AmMax Bio has announced the dosing of the first subjects in its Phase IIb clinical trial of AMB-05X to treat tenosynovial giant cell tumour (TGCT), a serious and debilitating locally aggressive tumour.

The trial has been designed for optimising the treatment regimen and evaluating the efficacy of a dosing period of more than six months.

The open-label, dose-ranging, adaptive trial will assess the efficacy, safety, and pharmacokinetics of intra-articular administration of the therapy in TGCT patients following treatment for 24 weeks, and an additional long-term extension period.

AmMax Bio CEO Larry Hsu said: “The expansion of our TGCT programme into this Phase IIb study builds on the strong proof-of-concept safety and efficacy data reported in 2022, which evaluated the treatment of AMB-05X in TGCT patients over a 12-week period.

“Since announcing those results, both FDA Fast Track designation and EMA PRIME designation have been granted to AMB-05X, reflecting its significant potential to address the unmet medical need for this patient population with few treatment options.

“With six months of treatment, we believe patients will receive greater benefit with AMB-05X than any other pharmacological options, and we plan to use the data from this trial to finalise our Phase III study design.”​

Initial results from the Phase IIb trial are expected in the second half of this year.

AMB-05X is a potent monoclonal antibody against CSF1R and received Fast Track designation and PRIME designation from the FDA and EMA, respectively, for TGCT.

It represents a therapeutic platform that acts on serious macrophage-driven inflammatory, fibrotic, and neovascular diseases.