Business Description

Unless the context otherwise requires, the terms “Janux Therapeutics,” “Janux,” “we,” “us,” “our” and similar references in this Annual Report on Form 10-K refer to Janux Therapeutics, Inc. Overview‌ We are an innovative clinical-stage biopharmaceutical company developing a broad pipeline of novel immunotherapies by applying our proprietary technologies to our Tumor Activated T Cell Engager (TRACTr), Tumor Activated Immunomodulator (TRACIr), and Adaptive Immune Response Modulator (ARM) platforms. The TRACTr platform produces T cell engagers (TCEs) with a tumor antigen-binding domain and a CD3 T cell binding domain, while the TRACIr platform produces bispecifics with a tumor antigen-binding domain and a costimulatory CD28 binding domain. The goal of our TRACTr and TRACIr platforms is to provide cancer patients with safe and effective therapeutics that direct and guide their immune system to eradicate tumors while minimizing safety concerns. Our initial focus is on developing a novel class of TRACTr therapeutics designed to target clinically validated TCE drug targets, while overcoming the liabilities associated with prior generations of TCEs. While TCE therapeutics have displayed potent anti-tumor activity in hematological cancers, developing TCEs to treat solid tumors has faced challenges due to the limitations of prior TCE technologies, namely (i) on-target healthy tissue immune activation that contributes to cytokine release syndrome (CRS) and healthy tissue toxicity and (ii) poor pharmacokinetics (PK) leading to short half-life. Our first clinical candidate, JANX007, is a prostate-specific membrane antigen (PSMA) TRACTr being investigated in a Phase 1 clinical trial in adult subjects with metastatic castration-resistant prostate cancer (mCRPC). In December 2024, we announced updated interim clinical data for JANX007 demonstrating meaningful and prolonged prostate-specific antigen (PSA) reductions, evidence of anti-tumor activity, a favorable safety profile with CRS and treatment-related adverse events (TRAEs) primarily limited to cycle 1 and lower grades, and pharmacokinetics consistent with the TRACTr mechanism of action. In May 2025, we provided updated results from the patients reported in December 2024 that demonstrated consistent durability and safety profile supporting the initiation of Phase 1b expansion studies. In December 2025, we announced updated interim clinical data demonstrating durability across both once-weekly (QW) and every-two-week (Q2W) Phase 1a expansion cohorts. JANX007 continued to demonstrate a manageable safety profile, with CRS primarily limited to cycle 1 and grades 1 and 2, and preliminary Phase 1b data in taxane-naïve patients demonstrated rapid and deep PSA reductions with primarily grade 1 CRS. Based on the safety, pharmacokinetic and preliminary efficacy data observed to date, we initiated the first of our planned Phase 1b expansion cohorts designed to further characterize JANX007 and inform potential registrational development strategies. These cohorts are designed to evaluate JANX007 in clinically relevant patient populations, including taxane-naïve mCRPC, combination with an androgen receptor pathway inhibitor (darolutamide), and patients whose disease has progressed following prior PARP inhibitor therapy. In May 2025, we announced initiation of the Phase 1b expansion study in taxane-naïve mCRPC. These studies are designed to help refine dosing, patient selection and combination strategies and provide insights to support the design of future late-stage clinical development. Our second clinical candidate, JANX008, is an epidermal growth factor receptor (EGFR) TRACTr being investigated in a Phase 1 clinical trial for the treatment of multiple solid tumors. The first patient in this trial was dosed in April 2023, and in February 2024 we announced early clinical data demonstrating anti-tumor activity across multiple tumor types, with low-grade CRS and predominantly low-grade treatment-related adverse events. In December 2025, we announced the initiation of Phase 1a expansion cohorts in selected solid tumor indications based on the efficacy and safety data observed in the completed dose-escalation portion of the study. Building on the results from dose escalation, the ongoing expansion cohorts are evaluating JANX008 in tumor types where early signals of activity and tolerability were observed.…