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Data Indicate that Whole-Inactivated HIV-1 Immunogen Induces HIV-Specific Immune Responses in HIV-Infected, HAART-Naïve Patients

10 Feb 2006

Final Data from IMNR.OB’s Italian Study Presented in Poster at CROI Annual Meeting

CARISBAD, CA, USA | Feb 10, 2006 | The Immune Response Corporation (OTCBB:IMNR.OB) announced today that the final

results from a Phase II clinical study indicate that the Company’s whole-inactivated HIV-1 immunogen induces HIV-specific immune responses in HIV-infected, antiretroviral drug-naïve patients. Specifically, this original formulation product showed potential to stimulate key immunologic parameters and to stabilize the loss of CD4+ cells, which could help prolong the time before these patients need to initiate antiretroviral therapy. The poster was presented at this week’s 13th Conference on Retroviruses and Opportunistic Infections (CROI) in Denver.

“CD4+ counts may be an especially important marker of disease progression and we plan to build on this data with our most potent clinical candidate, IR103,” noted Joseph O’Neill, M.D., President and Chief Executive Officer of The Immune Response Corporation. “We have two ongoing clinical studies that will investigate IR103 in the drug-naive patient population. We will be expanding them and look forward to reporting the findings.”

The analysis included data from 49 patients that completed the study, and showed that median absolute CD4+ cell counts remained stable through week 28 in the patients that received three injections of the HIV-1 immunogen but declined in both the IFA and saline groups. The HIV-1 immunogen’s effect on immune reconstitution was evidenced by an augmented production of factors known to reduce HIV replication, such as beta chemokines and alpha defensin. These data suggest a possible mode of action via boosting the body’s own defense against HIV, which could play a role in delaying the initiation of antiretroviral therapy.

The multi-center, single-blind, randomized study followed a total of 51 patients over 28 weeks following treatment with the Company’s patented HIV-1 immunogen, IFA or saline. Patients were antiretroviral-therapy naïve and had HIV RNA levels between 10,000 and 40,000 copies/mL and CD4+ counts between 400 and 800 cells/µL at study entry. Patients received three injections of the HIV-1 immunogen (n=19), IFA (n=10), or saline (n=11) at weeks 0, 12, and 24. A fourth group received only a single injection of the HIV-1 immunogen at week 0 (n = 11). Although minor adverse events were reported, no treatment-limiting toxicities have been recorded to date.

This trial was intended to explore the potential utility of the HIV-1 immunogen and was not designed to have enough statistical power to be used for regulatory approval. The Company is planning a clinical program that would use the data from this and other trials to design IR103 trials in the near future. The HIV-1 immunogen and IR103 are not approved by any regulatory agencies in any country at this time.

About IR103

More than 25 million people have died since human immunodeficiency virus (HIV) was first recognized in 1981 (source: UNAIDS, December 2005), and the new infection rate continues to grow at an alarming rate. Despite medical advances, the worldwide pandemic continues to claim more than 3.1 million lives each year (source: UNAIDS, December 2005). Additional safe and effective treatments are desperately needed.

IR103 is a second-generation HIV immunotherapy based on the Company’s patented whole-inactivated virus technology, which was co-invented by Dr. Jonas Salk and indicated to be safe and immunogenic in extensive clinical studies of the Company’s HIV-1 immungen (REMUNE®), the Company’s first generation HIV product candidate. Preclinical research and recent clinical data show that IR103 is a more potent formulation that combines its whole-inactivated antigen with a synthetic Toll-like receptor (TLR-9) agonist to create enhanced HIV-specific immune responses. This product differs from currently available antiretroviral drug therapies since it is designed to stimulate an HIV-infected individual’s immune system to fight the virus.

The Company recently completed the first part of a 49-patient Phase I/II five-arm, randomized, single-blind, controlled, multi-center clinical study of safety and bioactivity of IR103 in HIV patients on HAART (highly active antiretroviral therapy) at sites in the United Kingdom and Canada, and plans to report new data as they become available later this year. Preliminary results of this trial, reported last year, indicate that IR103 is safe, induces HIV-specific immune responses and greatly enhances IFN-gamma and RANTES mRNA. IFN-gamma and RANTES are considered immune system markers that give an estimate of the robustness of the immune response generated by IR103 in patients.

The second part of this study, along with another similar study in Italy, will investigate IR103 as a first-line treatment for drug-naïve HIV-infected individuals not yet eligible for antiretroviral therapy according to current medical guidelines. These studies, which the Company plans to expand, will ultimately enroll over 200 drug naïve patients. Along with tracking safety and measuring HIV-specific immune responses, these studies will assess IR103’s ability to affect patients’ CD4+ counts. CD4+ count is a critical marker of HIV disease progression that is used, along with viral load, to determine when a patient should begin antiretroviral therapy. The Company believes an immune-based therapy that could stabilize CD4+ counts could be used to delay initiation of antiretroviral therapy and serve as an important advance in the treatment of HIV. Final data from a drug-naïve patient Phase II Italian study of REMUNE® showed that median absolute CD4+ cell counts of patients that received three injections of the Company’s first generation immunotherapy remained stable through week 28, while declining in patients in the placebo groups. The Company believes that the increased potency of IR103 could translate to a more durable and pronounced effect on CD4+ counts.

About The Immune Response Corporation

The Immune Response Corporation (OTCBB: IMNR.OB) is an immuno-pharmaceutical company focused on developing products to treat autoimmune and infectious diseases. The Company’s lead immune-based therapeutic product candidates are NeuroVax™ for the treatment of multiple sclerosis (MS) and IR103 for the treatment of HIV infection. Both of these therapies are in Phase II clinical development and are designed to stimulate pathogen-specific immune responses aimed at slowing or halting the rate of disease progression.

NeuroVax™, which is based on the Company’s patented T-cell receptor (TCR) peptide technology, has shown potential clinical value in the treatment of relapsing forms of MS. NeuroVax™ has been shown to stimulate strong disease specific cell mediated immunity in nearly all patients treated and appears to work by enhancing levels of FOXP3+ Treg cells that are able to down regulate the activity of pathogenic T-cells that cause MS. Increasing scientific findings have associated diminished levels of FOXP3+ Treg cell responses with the pathogenesis and progression of MS and other autoimmune diseases such as rheumatoid arthritis (RA), psoriasis and Crohn’s disease. In addition to MS, the Company has open Investigational New Drug Applications (IND) with the FDA for clinical evaluation of TCR peptide-based immune-based therapies for RA and psoriasis.

IR103 is based on the Company’s patented whole-inactivated virus technology, co-invented by Dr. Jonas Salk and indicated to be safe and immunogenic in extensive clinical studies of REMUNE®, the Company’s first generation HIV product candidate. IR103 is a more potent formulation that combines its whole-inactivated antigen with a synthetic Toll-like receptor (TLR-9) agonist to create enhanced HIV-specific immune responses. The Company is currently testing IR103 in two Phase II clinical studies as a first-line treatment for drug-naïve HIV-infected individuals not yet eligible for antiretroviral therapy according to current medical guidelines.

SOURCE: The Immune Response Corporation

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