Immune Response: Phase 2 studies of HIV-1 immunogen promising

By E. Janene Geiss

Philadelphia, Feb. 10 - The Immune Response Corp. said Friday that the final results from a phase 2 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 begin antiretroviral therapy, according to a company news release.

The data was presented at this week's annual Conference on Retroviruses and Opportunistic Infections in Denver, officials said.

"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," Joseph O'Neill, president and chief executive officer, said in the release.

"We have two ongoing clinical studies that will investigate IR103 in the drug-naïve patient population. We will be expanding them and look forward to reporting the findings," O'Neill said in the release.

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, officials said.

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, officials said.

The multi-center, single-blind, randomized study followed 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/uL at study entry, officials said.

Patients received three injections of the HIV-1 immunogen, IFA or saline at weeks 0, 12, and 24. A fourth group received only a single injection of the HIV-1 immunogen.

Although minor adverse events were reported, no treatment-limiting toxicities have been recorded to date, officials said.

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 said it is planning a clinical program that would use the data from this and other trials to design IR103 trials soon.

The HIV-1 immunogen and IR103 are not approved by any regulatory agencies in any country at this time.

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 immunogen (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, officials said.

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, officials said.

The company recently completed the first part of a 49-patient phase 1/2 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 it becomes 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, officials said.

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, officials said.

These studies, which the company said it plans to expand, will ultimately enroll more than 200 drug naïve patients.

Immune Response is a Carlsbad, Calif., immuno-pharmaceutical company focused on developing products to treat autoimmune and infectious diseases.

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