New South Wales Government (NSW) Partner, Myeloid Therapeutics, Initiates Patient Dosing with MT-302 in Phase 1 Study at Clinical Site in Australia

NSW and Myeloid entered into a partnership in February 2023 to launch state-of-the-art GMP manufacturing RNA facility

CAMBRIDGE,Mass.,Sept. 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 programmingand delivers TROP2-targeting RNA chimeric antigen receptors that express selectively within myeloid cells. MT-302 is being manufactured and dosed at multiple clinical sites in Australia.

In February 2023,Myeloid announced its collaboration with the New South Wales (NSW) Government in Australia to create a world-class RNA manufacturing and research facility. The mission of the facility is to accelerate the commercialization of Myeloid's RNA therapeutics and building a RNA ecosystem in NSW. NSW is investing AU $96 million in the facility,enabling Myeloid to secure its supply chain for clinical development and future commercialization of RNA-based therapeutics.

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.

"Myeloid is thrilled to dose our first patient at a clinical site in Australia,which represents another significant milestone from our important partnership with the New South Wales government and underscores their commitment to bringing novel technology and treatments to the people of New South Wales," said Daniel Getts,Ph.D.,CEO of Myeloid. "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 vivoand 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 studyto investigate the safety,pharmacokinetics,pharmacodynamics,and preliminary efficacy of MT-302 in adultswith advanced or metastatic epithelial tumorsthat 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 profilethat 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 toprogram 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,leadingtopotent 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 oncologycompany 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. For more information,visit https://www.myeloidtx.com/.

Investor and Media Contact

Amy Conrad

Juniper Point

Amy@juniper-point.com

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