• Data demonstrates proof -of-mechanism for In Vivo CAR therapy in solid tumors

, /PRNewswire/ – CREATE Medicines Inc. (formerly Myeloid Therapeutics), a biotechnology company advancing in vivo immune-cell programming with mRNA-LNP therapeutics, today announced first-in-human results from its Phase 1 MYE Symphony trial (NCT05969041) evaluating MT-302, an mRNA-LNP-encoded TROP2-targeted in vivo CAR therapy in patients with advanced solid tumors, at the Society for Immunotherapy of Cancer (SITC) 40th Anniversary Annual Meeting.

“These data provide important mechanistic insights into how in vivo programmed myeloid cells behave within the tumor microenvironment,” said Rasha Cosman BSc (Med), MBBS, FRACP, Head of the Early Phase Clinical Trials Unit at The Kinghorn Cancer Centre, St. Vincents Hospital Sydney, “The degree of remodeling observed, combined with a manageable safety profile and repeat-dose feasibility, and early signal of anti-tumor activity in a heavily pre-treated population, is highly encouraging in tumor settings where immune infiltration has been historically limited. Seeing immune cells effectively reprogrammed inside the body to mount a targeted anti-tumor response represents a meaningful milestone and supports continued clinical advancement.”

**Results **27 patients with advanced TROP2-positive solid tumors were treated with MT-302 across seven dose cohorts.

• Manageable safety profile consistent with immune cell activation.
• Dose and tumor burden dependent low grade cytokine release syndrome observed in 51.9% of participants with kinetics consistent with tumor target engagement. There were no events of grade 3 or higher CRS.
• Maximum tolerated dose: 0.10 mg/kg without steroid premedication. One Grade 4 ICANS event was observed at the highest dose tested (0.15 mg/kg).
• Pharmacokinetics: terminal half-life of pegylated and ionizable lipids 45–50 hours.
• Biological activity: CAR⁺ myeloid cells observed within tumors with T-cell infiltration and cytokine induction (IFNγ, CXCL9/10); the CXCL9:SPP1 ratio correlated with tumor-burden change, indicating pro-inflammatory tumor-microenvironment remodeling.
• Clinical signal: one confirmed partial response in HR⁺ breast cancer in a patient on treatment for 16 months (20 doses) with pharmacological activity observed at 0.015 mg/kg.

“These data represent the first demonstration of an in vivo CAR therapy achieving tumor penetration and measurable biological activity in patients with solid tumors,” said Matt Maurer, MD, Chief Medical Officer of CREATE Medicines. “MT-302 showed proof-of-mechanism while maintaining a manageable safety profile and repeat dosing without preconditioning or immunosuppression.”

**Conclusions **In this first-in-human study, MT-302 demonstrated tolerable repeat dosing, robust immunologic activity, direct tumor penetration by CAR myeloid cells and broad immune activation in heavily pre-treated patients. These results provide clear proof-of-mechanism for in vivo CAR therapies in solid tumors and support advancement of MT-302 for front-line use. Dosing with MT-302 was recently initiated in the first ever front-line solid tumor trial with an in vivo CAR combined with a standard frontline regimen in the SPaCE-MT trial (EUCT 2024-520213-45-00).

“This is a foundational moment for our platform and for the field of in vivo cell therapy,” added Daniel Getts PhD, Chief Executive Officer and co-founder of CREATE Medicines. “We have clinical evidence demonstrating that immune cells can be reprogrammed inside the body to mount a targeted anti-tumor response, paving the way for a new, highly versatile modality in the fight against solid tumors.”

**Presentation Details: ** SITC 40th Anniversary Annual Meeting

• Title: First-in-Human Dose Escalation Study to Investigate the Safety, Pharmacokinetics, Pharmacodynamics and Initial Efficacy of mRNA-LNP MT-302 In Vivo CAR Therapy in Solid Tumors
• Presenting Author: Dr. Rasha Cosman, The Kinghorn Cancer Centre, St. Vincent’s Hospital Darlinghurst NSW Australia
• Category: Clinical Oral Abstract Session 1
• Publication Number: LBA 1342
• Session Date & Time: Friday, November 7, 2025: 11:30 AM ET- 12:15 PM
• Location: Gaylord National Resort & Convention Center, Potomac Ballroom, National Harbor, MD

**About MT-302 ** MT-302 is an investigational mRNA-LNP in vivo CAR therapy designed to program immune cells inside the body. Delivered systemically, MT-302 recognizes and eliminates TROP2-expressing solid tumors by encoding a TROP2-specific chimeric antigen receptor to transiently reprogram immune cells. This approach eliminates the need for ex vivo manipulation or preconditioning, while achieving repeatable dosing and controllable anti-tumor activity.

**About CREATE Medicines **CREATE Medicines (formerly Myeloid Therapeutics) is a clinical-stage biotech pioneering in vivo multi-immune programming. Its proprietary mRNA-LNP platform directly programs immune cells inside the body to deliver scalable, repeat-dose, off-the-shelf immunotherapies. With proven human validation and next-generation RNA technology, CREATE is advancing a pipeline of in vivo CAR therapies to transform outcomes in cancer, autoimmunity, and fibrosis. For more, visit createmedicines.com. Follow us on LinkedIn and X (Twitter).

**About The Kinghorn Cancer Centre, St. Vincent’s Hospital Sydney ** The Kinghorn Cancer Centre is a joint facility between St Vincent’s Hospital Sydney and the Garvan Institute of Medical Research, dedicated to combining medical expertise and research for personalized cancer care. It offers integrated services including medical oncology, clinical trials, and a Cancer Genetics Service. The center’s design fosters interaction between researchers and clinicians to accelerate the translation of research findings into patient treatments.

Business Development: [email protected]** Media Contact:** Susan Roberts, [email protected] | +1 (202) 779-0929 Investor Contact: Brian Korb, [email protected] | +1 (917) 653-5122

SOURCE CREATE Medicines, Inc.