What’s Next in Oligo Manufacturing: From Lyophilization Bottleneck To Liquid API

Written by Kimo Sanderson

As outlined in our previous article, the oligo manufacturing demand shift translates to productivity challenges as scale-up and larger batch capacities become crucial. For CDMOs, one of foremost operational constraints is the lyophilization bottleneck. Given per-batch lyo takes around 5-7 days, while the entire upstream synthesis to downstream concentration process takes only 4-5 days, lot release and productivity is significantly slowed down by lyo.

These challenges are anticipated to be exacerbated at larger kilogram scales, where implementations of parallel synthesis trains, continuous chromatography and other intensified operations will lead to a surge in the amount of bulk API. To be sure, lyo offers the advantages of long shelf life, simplified logistics, and flexible weight-based patient dosing. However, it is also cumbersome with lyophilized drug product being sometimes sticky (i.e. particles flying out during vial filling) with risk of contamination during open vial filling and cleaning before the next batch. Effective CIP/SIP for dryers can be difficult to validate and execute and becomes a critical area of regulatory audit. Further, lyo necessitates a significant CAPEX in the $2-$3M for freeze drying chambers, coupled with a recurrent high energy cost of operation that will only be amplified at larger scales amidst environmental concerns.

Lyo necessitates a significant CAPEX in the $2-$3M for freeze drying chambers, coupled with a recurrent high energy cost of operation that will only be amplified at larger scales amidst environmental concerns.

Thus, CDMOs and equipment vendors should consider newer approaches being discussed, such as single-use disposable trays, pre-validated or preinstalled CIP/SIP stations, closed systems, continuous batch-to-batch cycles, PAT spectroscopic sensors, spinning vials and simpler dryer handling and loading. In some ways, lyo is as much art as science. This is where CROs can play a vital role in oligo API characterization, PAT analytical method development, and lyo process development and modeling to find optimal processes.

Looking Beyond Lyo

An alternative approach to lyo for oligos was first proposed by Musleheddinoglu and several co-authors / key opinion leaders from big pharma in the article Technical Considerations for Use of Oligonucleotide Solution API, Nucleic Acid Ther. 2020. The authors suggest that the lyo step can be eliminated entirely because, ultimately, commercial oligos are injected or infused in liquid solution form as a parenteral. They propose to directly concentrate the oligo API at the final UFDF bulk drug substance step together with formulation buffer salts followed by excipient addition to form liquid API final drug product at the dosage concentration. Thus, the need of lyophilization along with its challenges at larger batch sizes is eliminated – resulting in a theoretically more efficient drug product process compared to the current approach.

The lyo step can be eliminated entirely because, ultimately, commercial oligos are injected or infused in liquid solution form as a parenteral.

In fact, this approach is similar to many current monoclonal antibody formulation processes during which bulk drug substance and final drug product are manufactured in the same process flow and facility. Another key enabler of the liquid API trend is that oligos are generally quite stable in solution condition at 2-8° C, and, when frozen, do not undergo significant oxidation, hydrolysis or other forms of degradation. For example, it is found that at neutral or alkaline pH with NaCl or phosphate buffer salts, oligos can withstand a long shelf-life of 2-3 years  – albeit not as robust as lyo powder form which is fairly stable against photolytic degradation as well. Through further contemplation of this approach via the European Pharma Oligonucleotide Consortium (EPOC), the liquid API trend for oligonucleotides may be set to rise for broad disease oligos in the pipeline, many of which have been acquired by big pharma.

An Opportunity for Suppliers and Service Providers

Against this emerging backdrop of liquid API, equipment and consumable vendors, CDMOs and CROs must prepare to leverage their expertise to offer solutions for liquid oligo formulations. This could include UFDF or other membranes with molecular cut-offs and equipment scales tailored towards oligo production; high concentration compatibility; better cleanability or single use systems; and automated or even robotic filling stations.

