Solu Therapeutics Lands $41M for Clinical Test of Novel Antibody Drug for Blood Cancer

Solu Therapeutics, a company developing a new type of antibody drug, unveiled $41 million in financing on Wednesday for clinical testing of a therapy with the potential to bring a safer and more effective approach to blood cancers.

Boston-based Solu has already begun dosing patients in a Phase 1 test of lead program STX-0712 in resistant or refractory chronic myelomonocytic leukemia (CMML) and other hematologic malignancies. The target of the drug is CCR2, a receptor that plays a role in cancer development and progression. The Solu drug is intended to eliminate CCR2-positive cells. It does so in a novel way.

Antibodies and small molecules are both well-established therapeutic modalities for treating cancer. Solu says its approach brings both modalities together to target cell surface proteins that cannot otherwise be addressed. The company uses small molecules to bind to elusive targets such as G protein-coupled receptors (GPCRs) and ion channels. CCR2 is a GPCR.

Solu’s molecules are bifunctional, with one arm that binds to the cell surface target and another arm that links to a proprietary antibody. Doing so imbues the therapy with the properties and functions of an antibody, such as longer durability in the body. Solu says this approach could offer a more targeted and effective treatment with minimal effects on healthy tissue.

“By directly depleting the CCR2-positive malignant monocytes driving CMML, STX-0712 has the potential to offer a highly specific and targeted therapy for patients who currently have limited treatment options available,” Chief Medical Officer Sergio Santillana said in a prepared statement.

During the annual meeting of the American Society of Hematology last December, Solu presented data showing STX-0712 successfully depleted CCR2-positive cells in patient samples of CMML and acute myeloid leukemia. Tests of the drug in monkeys showed it was safe and well tolerated with a favorable pharmacokinetic profile.

Solu’s platform technology, called Cytotoxicity Targeting Chimera (CyTac), and its drug candidates, were licensed from GSK. The startup was founded by venture capital firm Longwood Fund. Solu emerged in 2023 backed by $31 million in seed financing from Longwood and Santé Ventures. Beyond cancer, the company says its approach could have applications to immunology and other therapeutic areas.

The Series A financing announced Wednesday added new investors Eli Lilly & Company, Biovision Ventures, Pappas Capital, Hengdian Group Capital, and The Leukemia & Lymphoma Society Therapy Acceleration Program. Longwood and Santé also participated in the new financing along with other earlier investors DCVC Bio, Astellas Venture Management, and Alexandria Venture Investments.

With the new capital, Solu plans to complete dose escalation and expansion of its lead CMML program. The company also plans to develop additional drug candidates, including what it describes as a novel, first-in-class mast cell depletor for immunological diseases. Furthermore, Solu plans to start new discovery programs targeting pathogenic cells and explore new applications for its platform technologies.

Photo by Flickr user Ed Uthman via a Creative Commons license