On December 28, 2020 GT Biopharma, Inc. (OTCQB: GTBP) (GTBP.PA) an immuno-oncology company focused on innovative therapies based on the Company’s proprietary NK cell engager (TriKE) technology platform reported the filing of U.S. and international patent applications, and the initiation of clinical development of TriKE therapy for the treatment of HER2+, HER3+ and HER2+/HER3+ heterodimer complex breast and gastrointestinal cancers (Press release, GT Biopharma, DEC 28, 2020, View Source [SID1234573302]).

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Building upon the success of GTB-3550, where in FDA clinical trials patient #7 showed a 61.7% reduction in cancer cells for high-risk Myelodysplastic Syndromes (HR-MDS), GT Biopharma is expanding the therapeutic utility of its TriKE platform to attack solid tumor cancers. The Company’s HER2 TriKE is based on its modular therapeutic platform, which is composed of a single-chain, tri-specific scFv recombinant fusion protein conjugate composed of the variable regions of the heavy and light chains of anti-CD16 and anti-HER2 antibodies, and a modified form of IL-15. The natural killer (NK) cell stimulating cytokine human IL-15 portion of the molecule provides a self-sustaining signal that activates NK cells and enhances their ability to kill cancer cells.

Anthony Cataldo, Chairman and Chief Executive Officer of GT Biopharma commented, "We are pleased our HER2 TriKE therapeutic product candidate has shown good efficacy in animal models enabling us to initiate GMP manufacturing for FDA clinical trial development. We anticipate submitting our IND application to FDA next year requesting allowance to proceed with an evaluation in patients with complex breast and gastrointestinal cancers. The TriKE platform lends itself to liquid and solid tumors as well as infectious diseases."

HER2, HER3 and HER2/HER3 Heterodimer Complex

About 15% of breast cancer cells have a high density of human epidermal growth factor receptor 2 (HER2) expressed on the cell’s surface. The frequency of HER2 overexpression in gastric and gastroesophageal cancer ranges from 4.4% to 53.4%, with a mean of 17.9%1. HER2 is responsible for telling the cell to divide. Cells with too many HER2 receptors divide uncontrollably which causes the cancer to grow. HER3 is another receptor in the same family as HER2 whose levels can also be increased in cancer cells. HER2 and HER3 can bind together, and collectively accelerate the growth of cancer cells. While targeted therapy against HER2 is an effective first-line treatment in HER2+ breast cancer, acquired resistance remains a clinical challenge.

Breast Cancer

Breast cancer is a group of diseases in which cells in the breast divide in an uncontrolled manner, typically resulting in a lump or mass. Most breast cancers begin in the milk glands (lobules), or in the ducts that connect the lobules to the nipple. In 2020, it is estimated there will be 276,480 new cases of female breast cancer in the USA2. More than 3.8 million women in the USA have been diagnosed with breast cancer as of January 20193. Approximately 13% of women will be diagnosed with invasive breast cancer in their lifetime and 3% will die from breast cancer4.

Gastrointestinal Cancer

Gastrointestinal cancer is the fifth most common cancer worldwide, and accounts for 6.8% of all cancers. It is third most common cause of cancer-specific mortality worldwide according to the World Health Organization. In the USA, gastrointestinal cancers represent 1.5% of all new cancers with estimated annual new cases to be 26,240 and estimated deaths to be 10,800. Gastrointestinal cancer is often diagnosed at an advanced stage, defined as unresectable locoregional or metastatic disease, which has very poor prognosis with 5-year survival not exceeding 5–20%5.