On December 6, 2018 GT Biopharma, Inc. (OTCQB: GTBP and Euronext Paris GTBP.PA) ("GT Biopharma" or the "Company"), an immuno-oncology biotechnology company focused on innovative treatments based on the Company’s proprietary NK-engager and Bispecific Antibody Drug Conjugate platforms, reported that it presented data demonstrating the effectiveness of the Company’s Tri-specific Killer Engagers (TriKEs) for the treatment of acute myeloid leukemia (AML) presented at the American Society of Hematology (ASH) (Free ASH Whitepaper) Annual Meeting (Press release, GT Biopharma , DEC 6, 2018, View Source [SID1234539518]).
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Jeffrey Miller, MD, Deputy Director, Masonic Cancer Center, University of Minnesota commented, "These studies demonstrate the adaptability of the TriKE platform to optimize TriKE constructs and candidate selection in order to address unmet medical needs. We continue to work with our partners at GT Biopharma in moving the TriKE platform forward."
The Company’s TriKE product candidates are single-chain, tri-specific scFv recombinant fusion proteins composed of the variable regions of the heavy and light chains (or heavy chain only) of anti-CD16 antibodies, wild-type or a modified form of IL-15 and the variable regions of the heavy and light chains of an antibody designed to precisely target a specific tumor antigen. GT Biopharma utilizes the NK stimulating cytokine human IL-15 as a crosslinker between the two scFvs which is designed to provide a self-sustaining signal leading to the proliferation and activation of NK cells thus enhancing their ability to kill cancer cells mediated by antibody-dependent cell-mediated cytotoxicity (ADCC). GT Biopharma has an exclusive worldwide license agreement with the University of Minnesota to further develop and commercialize cancer therapies using proprietary TriKE technology developed by researchers at the university to target NK cells to cancer.
"We continue to be encouraged by the data from our Trike program being conducted by leading NK cell experts at the University of Minnesota. These findings have supported us with the confidence to proceed with our first-in-class TriKE, Phase 1 study," commented Raymond Urbanski, M.D., Ph.D., Chief Executive Officer of GT Biopharma. "We are grateful to renowned NK cell expert, Jeffrey Miller, MD, Deputy Director, Masonic Cancer Center, University of Minnesota and his team, and look forward to providing further updates as we continue to advance what we believe to be a potentially revolutionary product candidate."
Graduate student, Upasana Sunil Arvindam, MSc, BSc, working with Drs. Miller and Felices at the University of Minnesota, presented the abstract titled, "CD16-IL15-CLEC12A Tri-specific Killer Engager (TriKE) Drives NK Cell Expansion, Activation, and Antigen Specific Killing of Cancer Stem Cells in Acute Myeloid Leukemia," as part of the Acute Myeloid Leukemia: Novel Therapy, Excluding Transplantation: Poster I session at ASH (Free ASH Whitepaper). To access the presented poster, click here.
For the preclinical study, Dr. Arvindam and her team developed a 1615CLEC12A TriKE molecule to target AML cells using Natural Killer (NK) cells. This molecule contains an anti-CD16 camelid nanobody to activate NK cells, an anti-CLEC12A single chain variable fragment (scFv) to engage cancer targets, and an IL-15 molecule that drives NK cell priming, expansion and survival.
The CLEC12A TriKE was developed in a mammalian cell system to ensure that appropriate post-translational modifications are present. The researchers confirmed that the TriKE binds specifically to HL-60 and THP-1 target cells that express CLEC12A compared to Raji cells that do not express CLEC12A. Treatment of peripheral blood mononuclear cells (PBMCs) with the CLEC12A TriKE drives a significant increase in NK cell specific proliferation over 7 days as measured by Cell Trace dilution compared to treatment with a CLEC12A scFv or IL-15 alone (69.7 ± 6.7% vs 11.9 ± 2.5% vs 38.4 ± 7.3%). In these assays, the efficacy of the CLEC12A TriKE was comparable to the CD33 TriKE. The data demonstrates that the CLEC12A TriKE drives NK cell specific proliferation, degranulation, cytokine secretion, and killing of tumor targets in vitro. Apart from AML, CLEC12A is expressed on cancer cells and LSCs in patients with myelodysplastic syndromes (MDS).
