Investigational HIV Monoclonal Antibody Effective in Multiple Drug Resistant HIV-1

Ibalizumab binds primarily to the second extracellular domain of the CD4+ T-cell receptor.
Ibalizumab binds primarily to the second extracellular domain of the CD4+ T-cell receptor.

Theratechnologies has announced further results from its 24 week Phase 3 trial of ibalizumab (TMB-301, ClinicalTrials.gov Identifier: NCT02475629) showing that patients on ibalizumab plus an optimized background regimen (OBR) had a mean increase in CD4+ T cell of 48 cells/µL.

Ibalizumab, a humanized monoclonal antibody, is being investigated as a potential treatment for multidrug resistant (MDR) HIV-1 infection. Unlike other antiretroviral drugs, ibalizumab binds primarily to the second extracellular domain of the CD4+ T cell receptor, away from major histocompatibility complex II molecule binding sites. It potentially prevents HIV from infecting CD4+ immune cells while preserving normal immunological function. Ibalizumab is active against HIV-1 resistant to all approved antiretroviral agents.

The latest results supplement those previously reported, showing that 83% of the 40 enrolled patients achieved a ≥0.5 log10 decrease in viral load from baseline 7 days after the single loading dose of 2000mg of ibalizumab (primary endpoint) and a mean reduction in viral load of 1.6 log10 over the 24 week treatment period.

“These data suggest that for these [multidrug resistant] patients, ibalizumab could be an important new treatment option,” added Dr. Brinda Emu, assistant professor of medicine at Yale School of Medicine.

Patients with baseline CD4+ T cells lower than 50 cells/µL (17 patients) had an increase of 9 cells/µL, those with CD4T cells between 50 and 200 cells/µL (10 patients) had an increase of 75 cells/µL and those with CD4T cells higher than 200 cells/µL (13 patients) had an increase of 78 cells/µL.

“These results continue to support the submission of a Biologics License Application (BLA) to the FDA,” said Christian Marsolais, PhD, SVP, CMO of Theratechnologies. “If approved ibalizumab will be the first antiretroviral treatment with a new mechanism of action to be approved in close to 10 years.” The Phase 3 study is the last pivotal study necessary for the completion of a BLA, which is expected to be filed with the FDA.

There was one case of immune reconstitution inflammatory syndrome but apart from that there were no serious adverse events considered to be related to ibalizumab, which is consistent with previous trial results.

Ibalizumab has received “Breakthrough Therapy” designation from the FDA.

Reference

Theratechnologies announces comparative PK data on the intramuscular and intravenous administration of the monoclonal antibody and long-acting investigational antiretroviral ibalizumab [news release]. Montreal, Canada: Theratechnologies;  February 15, 2017. http://theratech.com/sites/default/files/news_release_en/nr-20170215-en.pdf. Accessed February 22, 2017.  

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