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Bulk production of the antiviral lectin griffithsin

View Article: PubMed Central - PubMed

ABSTRACT

Application of plant‐based protein expression systems for bulk production of recombinant protein pharmaceuticals is building momentum. There are considerable regulatory challenges to consider in commercialization of plant‐made pharmaceuticals (PMPs), some of which are inherent to plant‐production systems and others that are common with other production systems, but are new to PMPs because of the youth of the industry. In this review, we discuss our recent and ongoing experience with bulk production of the HIV microbicide candidate, griffithsin (GRFT), utilizing plant‐based transient protein expression, with specific focus on areas relevant to commercial manufacturing of bulk GRFT active pharmaceutical ingredient (API). Analytical programs have been developed for the qualification and monitoring of both the expression vector system and the API detailing our experience and plans for each. Monitoring postpurification protein modifications are discussed in relation to stability and safety programs. Expression, processing and analytics programs are associated with increased manufacturing costs in current good manufacturing practice (cGMP) production because of the required qualification testing. The impact of these costs on the overall cost of goods is particularly relevant to GRFT manufacturing because GRFT, as an HIV microbicide, is most needed in populations at high risk for HIV exposure in resource‐poor countries. Consequently, GRFT for microbicide applications is a very cost‐sensitive recombinant PMP. We have therefore emphasized maintaining a low cost of goods. We provide a review of the literature on the economics of PMPs with various expression systems and how they may impact production costs and complexity.

No MeSH data available.


GRFT Crystal Structure. The crystal structure of GRFT (PDB ID: 2GTY) is shown highlighting potentially oxidizable amino acids, methionine, cysteine and tryptophan. GRFT homodimer (yellow and green) has methionines at positions 61 and 78 (shown in black) with no cysteines or tryptophans. Images were created in Accelrys Discovery Studio Visualizer 2.5.
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pbi12433-fig-0003: GRFT Crystal Structure. The crystal structure of GRFT (PDB ID: 2GTY) is shown highlighting potentially oxidizable amino acids, methionine, cysteine and tryptophan. GRFT homodimer (yellow and green) has methionines at positions 61 and 78 (shown in black) with no cysteines or tryptophans. Images were created in Accelrys Discovery Studio Visualizer 2.5.

Mentions: In our work with GRFT, protein oxidation is and continues to be a potential concern because the amino acid sequence contains multiple potentially oxidizable amino acids (Figure 3). Scaled manufacture in conjunction with long‐term storage is a variable not generally simulated in the laboratory. Multiple contingency plans have been discussed, and preliminary data have been collected in an effort to preemptively resolve issues related to oxidation of GRFT. Alternative amino acid sequences, reducing the number of oxidizable amino acids, have been developed that would provide oxidation resistance, and formulations addressing oxidation protection are under development. These options are all being developed concurrently as contingencies for oxidation. The need for an alternative API or formulation has not been established in the field, but successful clinical development will require any issues with oxidation be resolved.


Bulk production of the antiviral lectin griffithsin
GRFT Crystal Structure. The crystal structure of GRFT (PDB ID: 2GTY) is shown highlighting potentially oxidizable amino acids, methionine, cysteine and tryptophan. GRFT homodimer (yellow and green) has methionines at positions 61 and 78 (shown in black) with no cysteines or tryptophans. Images were created in Accelrys Discovery Studio Visualizer 2.5.
© Copyright Policy - creativeCommonsBy-nc-nd
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC5016770&req=5

pbi12433-fig-0003: GRFT Crystal Structure. The crystal structure of GRFT (PDB ID: 2GTY) is shown highlighting potentially oxidizable amino acids, methionine, cysteine and tryptophan. GRFT homodimer (yellow and green) has methionines at positions 61 and 78 (shown in black) with no cysteines or tryptophans. Images were created in Accelrys Discovery Studio Visualizer 2.5.
Mentions: In our work with GRFT, protein oxidation is and continues to be a potential concern because the amino acid sequence contains multiple potentially oxidizable amino acids (Figure 3). Scaled manufacture in conjunction with long‐term storage is a variable not generally simulated in the laboratory. Multiple contingency plans have been discussed, and preliminary data have been collected in an effort to preemptively resolve issues related to oxidation of GRFT. Alternative amino acid sequences, reducing the number of oxidizable amino acids, have been developed that would provide oxidation resistance, and formulations addressing oxidation protection are under development. These options are all being developed concurrently as contingencies for oxidation. The need for an alternative API or formulation has not been established in the field, but successful clinical development will require any issues with oxidation be resolved.

View Article: PubMed Central - PubMed

ABSTRACT

Application of plant‐based protein expression systems for bulk production of recombinant protein pharmaceuticals is building momentum. There are considerable regulatory challenges to consider in commercialization of plant‐made pharmaceuticals (PMPs), some of which are inherent to plant‐production systems and others that are common with other production systems, but are new to PMPs because of the youth of the industry. In this review, we discuss our recent and ongoing experience with bulk production of the HIV microbicide candidate, griffithsin (GRFT), utilizing plant‐based transient protein expression, with specific focus on areas relevant to commercial manufacturing of bulk GRFT active pharmaceutical ingredient (API). Analytical programs have been developed for the qualification and monitoring of both the expression vector system and the API detailing our experience and plans for each. Monitoring postpurification protein modifications are discussed in relation to stability and safety programs. Expression, processing and analytics programs are associated with increased manufacturing costs in current good manufacturing practice (cGMP) production because of the required qualification testing. The impact of these costs on the overall cost of goods is particularly relevant to GRFT manufacturing because GRFT, as an HIV microbicide, is most needed in populations at high risk for HIV exposure in resource‐poor countries. Consequently, GRFT for microbicide applications is a very cost‐sensitive recombinant PMP. We have therefore emphasized maintaining a low cost of goods. We provide a review of the literature on the economics of PMPs with various expression systems and how they may impact production costs and complexity.

No MeSH data available.