January 1, 2009 (Vol. 29, No. 1)

Improving Delivery Strategies and Enhancing Pharmacokinetic Properties Are Key Concerns

Industry sources project a continuing 10 to 15% growth in the market for biotherapeutic peptide new chemical entities, and more modest growth of slightly greater than 10% for generic peptides. These projections, however, predate the current global economic downturn and ongoing financial instability, and there is growing concern that some projects presently in corporate pipelines might be stalled and new projects may be delayed, with a worried eye focusing primarily on the biotech sector and companies that rely on venture capital funding.

“There is reduced appetite for risk in the financial markets,” observes Johan Devenyns, Ph.D., head of Solvay Peptides, the parent company of Peptisyntha.

What had largely limited more widespread development of therapeutic peptides in the past has been the cost of manufacturing, according to Huw Nash, vp of corporate development and a cofounder of Aileron Therapeutics. Within the past five to ten years, though, “solid-phase synthesis of large helical peptides has become economically viable,” says Nash, citing the commercial success of Roche’s Fuzeon for HIV infection and Amylin’s Byetta for the treatment of type 2 diabetes.

Now, instead of worrying about manufacturing and cost issues, peptide drug developers are focused on expanding delivery strategies and improving the pharmacokinetic properties of therapeutic peptides.

The current absence of clear regulatory guidance from the FDA regarding impurity specifications for peptides in clinical trials presents challenges for manufacturers and their clients. “We continue to see drug product sponsors opting for the impurity guidelines for small molecules, even though complex peptides are specifically excluded from these,” says Rodney Lax, director of sales and marketing at PolyPeptide Laboratories (PPL). “Given the low toxicity for peptides in general, this approach places unreasonable technical and economic demands on the CMO, particularly for more complex peptides.”

Global Growth

“The therapeutic peptides market is still predominantly U.S.-oriented,” says Dr. Devenyns. More than two-thirds of demand comes from the U.S. market. The bulk of solid-phase synthesis capacity resides in the U.S., with solution-phase operations primarily located in Europe.

In describing the competitive landscape outside the U.S., Dr. Devenyns points to a trend in which peptide companies have gone through a round of consolidation and are currently looking to the east for increasing the scope of their manufacturing operations.

At Peptisyntha, the expansion under way at its Torrance, CA, site continues. The new QC/QA laboratories and offices, is scheduled to be ready by March. The company has also leased an additional building adjacent to its existing facility that will provide increased production capacity in 2010—predominantly for solid-phase peptide synthesis.

At the Brussels site, where the company’s solution-phase manufacturing capability is based, Peptisyntha took into operation new QC labs and a new synthesis pilot over the past 6-12 months. Additionally, new GMP warehouses went into use earlier this year in Brussels for receipt and storage of materials under controlled conditions. All of these expansions were built to comply with cGMP standards.

A key goal for 2009, according to Dr. Devenyns, is the installation and validation of a manufacturing execution system that will automate series of workflow processes involved in peptide production. This will include automated follow-up of the flow of materials moving in and out of the company’s new warehouses and will constitute the backbone of a productivity upgrade. Additionally, new pilot capacity for purification and lyophilization will also be brought on-stream. Peptisyntha was inspected in August 2008 by the Belgian Federal Agency for Medicines and Health Products, on behalf of EMEA, and a GMP certificate was granted.

With the acquisition of NeoMPS, previously the peptide manufacturing arm of Isochem, and its facilities in Strasbourg, France, and San Diego, PolyPeptide Laboratories has added substantial manufacturing capacity to its ongoing GMP operations in the U.S., Denmark, Sweden, and India. It also broadened its range of offerings, providing services to organizations seeking catalog peptides, radio-labeling services, small-scale non-GMP synthesis, as well as contract manufacture of amino acid derivatives and organics.

The acquisition of NeoMPS gave PPL a “broader window for pipeline projects,” says Lax, in particular enabling the company to pursue more small-scale GMP projects, such as vaccine production, for which initial GMP lots typically require only about 10 grams of peptide, as well as the general ability to compete for earlier-stage projects.

About 35% of PPL’s business is in generic peptides, which Lax describes as an established market that will likely remain fairly stable even in the current economic uncertainty. An additional 25% of the company’s revenue stream depends on contracts with large pharmaceutical companies, adding to Lax’s confidence that PPL is in a good position to weather the economic storm.

The company’s new facility in India will be operational later this year and will be dedicated initially to generic peptide production. Expansion of manufacturing capacity is also ongoing in Scandinavia and Torrance.

Aileron Therapeutics calls the synthetically locked, alpha-helical peptides it produces “stapled peptides.”

Manufacturing Trends

In general, therapeutic peptides currently in development across the industry tend to be a mix of long and short, simple and complex peptides. While agreeing with this assessment, Lax reports seeing a substantial increase in demand for “very complex” peptides moving through corporate pipelines. These include sequences of 40 amino acids or more, PEGylated peptides, and multicomponent peptide conjugates that require assembly using hybrid fragment technologies. The development of robust manufacturing processes for such molecules can take four to six months, far longer than for the typical peptide drug.

Another issue is the use of novel amino acid derivatives or coupling reagents. Access to such materials may prove challenging as projects move into larger-scale production. These reagents may not be readily available in bulk and may require time to produce; they may also introduce additional costs.

