This is a study to evaluate the maximum tolerated dose (MTD), occurrence of all adverse events (AEs) and serious adverse events (SAEs), pharmacokinetic parameters and antitumor effect of TQB3912 tablets in Chinese adult patients with advanced malignant neoplasm. The study was divided into phase Ia and phase Ib, Phase Ia: Dose escalation period, to evaluate the safety and tolerability of TQB3912 tablets, determine MTD; Phase Ib: Effectiveness exploration period, to expand the safe and effective dose group, and to recommend appropriate dosage and method for subsequent clinical research.

Inclusion Criteria:

• Subjects who voluntarily join the study, sign the informed consent form, and have good compliance.
• Aged from 18 to 75 years; Eastern Cooperative Oncology Group performance status score: 0-2; at least 3 months of expected survival period.
• Subjects with relapse advanced malignant solid tumors clearly diagnosed by pathology and/or cytology.
• The function of main organs is normal.
• Subjects need to adopt effective methods of contraception.

Exclusion Criteria:

• Subjects with other malignancies currently or suffered within 3 years.
• Subjects with Grade 1 or above unhealed toxicity reaction of Common Terminology Criteria for Adverse Events Version 5.0 due to previous antitumor treatment.
• Subjects who have received major surgical treatment, open biopsy or obvious traumatic injury within 28 days before first administration.
• Subjects with long lasting wounds or fractures.
• Subjects with a history of psychotropic drug abuse unable to quit or with mental disorders.
• Subjects with any severe and/or uncontrolled disease.
• Subjects who have received surgery, chemotherapy, radiotherapy or other anticancer therapies 4 weeks before the first administration.
• Subjects who have taken Chinese patent medicines with anti-tumor indications in the drug instructions that National Medical Products Administration approved within 2 weeks before the first administration.
• Subjects with pleural effusion, pericardial effusion or ascites that cannot be controlled and need repeated drainage.
• Subjects who have participated in other clinical studies within 4 weeks before the first administration.
• According to the judgment of the investigators, there are accompanying diseases that seriously endanger the safety of patients or affect the completion of the study.