CROs/CDMOs should consider offering stability testing and comparability of liquid API oligo formulations with oligo API in water, or lyophilized solid API with 20-40% water content. Expertise should be developed in oligo characterization analytical techniques and formulation salts, excipients, pH, viscosity, membrane fouling, and environmental green chemistry gain analysis. CDMOs should also consider transforming their facilities towards closed systems, continuous environmental monitoring, automated filling stations and aseptic methods as stricter compliance may be necessary for final drug product manufacturing within the same facility.

A Look at Oligo Doses

Current commercial oligotherapeutics are dosed in the range of 2.1 mg/mL to 200 mg/mL as shown in the table below.

Meanwhile, UFDF may concentrate oligo API up to 50-100 mg/mL before membrane gel phenomena take place. Thus, liquid oligo API formulations are already feasible within the context of current production platforms. However, as higher concentrations will be required for new oligo delivery approaches such as subcutaneous, offering technologies that permit higher liquid API concentrations should also be considered by CDMOs. This may include thin film evaporation, spray drying, high-speed electrospinning, microwave, and osmosis technologies. Ultimately, by enabling higher concentrations in the final oligo drug product, this may result in significant benefits such as reduced dose frequency for patients, while supporting overall green initiatives. Finally, liquid API may also enable terminal sterilization of final drug product by sterile filtration to better meet the expectations of parenteral drug regulators.

To Summarize:

As oligo manufacturing demand accelerates due to a growing pipeline and larger patient populations, the demand for lyophilization will dramatically increase. Novel approaches to reduce the lyo cost and time burden, such as liquid API, will become a key theme in the future of oligonucleotide processing.

Are you interested in custom market research services to gain deeper insights into future oligonucleotide manufacturing trends? Reach out for a consultation.

References:

1. Wolfgang Frieß, Gerhard Winter, https://nap.nationalacademies.org/read/26009/chapter/5#28
2. Nagavendra Kommineni et al., Freeze-drying for the preservation of immunoengineering products, iScience 25, 105127, October 21, 2022; https://doi.org/10.1016/j.isci.2022.105127
3. Lyophilization of Complex Drug Products: Formulation Challenges and Scale-Up, Lubrizol
4. Meg Snyder, March 2017, https://www.drugdiscoverytrends.com/lyophilization-the-basics/
5. Michael Eder, July 2023, Lyophilization considerations: Freeze-drying vs. Freezing in Biopharma
6. https://berkshiresterilemanufacturing.com/resources/blog/optimizing-oligonucleotide-drug-products-strategies-for-formulation-lyophilization-and-fill-finish-processes
7. https://atdbio.com/nucleic-acids-book/Storage-of-oligonucleotides
8. Johanna Poecheim et al., Development of stable liquid formulations for oligonucleotides, European Journal of Pharmaceutics, Vol: 129, August 2018, Pages 80-87
9. Judy Lee, Formulated oligonucleotide APIs: Regulatory aspects. Therapeutic innovation & regulatory science, 2022 (56).pp. 386-393. ISSN 2168-4790; 2168-4804
10. Christian Wetter, Solution Oligonucleotide APIs: Regulatory Considerations, Therapeutic Innovation & Regulatory Science (2022) 56:386–393, https://doi.org/10.1007/s43441-022-00384-2
11. Jale Muslehiddinoglu et al., Technical Considerations for Use of Oligonucleotide Solution API, Nucleic Acid Ther. 2020 Aug 6;30(4):189–197. doi:10.1089/nat.2020.0846
12. Bhavani Prasad Vinjamuri et al., A Review of Commercial Oligonucleotides, Journal of Pharmaceutical Sciences, Vol: 113, Issue 7, July 2024, Pages 1749-1768
13. https://www.americanpharmaceuticalreview.com/Featured-Articles/587162-Assuring-Quality-of-Oligonucleotide-APIs-and-DPs/
14. Mingyuan Li, Lyophilization process optimization and molecular dynamics simulation of mRNA-LNPs for SARS-CoV-2 vaccine, Nature npj Vaccines (2023) 8:153; https://doi.org/10.1038/s41541-023-00732-9