Producing cGMP Oligos
Dowpharma´s (pharma.dow.com) addition of the OligoPilot 400 synthesizer (GE Healthcare; www.gehealthcare.com) to its commercial-scale cGMP manufacturing facility has given the company greater flexibility in oligo synthesis and increased production speeds. Sufficient manufacturing capacity is in place to meet current demand, says Noel Irizarry, business director of nucleic acid medicines at Dowpharma, as most oligo therapeutics are still in relatively early stages of development. The need for future scale-up is as yet unclear.
“Oligos continue to be a highly speculative field,“ says Irizarry. In 2005, some players had setbacks in product development, “but we are fully committed to this market and have the analytical expertise and manufacturing unit in place.“
OligoPilot 400 was designed to synthesize intermediate quantities of therapeutic-grade oligonucleotides. Nominal synthesis scales range from 4 mmol using 70- or 100-mm diameter columns. This translates into more than 150 grams of crude 20-mer oligos per run.
With the additions of AKTA OligoPilot 10 Plus and AKTA OligoPilot 100 Plus, GE Healthcare has a full range of systems for manufacturing of oligonucleotides going from 1 µmol to 1 mol. The AKTA OligoPilot 10 Plus is an upgraded version of AKTA oligopilot 10 in which hardware as well as methods have been optimized for 1 µmol scale synthesis of both DNA and RNA.
The AKTA OligoPilot 10 Plus operates in the 1 µmol range and the AKTA OligoPilot 100 Plus operates in the 100 µmol to 9 mmol range. OligoProcess systems from GE Healthcare have been designed for manufacturing of kg quantities of clinical and commercial material. Two models are currently available, operating in the 50 and 100,000 mmol scales respectively
Lonza (www.lonza.com), another supplier of cGMP oligos—including DNA, RNA, and siRNA—manufactures oligos at small to industrial scale.
Scandinavian Gene Synthesis (SGS, www.sgsdna.com) produces cGMP DNA oligos primarily for the in vitro diagnostics market.
With a focus on developing RNAi drugs, Sirna Therapeutics (www.sirnatherapeutics.com) produces its own cGMP oligos and recently received a U.S. patent covering the chemical synthesis and manufacturing of ribonucleic acids. Sirna´s process comprises six major steps—synthesis, deprotection, purification, annealing, ultrafiltration, and lyophilization—that encompass the 150 discrete chemical steps involved in manufacturing a siRNA.
According to Sirna, the process achieves chemical yields in excess of 60%, with high-product purity. Sirna also produces oligos on a contract-manufacturing basis. Its processes are readily scaleable to hundreds of kilograms of siRNAs.
“We have seen a major drop in the price of RNA-based raw materials,“ says Mark Egan, vp of operations at Sirna. “The DNA market has historically been a much bigger market,“ and DNA amidites “are cheap compared to the RNA amidites. But when you look at the actual cost of the RNA nucleosides versus the DNA nucleosides, which are the starting materials, RNA is actually cheaper than DNA.“
The difference in price is due to economies of scale and the size of the DNA market, Egan observes. “With the evolution and development of the siRNA field, we are starting to see economies of scale and a reduction in the cost of those RNA amidites.“