Greenwich LifeSciences announced that the FDA has granted Fast Track designation for GLSI-100, an immunotherapy designed to prevent breast cancer recurrences in patients with HLA-A*02 genotype and HER2-positive breast cancer who have completed standard HER2/neu targeted therapy. The designation specifically recognizes GLSI-100's potential to improve invasive breast cancer-free survival in this patient population.
The Fast Track designation enables enhanced communication between Greenwich LifeSciences and the FDA throughout the drug development process, potentially leading to earlier approval. The company may utilize a rolling review process, allowing submission of completed sections of the Biologic License Application (BLA) for review while other portions are still being finalized.
"Greenwich is pleased that the FDA sees the potential of GLSI-100 to change important clinical outcomes in this population of breast cancer patients," commented Dr. Jaye Thompson, VP Clinical and Regulatory Affairs. "We continue to work earnestly to collect data to support a BLA filing demonstrating this benefit."
Promising Phase IIb Results Support FDA Decision
The Fast Track designation builds on compelling Phase IIb clinical trial data that demonstrated significant efficacy in preventing breast cancer recurrence. In the prospective, randomized, single-blinded, placebo-controlled, multi-center trial led by MD Anderson Cancer Center across 16 sites, 46 HER2/neu 3+ over-expressor patients received GLSI-100 treatment while 50 placebo patients received GM-CSF alone.
After 5 years of follow-up, patients treated with GLSI-100 who remained disease-free over the first 6 months showed an 80% or greater reduction in cancer recurrences. This represents a substantial improvement compared to the 20-50% reduction in recurrence rates achieved by other approved products. The treatment demonstrated peak immune response at 6 months with no reported serious adverse events attributable to treatment and a well-tolerated safety profile.
The Primary Immunization Series, consisting of the first 6 GLSI-100 injections over 6 months, elicited a potent immune response as measured by local skin tests and immunological assays. Booster injections administered every 6 months prolonged the immune response, providing longer-term protection. Across Phase IIb and three Phase I clinical trials involving 146 patients, the GP2 immunotherapy was well tolerated with no reported serious adverse events related to GLSI-100.
Phase III FLAMINGO-01 Trial Underway
Greenwich LifeSciences is currently conducting FLAMINGO-01 (NCT05232916), a Phase III clinical trial evaluating GLSI-100's safety and efficacy in HER2-positive breast cancer patients who had residual disease or high-risk pathologic complete response at surgery and completed both neoadjuvant and postoperative adjuvant trastuzumab-based treatment.
The trial, led by Baylor College of Medicine, includes US and European clinical sites from university-based hospitals and academic networks, with plans to expand to up to 150 sites globally. In the double-blinded arms, approximately 500 HLA-A*02 patients will be randomized to GLSI-100 or placebo, while up to 250 patients of other HLA types will receive GLSI-100 in a third arm.
The trial design targets detection of a hazard ratio of 0.3 in invasive breast cancer-free survival, requiring 28 events. An interim analysis for superiority and futility will be conducted when at least 14 events have occurred. The sample size provides 80% power if the annual rate of events in placebo-treated subjects is 2.4% or greater.
Addressing Significant Medical Need
CEO Snehal Patel emphasized the potential impact of GLSI-100, stating, "By showing the potential of GLSI-100 to prevent metastatic breast cancer recurrence in the patient population that we are studying, we were able to estimate the potential lives that could be saved." The company plans to continue discussions with the FDA and potentially European regulatory authorities to explore making GP2 and GLSI-100 available to larger populations.
The treatment addresses a significant medical need, as one in eight U.S. women will develop invasive breast cancer over her lifetime, with approximately 300,000 new breast cancer patients and 4 million breast cancer survivors. HER2 protein is expressed in 75% of breast cancers at various levels, including low (1+), intermediate (2+), and high (3+ or over-expressor) levels.
GLSI-100 consists of GP2, a 9 amino acid transmembrane peptide of the HER2 protein, combined with GM-CSF as an immunological adjuvant. The immunotherapy is designed to prevent breast cancer recurrences in patients who have previously undergone surgery by targeting the HER2 protein expressed across multiple cancer types.
