells has seen progress recently, but with the innovations in lipid chemistry we are likely to see new products which advance this fi eld. Reducing toxicity and better targeting of the RNA to specifi c areas or even particular cell types could be the next step in this journey. The part these drugs play in the treatment of Covid-19 remains to be seen but the information gained from these molecules used in large scale clinical trials that are going on currently will be invaluable.
Author: GABRIELA
MIKHAIEL - marketing manager at Dec Group
SAFETY GUARANTEED
How a fully integrated isolator and process equipment solution off ers high safety, effi cient control and cleaning features as well as full compliance in terms of manufacturing regulations.
The pharmaceutical industry is developing at a faster pace than ever before. New drugs and forms of therapies, persistent market growth, Industry 4.0 and the current Covid-19 pandemic are synonymous to enormous challenges for manufacturing companies.
Due to the high potency of certain active pharmaceutical ingredients (APIs), machine operators have to be protected. At the same time, humans are a high source for product contamination and the key to a successful operation lies in reliably engineered technologies that bring forth equipment capable of off ering suitable containment solutions to protect people and products from each other.
In pharmaceutical manufacturing facilities, isolators are becoming increasingly important as they can achieve the desired level of protection and security.
HIGH CONTAINMENT TRAY DISCHARGE, MILLING, MIXING AND PACK-OFF ISOLATION SYSTEM For a recent project with the aim to replace parts of an existing thyroid hormone production facility, a new high containment fully integrated isolation system for several interlinked process stages was designed and implemented. The new facility guarantees closed product handling and achieves a very low Occupational Exposure Limit (OEL < 400 ng/m 3 ).
The plant accommodates two distinct process phases starting with the introduction of trays from an adjoining process room through a transfer door into the conditioning chamber which is equipped with an ergonomic lift system. The conditioning chamber is connected to the rear of the tray offl oading and milling chamber.
MILLING AND BLENDING Equipped with a tray offl oading rack and situated at right angles to the conditioning chamber, this chamber collects the product into an integrated discharge hopper able to de-agglomerate the product and connected to feed the cone mill. After the milling, the product is then collected into a suction hopper and automatically transferred to an integrated PTS Batchmixer system where it is homogenised and from which samples from two to 10 grams can be collected.
This mixer is a novel system and off ers the advantage of working without rotating tools. The substances are thus mixed or homogenised very gently. With limited circulation speed, particles are not damaged. The system operates under inert conditions and handles hygroscopic, oxygen sensitive or explosive materials. Powders can be transferred automatically from drums, bags or directly from process equipment like a granulator.
It operates on recirculating a single or several products via two circulation lines using a PTS (Powder Transfer System) which is mounted on top of the blender. To ensure a contained closed transfer the PTS Batchmixer is mounted directly above the pack-off isolator chamber discharging the product into a 50 l feeder hopper. PACK-OFF AND DISCHARGE The pack-off isolator consists of two chambers, of which the upper chamber is fi tted with an integrated weigh scale mounted on a slide rail system. This allows the scale to be moved to the side when direct bulk discharge into the lower chamber is required. In the upper chamber, the homogenised APIs are fi lled into bottle containers and stored on a rack before leaving through the
SAFETY GUARANTEED
rear wall into the fi nal transfer chamber. The lower chamber permits the direct discharge of APIs into bags using an EziDock containment valve system. The fi nal transfer chamber serves for the initial empty clean container transfer into the isolator prior to commencing the batch and for the contained transfer of the fi lled containers prior to exiting the chamber through a Rapid Transfer Port continuous liner system providing high containment.
SECOND PROCESS PHASE The second process phase encompasses reactor charging from bags and previously fi lled Ezi-Dock bags and the fi lter dryer discharge, after the product has gone through the pressure fi ltration, crystallisation, washing and drying processes. To maintain security and high containment, the material is transferred into a fi lter dryer discharge isolator before it is milled and transferred to the blending process. In this second phase, PTS Batchmixer discharge is set to deliver the product in trays again to be reintroduced in the isolator conditioning chamber for equilibration purposes where humidity is added to the material. Once more the product repasses into the blender for homogenisation and the automated collection of samples as small as from 1g upwards. The product is fi nally accurately dosed into 1kg containers with a tolerance of +/- 1 g.
Reactor charging with PTS allows for oxygen elimination during the charging process and therefore excludes any explosion risks. PTS is an exceptionally eff ective and reliable method for transferring and dosing both dry and wet powders. Its unique fi ltration concept with a fl at membrane prevents fi lter clogging thus avoiding operation failures. The system uses vacuum and pressure to convey materials and can be used in sterile operations as well.
FULLY INTEGRATED CONTROL AND IN-PLACE HYGIENE FEATURES The plant is controlled by using an integrated PLC system controlling both the isolators and the complete process system. The facility is designed for clean-in-place with integrated fi xed and rotating spray nozzles as well as manual hand guns.
Equipment providers to the pharmaceutical manufacturing industry play an important role in supporting manufacturers. Which legal requirements have to be observed and which regulations will be changed in the coming years? How will changing conditions aff ect the production process and what technologies are required to be immediately and seamlessly integrated into the overall process off ering enough fl exibility in case of process changes? These are some of the questions to be considered during the preliminary design phase.
Manufacturers should not focus exclusively on individual technologies and machines but rather on complete system integration capabilities and process linkage competences as well as the benefi t of receiving advice, in-depth industry knowledge and aftersales services.
