Greenwich LifeSciences, Inc.: directors' dealings · United States · SEC (Form 4)

About Greenwich LifeSciences, Inc.

Greenwich LifeSciences, Inc. (NASDAQ: GLSI) is a United States-based clinical-stage biopharmaceutical company headquartered in the Houston, Texas area. Its business is highly focused: the company is developing GP2, a peptide immunotherapy designed to help prevent breast cancer recurrence in selected HER2/neu-positive patients. Greenwich LifeSciences refers to the GP2 plus GM-CSF combination as GLSI-100, which is the centerpiece of its clinical strategy and the asset around which investor attention is currently concentrated. The company’s history is typical of a specialty biotech built around a single lead program. Rather than operating a broad commercial portfolio, Greenwich LifeSciences has pursued a focused development path aimed at advancing GLSI-100 through late-stage clinical evaluation and, ultimately, toward potential regulatory submission. Its flagship trial, FLAMINGO-01, is a global Phase III study designed to assess the safety and efficacy of GLSI-100 in HER2-positive breast cancer patients who have completed standard trastuzumab-based therapy. According to company disclosures, the trial is enrolling at up to 150 sites globally, underscoring the operational scale of the program. From a market-positioning perspective, Greenwich LifeSciences competes in a crowded and scientifically demanding oncology landscape. The target setting—HER2-positive breast cancer recurrence prevention—includes established therapies from large multinational pharmaceutical companies and a high evidentiary bar for any new entrant. Greenwich’s competitive angle is not breadth, but specificity: it is betting on a differentiated immunotherapy approach in a well-defined patient segment. That makes the investment case relatively easy to understand but also inherently binary, as value creation depends heavily on clinical execution, trial outcomes, and regulatory progress. Several recent corporate developments are relevant for investors. In 2025, the company announced that GLSI-100 received U.S. FDA Fast Track designation in the HLA-A*02 population, a meaningful regulatory milestone that can facilitate more frequent interactions with the FDA and potentially speed development. Greenwich also said it was building out an internal clinical operations team to reduce reliance on external CROs and improve efficiency as FLAMINGO-01 expands. In 2026, the company continued to update investors on its annual filing status and financing strategy, highlighting the ongoing capital requirements of a Phase III oncology program. For French-speaking investors in Europe, Greenwich LifeSciences is best viewed as a narrowly focused NASDAQ-listed biotechnology company in the United States, with a single leading asset, clear clinical ambition, and substantial execution and financing risk.