Prime-and-boost via electroporation yields potential HIV vaccine

First candidate from Profectus-Ichor collaboration set to enter clinic in Q2 2010

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BALTIMORE, Md.—Profectus Biosciences will use Ichor Medical Systems' TriGrid electroporation delivery system for the clinical development of its DNA vaccine programs. The long-term development, license and supply agreement entered into by the two companies also provides Ichor with the option to co-develop any vaccines that result. Financial details of the agreement were not disclosed.

The Profectus VAX approach is three-pronged, notes Dr. John Eldridge, the company's chief scientific officer.

"Our recently completed in-licensing transaction with Wyeth Vaccines," Eldridge says, "brought us two mature, heavily funded and patent-protected vaccine programs that enable a potent 'prime-boost' therapeutic vaccine strategy that uses the delivery of a plasmid DNA (pDNA) vaccine to 'prime' the immune system, followed by a 'boost' using a recombinant vesicular stomatitis virus (rVSV) vector. Relative to earlier pDNA vaccines, the immunogenicity of the Profectus pDNA vaccine platform is substantially enhanced by incorporation of the molecular adjuvant interleukin-12 (IL-12), delivery via electroporation (EP) and formulation with the transfection and stability-enhancing agent bupivicaine."

Both in-licensed vaccine platforms have been scaled, clinical trials materials are released and both have demonstrated robust immunogenicity and safety in non-human primates (NHPs), Eldridge adds.

A National Institutes of Health-supported clinical evaluation of the Profectus prime-boost approach in HIV uninfected subjects is projected to initiate in the third quarter of this year. With the start of this proof-of-concept trial assured, the company is currently focused on advancing prime-boost vaccines in additional commercially attractive fields.  According to Eldridge, these programs—in descending order of priority and maturity—will focus on chronic infections caused by hepatitis C virus (HCV), human papilloma virus (HPV), herpes simplex virus type 2 (HSV-2) and malaria.

"We believe that by combining our proprietary DNA vaccine technology with novel molecular adjuvants, improved formulation and a powerful delivery system, Profectus will overcome the previous challenges of efficiently delivering DNA vaccines in vivo," he states.

Already, he notes, the army in Thailand has used the prime-boost approach to demonstrate a 31 percent decrease in HIV transmission. The TriGrid device is also being tested by the U.S. military as an efficient means of delivering biodefense countermeasures.

In an earlier clinical study, Ichor's TriGrid delivery system was shown to significantly enhance immune responses to DNA vaccination in human subjects compared to conventional injection, says company CEO Bob Bernard. He explains that the delivery system comprises a drug-containing syringe and fine-tip electrodes that is held up to the deltoid muscle for injection.

"For more than 15 years, it's been known that electroporation is a good way to transect cells in vitro," he says. "Early work used plate-type electrodes against surface tumors such as skin cancer to deliver chemotherapeutics. Our challenge has been to take a crude research instrument and turn it into a human therapeutic tool."

The system that resulted is "an automated, push-button electroporation system that minimizes operator error and ensures the safe, rapid, effective and reproducible administration of DNA, thereby supporting the development and commercialization of DNA-based products," he states.

In addition to Profectus, San Diego-based Ichor is collaborating with partners in a wide range of studies to test the TriGrid system for delivery of DNA drugs and vaccines to treat diseases such as pandemic flu, hepatitis B, HIV, melanoma, Alzheimer's disease and others. The company doesn't sell its devices, but provides the equipment for partners' labs and trains them in its use. Current research partners include Delphi Genetics, FIT Biotech, Genexine, INSERM, the Johns Hopkins Bloomberg School of Public Health, Leiden University Medical Center, Memorial Sloan-Kettering Cancer Center, the Pasteur Institute, ScanCell, the Scripps Research Institute, the U.S. Army Medical Research Institute of Infectious Diseases (USAMRIID), the Naval Medical Research Center (NMRC), the University of Georgia, the University of Constance and the Vaccine and Infectious Disease Organization (VIDO).

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