Investigative Agent Elicits Responses in Phase 3 Breast Cancer Trial

Treatment with the investigative agent GLSI-100 (GP2 plus GM-CSF) demonstrated an increased immune response over time in patients with HER2-positive breast cancer following surgery, according to preliminary immune response data from the phase 3 FLAMINGO-01 trial.

Data from the trial, which were shared in a news release from a Greenwich LifeSciences Inc., showed that the investigative agent is creating an immune response over time. Notably, the treatment is creating visible skin reaction at the injection site, which is a positive sign that their immune system is responding to the treatment. Moreover, patients on both the HLA-A*02 (a genetic marker that helps the immune system recognize diseases) and non-HLA-A*02 arms experienced an immune response which increased over time from baseline through the fourth to sixth month.

HLA-A*02 is a common cell surface marker that is part of human leukocyte antigen (HLA) antigens, which determine a person’s tissue type. These antigens, found on most cells, play a key role in the body’s immune response to foreign substances.

Additional findings from the trial note that before receiving the treatment, some patients already had an immune response to GP2, which is the key component of the investigative agent GLSI-100. This suggests that past cancer treatments, like Herceptin (trastuzumab), may have helped the immune system recognize GP2.

The FLAMINGO-01 trial is designed to evaluate the safety and efficacy of GLSI-100 in patients with HER2-positive breast cancer who had residual disease or high-risk pathologic complete response at surgery and who have completed both neoadjuvant and postoperative adjuvant Herceptin-based treatment. 

"We are very encouraged to see that the preliminary results from FLAMINGO-01 show immune responses in both HLA-A*02 and non-HLA-A*02 patients,” CEO Snehal Patel said in the news release. “We are now considering the merits of adding a randomized placebo arm for non-HLA-A*02 patients, transforming this current open-label third arm into effectively a second pivotal and blinded phase 3 trial. If successful, the Company could pursue approval for both HLA-A*02 and non-HLA-A*02 patients in similar time frames using independent or combined analysis of the two patient groups with the potential to double the market for GP2 to up to $10 billion in revenue per year."

More Information on the Investigation

In the phase 3 trial, approximately 500 HLA-A*02 patients are randomized to GLSI-100 or placebo, and up to 250 patients of other HLA types will receive GLSI-100 in a third arm. As reported in a prior news release, the non-HLA-A02 types that are most commonly being enrolled in FLAMINGO-01 include HLA-A*03, HLA-A*24, HLA-A*01, HLA-A*11, HLA-A*68, HLA-A*29, HLA-A*30, HLA-A*23 and HLA-A*33.

During the prospective, randomized, single-blinded, placebo-controlled phase 2b clinical trial, 46 patients with HER2/neu 3+ over-expressor breast cancer were treated with GLSI-100, while 50 placebo patients received GM-CSF alone. After five years of follow-up, the HER2/neu 3+ patients treated with GLSI-100 showed an 80% or greater reduction in cancer recurrences and remained disease-free during the first six months, which is believed to be the time required to reach peak immunity and maximum efficacy.

HER2 (human epidermal growth factor receptor 2) is a cell surface protein expressed in various cancers, including 75% of breast cancers at low (1+), intermediate (2+) and high (3+ or over-expressor) levels, according to the National Cancer Institute.

"The Company may choose to expand its immune response analysis of GP2 specific T cells by sequencing the DNA of the T cells at baseline and after treatment with GP2, continued Patel in the news release. “The T cell sequences can be compared to the immune response increases over time. Expansion into GP2-specific CAR-T cells could potentially become another platform technology to complement GP2 peptide treatment for non-responding higher-risk patients. Blood samples have been collected at multiple time points for future T cell and immune response analysis."

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