Shares of Greenwich LifeSciences Inc. (GLSI) have been on a tear over the past ten days as the clinical-stage biotech pushes ahead with its financing strategy and prepares to implement risk-reducing modifications to the phase III trial of its investigational breast cancer immunotherapy, GLSI-100, upon the regulatory go-ahead.
GLSI-100 is a combination of GP2 peptide vaccine and GM-CSF, an immune system booster, which is designed to help the body recognize and fight cancer cells that express the HER2/neu protein. HER2/neu is a cell surface receptor protein that is expressed in 75% of breast cancer cases, in addition to a variety of other common cancers. GLSI-100 is being developed for patients with breast cancer who are at high risk of the disease coming back after surgery and standard treatments.
A double-blind, placebo-controlled phase 3 trial of GLSI-100, dubbed FLAMINGO-01, is currently underway in HLA-A*02-positive and HER2/neu-positive breast cancer patients who are at high risk for disease recurrence and have completed both neoadjuvant and postoperative adjuvant standard of care therapy. In this study, about 500 HLA-A*02 patients are planned to be randomly assigned to receive either GLSI-100 or a placebo, while up to 250 patients with other HLA types received GLSI-100 in the third open-label arm.
A preliminary analysis of the fully enrolled 250-patient open-label non-HLA-A*02 arm of the FLAMINGO-01 study, announced earlier this month, showed encouraging results, including an approximately 80% reduction in recurrence rate.
The company is planning to implement certain modifications to the FLAMINGO 01 study, pending regulatory approval, including:
-- Increasing the study size, which would enhance the statistical power and reduce risk by designing the trial to assume a greater number of recurrences, even though fewer recurrences may be anticipated and observed.-- Doubling or quadrupling the enrollment rate, thereby increasing patient-years in the study more rapidly, proportionally raising the event rate, and potentially shortening the time to reach interim analyses or other key milestones.-- Continuing enrollment past interim analyses to maintain momentum at active clinical sites.-- Using interim analyses to potentially resize the study, adjust subsequent interim analyses, modify the number of events triggering an analysis, or change the study timeline based on recommendations from an independent committee.-- Incorporating a recently manufactured GP2 commercial drug product lot in the FLAMINGO 01 study.
As per the official listing on ClinicalTrials.gov, the projected completion date of the FLAMINGO 01 trial remains December?31,?2026.
Breast cancer is the most common cancer in women in the United States, with more than 4 million breast cancer survivors, according to the American Cancer Society. As mentioned earlier, about 75% of breast cancers express HER2 (human epidermal growth factor receptor 2), a cell-surface receptor protein, at low (1+), intermediate (2+), or high (3+ or overexpressed) levels. HER2 causes cancer cells to grow and divide faster than normal.
Partnering Strategy
The company actively attends partnering conferences, creating potential opportunities to collaborate with large pharmaceutical companies that often acquire or partner with smaller biotechs developing promising breast cancer therapies.
Roche, the developer of HER2-targeted therapies such as Herceptin, Perjeta, and Kadcyla; AstraZeneca and Daiichi Sankyo, co-developers of Enhertu; Pfizer, the marketer of Ibrance; Gilead Sciences, with Trodelvy; Novartis, developer of Kisqali; and Merck, with Keytruda, are some of the major pharmaceutical companies actively shaping the breast cancer treatment landscape.
Financing Strategy
The company, which held $3.81 million in cash as of September 30, 2025, is utilizing its ATM (At-the-Market) offering strategy to manage cash efficiently, maintain a lean cash burn, and minimize shareholder dilution.
Between January 1, 2025, and September 30, 2025, the company completed ATM offerings through H.C. Wainwright, selling 621,674 shares of common stock at an average price of $10.44 per share, generating gross proceeds of $6.49 million.
Lock-Up Period for Insider and Pre-IPO Shares Extended
The Board of Directors has extended the lock-up period for shares held by the company's directors, officers, and existing pre-IPO investors until September 30, 2026, approximately 72 months from the date of its IPO.
Greenwich LifeSciences shares began trading on the Nasdaq Capital Market on September 25, 2020, under the symbol "GLSI" priced at $5.75 each.
When we alerted readers to GLSI on April 3, 2025, it was trading around $9.05. The stock touched a 52-week intraday high of $22.31 on Friday (Dec.26, 2025), before closing at $20.68.
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