Phase 1/2 Clinical Study of HY07121 Powder for Solution for Infusion in Patients With Advanced Solid Tumors

Inclusion Criteria: * Written informed consent; * ≥18 years old and ≤80 years old, gender: male or female; * Histologically or cytologically confirmed unresectable advanced/metastatic solid tumor that has relapsed or progressed on or after standard systemic treatments, or refused the standard treatment, or for which no standard treatment is available; * Presence of at least one measurable lesion according to Response Evaluation Criteria in Solid Tumours (RECIST) Version 1.1; * Eastern Cooperative Oncology Group (ECOG) performance status score is 0 or 1; * Life expectancy ≥3 months; * Participant must have adequate main organ function; * Fertile female patients must have a negative serological pregnancy test within 7 days before the first dosing and be willing to use effective birth control/contraception to prevent pregnancy during the study period up to 6 months after the last dosing of the study. Male patients must agree to have no sperm donation plans and to use effective contraceptive methods during the study period until 6 months after the last dose of the study. Postmenopausal women must have amenorrhea for at least 12 months before they are considered infertile. Exclusion Criteria: * Within the defined washout periods for prior anti-cancer treatments; * Participant is currently participating or has participated in a study of an investigational agent or using an investigational device within 4 weeks of first dose of HY07121. * Any other malignancy within 2 years prior to the first dose of the study treatment except for localized cancers that are considered to have been cured and in the opinion of the Investigator present a low risk for recurrence. * Participant has not recovered (i.e., to Grade 1 or to baseline) from previous anticancer therapy-induced Adverse Events (AEs). * Participants with a history of recently (within previous 2 years of the first dose of the study treatment) active diverticulitis or symptomatic peptic ulcer disease; * Major surgery within 4 weeks of receiving the first dose of study treatment; * Participant has Symptomatic Central Nervous System (CNS) metastases, or CNS metastases requiring CNS-directed local therapy (such as radiotherapy or surgery) or corticosteroids therapy within 4 weeks of first dose of study treatment; * Participants with untreated or under treatment for tuberculosis, including but not limited to tuberculosis; Patients who have received standardized anti-tuberculosis treatment and have been confirmed cured by the researchers can be included; * Participants with clinically significant cardiovascular diseases, in the past 6 months prior to the first dose of the study treatment; symptomatic coronary heart disease requiring drug treatment; arrhythmia requiring drug treatment; or uncontrolled hypertension; * Known Human Immunodeficiency Virus (HIV) infection or known Acquired Immunodeficiency Syndrome (AIDS); * Active or chronic hepatitis B or hepatitis C infection; treponema pallidum antibody positive, and confirmed positive test; * Active known or suspected autoimmune disease. * History of non-infectious pneumonitis that has required a course of oral or intravenous steroids to assist with recovery, or interstitial lung disease or severe obstructive pulmonary disease; * History of severe allergy; * History of allogeneic organ transplantation or graft-versus-host disease; * Have received live/attenuated vaccines and mRNA vaccines within 4 weeks prior to screening or plan to receive live/attenuated vaccines and mRNA vaccines during the study period; * Any active infection requires systemic treatment via intravenous infusion within 4 weeks prior to the first dose of study treatment; * Known psychiatric disorder or drug abuse that would interfere the trial requirements; * Participant with uncontrolled pleural effusion, pericardial effusion or peritoneal effusion or need drainage; * In addition to the tumors present at the time of entry into the study, other active malignancies were present within 3 years prior to the first dose (not excluding locally cured tumors, such as skin basal cell carcinoma, superficial bladder cancer or carcinoma in situ of the breast, etc.); * Participants considered unsuitable for participation in this study by the investigators.