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Ibalizumab (TMB-355) Intramuscular Injection

Ibalizumab (TMB-355) Intramuscular Injection

Ibalizumab (TMB-355) is the first humanized monoclonal antibody (mAb) developed for the treatment of HIV-1 infection by blocking viral entry. Unlike other antiretroviral agents, ibalizumab binds to the second extracellular domain of the CD4 receptor, away from Major Histocompatibility Complex II molecule (MHC II) binding sites, ultimately interfering with post-attachment steps required for entry of HIV-1 virus particles into host cells and preventing the viral transmission that occurs via cell-cell fusion. It prevents HIV from infecting CD4+ immune cells while preserving normal immunological function. Intravenous ibalizumab was launched in the US in 2018 under the trade name Trogarzo™.

Ibalizumab Intramuscular / Subcutaneous Injection Dosage Form Development

Along with the successful development of ibalizumab (i.v.) infusion dosage, TaiMed Biologics dedicates to provide a more convenient administration options for HIV patients. A phase-1 clinical trial of the subcutaneous (s.c.) dosage was funded by the Bill & Melinda Gates Foundation and was completed in 2012 in U.S. No serious adverse events (SAE) and no injection site reactions were reported in this HIV-negative human pharmacokinetics bridging study, which provided the possibility for s.c. development. 

A phase-1/2 study for subcutaneous/intramuscular (i.m.) injection was completed in 2016 in Taiwan. The data shows tremendous antiviral activity in both s.c. and i.m. dosages with no additional safety concern. The pharmacokinetic profiles in HIV patients between i.m. and i.v. were comparable at the dosages of 2000 mg and 800 mg of ibalizumab, which are the same doses of approved ibalizumab i.v. product.

Ibalizumab Intramuscular Injection

A phase-3 study for i.m. injection was initiated in 2021 in order to provide a more convenient and efficient dosing option to patients and health professionals. After completion of the trial, a label extension application will be submitted to U.S. FDA to include i.m. as an additional route of administration.

The same formulation is used for both ibalizumab i.v. and i.m. The i.m. route of administration will inject undiluted ibalizumab.   


2003: fast track status granted by U.S. FDA.
2012: completion of a phase-1 clinical trial for s.c. injection dosage form.
2014: orphan drug designation granted for HIV MDR patients by U.S. FDA.
2016: completion of a phase-1/2 clinical trial for s.c. and i.m. injection dosage forms.
2021: Initiation of a phase-3 clinical trial for i.m. in U.S.


CROI 2017