On May 27, 2015 MacroGenics reported the publication of a nonclinical research paper on MGD006 in Science Translational Medicine (Press release, MacroGenics, MAY 27, 2015, View Source [SID:1234504851]). MGD006 is a humanized, Dual-Affinity Re-Targeting (DART) molecule that recognizes both CD123 and CD3. CD123, the Interleukin-3 receptor alpha chain, is expressed on malignant cells, including leukemic stem cells (LSC), in acute myeloid leukemia (AML) and other hematological diseases. The primary mechanism of action of MGD006 is its ability to redirect T lymphocytes to kill CD123-expressing cells. To achieve this, the DART combines a portion of an antibody recognizing CD3, an activating molecule expressed by T cells, with an arm that recognizes CD123 on the target cells. The recently published research shows anticancer activity in vitro and in mouse models together with favorable pharmacodynamic and safety profile in nonhuman primates.
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The prognosis of patients with AML remains poor overall despite existing therapy, and substantial unmet need exists for these individuals. AML patients may benefit from targeted immunotherapy approaches. The paper titled "A CD3xCD123 bispecific DART for redirecting host T cells to myelogenous leukemia: Preclinical activity and safety in nonhuman primates," describes how MacroGenics’ scientists engineered the MGD006 DART and demonstrated in vitro that the molecule can arm T cells from AML patients to reduce blast counts and is effective in eliminating AML cells implanted in mice. Furthermore, MGD006 administered to cynomolgus monkeys demonstrated potent pharmacodynamic activity in the form of near complete elimination of circulating CD123-positive cells at doses that were safe and well tolerated.
"This research paved the way for our initiation of a Phase 1 clinical study of MGD006 in 2014," said Scott Koenig, M.D., Ph.D., President and CEO of MacroGenics. "This was a significant milestone for our DART platform and I am pleased to say that the study is progressing well. MGD006 has demonstrated great promise as a T-cell re-directed cancer immunotherapy in pre-clinical studies. We are hopeful that these studies will translate into clinical trial results indicative of clinical improvement for patients with AML, myelodysplastic syndrome and several other forms of leukemia and lymphoma."
About the Phase 1 Study of MGD006
MacroGenics continues to enroll patients in the dose escalation portion of a Phase 1 study of MGD006 for the treatment of AML. The Phase 1 dose-escalation study is designed to assess the safety and tolerability of MGD006 in patients with relapsed or refractory AML. In addition to the primary safety endpoint, secondary endpoints of pharmacokinetics and pharmacodynamic activity will be evaluated, as will a number of biomarkers examining the immunobiology of MGD006. The Phase 1 study was initiated at Washington University School of Medicine in St. Louis. In addition, Emory University and Providence Portland Medical Center are now recruiting patients and a fourth site is expected to commence patient recruitment in June.
About MGD006
MGD006 is a humanized DART molecule that can simultaneously bind CD123 and CD3. CD123 has been reported to be overexpressed on malignant cells in a wide range of hematological malignancies including AML and myelodysplastic syndrome (MDS). AML and MDS are thought to arise in, and be perpetuated by, a small population of LSCs that generally resist conventional chemotherapeutic agents. LSCs are characterized by comparably high levels of CD123 expression in contrast to the limited or absent CD123 expression in the corresponding hematopoietic stem cell population in normal human bone marrow.
MacroGenics has retained development and commercialization rights to MGD006 in the U.S., Canada, Mexico, Japan, South Korea and India. MacroGenics’ partner, Servier, has rights to MGD006 in all other countries.
About the DART Platform
MacroGenics’ DART platform enables the targeting of multiple antigens or cells by using a single molecule with dual antibody-like binding regions. The Company has created over 100 DART molecules, which have been designed for evaluation in the potential treatment of cancer, autoimmune disorders and infectious disease. These DART molecules can be tailored for either short or prolonged pharmacokinetics and have demonstrated good stability and manufacturability. MacroGenics and its partners expect to have a total of five DART molecules in clinical development by the end of 2015.