PRO 140 quashes HIV

VANCOUVER, Wash.—CytoDyn Inc., a biotechnology company focused on the development of new therapies for combating human immunodeficiency virus (HIV) infection, today announced that 11 HIV-1 patients receiving PRO 140 monotherapy in an extension study have now successfully reached one year of maximal virologic suppression. These patients substituted their daily Highly Active Antiretroviral Therapy (HAART) regimen with weekly subcutaneous injections of PRO 140. These 11 patients continuing on the extension study have experienced successful monotherapy with PRO 140 for a period ranging from 12 to 15 months to date.

Following the initial 13-week treatment period in the Phase 2b study, patients with full viral load suppression could continue receiving weekly PRO 140 monotherapy (one 350 mg dose) in an extension study. Full or maximal virologic suppression is defined as plasma HIV-1 RNA less than 40 copies/milliliter, the lower limit of detection of the commercial assay. Patients enrolled in this study are infected with strains of HIV-1 that utilize the CCR5 co-receptor. The PRO 140 monoclonal antibody targets CCR5 with high affinity and potently blocks HIV-1 infection.

Jacob P. Lalezari, M.D., the principal investigator of the PRO 140 Phase 2b trial and extension study from Quest Clinical Research, commented, "We are very pleased to report maximal virologic suppression with PRO 140 monotherapy in 11 out of 14 HIV-1 patients who are participating in this treatment-substitution study. The durability of the response to PRO 140 monotherapy over at least a one year period is remarkable. In addition, PRO 140 appears well tolerated in all patients treated to date."

Dr. Nader Pourhassan, CytoDyn's president and CEO, commented, "As a result of these 11 patients reaching this significant milestone of one year without taking any HAART drugs, we are planning to request a meeting with the FDA to discuss a second Phase 3 trial (expanded label) for long-term monotherapy, in addition to our current Phase 3 trial that is underway. We will also discuss with the FDA possibilities of a breakthrough designation for resistance patients. We believe the solution for nonadherence to the current HAART regimen of oral drugs could be a monotherapy with PRO 140, which allows patients to rotate off their toxic drugs for potentially many months. The top-line report for our monotherapy study has been prepared and CytoDyn will be publishing the results from this trial in a peer reviewed journal."

CytoDyn is a biotechnology company focused on the clinical development and potential commercialization of humanized monoclonal antibodies for the treatment and prevention of Human Immunodeficiency Virus (HIV) infection. The company has one of the leading monoclonal antibodies under development for HIV infection, PRO 140, which has finished Phase 2 clinical trials with demonstrated antiviral activity in man and is currently in Phase 3. 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 six Phase 1 and Phase 2 human clinical trials have shown that PRO 140 can significantly reduce viral burden in people infected with HIV. A recent Phase 2b clinical trial demonstrated that PRO 140 can prevent viral escape in patients during several weeks 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.

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 fully 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 towards 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.