Alternatives for viral deactivation with promising candidates on the horizon were outlined during a recent AAPS webinar.
By David Pittman
A looming move by the European Union to ban the gold standard of detergents used in the manufacturing of plasma products and monoclonal antibodies is forcing the industry to scramble to come up with new alternatives.
The detergent Triton X-100—widely used by industry for nearly three decades because of its performance—may be removed from the market in two years due to safety concerns, according to a recent American Association of Pharmaceutical Scientists webinar, How to Rescue a pH Sensitive Protein: Detergent Viral Inactivation and Analytical Quantitation of Residual Detergent.
Researchers have tried to identify alternatives to Triton X-100 given its uncertain future. Besides efficacy and safety, an alternative needs to have little impact on proteins, be able to be safely removed, cause little or no foaming, yet be sensitive enough for analytics.
That alternative might be octyl-d-glucopyranoside (ODG), as Jessica Dawson, Ph.D., associate director for the analytical development group at EMD Serono, and Corinne Miller, Ph.D., research and development manager for virology and microbiological sciences at Millipore Sigma, said during the webinar.
The problem is that ODG is not yet available in a grade acceptable for good manufacturing practices (GMP), said Miller. But the industry is busy trying to change that. “It’s something that we’re working on, but it’s a very long-term project.”
“I think part of what this work we did showed is that there are very limited options other than the Triton really out there,” Dawson said. “And if it does end up being banned [by the E.U.], then we don’t really have anything else to fall back on, or at least not a range of options of the quality that we need.”
Manufacturers take a few steps for optimal viral clearance, including nanofiltration and chromatography. But detergents are effective against enveloped viruses. However, those detergents must be removed. Guidance from the Food and Drug Administration, European Medicines Agency (EMA), and International Conference on Harmonisation state that viral clearance should total at least 12 to 15 log reduction values, calculated at the log-based 10 of the virus preclearance compared to postclearance.
The EMA and World Health Organization recommend Triton X-100 for viral removal in plasma products including HIV and more recently monoclonal antibodies. Triton X-100, which has a number of synonyms including octylphenol ethoxylate, could be easily removed downstream and yield good product in both quality and quantity recovered.
“With all of these attributes, Triton X-100 has been identified as one of the most widely used and approved viral-clearance steps for clinical and commercial products globally,” Miller added.
But recent research has shown that Triton X-100 has created some acute oral toxicity, eye damage, skin irritation, and chronic aquatic toxicity. The compound derogates to 4-tert-octylphenol, a known endocrine disruptor that accumulates in sediment and drinking water.
As a result, the detergent was placed on the “substance of very high concern list” in December 2016 by the European Chemicals Agency under REACH regulations after several years of debate about its safety. REACH, which stands for Registration, Evaluation, Authorisation and Restriction of Chemicals, is a European Union regulation enacted in December 2006 to address chemical safety on both human health and the environment.
The detergent is scheduled to be banned in January 2021, and other regions of the globe could follow or suffer in Europe’s wake. Some exemptions are possible including those for medicinal products made outside the European Union.
“While this regulation applies to the E.U., companies manufacturing and distributing drugs globally should be aware of similar restrictions in other geographies that could eventually be adopted,” Miller warned.
Miller noted nearly a dozen instances of viral contamination over the last twenty years, although the source of most of the contaminations was never definitively determined, “but for several, the likely source was animal- derived materials including serum or trypsin,” Miller explained. Contamination can be costly to manufacturers for lost product and regulatory corrections, but it also hurts patients with a disrupted drug supply.
Studying Alternatives
Because of Triton X-100’s status under REACH regulations, Miller set out to identify alternatives in viral removal that are also easily used and have little to no impact on the final product.
After looking at a range of detergents and how well they perform both in ability to remove virus and time needed to completely work, they found ODG worked best under time and temperature parameters typically used in biopharma production.
During the webinar, Dawson from EMD Sereno explained in detail how they screened potential detergents. They started with five that Miller had identified through her work as good places to start. Dawson looked at detergents’ effectiveness at viral removal and then examined protein quality after viral removal.
Unfortunately for their work, two detergents that showed good response to either of those aspects—Ecosurf EH-9 and Triton CG-110—were not available in GMP-compliant grade. That left ODG, which was costly but still a possibility to obtain a GMP-compliant grade, as the only other possible option.
A 1 percent concentration of ODG provides complete viral inactivation similar to Triton X-100 at a range of reasonable time and temperatures.
Dawson explained how she and her team were developing ways to detect ODG levels in product, using a combination of evaporative light scattering detector and high-performance liquid chromatography, and safely remove ODG with proteins. Protein removal needed to be addressed as well because of the hydrophobic nature of certain resins in the mixture.
“We actually had a process, a detergent that could follow everything we needed it to do,” Dawson said. “This is great.” But work on making GMP-grade ODG continues.
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David Pittman is a science and medical writer based in Washington, D.C.