Sep 17 2013
NanoViricides, Inc. reports that it has successfully improved upon its previous lead anti-HIV drug candidate, based on cell culture studies. An improved broad-spectrum anti-HIV nanoviricide that inhibited two distinctly different types of HIV-1 viruses equally well has been identified.
This drug candidate also exhibited a very large therapeutic index. The Company has previously reported that it is optimizing the anti-HIV drug candidate. These cell culture studies were conducted by Southern Research Institute, Frederick, MD.
The Company reports that it has identified an improved broad-spectrum anti-HIV ligand, based on the previous best ligand from the 2011 study. Also, both of these broad-spectrum ligands, when connected to a different backbone polymer than in the 2011 study, have shown substantially improved inhibition of two different types of HIV-1 virus in a standard cell culture study of virus neutralization and inhibition. HIV-1 Ba-L, a CCR5-using strain as well as HIV-1 IIIB, a CXCR4-using strain, were both inhibited equally well by these two different nanoviricide drug candidates in the standard MAGI HIV Antiviral Assay.
The present cell culture data also showed that the two nanoviricides under study were safe to cells at far greater levels than the level needed for therapeutic effects.
The Company has designed these anti-HIV ligands using reported gp120 protein structures of several HIV-1 strains in order to achieve broad-spectrum effectiveness. The HIV-1 gp120 protein binds to the human cell surface receptors CD4 and CCR5 or CXCR4 thereby enabling entry of the virus into the cell.
The MAGI-R5 cells used in the current study express CD4 and both CXCR4 and CCR5 co-receptors. Different HIV-1 strains are known to use CD4 as a required receptor and, additionally, at least one of the CCR5 or CXCR4 (or both) as a co-receptor. The CCR5+ HIV strains generally transmit from human to human, whereas in the patient’s body, over time, the CXCR4+ HIV strains dominate. Thus it is important to develop a drug that is effective against both of these types of HIV-1 viruses.
The Company believes that its strategy of mimicking the CD4 binding to HIV-1 should allow the development of broad-spectrum anti-HIV drugs. The site on CD4 at which HIV-1 binds remains the same in spite of the large number of mutations that the HIV virus undergoes. The Company’s nanoviricide® technology enables creation of a nanomicelle that looks like the surface of the human cell to the virus, attracting the virus to bind and thereupon neutralizing the virus.
The Company has previously reported unprecedented anti-HIV efficacy from our previous anti-HIV drug candidate, matching or exceeding the effectiveness level of a three drug HAART cocktail in the standard humanized mouse model studies. In this mouse model, the mouse immune system is wiped out and replaced by human immune system, thereby allowing drug effects against HIV-1 infection of human T cells to be observed. In August 2011, the Company reported that it had identified an anti-HIV ligand that was superior to the ones employed by us previously. This new ligand was identified as superior by employing a less effective backbone polymer to make the nanoviricides for the 2011 study. In this study, the clinical benefit of HIVCide was found to be sustained for at least four weeks after the last drug dose. Treatment with the lead anti-HIV nanoviricide both (1) reduced the HIV viral load and (2) also protected the human T cells (CD4+,CD8+), equally well as compared to treatment with the three-drug HAART cocktail, at 24-days as well as at 48-days, even though the HIVCide treatment was stopped at 20 days. In addition, the lead HIVCide drug candidate provided these clinical benefits at a much lower drug load than that of the HAART therapy.
With further optimization, the Company believes that it has now achieved extremely high efficacy levels for its lead and backup HIVCide candidates. Further optimization of the nanomicelle portion of the anti-HIV drug candidates is now in progress.
The anti-HIV animal studies were performed in the standard anti-HIV animal model known as the “SCID/hu-Thy/Liv mouse model” at KARD Scientific, Inc., Beverly, MA, in a Bio-Safety Level 3 (BSL-3) facility under the guidance of Dr. Krishna Menon who has extensive experience in pre-clinical evaluation of drug candidates in disease-relevant animal models. The three drug HAART cocktail used for comparison in this study is one of the combination therapies recommended for initial therapy in humans, viz. AZT, 3TC and Efavirenz. Other specific results of these prior studies were previously reported by the Company.