Patients administered PRO 140 monotherapy reach 2 years of complete remission in trial.
The first of 11 patients with HIV-1 administered PRO 140 monotherapy in a phase 2b extension study reached 2 years of complete virologic suppression.
PRO 140 is a humanized IgG4 monoclonal antibody against CCR5, and is designed to block the predominant HIV (R5) subtype entry into T cells by masking CCR5. Four additional patients are expected to hit the 2-year benchmark in the next 3 weeks, followed by 5 more in about 2 months, according to a press release by CytoDyn.
“We are pleased that 10 HIV patients who participated in our phase 2b study are approach the significant milestone of 2 years of complete virologic suppression on PRO 140 as a single agent,” said Nader Pourhassan, PhD, president and CEO of CytoDyn Inc. “These patients are receiving weekly subcutaneous PRO 140 injections as a substitution for daily regiments of Highly Active Antiretroviral Therapy (HAART) regimens without the notable drawbacks of HAART.”
Patients enrolled in the phase 2b extension study showed full HIV viral load suppression during a 12-week phase 2b study, where they received weekly subcutaneous injections of PRO 140 in a 350-mg dose instead of their HAART regimens.
The phase 2b trail enrolled 40 patients, 35 of whom were evaluable, while the other 5 were excluded for tropism screening failures or protocol violations. Twenty patients completed the 12-week, phase 2b study with HIV viral load suppression and were eligible for the extension arm, but only 15 were granted entry.
Four of the 15 patients who entered the extension arm were disqualified because of a lack of follow-up (relocation), or a disqualification unrelated to PRO 140. One of these patients was disqualified because of treatment failure.
This left 10 evaluable patients, who are now at, or close to, the 2-year benchmark or complete HIV viral load suppression.
In the ongoing phase 2b extension study, 1 of 11 patients who recently entered show complete HIV viral load suppression following an initial 12-week treatment period. Complete virologic suppression is defined as plasma HIV-1 RNA less than 40 copies/mL, which is the lower limit of detection in the commercial assay.
Individuals eligible for the phase 2b monotherapy study were evaluated for infections with strains of HIV-1 that utilize the CCR5 co-receptor, according to the press release. Blood was drawn from 9 of the patients in the extension study after a year of monotherapy.
Six of the 9 patients, who had their viral load checked with a single copy assay, were found to have their viral load less than one HIV-1 RNA copy/mL blood and 2 patients had less than 4 copies/mL.