On June 22, 2020 MacroGenics, Inc. (NASDAQ: MGNX), a clinical-stage biopharmaceutical company focused on discovering and developing innovative monoclonal antibody-based therapeutics for the treatment of cancer, reported presentations at the American Association for Cancer Research (AACR) (Free AACR Whitepaper) Virtual Annual Meeting II, taking place June 22-24, 2020 (Press release, MacroGenics, JUN 22, 2020, View Source [SID1234561287]).

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"We are pleased to present data at this year’s AACR (Free AACR Whitepaper) 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 poster presented at AACR (Free AACR Whitepaper) 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 poster presented at AACR (Free AACR Whitepaper) 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 (Free AACR Whitepaper) Virtual Annual Meeting II at www.aacr.org

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

On June 22, 2020, Revolution Medicine Presented a corporate presentation (Presentation, Revolution Medicines, JUN 22, 2020, View Source [SID1234561310]).

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On June 22, 2020 Provectus (OTCQB: PVCT) reported that data from ongoing preclinical study of investigational autolytic cancer immunotherapy PV-10 (rose bengal disodium) is being presented at the American Association for Cancer Research (AACR) (Free AACR Whitepaper) 2020 Virtual Annual Meeting II, held online June 22-24, 2020 (Press release, Provectus Biopharmaceuticals, JUN 22, 2020, View Source [SID1234561326]). This PV-10 research has been led by Aru Narendran, MD, PhD and his team of researchers at the University of Calgary in Alberta, Canada (UCalgary).

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Dr. Narendran and his colleagues studied the effects of PV-10 treatment on primary cells and cell lines derived from pediatric leukemia patients. UCalgary showed that PV-10 treatment led to STING dimerization and the release of interferon gamma (IFNγ), indicating a potential immune activation mechanism of PV-10. UCalgary further showed that heat shock proteins (HSPs), which chaperone misfolded or abnormally folded proteins, associated with STING dimerization in PV-10-treated cells, indicating a mechanism that may lead to enhanced STING activation following PV-10 treatment.

A copy of the AACR (Free AACR Whitepaper) poster presentation is available on Provectus’ website at View Source

"The essence of cancer is the struggle for survival of these abnormal cells in the body. Over the course of their existence, cancer cells acquire multiple cellular pathways that become active or inactive in order for cancer to have a survival advantage against our immune system. This struggle changes the biology of cancer cells, which may have a direct impact on the activity of anticancer drugs within these cells," Dr. Narendran said. "We observed these very dynamics from our research on PV-10 and pediatric leukemia cells. Classic STING activation does not occur through PV-10 treatment. Rather, STING forms a dimer complex following PV-10 treatment, which may potentially lead to effective immune activation and anticancer activity."

Dr. Narendran added, "Our PV-10 research has enabled us to show, we believe for the first time, that heat shock proteins, which play important roles in the survival of cancer cells, are involved in STING activation. We also believe the involvement of heat shock proteins with STING is an important observation that requires further study."

Dominic Rodrigues, Vice Chair of Provectus’ Board of Directors, said "We are grateful to Dr. Narendran, his team, and the University of Calgary for their consequential research on PV-10 to better understand the basic biology of cancer. This seminal discovery of PV-10-induced alterations of the STING pathway, which plays a pivotal role in innate immunity, contributes to an increasing body of knowledge about how and why PV-10 may function as an immunotherapy across a growing number of cancer types."

About PV-10

By targeting tumor cell lysosomes, investigational new drug PV-10 treatment may yield immunogenic cell death in solid tumor cancers that results in tumor-specific reactivity in circulating T cells and a T cell mediated immune response against treatment refractory and immunologically cold tumors.1-3 Adaptive immunity can be enhanced by combining checkpoint blockade (CB) with PV-10.4

PV-10 is undergoing clinical study for adult solid tumor cancers, such as relapsed and refractory cancers metastatic to the liver and metastatic melanoma. PV-10 is also undergoing preclinical study for relapsed and refractory pediatric solid tumor cancers (e.g., neuroblastoma, Ewing sarcoma, rhabdomyosarcoma, and osteosarcoma)5,6 and relapsed and refractory pediatric blood cancers (such as acute lymphocytic leukemia and acute myelomonocytic leukemia)7,8.