Aileron Therapeutics was established based on chemical cross-linking technology licensed from Harvard University and the Dana-Farber Cancer Institute. Aileron calls the synthetically locked, alpha-helical peptides it produces “stapled peptides.” Each “staple” is formed by cross-linking the olefin-tipped hydrocarbon side chains of two non-natural amino acids—merging two double bonds into one—in a process called olefin metathesis. An individual stapled peptide may contain one or more staples depending on the molecular conformation needed to achieve the desired activity, potency, and pharmacokinetic properties. Aileron has synthesized alpha-helical peptides that range in length from 10 to about 35 amino acids.

Early on, “we saw that the stapled peptides developed at Dana-Farber had a broader, more profound effect than small molecules,” says Nash.

The configuration of stapled peptides mimics the molecular structures typically found at the interface of protein-protein interactions. When locked into this stable configuration, stapled peptides are able to penetrate cells efficiently and to exert their effects on intracellular protein targets. The large surface area of the peptides gives them advantages over small molecules in their ability to disrupt specific signaling pathways by inhibiting targeted protein-protein interactions.

“Stapled peptides have a circulating half-life in rodents of more than 20 hours,” says Nash. If left unmodified, they would have a half-life of about five minutes.

Aileron is currently optimizing production of the one or more non-natural amino acids that are incorporated into each stapled peptide. The company has conducted pilot studies of its lead compounds in GMP manufacturing with CMO partners.

“We are about a year away from our first IND,” says Nash.

Aileron chose cancer as the first therapeutic target for its stapled peptides program with the aim of intervening in the BCL-mediated apoptotic pathway and, specifically, mimicking the activity of pro-apoptosis proteins such as BAX, a member of the BCL-2 protein family.

The natural apoptotic pathway is a multifaceted one, Nash explains. Recently in Nature, it was reported that a stapled alpha-helix of BIM BH3 domains directly activates BAX-mediated mitochondrial apoptosis. Because this mechanism directly reactivates the cell death pathway, Aileron is confident that these peptides will have efficacy against a broad range of cancers, and that the nature of the mechanism of action will minimize the ability of tumors to develop resistance to these drugs.

Looking to the future, the company is applying its technology to target transcription factors in the cell nucleus to modulate gene expression.

Equipment and piping in Peptisyntha’s facilities were designed to minimize cross-contamination. In addition, drainability and clean-in-place features were incorporated in the design and validated.

Demand Diversifies

Frank Zhang, Ph.D., CEO of GenScript, describes a growing market for research-grade peptides, especially for epitope-mapping applications in antibody drug discovery and for the production of peptide arrays for screening. Custom peptide synthesis is one facet of GenScript’s CRO business, which also includes gene synthesis and cloning services, antibody development, and protein expression and purification.

In October, GenScript launched a series of GMP-grade peptides for use as anti-aging ingredients in cosmeceuticals and dermaceuticals. These peptides contain various modifications intended to enhance skin-permeating and antiwrinkle properties; examples include acetyl hexapeptide-3, palmitoyl hexapeptide, palmitoyl tetrapeptide-3, palmitoyl pentapeptide, GHK-Cu2+, and PAL-GHK, which have been incorporated into the products of companies such as Replexion, Bioque, Urban Nutration, Avon, Osmotics, Newspirit, and Neova.

GenScript’s FlexPeptide™ synthesis platform integrates solid-phase synthesis, liquid-phase synthesis, microwave technology, and the company’s ligation technology. The company uses a combination of these synthesis tools, basing the selection of which methods to use on the properties of the peptide to be synthesized. For difficult synthesis steps, Dr. Zhang notes that the increased coupling rates enabled by microwave energy offer particular advantages. Microwave technology is also useful for introducing site-specific modifications.

“We do not only use machines,” says Dr. Zhang, “we may also use manual synthesis,” which allows for greater control over the process.

GenScript can synthesize peptide fragments up to 50 amino acids in length, producing batches from a few milligrams up to two kilograms, according to Dr. Zhang. The company’s ligation technology allows for the production of peptides up to 200 amino acids in length.

The demand for synthetic peptides for use in proteomic research applications continues to increase, enjoying a growth spurt that began a few years ago, according to Heinrich Gausepohl, Ph.D., director of development at Intavis Bioanalytical Instruments, a manufacturer of automated peptide synthesizers. Demand is particularly strong for small-scale peptide synthesis of large numbers of different peptides, with orders in the tens of thousands not uncommon. Dr. Gausepohl attributes the rising interest in isotope-labeled peptides to a growing number of mass spectrometry-based research projects.

Intavis’ MultiPep RS employs solid-phase Fmoc peptide synthesis to generate milligram quantities of up to 384 peptides in four 96-well filter plates. For larger-scale syntheses, an optional column module allows for production of up to 72 peptides in volumes ranging from 10 to 100 µmol.

The MultiPep RS can also perform automated SPOT synthesis to produce peptide arrays on a derivatized cellulose membrane. Recently, Intavis added a new capability, enabling the instrument to produce peptide microarrays on glass slides, with up to 384 peptides arrayed in duplicate on each slide.

Intavis Bioanalytical Instruments’ MultiPep RS employs solid-phase Fmoc peptide synthesis to generate milligram quantities of up to 384 peptides in four 96-well plates.

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