A Phase 1 Study of JMT108 in Participants With Advanced Solid Tumors

The goal of this clinical trial is to test JMT108, a type of drug called a bispecific antibody in adult patients with locally advanced or metastatic solid tumors. The main questions it aims to answer are: * To assess the safety and tolerability of JMT108 at increasing doses and determine the dose and schedule to be used in the second part of the study (Phase 1a) * To assess effectiveness of JMT108 in participants with locally advanced or metastatic tumors (Phase 1b) * To evaluate how quickly JMT108 is metabolized by the body (pharmacokinetics or PK) * To evaluate if antibodies to the study drug develop (immunogenicity) * To evaluate preliminary efficacy to the drug * To explore the pharmacodynamic (PD) characteristics of JMT108 * To explore the correlation between biomarker levels and preliminary efficacy Participants will: * Provide written informed consent * Undergo screening tests to ensure they are eligible for study treatment * Attend all required study visits and receive JMT108 by intravenous injection every 2 weeks until the study doctor determines study treatment should be stopped, based on how well a participant is doing on treatment * Be followed for progression every 3 months for up to 2 years

This Phase 1 study is a single agent, 2-part (including dose escalating and expansion) study conducted in patients with locally advanced or metastatic solid tumors who are unresponsive or intolerant to all standard of care or have no standard of care available. Dose escalation (Phase 1a) - Dose escalation will be conducted using a BOIN design. In the dose-escalation phase, a total of 4 dose levels-0.1 mg/kg, 0.3 mg/kg, 1 mg/kg, and 2 mg/kg-will be sequentially escalated. The BOIN design is adopted for the dose-escalation part of this study to determine the MTD. The target toxicity rate for the MTD is 0.3, and the maximum sample size for the dose-escalation BOIN design is 30 participants. Participants are enrolled to receive treatment in cohorts of size 3. Dose escalation and de-escalation decisions are made based on the occurrence of DLTs within the DLT observation window. After thorough evaluation by the SMC, one or more dose levels may be added between the highest escalated dose level and the next lower dose level for better DLT assessment. The dose escalation phase includes a screening period (D-28 to D-1), a treatment period, an end of treatment (EOT) visit, and a follow-up period. Cohort expansion (Phase 1b) - Based on the results of Phase 1a, the administration dose and frequency for the cohort expansion phase of study will be determined. If necessary, several different doses/frequencies may be selected for cohort expansion. Participants may be enrolled in the cohort expansion study with tumor types including but not limited to Cohort 1: lung cancer, Cohort 2: colorectal cancer, Cohort 3: liver cancer, Cohort 4: gastric cancer, Cohort 5: melanoma and Cohort 6: other advanced solid tumors (including cervical cancer, renal cancer, bile duct cancer, head and neck squamous cell head and neck cancer, etc.).