1. A Sector in Rapid Ascent
Oligonucleotide therapeutics spanning antisense oligonucleotides (ASOs), small interfering RNAs (siRNAs), microRNA modulators, and aptamers, operate through post-transcriptional gene regulation, silencing disease-driving proteins at the mRNA level. This mechanism of action unlocks a vast universe of previously “undruggable” targets and enables a selectivity and durability that has attracted sustained investment from both established pharmaceutical companies and the venture capital community.
The global oligonucleotide therapeutics market was valued at approximately USD 5.92 billion in 2024 and is projected to advance at a compound annual growth rate (CAGR) of approximately 19.7% from 2025 to 2030, reaching an estimated USD 17.70 billion by the end of that period, driven by the broader clinical acceptance of siRNA and antisense candidates, and supported by advances in delivery technologies including GalNAc conjugates and lipid nanoparticles (LNPs). Alongside this therapeutic market, the oligonucleotide contract development and manufacturing organisation (CDMO) sector that supplies the synthesis services and raw materials underpinning the entire field is projected to grow from USD 2.51 billion in 2024 to USD 6.73 billion by 2029, at an even faster CAGR of 21.8%. As of 2025, the number of approved nucleic acid drugs reached 23, up from 14 ASOs and 7 siRNAs in 2024, confirming that the regulatory pipeline is broadening steadily. DataMIntelligence Beyond rare disease indications, the sector is now expanding into high-prevalence therapeutic areas, including cardiovascular disease, metabolic disorders, and oncology, signaling a maturation from orphan drug niche to mainstream medicine. Nucleic acid therapeutics are increasingly recognised as a key pillar of what many in the field describe as the “third wave” of modern medicine, following the eras of small-molecule inhibitors and monoclonal antibody drugs.
2. The Two Pillars of Molecular Architecture
2.1 Phosphoramidite Monomers: The Chemical Foundation of Every Oligonucleotide Drug
All synthetic oligonucleotide drug substances are assembled through solid-phase synthesis, in which phosphoramidite monomers serve as the fundamental building blocks. This process follows a repetitive four-step cycle, detritylation, coupling, capping, and oxidation/thiolation, through which individual nucleotide units are added sequentially to a growing chain.
In their unmodified state, RNA molecules are rapidly degraded by endogenous nucleases and may trigger innate immune responses, making natural nucleotides unsuitable as drug substrates. Chemical modifications introduced at the monomer level are therefore not optional enhancements but pharmacological necessities. The most clinically validated modifications include phosphorothioate (PS) backbone substitution and 2′-sugar modifications such as 2′-O-methyl (2′-OMe), 2′-fluoro (2′-F), and 2′-methoxyethoxy (2′-MOE). These modifications, incorporated during synthesis via appropriately functionalized phosphoramidite monomers, markedly improve nuclease resistance, extend plasma half-life, and reduce off-target immunostimulation, directly determining whether a candidate molecule achieves the pharmacokinetic profile required for clinical development.
2.2 Delivery Molecules: Overcoming the Cellular Barrier
The biophysical properties of oligonucleotides, their high molecular weight, strong negative charge, and hydrophilicity, render passive cellular uptake negligible. Delivery technology, therefore, represents the principal translational bottleneck for the entire field. As of early 2024, more than 40% of oligonucleotide candidates in Phase II trials faced challenges with effective in vivo delivery due to off-target effects and limited cellular uptake.
Two delivery platforms have achieved commercial validation: LNPs, exemplified by the approval of patisiran (ONPATTRO), and GalNAc conjugate systems, which have since become the dominant modality for hepatocyte-targeted therapies. As of November 2024, six siRNAs had received FDA approval as therapeutic agents, and notably, all commercially approved siRNAs except patisiran employ the GalNAc conjugate system to achieve ASGPR-mediated delivery to hepatocytes.
GalNAc conjugate delivery exploits the asialoglycoprotein receptor (ASGPR), which is expressed at high density on liver hepatocytes. Upon binding, the conjugate is internalised via receptor-mediated endocytosis, enabling selective hepatocyte targeting with a potency and organ-specificity that has supported the approval of givosiran for acute hepatic porphyria, with multiple further GalNAc-conjugated candidates in registrational review or Phase 3 trials as of publication. The practical consequence for drug development is substantial: GalNAc conjugation allows subcutaneous administration at milligram-range doses with dosing intervals of months, significantly improving patient adherence in chronic disease management compared to intravenous delivery regimens.
3. Quality Control: How Raw Material Purity Shapes Drug Safety and Regulatory Fate
The repetitive, sequential nature of solid-phase oligonucleotide synthesis creates a unique and underappreciated quality dynamic: impurities present in phosphoramidite starting materials are not diluted but are incorporated and amplified with each coupling cycle.
Because the repetitive nature of oligonucleotide synthesis amplifies the impact of phosphoramidite impurities, the quality of raw materials exerts a major influence on the quality of the drug itself, as certain impurities can be incorporated into the final oligonucleotide product and are difficult to remove by downstream purification. Critical impurities in phosphoramidites are defined as those that may be incorporated into the oligonucleotide during synthesis and persist in the drug substance. Because solid-phase synthesis offers no purification opportunity between individual coupling steps, these impurities accumulate in the final product, and the extent of accumulation is proportional to the number of times the affected phosphoramidite appears in the sequence.
The major product-related impurity classes arising from suboptimal phosphoramidite quality include sequence deletion fragments (n−1, n−2), insertion products (n+1), and modified positional isomers. The most prevalent of these, n−1 and n−2 deletions, arise from failures during coupling steps and are among the most difficult to completely resolve by preparative chromatography. Beyond sequence-truncated species, oxidative or hydrolytic impurities in the monomer feedstock can introduce modified nucleobases or altered sugar stereocenters that directly compromise target binding affinity and selectivity.
From a regulatory standpoint, the USP has developed DNA phosphoramidite reference standards specifically to help manufacturers identify and control impurity profiles during oligonucleotide synthesis, recognising that these standards are necessary to support quality assessment of critical raw materials throughout the product lifecycle from development to lot release. While dedicated ICH guidelines specifically addressing quality expectations for synthetic oligonucleotide therapeutics are still under development, regulatory agencies have indicated that principles from ICH Q3 and Q11 can be applied, and the Oligonucleotide Safety Working Group (OSWG) has proposed a risk-based classification framework for impurity assessment. The EMA has issued a draft guideline on the development and manufacture of oligonucleotides, and the FDA has signalled increasing attention to starting material designation and impurity control strategies in IND and NDA submissions.
The consequences of inadequate upstream quality control extend beyond regulatory risk. Oligonucleotide impurities containing aberrant sequences may engage unintended mRNA targets, producing off-target gene silencing effects with unpredictable toxicological consequences. Impurity species bearing structural modifications foreign to the intended sequence may also activate innate immune receptors, including Toll-like receptors 3 and 7, triggering inflammatory responses that can confound both safety and efficacy assessments in clinical trials.
4. Summary
The rapid commercial expansion of the oligonucleotide therapeutics sector depends critically on the availability of high-purity, well-characterised starting materials supplied through robust and auditable manufacturing systems. For downstream drug developers, raw material quality is not merely a compliance checkbox—it is a determinant of program timeline, clinical outcome, and regulatory success.
Glycogene is structured to serve the full development continuum, from milligram-scale discovery synthesis to multi-kilogram commercial campaigns, providing the supply chain continuity that clinical-stage and commercial-stage oligonucleotide programs require.
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