VIRxSYS is currently conducting clinical trials to determine the safety, efficacy, and target patient population for VRX496. The Company is currently conducting trials in HIV-infected individuals who are failing traditional drug therapies. In addition, we also have clinical trials planned for patients whose viral load is well controlled by antiretroviral drugs as well as for patients who are on no antiretroviral drugs at all. The combination of these patient populations represents approximately 95% of the HIV patient segments in the industrialized world.
Phase I – Single dosing study in HIV infected patients failing drug therapy
In a Phase I clinical trial concluded in 2005, a single infusion of VRX496 was shown to be safe and tolerable, and evidence indicated some antiviral effects. This five-patient study was conducted at the University of Pennsylvania. No adverse events due to the product, or dose limiting toxicities occurred during the trial. In addition, with the small initial dose used for Phase I, encouraging indications of efficacy were observed as described below, which was unexpected.
In HIV patients who have failed two or more HIV drug regimens, data shows that patients have an average increase in viral load of 0.2 logs over a one-year period of time. However, patients in this trial demonstrated no increase in viral load, and several demonstrated a significant drop.
In late-stage patients who have failed two or more HIV drug regimens, CD4 T cell counts are at best expected to remain stable, and often decrease by a count of 70 or more over a one-year period. In our trial we found that patients in general demonstrated either stability or improvement in their CD4 T cell counts.
HIV is a disease that destroys the immune system of the person infected. After dosing of Phase I patients with VRX496, we have seen evidence of improvement in patients' immune systems.
The encouraging results from this Phase I trial were unexpected, and have been instrumental in designing the protocols for future trials, such as the ongoing Phase II trial described below.
Phase II – Single and repeated dose study in patients failing drug therapy
In an ongoing Phase II clinical trial for VRX496, the Company has dosed a total of 24 patients with multiple-doses of VRX496, with half the patients receiving 4 doses of the therapy, and the other half receiving 8 doses. To date, this trial has demonstrated the safety and tolerability of multiple infusions. We are currently monitoring these patients and we are trying to determine the optimal dose for patients.
In addition, we have expanded our Phase II trial to add approximately 15 patients who will receive a larger, single dose of the VRX496 therapy, instead of the multiple smaller doses given to the other patients in this trial. This could be more effective and would also have several advantages in being less costly, less time consuming, and more convenient for patients.
This 40-patient study is being conducted at Jacobi Medical Center in New York, New York; Circle Medical Center in Norwalk, Connecticut; Stanford University in Stanford, California; the University of Kentucky in Lexington, Kentucky; and Mercy Medical Center in Miami, Florida.
Phase I/II – Study in well-controlled patients
The well-controlled clinical trial, being conducted at the University of Pennsylvania, will include 25 patients whose viral load is under the level of detection through the use of antiretroviral drugs. In this trial, patients will be transferred from drug therapy to VRX496; the goal is to determine if they can go off those drugs permanently. The purpose of this trial is to evaluate the safety and efficacy of VRX496 in a very large segment of the HIV-infected population.
Phase I/II – Study in patients not on antiretroviral therapy
There are two segments of the HIV population that are not on antiretroviral drugs: (i) HIV-positive patients who have not yet reached viral load and CD4 T cell count thresholds judged to be severe enough to warrant drugs, and (ii) HIV patients who have previously been on drugs but suspended those drugs due to either toxicities or the drugs not being effective.
This trial will test VRX496 in these patient populations to determine if VRX496 gene therapy can control their viral loads and postpone or prevent those patients from having to go on antiretroviral drugs.
This trial will include 20 patients and will be conducted at Harvard University, the University of Pennsylvania, and the University of Amsterdam. Funding for the US arm of the trial has been approved by the AIDS Clinical Trial Group of the NIH.
For additional information about our clinical trial program, contact VIRxSYS at clinicaltrials@virxsys.com.
"VIRxSYS has demonstrated the safety and tolerability of the VRX496 therapy in its first-in-class Phase I clinical trial. In addition, the therapy showed some indications of efficacy which is highly encouraging for a Phase I trial."
Tessio Rebello, VIRxSYS Vice President of Clinical Affairs