Janux Therapeutics, Inc. (NASDAQ:JANX) (Janux), a clinical-stage biopharmaceutical company developing a broad pipeline of novel immunotherapies, today announced that the first participant has been dosed in a Phase 1 clinical study of JANX011, a CD19-targeted bispecific engineered using the company's proprietary Adaptive Immune Response Modulator (ARM) platform. JANX011 is being developed for autoimmune diseases and is designed to enable deep and durable immune reset through targeted depletion of CD19-expressing B cells in blood and tissue.

JANX011 is the first clinical candidate from Janux's proprietary ARM platform, which is designed to deliver sustained target B-cell depletion by harnessing an adaptive-like immune response while improving the safety and convenience of immune-engaging therapies. Unlike conventional T-cell engagers, which typically require repeated dosing to maintain B-cell depletion, ARM molecules are engineered to drive controlled T-cell expansion while target cells are present, followed by contraction after target cell elimination. This response is designed to enable deep tissue-level target cell clearance without the need for lymphodepletion or pre-conditioning. In preclinical studies, a single, subcutaneous dose of JANX011 demonstrated deep and durable B-cell depletion in both blood and tissue compartments along with prolonged memory B-cell reset. Across a greater than 100-fold preclinical dose range, cytokine levels remained low, supporting a wide safety window and reduced risk of cytokine release syndrome while maintaining ongoing target cell depletion.

"Dosing the first participant with JANX011 marks an important milestone for Janux and the first clinical evaluation of our ARM platform," said David Campbell, Ph.D., President and CEO, Janux Therapeutics. "While JANX011 is initially being developed for autoimmune diseases, the differentiated immune profile of the ARM platform may also have broader implications across CD19-expressing diseases, including hematologic malignancies."

"Based on compelling preclinical data, we believe JANX011 has the potential to achieve pharmacodynamic effects comparable to those seen with CAR-T therapies, including stable immune cell population changes and reductions in autoantibody drivers of disease, while offering the safety, convenience, and re-dosing flexibility required for autoimmune patients," said Tommy DiRaimondo, Ph.D., Chief Scientific Officer and Co-founder.

The Phase 1 study (NCT07291323) is an open-label, dose-escalation trial designed to evaluate the safety, tolerability, pharmacokinetics, and pharmacodynamics of JANX011 in healthy adult volunteers. The study is intended to characterize key immune effects, including B-cell depletion, memory B-cell reset, T-cell expansion, and cytokine release risk. The study is expected to generate early pharmacodynamic insights to inform dose selection and prioritization of autoimmune indications for subsequent clinical development.

About Janux Therapeutics

Janux is a clinical-stage biopharmaceutical company developing a broad pipeline of novel immunotherapies by applying its proprietary technology to its Tumor Activated T Cell Engager (TRACTr), Tumor Activated Immunomodulator (TRACIr), and Adaptive Immune Response Modulator (ARM) platforms. Janux's first clinical candidate, JANX007, is a TRACTr that targets prostate-specific membrane antigen (PSMA) and is being investigated in a Phase 1 clinical trial in adult patients with mCRPC. Janux's second clinical candidate, JANX008, is a TRACTr that targets epidermal growth factor receptor (EGFR) and is being studied in a Phase 1 clinical trial for the treatment of multiple solid tumors. Janux is also advancing its first ARM platform clinical candidate, JANX011, a CD19-ARM for the potential treatment of autoimmune diseases in a Phase 1 study in healthy adult volunteers. Janux continues to generate a number of additional TRACTr, TRACIr, and ARM programs for potential future development. For more information, please visit www.januxrx.com and follow us on LinkedIn.

Forward-Looking Statements

This news release contains certain forward-looking statements that involve risks and uncertainties that could cause actual results to be materially different from historical results or from any future results expressed or implied by such forward-looking statements. Such forward-looking statements include statements regarding, among other things, Janux's ability to bring new treatments to cancer patients in need, expectations regarding the timing, scope and results of Janux's development activities, including its ongoing and planned preclinical studies and clinical trials, the potential benefits of Janux's product candidates and platform technologies, and expectations regarding the use of Janux's platform technologies to generate novel product candidates. Factors that may cause actual results to differ materially include the risk that interim results of a clinical trial are not necessarily indicative of final results and one or more of the clinical outcomes may materially change as patient enrollment continues, following more comprehensive reviews of the data and as more patient data becomes available, including the risk that unconfirmed responses may not ultimately result in confirmed responses to treatment after follow-up evaluations, the risk that compounds that appear promising in early research do not demonstrate safety and/or efficacy in later preclinical studies or clinical trials, the risk that Janux may not obtain approval to market its product candidates, uncertainties associated with performing clinical trials, regulatory filings and applications, risks associated with reliance on third parties to successfully conduct clinical trials, the risks associated with reliance on outside financing to meet capital requirements, and other risks associated with the process of discovering, developing and commercializing drugs that are safe and effective for use as human therapeutics, and in the endeavor of building a business around such drugs. You are urged to consider statements that include the words "may," "will," "would," "could," "should," "believes," "estimates," "projects," "promise," "potential," "expects," "plans," "anticipates," "intends," "continues," "designed," "goal," or the negative of those words or other comparable words to be uncertain and forward-looking. For a further list and description of the risks and uncertainties Janux faces, please refer to Janux's periodic and other filings with the Securities and Exchange Commission, which are available at www.sec.gov. Such forward-looking statements are current only as of the date they are made, and Janux assumes no obligation to update any forward-looking statements, whether as a result of new information, future events or otherwise. All forward-looking statements are qualified in their entirety by this cautionary statement, which is made under the safe harbor provisions of the Private Securities Litigation Reform Act of 1995.

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Janux Therapeutics Announces First Patient Dosed in Phase 1 Study of JANX011