Data from a phase 2b trial of the humanized monoclonal antibody, PRO 140, show that it has the potential to become a standalone treatment for patients with an HIV infection, according to data presented this morning at ASM Microbe.

“The PRO 140 treatment was well tolerated by patients with no discontinuation or drug-related adverse effects,” Paul J. Maddon, MD, PhD, Senior Science Advisor to CytoDyn Inc. said in a prepared statement on the antibody. Dr Maddon is a pioneer in the field of HIV entry and viral receptors and he is an inventor of PRO 140. “Importantly, PRO 140 monotherapy can allow patients to avoid the potential toxicity of ART while preserving future drug options,” he added.

Thirty-nine patients enrolled in this phase 2b study were infected with HIV strains that exclusively use CCR5 co-receptors, with ten continuing treatment today (one and a half years on PRO 140). This specific HIV strain appears in approximately 70% of HIV-infected individuals and up to 90% of those newly diagnosed with HIV in the U.S.  CCR5 is a cell surface receptor that is required for HIV entry into target cells and the initiation of viral infection.  The PRO 140 monoclonal antibody binds CCR5 with high affinity and blocks the HIV infection.  To date, more than 200 subjects have been evaluated in all clinical trials of PRO 140.  

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Patients in this 13-week study replaced their daily regimen of oral pill(s) with one weekly dose of a self-administered subcutaneous injection of PRO 140.  In an ongoing extension study of 10 subjects who were successfully treated with PRO 140 alone, full viral suppression has been achieved for nearly one and a half years. The next steps include conducting a larger phase 2b/3 clinical trial for product approval as a standalone treatment.

“PRO 140 may offer a simple, long-acting, single-agent maintenance therapy after initial ART in selected patients with HIV infection,” said Maddon.


Maddon PJ, Dody K, Kazempour K, et al. PRO 140 SC Monotherapy Provides Long-term, Full Virologic Suppression in HIV Patients. Presented atASM Microbe 2016. Boston. June 16-20, 2016.