MacroGenics Announces Presentation of Preclinical Data at the 2020 AACR Annual Meeting

Rockville, MD, June 22, 2020 (GLOBE NEWSWIRE) --

MacroGenics, Inc. (NASDAQ: MGNX), a clinical-stage biopharmaceutical company focused on discovering and developing innovative monoclonal antibody-based therapeutics for the treatment of cancer, today announced presentations at the American Association for Cancer Research (AACR) , taking place June 22-24, 2020.

“We are pleased to present data at this year’s AACR that highlight three platform technologies upon which multiple molecules are being developed at MacroGenics. We are presenting preclinical data for MGC018, our investigational antibody-drug conjugate targeting B7-H3, that provide evidence for an immune-mediated anti-tumor mechanism, as well as a rationale for clinical investigation of this molecule in combination with checkpoint blockade. Separately, we are presenting data from our novel Fc-engineered, bispecific DART® molecule that binds CD25 and CTLA-4 that is capable of depleting tumor-infiltrating regulatory T cells with high specificity in vitro,” said Ezio Bonvini, M.D., Senior Vice President and Chief Scientific Officer of MacroGenics. “Finally, one of the clinical investigators for flotetuzumab, our investigational CD123 x CD3 DART molecule, will be presenting preclinical data from his research with this molecule during an oral Education Session.”

AACR II Presentations

MGC018, a duocarmycin-based antibody-drug conjugate targeting B7-H3, exhibits immunomodulatory activity and enhanced antitumor activity in combination with checkpoint inhibitors

Poster Session: PO.ET07.01 - Cell Surface Antigens and Receptors as Drug Targets

MGC018 is an investigational antibody-drug conjugate targeting B7-H3 that has shown preliminary anti-tumor activity in an ongoing Phase 1 dose escalation study in patients with advanced solid tumors. The  presented at AACR describes preclinical data suggesting that MGC018 can promote immune surveillance or stimulate immune responses to dying cancer cells that led to immunological memory, and when combined with checkpoint blockade may enhance anti-tumor activity.

These studies used a mouse model system designed to evaluate anti-tumor activity in an intact and functioning immune system. In this in vivo model, MGC018 demonstrated targeted activity against tumors expressing human B7-H3. Mechanistically, in vitro data suggested that MGC018 induced immunogenic cell death of target cells with the translocation of calreticulin to the cell surface during apoptosis. In addition, treatment with MGC018 in this model system led to an increased infiltration of T cells into the tumor microenvironment. Depleting these T cells attenuated the anti-tumor activity by MGC018, demonstrating their role in mediating response. Furthermore, MGC018 combined with an anti-PD-1 antibody enhanced anti-tumor activity observed in this study. Finally, mice that had achieved a complete response to initial treatment with MGC018 with or without checkpoint blockade survived longer when re-challenged with tumor without subsequent treatment compared to mice that had not received treatment with MGC018, suggesting immunological memory.

Investigational CD25 x CTLA-4 bispecific DART® molecule for depletion of tumor infiltrating Tregs via an enhanced Fc-dependent effector mechanism

Poster Session: PO.IM02.23 - Therapeutic Antibodies 1

The  presented at AACR described a preclinical bispecific CD25 x CTLA-4 DART molecule containing an Fc region engineered to enhance clearance of target cells by antibody-dependent cellular cytotoxicity. This molecule was designed to deplete tumor-associated regulatory T cells co-expressing CD25 and CTLA-4 to reduce immune suppression mediated by these cells but preserve effector T cell function. CD25 is the alpha subunit of IL-2 receptor and CTLA-4 is a molecule involved in regulatory T cell function.

In vitro studies showed that the Fc-engineered bispecific CD25 x CTLA-4 DART molecule depleted regulatory T cells, with minimal effect on effector T cells. This depletion of regulatory T cells was shown to occur through an Fc-dependent mechanism, as a control CD25 x CTLA-4 DART molecule with an inactivated Fc domain had no effect in this assay. In addition, the bispecific CD25 x CTLA-4 DART molecule preserved cytotoxic T cell effector function in vitro compared to a combination of Fc-engineered monoclonal antibodies independently targeting CD25 and CTLA-4.

Immune escape after bone marrow transplantation: Hiding in plain sight

Educational Session: ED52 - Immunotherapy, Immune Evasion in Myeloid Malignancies, and Therapeutic Implications

John F. DiPersio, M.D., Ph.D., from Washington University School of Medicine in St. Louis, will present an overview of his research related to immune evasion and mechanisms of relapse after allogeneic hematopoietic cell transplantation (allo-HCT). The presentation will include preclinical data on flotetuzumab (MGD006), an investigational CD123 x CD3 bispecific DART molecule, suggesting a potential role for this molecule in treating patients with acute myeloid leukemia whose disease is relapsing after allo-HCT.

Date: June 24, 2020

Time: 5:30 - 5:50pm ET

Location: AACR Virtual Annual Meeting II at

The posters will be available on the Events & Presentations page on MacroGenics’ website at .

About MacroGenics, Inc.

MacroGenics is a clinical-stage biopharmaceutical company focused on discovering and developing innovative monoclonal antibody-based therapeutics for the treatment of cancer. The Company generates its pipeline of product candidates primarily from its proprietary suite of next-generation antibody-based technology platforms, which have applicability across broad therapeutic domains. The combination of MacroGenics' technology platforms and protein engineering expertise has allowed the Company to generate promising product candidates and enter into several strategic collaborations with global pharmaceutical and biotechnology companies. For more information, please see the Company's website at MacroGenics, the MacroGenics logo and DART are trademarks or registered trademarks of MacroGenics, Inc.

Cautionary Note on Forward-Looking Statements

Any statements in this press release about future expectations, plans and prospects for the Company, including statements about the Company's strategy, future operations, clinical development of the Company's therapeutic candidates, milestone or opt-in payments from the Company's collaborators, the Company's anticipated milestones and future expectations and plans and prospects for the Company and other statements containing the words "subject to", "believe", "anticipate", "plan", "expect", "intend", "estimate", "project", "may", "will", "should", "would", "could", "can", the negatives thereof, variations thereon and similar expressions, or by discussions of strategy constitute forward-looking statements within the meaning of Section 27A of the Securities Act of 1933 and Section 21E of the Securities Exchange Act of 1934. Actual results may differ materially from those indicated by such forward-looking statements as a result of various important factors, including: the uncertainties inherent in the initiation and enrollment of future clinical trials, expectations of expanding ongoing clinical trials, availability and timing of data from ongoing clinical trials, expectations for the timing and steps required in the regulatory review process, expectations for regulatory approvals, the impact of competitive products, our ability to enter into agreements with strategic partners and other matters that could affect the availability or commercial potential of the Company's product candidates, business or economic disruptions due to catastrophes or other events, including natural disasters or public health crises such as the novel coronavirus (referred to as COVID-19), and other risks described in the Company's filings with the Securities and Exchange Commission. In addition, the forward-looking statements included in this press release represent the Company's views only as of the date hereof. The Company anticipates that subsequent events and developments will cause the Company's views to change. However, while the Company may elect to update these forward-looking statements at some point in the future, the Company specifically disclaims any obligation to do so, except as may be required by law. These forward-looking statements should not be relied upon as representing the Company's views as of any date subsequent to the date hereof.