Tumor Cell Lysosomes as the Seminal Drug Target

Lysosomes are the central organelles for intracellular degradation of biological materials, and nearly all types of eukaryotic cells have them. Discovered by Christian de Duve, MD in 1955, lysosomes are linked to several biological processes, including cell death and immune response. In 1959, de Duve described them as ‘suicide bags’ because their rupture causes cell death and tissue autolysis. He was awarded the Nobel Prize in 1974 for discovering and characterizing lysosomes, which are also linked to each of the three primary cell death pathways: apoptosis, autophagy, and necrosis.

Building on the Discovery, Exploration, and Characterization of Lysosomes

Cancer cells, particularly advanced cancer cells, are very dependent on effective lysosomal functioning.9 Cancer progression and metastasis are associated with lysosomal compartment changes10,11, which are closely correlated with (among other things) invasive growth, angiogenesis, and drug resistance12.

PV-10 selectively accumulates in the lysosomes of cancer cells upon contact, disrupting the lysosomes and causing the cells to die. Provectus1,13, external collaborators6, and other researchers14,15,16 have independently shown that PV-10 (RB) triggers each of the three primary cell death pathways: apoptosis, autophagy, and necrosis.

Cancer Cell Autolytic Death via PV-10: PV-10 induced autolytic cell death, or death by self-digestion, in Hepa1-6 murine hepatocellular carcinoma (HCC) cells can be viewed in this Provectus video of the event (ethidium homodimer 1 [ED-1] stains DNA, but is excluded from intact nuclei; lysosensor green [LSG] stains intact lysosomes; the video is provided in 30-second frames; the event has a duration of approximately one hour). Exposure to PV-10 triggers the disruption of lysosomes, followed by nucleus failure and autolytic cell death. Identical responses have been shown by the Company in HTB-133 human breast carcinoma (which can be viewed in this Provectus video; this event has a duration of approximately two hours) and H69Ar human multidrug-resistant small cell lung carcinoma. Cancer cell autolytic cell death was reproduced by research collaborators in neuroblastoma cells to show that lysosomes are disrupted upon exposure to PV-10.5

PV-10 causes acute autolytic destruction of injected tumors (i.e., cell death), mediating the release of danger-associated molecular pattern molecules (DAMPs) and tumor antigens that may initiate an immunologic cascade where local response by the innate immune system may facilitate systemic anti-tumor immunity by the adaptive immune system. The DAMP release-mediated adaptive immune response activates lymphocytes, including CD8+ T cells, CD4+ T cells, and NKT cells, based on clinical and preclinical experience in multiple tumor types. Mediated immune signaling pathways may include an effect on STING, which plays an important role in innate immunity8.

Orphan Drug Designations (ODDs)

ODD status has been granted to PV-10 by the U.S. Food and Drug Administration for the treatments of metastatic melanoma in 2006, hepatocellular carcinoma in 2011, neuroblastoma in 2018, and ocular melanoma (including uveal melanoma) in 2019.

Drug Product

Rose bengal disodium (RB) (4,5,6,7-tetrachloro-2’,4’,5’,7’-tetraiodofluorescein disodium salt) is a small molecule halogenated xanthene and PV-10’s active pharmaceutical ingredient. The Company manufactures RB using a patented process designed to meet stringent modern global quality requirements for pharmaceuticals and pharmaceutical ingredients (Good Manufacturing Practice, or GMP). PV-10 drug product is an injectable formulation of 10% w/v GMP RB in 0.9% saline, supplied in single-use glass vials containing 5 mL (to deliver) of solution, and administered without dilution to solid tumors via intratumoral injection.

Intellectual Property (IP)

Provectus’ IP includes a family of US and international (a number of countries in Asia, Europe, and North America) patents that protect the process by which GMP RB and related halogenated xanthenes are produced, avoiding the formation of previously unknown impurities that exist in commercial grade RB in uncontrolled amounts. The requirement to control these impurities is in accordance with International Council on Harmonisation (ICH) guidelines for the manufacturing of an injectable pharmaceutical. US patent numbers are 8,530,675, 9,273,022, and 9,422,260, with expirations ranging from 2030 to 2031.

The Company’s IP also includes a family of US and international (a number of countries in Asia, Europe, and North America) patents that protect the combination of PV-10 and systemic immunomodulatory therapy (e.g., anti-CTLA-4, anti-PD-1, and anti-PD-L1 agents) for the treatment of a range of solid tumor cancers. US patent numbers are 9,107,887, 9,808,524, 9,839,688, and 10,471,144, with expirations ranging from 2032 to 2035; US patent application numbers include 20200138942.

