Due to the change in study plan and not due to safety reasons

This is a Phase 1 dose escalation and dose expansion study to evaluate the safety, tolerability, pharmacokinetics, and preliminary efficacy of RGT-264 as monotherapy in subjects with advanced solid tumors.

This first-in-human (FIH) study of RGT-264 will evaluate safety, pharmacokinetics (PK) and efficacy of RGT-264 in subjects with advanced solid tumors. The primary objective is to determine the maximum tolerated dose (MTD)/maximum administered dose (MAD) and the recommended phase II dose (RP2D) of RGT-264 as monotherapy, and to evaluate the safety and tolerability of RGT-264. The secondary objectives include the assessments of PK profile and preliminary efficacy of RGT-264.

Inclusion Criteria:

• Able to sign the ICF and agree to comply with the requirements of the study;
• Subjects with pathologically confirmed advanced solid tumors who have failed standard-of-care therapy, or have no standard-of-care therapy available, or are currently not eligible for standard-of-care therapy;
• ECOG performance status score of 0 to 1;
• Expected survival ≥ 3 months;
• With at least one measurable lesion per RECIST v1.1;
• Subjects should discontinue all anti-tumor therapies prior to receiving study treatment, and the toxicity caused by prior anti-tumor therapy has recovered to ≤ Grade 1 per CTCAE v5.0;
• The specific requirements of washout period should be met before first dose;
• Adequate organ function
• Female subjects of childbearing potential must have a negative pregnancy test prior to the first dose and are required to use effective contraception from signing the ICF until 6 months after the last dose of study treatment

Exclusion Criteria:

• Presence of risks that may significantly affect the absorption of the investigational product (e.g. inability to swallow, intestinal obstruction, chronic diarrhea, etc.);
• Having received immunotherapy and experienced ≥ Grade 3 immune-related adverse events (irAEs) or ≥ Grade 2 immune-related myocarditis;
• Having received systemic glucocorticoids (> 10 mg/day of prednisone or equivalent) or other immunosuppressants within 14 days prior to the first dose of investigational product;
• Presence of symptomatic parenchymal brain metastasis or leptomeningeal metastasis;
• Active, or previous autoimmune disease with the potential for relapse (excluding well-controlled type 1 diabetes mellitus; manageable hypothyroidism with hormone replacement therapy only).;
• Any other malignancy (except cured basal cell carcinoma of skin and in-situ carcinoma of the cervix) within 3 years prior to the first dose;
• History of serious cardiovascular and cerebrovascular diseases;
• Presence of active interstitial lung disease or history of interstitial lung disease requiring glucocorticoid treatment;
• Presence of severe chronic or active infections (including tuberculosis infection, etc.) requiring intravenous antimicrobial, antifungal or antiviral therapy;
• Active HBV or HCV infection;
• History of immunodeficiency or organ transplantation;
• Presence of uncontrolled third spacing fluid;
• Concomitant diseases or any other conditions that may seriously jeopardize the subject's safety or affect the subject's completion of the study, at the discretion of the investigator.