Janux Therapeutics, Inc., a clinical-stage biopharmaceutical company developing a broad pipeline of novel immunotherapies based on its proprietary Tumor Activated T Cell Engager (TRACTr), Tumor Activated Immunomodulator (TRACIr), and Adaptive Immune Response Modulator (ARM) platforms, today announced that William Go, M.D., Ph.D., has been appointed Chief Medical Officer, effective January 26, 2026. Dr. Go succeeds Zachariah McIver, D.O., Ph.D., who will be leaving the Company to pursue other opportunities.

Dr. Go brings more than 20 years of hematology and oncology experience, leading programs from early clinical development through pivotal trials, global regulatory approvals, and first-in-class launches. He joins Janux at an important stage as the Company advances its pipeline and continues to scale its clinical and regulatory operations.

Most recently, Dr. Go served as Chief Medical Officer at A2 Biotherapeutics, where he led development of logic-gated CAR T-cell therapies for solid tumors. During his tenure, A2 Bio initiated three Phase 1 clinical trials across multiple solid tumor indications.

Previously, Dr. Go held senior leadership roles at Kite Pharma, where he led the pivotal ZUMA-1 trial supporting the FDA and EMA approvals of YESCARTA®, the first CAR T-cell therapy approved for large B-cell lymphoma. Following Kite's acquisition by Gilead Sciences, he continued in a senior clinical development leadership role overseeing programs in large B-cell lymphoma.

Earlier in his career at Amgen, Dr. Go contributed to the global label expansion of Vectibix® and helped advance extended RAS next-generation sequencing strategies in colorectal cancer to identify predictive biomarkers.

Dr. Go earned a B.A. in Biology from Carleton College and completed an M.D. and Ph.D. through the UC San Diego Medical Scientist Training Program. He completed residency training in internal medicine and a fellowship in hematology/oncology at UC San Diego, with tumor immunology research supported by fellowships from the California Institute for Regenerative Medicine and the American Association of Cancer Institutes.

"Janux is entering an important new phase as our programs advance and the complexity of our clinical and regulatory efforts increases," said David Campbell, Ph.D., President and Chief Executive Officer of Janux Therapeutics. "Will brings a combination of early- and late-stage development experience, regulatory leadership, and launch execution that will strengthen our organization as we scale. I would also like to thank Zach for his important contributions during a formative period for Janux and wish him well in his future endeavors."

"What attracts me to Janux is the strength of its science and the breadth and depth of its oncology pipeline, anchored by a differentiated, tumor-activated T-cell engager platform," said Dr. Go. "Janux is tackling important clinical challenges with programs designed to build on existing standards of care, and I believe the Company is well positioned to deliver meaningful advances for patients. I'm excited to work with the Janux team, investigators, and partners as we move these programs forward."

Janux's TRACTr, TRACIr and ARM Pipeline

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 cancers including colorectal carcinoma, squamous cell carcinoma of the head and neck, non-small cell lung cancer, renal cell carcinoma, small cell lung cancer, pancreatic ductal adenocarcinoma and triple-negative breast cancer. Janux is also advancing additional CD3-based TRACTr and CD28-based TRACIr programs for future clinical development, including a PSMA-TRACIr for use in combination with our PSMA-TRACTr JANX007, and a TROP2-TRACTr for the treatment of TROP2+ solid tumors. Janux is advancing its first ARM platform program candidate, a CD19-ARM for the potential treatment of autoimmune diseases toward clinical trials. Janux is also generating a number of additional TRACTr, TRACIr and ARM programs for potential future 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 has two TRACTr therapeutic candidates in clinical trials, the first targeting PSMA is in development for prostate cancer, and the second targeting EGFR is being developed for colorectal carcinoma, squamous cell carcinoma of the head and neck, non-small cell lung cancer, renal cell carcinoma, small cell lung cancer, pancreatic ductal adenocarcinoma and triple-negative breast cancer. 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, and 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 Appoints William Go, M.D., Ph.D., as Chief Medical Officer