Ibalizumab is a non-immunosuppressive monoclonal antibody that binds CD4

CD4

CD4 is a glycoprotein expressed on the surface of T helper cells, monocytes, macrophages, and dendritic cells. It was discovered in the late 1970s and was originally known as leu-3 and T4 before being named CD4 in 1984...

, the primary receptor for HIV

HIV

Human immunodeficiency virus is a lentivirus that causes acquired immunodeficiency syndrome , a condition in humans in which progressive failure of the immune system allows life-threatening opportunistic infections and cancers to thrive...

, and inhibits the viral entry process. It is being investigated as an HIV entry inhibitor with the ability to block both CCR5- and CXCR4

CXCR4

C-X-C chemokine receptor type 4 also known as fusin or CD184 is a protein that in humans is encoded by the CXCR4 gene.- Function :...

-tropic viruses, and is currently undergoing a Phase II clinical trial

Clinical trial

Clinical trials are a set of procedures in medical research and drug development that are conducted to allow safety and efficacy data to be collected for health interventions...

 with an estimated study completion date in December 2010. Specific Research is also conducted at the Aaron Diamond AIDS Research Center

Aaron Diamond AIDS Research Center

Aaron Diamond AIDS Research Center, often abbreviated as ADARC, is a medical research institution dedicated to finding a cure for HIV/AIDS. It is headed by prominent scientist Dr...

 under the direction of David Ho.

Results from a previous Phase II of ibalizumab, reported by the original developer Tanox

Tanox

Tanox was a biopharmaceutical company based in Houston, Texas. The company was founded by two biomedical research scientists, Nancy T. Chang and Tse Wen Chang in March 1986. Nancy was the President and CEO of the company in its 21 year history, while Tse Wen was responsible for creating most of the...

 in 2006, showed that HIV-infected patients who received the drug, in combination with an optimized background regimen (OBR), maintained a considerably greater reduction in viral load

Viral load

Viral load is a measure of the severity of a viral infection, and can be calculated by estimating the amount of virus in an involved body fluid. For example, it can be given in RNA copies per milliliter of blood plasma...

 and experienced a statistically significant increase in CD4+ cells than did patients given placebo

Placebo

A placebo is a simulated or otherwise medically ineffectual treatment for a disease or other medical condition intended to deceive the recipient...

 in combination with OBR. Thus, pending results of further trials, it is presently one of a limited number of viable alternative strategies to contain the virus without recourse to antiretroviral drug cocktails or a vaccine.

Development

Ibalizumab is currently being developed by TaiMed Biologics but was originally developed by Tanox, now part of Genentech

Genentech

Genentech Inc., or Genetic Engineering Technology, Inc., is a biotechnology corporation, founded in 1976 by venture capitalist Robert A. Swanson and biochemist Dr. Herbert Boyer. Trailing the founding of Cetus by five years, it was an important step in the evolution of the biotechnology industry...

. As part of Genentech's takeover of Tanox, the patent for ibalizumab was sold to TaiMed Biologics, a biotech company formed in 2007 with support from the Taiwanese Government through a $20 million investment by the state-owned National Development Fund.