MT-302 arms myeloid cells with an mRNA-encoded CAR to kill tumor cells expressing TROP2, and trigger an adaptive immune response to metastatic epithelial tumors

CAMBRIDGE, Mass, September 12, 2023 – Myeloid Therapeutics, Inc. (“Myeloid”), a clinical stage oncology company, has dosed the first patient with MT-302 in a Phase 1 study for advanced or metastatic epithelial tumors. MT-302 is the Company’s lead development candidate for in vivo immune cell programming and delivers TROP2-targeting RNA chimeric antigen receptors that express selectively within myeloid cells.

Dosing with MT-302 represents a significant advance in the development of new therapies for solid tumors, particularly those arising from epithelial tissues. Unlike traditional CAR-T cell therapies, Myeloid’s approach focuses on in vivo programming of immune cells with an off-the-shelf mRNA encoded CAR technology.

TROP2 is a clinically relevant target, as evidenced by clinical findings with several TROP2-targeting antibody-drug conjugates (ADCs). MT-302 advances upon the progress of these existing approaches, by not only targeting TROP2, but also eliciting a comprehensive immune response against the tumor. This immune response is pivotal for sustained immune surveillance and defense against tumor recurrence, aligning with Myeloid’s overarching clinical vision to improve clinical outcomes.

“Initiation of patient dosing with MT-302 is a major milestone for Myeloid in our effort to deliver better treatment options for patients living with solid tumors. We are leading the way with our proprietary approach to in vivo programming, including with many novel CAR constructs designed for selective expression in a wide range of immune cells,” said Daniel Getts, Ph.D., CEO of Myeloid. “By advancing MT-302 into the clinic, we are harnessing the power of the innate immune system to overcome many observed limitations of CAR-Ts for solid tumors. We look forward to advancing MT-302 in our Phase 1 study and demonstrating the potential of our innate immunity platform to program cells directly in vivo and drive better outcomes.”

Myeloid’s in vivo programming candidates are designed to deliver the highest standard in personalized therapy, providing benefit to patients while reducing time and costs through the elimination of ex-vivo handling of patient cells and complex neoantigen sequencing. The Myeloid platform integrates validated antibody-antigen binding, with novel combinations of myeloid-signaling domains, coded within a simple mRNA that can be delivered repeatedly using LNPs. The platform versatility provides a range of signaling domains and immune cell types useful for combination approaches.

Over 500,000 patients per year in the United States present with TROP2 expressing tumors. Despite the clinical progress observed within the class of TROP2-targeting ADCs, MT-302 goes further, by combining direct tumor targeting and adding immune-stimulation and an adaptive immune response to the tumor neoantigens. The adaptive response is central to long-term immune surveillance and defense against disease recurrence.

About the Phase 1 Study of MT-302

The MT-302 Phase 1 study (NCT05969041) is an open-label dose escalation study to investigate the safety, pharmacokinetics, pharmacodynamics, and preliminary efficacy of MT-302 in adults with advanced or metastatic epithelial tumors that overexpress TROP2. This study will also define the recommended Phase 2 dose (RP2D) of MT-302. The study is currently enrolling patients at multiple clinical sites in Australia.

About MT-302

MT-302 represents the first candidate in an entirely new, therapeutic modality. It is a first-in-class, TROP2-FcA-LNP, with a strong preclinical profile that supports its advance into this first-in-human trial. TROP2 is overexpressed in most human solid epithelial cancers, with lower expression in corresponding normal tissue. Increased TROP2 expression has been linked to tumor growth.

Treatment with MT-302 demonstrates activity as a monotherapy in a TROP2/TNBC preclinical model, confirming the tumor-fighting potency of programmed myeloid cells even in the absence of T cells. Unlike ADCs, MT-302 brings the potential advantages of eliciting a full immune response by also presenting tumor neoantigen to stimulate T cells. MT-302 has demonstrated strong expression and a favorable safety profile in myeloid cells in rodents and in non-human primates.

About Myeloid’s ATAK™ CAR receptors

Myeloid’s novel class of CARs, known as ATAK™ Receptors, combine tumor recognition with multiple proprietary innate-immune signaling domains. Myeloid scientists have screened multiple unexplored combinations of innate-immune signals and uncovered optimal multi-signal pathways. The combination of cancer recognition binders with these novel intracellular signaling domains allows myeloid cells to be reprogrammed with previously unexplored combinations of immune signals, leading to tumor killing and broad systemic anti-tumor responses.

About in vivo mRNA Programming

Myeloid’s novel in vivo engineering platform is designed to program myeloid cells in vivo, so these cells recognize tumor cells, resulting in direct tumor cell killing and the elicitation of broad anti-tumor adaptive immunity. Myeloid has demonstrated that its novel CAR constructs can selectively program myeloid cells and do so directly in vivo, leading to potent tumor killing in multiple “cold tumor” preclinical models where alternative therapies, including CAR Ts and checkpoints show no activity.

Myeloid’s current in vivo programming portfolio consists of novel CAR constructs that have been tailored for selective expression in various immune cells, including myeloid cells, NK cells and T-cells. Active programs within Myeloid’s in vivo preclinical pipeline include known tumor antigens as well as confidential novel epitopes.

About Myeloid Therapeutics

Myeloid Therapeutics is a clinical stage oncology company developing novel therapies for cancer. Integrating the fields of mRNA-based therapeutics, immunology, and cancer biology, the Company’s proprietary platform provides clinical solutions for patients with solid tumors.

Investor and Media Contact
Amy Conrad
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