The presented preclinical findings highlight the clinical potential of the CLEC12A TriKE individually or in combination with the CD33 TriKE for the treatment of MDS and AML and ultimately led to the establishment of a first-in-human Phase 1 study with GTB-3550 (OXS-3550), its first-in-class (TriKE), for the treatment of AML, MDS and mastocytosis, which GT Biopharma recently announced. The study will be led by Principal Investigator, Sarah A. Cooley, MD, MS, Associate Professor, Division of Hematology, Oncology and Transplantation at Masonic Cancer Center, University of Minnesota.
The abstract titled, "Induced Pluripotent Stem Cell-Derived NK Cells Genetically Modified to Express NKG2C/DAP12 Mediate Potent Function When Targeted through an NKG2C/IL-15/CD33 Tri-Specific Killer Engager (TriKE)," was presented in an oral presentation by graduate student Emily Chiu, PhD, Medical School, University of Minnesota. To access the presentation slides, click here.
Having demonstrated stable expression and intact signaling of NKG2C/DAP12 in iNK cells, Dr. Chiu and her team next created a TriKE molecule with single chain Fv fragments specific for NKG2C (on iNK cells) and CD33 (on AML cells), as well as IL15 (to support iNK cell survival and proliferation). Without the addition of NKG2C/CD33/IL15 TriKE, the frequencies of both NKG2C iNK cells and NKG2C/DAP12 iNK cells producing IFNg was relatively low (< 10%). Addition of NKG2C/IL15/CD33 TriKE in the assay markedly increased the frequency of IFNg production by both NKG2C iNK cells (19.1%) and NKG2C/DAP12 iNK cells (25.8%). Finally, the team directly tested the ability of the NKG2C/IL15/CD33 TriKE molecule to trigger target killing by engineered iNK cells monitored over a 24hour period. THP1 target cells were dye labeled and plated in wells with either NKG2C iNK cells or NKG2C/DAP12 iNK cells at a 5:1 effector-to-target ratio with or without NKG2C/CD33/IL15 TriKE. The researchers found that in the absence of TriKE, there was no killing of THP1 targets. In contrast, both NKG2C iNK cells and NKG2C/DAP12 iNK cells mediated robust THP1 killing with the addition of NKG2C/CD33/IL15 TriKE, with NKG2C/DAP12 iNK cells exhibiting the strongest response.
Results from the study provided a proof-of-concept that iNK cells engineered to express NKG2C/DAP12 can be used in combination with a novel NKG2C/IL15/CD33 TriKE molecule to effectively target cancer cells. Engaging NK cells through NKG2C, restricted to adaptive NK cells or genetically modified iPSC will be more specific than CD16, which will bind to CD16A on NK cells but also have off-target binding to CD16B on neutrophils. Because of the enormous expansion and engineering capacity of the iNK cell platform, the Company believes it is in a unique position to create an "off-the-shelf" NK cellular therapy that is targeted, specific and efficacious.
About Acute Myelogenous Leukemia (AML)
AML is the most common form of adult leukemia with 21,000 new cases expected in 2018 alone, according to the American Cancer Society. AML patients typically receive frontline therapy, most commonly chemotherapy, which includes cytarabine and an anthracycline, a therapy that has not changed in over 40 years. However, there remains a significant unmet need in these therapies with about half of AML patients experiencing relapses or requiring alternative therapies. The Company is developing GTB-3550 to serve as a relatively safe, cost-effective, and easy-to-use therapy for resistant/relapsing AML and could also be combined with chemotherapy as frontline therapy thus targeting the larger patient population