Privately held VIRxSYS Corp. raised $20 million in a Series G round, bringing the company's total fund raising to $87 million since it was founded in 1998 to develop genetic therapies against HIV and cancer.

Funds in the latest round came from warrants offered to investors - comprised primarily of high net worth individuals - in the company's $31 million Series F closed in October 2005. More than 60 percent of investors returned for the Series G, said Riku Rautsola, president and CEO of Gaithersburg, Md.-based VIRxSYS, "so we were very pleased with that." (See BioWorld Today, Oct. 12, 2005.)

Rautsola called the recent financing "a very important milestone for us," and said money would support ongoing research and clinical activities, particularly the development of VRX496, a gene-based immunotherapy for HIV that uses the company's lentiviral vector platform.

That product is in several Phase II studies and the recent financing "should carry us to the end of Phase II," Rautsola said, as well as "enable us to complete discussions with potential strategic partners" to take VRX496 into Phase III.

VIRxSYS' work uses a delivery system based on a lentiviral vector as the delivery vehicle. To create VRX496, the company inserted a long antisense sequence targeting the HIV envelope protein into the vector aimed at inhibiting HIV replication. When HIV replicates with a T cell, it's designed to trigger the replication of the drug, which binds to the virus and destroys it.

The company reported promising findings from a Phase I study, which tested VRX496 in five patients with chronic HIV infection who had failed at least two antiretroviral regimens. Those data demonstrated a decrease in viral load, and the drug was shown to be safe and well tolerated.

The ongoing Phase II program includes a multiple-dosing stage, and results of that are expected in the spring. The second stage of the Phase II is a dose-escalation study, the results of which are expected in September or October.

Beyond that, there are exploratory trials, including a study at the University of Pennsylvania in HIV patients who achieved stabilized viral loads with standard therapy, and studies at the University of Harvard and the University of Amsterdam that are testing the VRX496 in treatment-na ve patients and patients who are not on any treatment.

"We've segmented Phase II to explore as much as we can," Rautsola said, adding that data should help VIRxSYS determine which patient populations would be most helped by the treatment.

"We believe the best impact would be in patients whose immune systems are fairly well intact," he said, and there are "some signs that initial treatment would be given in combination with [standard antiretroviral treatment]. Then, once the immune system is more restored, [patients] may be able to drop the antiretroviral drugs."

By the end of Phase II, the company hopes to have "enough information to create a good basis for a Phase III trial," Rautsola told BioWorld Today.

Positive Phase II results also could "show that gene therapy has a future," he added.

Despite the attention and funding gene therapy work has received over the past 10 or 20 years, there has been little to show for it, a fact Rautsola attributes to the difficulty in getting the treatment into cells.

VIRxSYS is the first to try lentiviral vectors as a delivery vehicle, and the company is "seeing a remarkable capability in transferring the payloads into the genome of the cell," he said.

Following VRX496, the company is using its lentiviral vector technology to develop treatments for genetic diseases, such as hemophilia, and a vector program in cancer, with an initial focus on myeloma, using an autologous stem cell approach.

Early work also is ongoing on a biologic targeting HDL via the ApoA-1 gene.

The 65-employee company, which Rautsola described as a "serial incubator," intends to seek partners for all those programs after Phase II, though it might partner the HDL program earlier, "especially if we can show proof of concept in another area like HIV or cancer before that."