The goal of this clinical trial is to learn if the study drug can work in advanced cancer patients. The main questions it aims to answer are:

• Is the drug safe and tolerable ?
• Does the drug exhibit antitumor activity ?

Participants will receive the study drug once every three weeks, and imaging-based efficacy assessments will be performed every six weeks.

Target population are patients with advanced solid tumors .

Inclusion Criteria:

• 1. Participants who voluntarily participate in this study and sign the written Informed Consent Form (ICF) after being fully informed.
• 2. Male or female participants aged 18 to 75 years (inclusive).
• 3. Participants with histologically or cytologically confirmed locally advanced unresectable or metastatic solid tumors who have experienced disease progression on or after standard therapy , or are intolerant to standard therapy, or for whom no effective standard of care is available.
• 4. Participants who are able to provide fresh or archival tumor tissue during the screening period. Tumor tissue will be collected for biomarker testing at a central laboratory, including immunohistochemistry for EGFR and HER3 .
• 5. Eastern Cooperative Oncology Group Performance Status (ECOG PS) of 0 or 1 .
• 6. Life expectancy ≥3 months.
• 7. According to RECIST v1.1, the participant must have at least one measurable lesion .
• 8. Participants with good organ function as demonstrated by screening laboratory test results.
• 9. The fertile participants agreed to take effective contraceptive measures during the study and after its conclusion; and must have a negative serum human chorionic gonadotropin (HCG) test within 7 days before dosing.
• 10. Participants should be willing and able to complete regular visits, treatment plans, laboratory tests, and other study procedures.

Exclusion Criteria:

• 1. Participants who have previously received ADC containing exatecan , or an ADC primarily directed against EGFR and/or HER3.

• 2. Participants who have received the following treatments:

  1. Participants who have undergone major surgery within 4 weeks before the first dose;
  2. Participants who have received radiotherapy involving the bone marrow or extensive radiotherapy within 4 weeks before the first dose; or local radiotherapy within 2 weeks before the first dose;
  3. Participants who are receiving continuous systemic corticosteroid therapy ; low-dose corticosteroids are permitted if the dose of systemic corticosteroids has been stable for 4 weeks;
  4. Participants who have received anti-tumor treatments within 4 weeks before the first dose, or are still within 5 half-lives of the last dose of the most recent anticancer therapy (whichever is longer). Traditional Chinese medicines with approved anticancer indications within 2 weeks prior to the first administration of study drug.

• 3. Participants with other malignant tumor within the past 5 years, other than the tumor treated in this study, with the exception of locally cured tumors .

• 4. Participants with related AEs (except for alopecia and ≤ Grade 2 sensory neuropathy) caused by previous treatment that have not recovered to ≤ Grade 1 or baseline level.

• 5. Participants with known weight loss of >10% within 2 months before the first dose of the study drug or other indicators showing severe malnutrition.

• 6. Participants with serious complications or medical histories involving important organs.

• 7. Participants with known active central nervous system (CNS) metastasis.

• 8. Participants with any of the cardiovascular/cerebrovascular disorders, symptoms, or manifestations.

• 9. Participants with the following conditions will be excluded at screening: active syphilis, history of human immunodeficiency virus (HIV) infection, active hepatitis B virus (HBV) or active hepatitis C virus (HCV), with the exception of asymptomatic chronic hepatitis B or C virus carriers.

• 10. Participants with a history of interstitial pneumonia or other moderate to severe lung disorders that seriously affect lung function.

• 11. Participants with severe infection during the screening period.

• 12. Participants with other diseases that may affect the efficacy and safety of the study drug.

• 13. Participants with uncontrolled pericardial effusion, uncontrolled pleural effusion, or clinically significant moderate or greater ascites during the screening period.

• 14. Participants with unstable thrombotic events requiring therapeutic intervention within 6 months before screening; however, thrombosis related to infusion devices is not included.

• 15. Participants who have received a live vaccine within 30 days before the first dose, or plan to receive a live vaccine during the study period.

• 16. Participants who have received strong CYP3A4 inhibitors and inducers therapy within 1 week before dosing, or are expected to require long-term use of strong CYP3A4 inhibitors and inducers during the study intervention and within 30 days after the last dose .

• 17. Participants with history of solid organ transplant.

• 18. Participants with known or suspected history of severe allergy to any component of the study drug or its analogues.

• 19. Pregnant and lactating women.

• 20. Participants who are deemed unsuitable for this study (e.g., poor compliance, etc.) by the investigator.