US biopharmaceutical company Greenwich LifeSciences, Inc. (NASDAQ: GLSI) said on Wednesday it has received regulatory clearance to extend its Phase III FLAMINGO-01 trial into the United Kingdom, enabling the addition of 5–10 UK sites to the 170–180 centres already authorised across the US and Europe.

The Company is working with The Royal Marsden, a specialist cancer centre in London, and has held start-up discussions with academic sites in London, Cambridge, Edinburgh, Oxford, Manchester, Southampton, Cardiff and other cities. The Royal Marsden, founded in 1851, operates as the UK's only cancer-focused NIHR Biomedical Research Centre in partnership with The Institute of Cancer Research.

More than 1,500 patients have been screened in FLAMINGO-01, with 250 non-HLA-A*02 patients fully enrolled and treated with GLSI-100. Preliminary analysis indicates a 70–80% reduction in recurrence rates after completion of the Primary Immunisation Series, with immune response and safety trends consistent with earlier studies.

Open-label data remain preliminary and blinded, and may differ once full review is completed. Phase IIb results in HLA-A*02 patients previously showed an 80% or greater reduction in metastatic recurrence over five years, supported by strong immune responses.

FLAMINGO-01 is evaluating Fast Track-designated GLSI-100 in HER2-positive breast cancer patients who have completed trastuzumab-based treatment, with global expansion planned.

Cancer Research UK data show around 59,400 new breast cancer cases annually in the UK, representing 30% of all new female cancer diagnoses.