Dr. Xufeng Sun, VP, manufacturing science and technology at Sharp, discusses how carefully mapping lyophilisation cycles and meticulous fill finish studies help bring oligonucleotide therapies to patients seamlessly.
How the development pipeline for oligonucleotide therapies continues to expand rapidly, growing from three FDA- or EMA-approved treatments in 2015 to 20 by 2024. Using engineered single- or double-stranded nucleic acid polymers, these therapies precisely target RNA and, in some cases, DNA within cells. By inducing degradation, blocking protein translation or modulating splicing events, oligonucleotide therapies offer a way to overcome disease-causing gene expression with minimal side effects.
However, delivering these life-saving medicines requires developers and manufacturers to overcome a number of logistical hurdles. As well as needing to navigate the production of very small batches of these precision personalised medicines, oligonucleotide producers also need to overcome the challenge of maintaining stability.
Oligonucleotide sensitivity and stability challenges
Although oligonucleotides (or “oligos”) are unlocking new therapies for previously incurable and untreatable diseases, the challenges associated with producing these new drugs can prevent them from reaching commercial markets. One of the biggest challenges in developing and manufacturing oligo therapeutics is the fact that they have inherent sensitivities:
- Temperature-sensitivity: Requiring specialised handling throughout the supply chain.
- Aqueous instability: Necessitating drying processes like lyophilisation to extend their shelf life and stability.
- Shear-sensitivity: Especially when delivered in lipid nanoparticles (LNPs), physical stress from mixing or pumping can cause aggregation, diminishing the drug's efficacy.
- Vulnerability to RNases: Unprotected RNA can be rapidly degraded by naturally occurring ribonucleases found in the environment, demanding strictly controlled, RNase-free manufacturing conditions.
Used to treat rare or genetic diseases, the cost of oligo therapeutics is often exceptionally high, while the volumes required are relatively low. As a result, successfully translating these molecules into commercial supply requires stringent controls that directly address their inherent molecular sensitivities and prevent costly product loss while guaranteeing long-term stability.
Implementing essential protection strategies
Protecting oligo therapeutics from degradation requires a multifaceted strategy that addresses their mechanical, biological and thermal sensitivities across all stages of development and manufacturing.
1. Mechanical protection
Oligo formulations, particularly those encapsulated in LNPs, require mitigation against the physical stress generated by mixing and pumping. To prevent product aggregation and loss of efficacy, developers must use specialised equipment and precisely optimised processes. This involves calibrating mixing speeds and shafts to achieve a homogeneous blend while maintaining the lowest possible mechanical force. For the most fragile drug products, utilising a time-over-pressure valve in filling helps to minimise physical stress by gently pushing the solution out of the fill line using low pressure, critically limiting damage during the filling step.
2. Biological protection
The defense against degradation by ubiquitous RNases involves both inherent drug protection and stringent environmental control. Developers commonly use chemical modification or protective carriers (like LNPs), but manufacturing must ensure a rigorous environment using certified RNase-free equipment and water for injection (WFI). This requires establishing dedicated clean processing areas and strictly enforcing staff protocols to avoid contamination. Additionally, keeping the product cool during processing is a simple but effective way to significantly decrease the rate of degradation and improve product hold times.
3. Thermal protection
Since formulation and filling often occur at room temperature (20–25°C), developers must implement specific procedures and equipment to limit heat exposure. Water-jacketed mixing vessels are the primary tool for this purpose; they actively circulate chilled water (typically 6–15°C) around the vessel shell, cooling the drug product solution during formulation, filtration and filling. Process controls should also be implemented, such as performing controlled thawing in a 2–8°C temperature-controlled unit and expediting post-filling activities, like visual inspection, to minimise the overall time the final product spends outside of its target cold storage condition.
The implementation of these measures demands both specialised manufacturing infrastructure and validated expertise in meticulous process control. Accessing this level of highly specialised capability is a primary reason developers choose to partner with an experienced contract development and manufacturing organisation (CDMO).
The lyophilisation development process
In addition to the above, oligo therapies are also typically lyophilised to help tackle instability challenges. Lyophilisation can extend shelf life, improve stability and minimise frozen storage and distribution chain risks. It does, however, add a crucial layer of development to characterise an effective and efficient lyophilisation cycle.
There are four vital steps required for cycle design and optimisation:
1. Thermal characterisation
The first step is to precisely define the thermal properties of the frozen drug product using techniques like differential scanning calorimetry. Key temperatures, such as the glass transition temperature, eutectic temperature and collapse temperature, determine the product's solid state and how it will behave during drying.
2. Solvent removal optimisation
Solvent removal optimisation in lyophilisation begins by establishing a high-quality, reproducible cycle based on the drug product's thermal characteristics, while troubleshooting common issues like cake collapse or meltback. Once acceptable cake quality is confirmed, the cycle time can be safely reduced by analyzing the relationship between temperature and pressure.
3. Stability studies
The next step is to evaluate the stability of the cake. This includes performing freeze-thaw testing on the drug substance to determine its robustness against temperature fluctuations encountered during storage and shipment. Accelerated stability studies over three to six months predict the product's long-term shelf life, aiming for an expiry date of one to three years.
4. Process robustness and tech transfer
The final step to lyophilisation development is to test the lyophilisation cycle on the current good manufacturing practice (cGMP) equipment that will be used for filling the drug product. Navigating the necessary transfer to cGMP equipment is complex, often introducing friction through poor knowledge transfer and discrepancies during equipment scale-up, which can necessitate expensive re-optimisation. These difficulties can be significantly reduced when partnering with a CDMO that manages both development and production in-house.
Successfully executing these four crucial steps requires highly specialised knowledge and practical experience. The inherent complexity of defining and optimising the cycle while navigating scale-up and ensuring process robustness demands significant expertise. By leveraging proven lyophilisation experience, developers can minimise product risk and ensure a commercially viable and robust manufacturing process.
Preparing for the next generation of oligo therapies
As the pipeline for oligo therapies rapidly expands, the primary challenge remains translating these complex molecules into commercial, life-saving medicines. Success in this critical market demands a dual strategy: meticulous process controls (covering mechanical, biological and thermal stability) and a strategic partnership with an experienced CDMO. This approach allows developers to leverage specialised expertise in complex areas like lyophilisation cycle design and technology transfer, enabling them to confidently mitigate product risk, secure long-term stability and ensure these high-value treatments reach patients efficiently and robustly.