– MT-303 programs immune cells directly in patients; the first time an in vivo CAR has been evaluated clinically in HCC –

CAMBRIDGE, Mass., Nov. 8, 2024 /PRNewswire/ — Myeloid Therapeutics, Inc. (“Myeloid”), a clinical-stage immunology company advancing RNA therapeutics to conquer cancer, announced today an oral presentation at the Society for Immunotherapy in Cancer (SITC) 2024 annual meeting, occurring November 6 – 10, 2024, in Houston, Texas. Dr. Matthew Maurer, Myeloid’s Chief Medical Officer, will present on Myeloid’s discovery and development of MT-303. MT-303 is the Company’s second in vivo mRNA CAR program to enter the clinic from its pipeline of in vivo immune cell programming therapies. 

MT-303 is a first-in-class Glypican-3 (GPC3) targeting CAR encoded from mRNA and encapsulated in lipid nanoparticles. It is currently in a first-in-human Phase 1 clinical trial of advanced hepatocellular carcinoma (HCC). There are limited treatment options to combat HCC.

GPC3 is a target of growing therapeutic interest given its overexpression in many cancers, including the majority of hepatocellular carcinomas, coupled with limited expression in normal tissues. GPC3 expression has been linked to aggressive tumor behavior and poor prognosis.

Myeloid’s treatment approach focuses on selective in vivo programming of immune cell subsets with innovative off-the-shelf mRNA-encoded CAR technologies. These candidates are administered without the need for preconditioning. MT-303 arms myeloid cells with a proprietary chimeric antigen receptor that expresses specifically within myeloid cells. This approach directs and enables myeloid cells to kill GPC3 expressing cancers while orchestrating a coordinated adaptive immune anti-tumor response marked by expansion of new T cell clones.

“Myeloid has rapidly advanced MT-303 into first-in-human testing as our second in vivo CAR clinical program. Dose escalation of MT-303 and MT-302  continues, and we are encouraged by the ongoing biologic indications of proof-of-mechanism, as well as the early observed safety and efficacy experience,” said Dr. Matthew Maurer, Chief Medical Officer of Myeloid. “The clinical observations extend the earlier preclinical results, that also demonstrated selective activation of CAR myeloid cells and robust anti-tumor activity in mouse hepatocellular tumor models.”

Oral presentation details are as follows:

Abstract #: 1125
Title: “Preclinical Development of MT-303, a Novel LNP-Formulated GPC3-Specific CAR mRNA, for in vivo Programming of Monocytes to Treat Hepatocellular Carcinoma”
Session Title: Protein and Cellular Engineering Strategies
Session Date and Time: Friday, November 8, 2024, 5:10 pm
Presenting Author: Matthew Maurer – Myeloid Therapeutics

For more information, please visit the SITC 2024 website.

Myeloid’s in vivo programming candidates are designed with proprietary insights to deliver personalized therapy, providing benefits 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 lipid nanoparticles (LNPs). The platform’s versatility provides a range of signaling domains and immune cell types useful for combination approaches.

About Liver Cancer

With limited treatment options, and over 850,000 new cases diagnosed globally each year, liver cancer has become the third leading cause of cancer death. After initial treatment success with small molecule therapies, the development of new treatment approaches in the field of liver cancer has been limited.  Today, patients with liver cancer who are refractory to first line treatment are left with few treatment options, creating a substantial unmet medical need.  Myeloid sees an opportunity to make a significant contribution to address this need, by providing a new CAR for these patients who are living with liver cancer.  The CARs are capable of providing a coordinated and durable immune response to counter advanced disease.  The CARs are combinable and will expand the treatment options for physicians.

About the Phase 1 Study of MT-303

The MT-303 Phase 1 study (NCT06478693) is an open-label dose escalation study to investigate the safety, pharmacokinetics, pharmacodynamics, and preliminary efficacy of MT-303 in adults with advanced or metastatic hepatocellular carcinoma that overexpresses GPC3. This study will also define the recommended Phase 2 dose (RP2D) of MT-303.

About MT-303

MT-303 represents the first candidate in a new therapeutic modality targeting hepatocellular carcinoma (HCC). This clinical candidate is a first-in-class, GPC3-FcA-LNP, with a strong preclinical profile supporting its advance into this first-in-human trial. GPC3 is overexpressed in most human hepatocellular carcinomas, with limited expression in corresponding normal tissues. Increased GPC3 expression has been linked to tumor growth.

Treatment with MT-303 as a monotherapy demonstrates activity in a GPC3/HCC preclinical model, confirming the tumor-fighting potency of programmed myeloid cells even in the model’s absence of T cells. MT-303 has demonstrated strong expression in myeloid cells and a favorable safety profile in rodents and non-human primates. Unlike other therapies, MT-303 brings the potential advantages of eliciting a full immune response by also presenting tumor neoantigen to stimulate T cells.

MT-303 represents Myeloid’s second in vivo CAR clinical program, building on the company’s innovative approach to cancer treatment through immune cell programming.

 About Myeloid Therapeutics

Myeloid Therapeutics is a clinical stage immunology company, engineering cutting-edge RNA technology to program immune cells to combat cancer and other deadly diseases. Myeloid is headquartered in Cambridge, MA.

For additional information, please visit, https://www.myeloidtx.com/ and follow us on LinkedIn and X/Twitter. For collaborative interests, write to [email protected].

Investor Contact
Amy Conrad
Juniper Point
[email protected]

SOURCE Myeloid Therapeutics, Inc.

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