On June 22, 2020 EpimAb Biotherapeutics, an emerging Shanghai-based biopharmaceutical company specializing in bispecific antibodies, reported that preclinical data at the 2020 American Association for Cancer Research (AACR) (Free AACR Whitepaper) Virtual Annual Meeting II (Press release, EpimAb Biotherapeutics, JUN 22, 2020, View Source [SID1234561342]). The data presented in the poster titled, "EMB-01: An innovative bispecific antibody targeting EGFR and cMet on tumor cells mediates a novel mechanism to improve anti-tumor efficacy", characterizes EMB-01, EpimAb’s lead bispecific antibody candidate developed based on the company’s proprietary FIT-Ig platform to target EGFR and cMet on tumor cells simultaneously. EMB-01 is currently progressing through a Phase I/II clinical trial in patients with advanced metastatic solid tumors.

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"The characterization of EMB-01 shows that the FIT-Ig-based design enables it to bind simultaneously to EGFR and cMet, both found on the surface of various tumor cells, where it then induces co-degradation of these two receptors," said Dr. Chengbin Wu, CEO and founder of EpimAb. "The resulting highly potent and durable anti-tumor effect in animal models encouraged EpimAb to rapidly advance EMB-01 to the clinic where it is currently being investigated in oncology indications. The unique biology underlying EMB-01 encouraged our research teams to explore various options in human research, and the clinical validation of our FIT-Ig platform facilitated our efforts in advancing additional bispecific antibody programs, such as EMB-02 and EMB-06, for which we expect to file two new INDs in 2020."

"With the unique mechanism of action, EMB-01 could provide a new treatment option for non-small cell lung cancer patients previously treated with current drugs on the market but who later developed resistance, as well as for other solid tumors where disease progression is mediated by EGFR and/or cMet," said Dr. Bin Peng, Chief Medial Officer of EpimAb. "EpimAb is excited to learn more from our ongoing clinical trials."

The preclinical study shows that EMB-01 binds to EGFR and cMet simultaneously and induces co-degradation of both targets in various tumor cells, an effect unattainable by parental monoclonal antibodies (mAbs) alone or in combination. EMB-01 was also shown to exhibit more extensive inhibition of EGFR and cMet downstream signals, and a more potent and durable in vivo efficacy in various PDX tumor models compared to parental mAbs. This enhanced potency could likely be driven by EMB-01-mediated co-degradation of the EGFR and cMet in tumor cells.

EMB-01 is a novel bispecific antibody developed based on EpimAb’s proprietary FIT-Ig platform to simultaneously target EGFR and cMet on tumor cells. The anti-EGFR and anti-cMet Fab-domains in each EMB-01 arm are fused directly in-tandem in a unique crisscross orientation without any mutations or use of peptide linkers to form a final tetravalent binding complex with the corresponding receptors on the cell surface.

On June 22, 2020 Castle Biosciences, Inc. (Nasdaq: CSTL), reported that it has commenced a proposed underwritten public offering of 1,500,000 shares of its common stock (Press release, Castle Biosciences, JUN 22, 2020, View Source [SID1234561358]). Castle Biosciences also intends to grant the underwriters a 30-day option to purchase up to an additional 225,000 shares of common stock at the public offering price, less the underwriting discounts and commissions. The public offering price has not yet been determined. The offering is subject to market and other conditions, and there can be no assurance as to whether or when the offering may be completed, or as to the actual size or terms of the offering.

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SVB Leerink and Baird are acting as joint book-running managers for the proposed offering and as representatives of the underwriters. Canaccord Genuity is acting as passive book-runner, and BTIG is acting as co-manager for the offering.

A registration statement on Form S-1 relating to these securities has been filed with the Securities and Exchange Commission (SEC) but has not yet become effective. These securities may not be sold, nor may offers to buy be accepted, prior to the time the registration statement becomes effective. The proposed offering will be made only by means of a prospectus.

Copies of the preliminary prospectus relating to the proposed offering may be obtained, when available, from: SVB Leerink LLC, Attention: Syndicate Department, One Federal Street, 37th Floor, Boston, MA 02110, by telephone: (800) 808‐7525, ext. 6218, or by e-mail: [email protected]; or from Robert W. Baird & Co. Incorporated, Attention: Syndicate Department, 777 East Wisconsin Ave., Milwaukee, WI 53202, by telephone: (800) 792-2473, or by email: [email protected].

This press release shall not constitute an offer to sell or a solicitation of an offer to buy, nor shall there be any offer or sale of these securities in any state or jurisdiction in which such offer, solicitation or sale would be unlawful prior to registration or qualification under the securities laws of such state or jurisdiction.