leronlimab

Leronlimab, also known as PRO 140, is a humanized monoclonal antibody directed against CCR5, a chemokine receptor on white blood cells. It is administered by subcutaneous injection and has been studied as a potential therapy for HIV-1 infection and other inflammatory conditions.

Mechanism: Leronlimab binds CCR5 and blocks its interaction with natural chemokines and the HIV-1 envelope gp120, inhibiting entry of CCR5-tropic virus into CD4+ T cells. By modulating CCR5 signaling, it may alter immune cell trafficking, which underpins exploration in inflammatory diseases and cancer.

Development for HIV: Leronlimab has undergone Phase 2 and Phase 3 trials as an adjunct to antiretroviral therapy in HIV-1 infection, particularly in patients with limited options. Results have been mixed, and as of 2024 the drug had not received FDA approval for HIV-1. Regulatory submissions have faced requests for additional data and manufacturing information, and CytoDyn has pursued filings in other jurisdictions.

Other indications and research: Beyond HIV, leronlimab has been investigated for oncology, graft-versus-host disease, autoimmune and inflammatory conditions, and more recently in studies related to post-acute sequelae of SARS-CoV-2 infection. Most non-HIV programs remain early-phase, with no proven clinical benefit established.

Safety: Reported adverse events in trials include injection-site reactions, fatigue and headaches. Serious safety concerns have not been definitively established, but long-term safety requires further study.

Availability: Leronlimab is not approved by major regulators for any indication and is generally available only through clinical trials or expanded-access programs.