CytoDyn, a biotechnology company focused on the development of new antibody therapies for combating human immunodeficiency virus (HIV) infection, announces that its application for Orphan Drug Designation (ODD) was not granted by the Office of Orphan Products Development of the FDA because PRO 140 appears to have the potential to treat more than just the subset of multi-drug resistant HIV patients for which the designation was requested.

CytoDyn is currently conducting a pivotal phase IIb/III trial with PRO 140 in combination with other antiretroviral agents in the patient population submitted to the FDA in the ODD application. However, CytoDyn is also conducting a 300-patient phase IIb/III trial with PRO 140 as a single-agent maintenance therapy for HIV-infected patients which is a U.S. patient population that far exceeds the 200,000-patient threshold for ODD.

CytoDyn is a biotechnology company focused on the clinical development and potential commercialization of humanized monoclonal antibodies for the treatment and prevention of HIV infection. The company has one of the leading monoclonal antibodies under development for HIV infection, PRO 140, which has completed phase II clinical trials with demonstrated antiviral activity in man and is currently in phase III. PRO 140 blocks the HIV co-receptor CCR5 on T cells, which prevents viral entry. Clinical trial results thus far indicate that PRO 140 does not negatively affect the normal immune functions that are mediated by CCR5.

Results from seven phase I and phase II human clinical trials have shown that PRO 140 can significantly reduce viral burden in people infected with HIV. A recent phase IIb clinical trial demonstrated that PRO 140 can prevent viral escape in patients during several months of interruption from conventional drug therapy. CytoDyn intends to continue to develop PRO 140 as a therapeutic anti-viral agent in persons infected with HIV and to pursue non-HIV indications where CCR5 and its ligand CCL5 may be involved.

PRO 140 belongs to a new class of HIV/AIDS therapeutics—viral-entry inhibitors—that are intended to protect healthy cells from viral infection. PRO 140 is a humanized IgG4 monoclonal antibody directed against CCR5, a molecular portal that HIV uses to enter T-cells. PRO 140 blocks the predominant HIV (R5) subtype entry into T-cells by masking this required co-receptor, CCR5. Importantly, PRO 140 does not appear to interfere with the normal function of CCR5 in mediating immune responses. PRO 140 does not have agonist activity toward CCR5 but does have antagonist activity to CCL5, which is a central mediator in inflammatory diseases. PRO 140 has been the subject of seven clinical trials, each demonstrating efficacy by significantly reducing or controlling HIV viral load in human test subjects.

PRO 140 has been designated a Fast Track product candidate by the FDA. The PRO 140 antibody appears to be a powerful antiviral agent leading to potentially fewer side effects and less frequent dosing requirements as compared to daily drug therapies currently in use.