A Multi-Regional, Open-Label, Dose Escalation and Dose Expansion Phase I Clinical Study to Investigate the Safety, Tolerability, Pharmacokinetics, Immunogenicity and Preliminary Efficacy of HF158K1 in Participants with HER-2 Positive or HER-2 Low Expression Advanced Solid Tumors

1. Participants who are known to be allergic to doxorubicin and/or other similar compounds, or to any of excipients of HF158K1, or participants with allergic constitution (multiple drug and food allergies).

2. Participants who have used doxorubicin prior to screening with a total cumulative dose > 350 mg/m2 (other anthracyclines converted by 1 mg doxorubicin equivalence: 2 mg epirubicin, or 2 mg epirubicin, or 2 mg zolpidem, or 0.5 mg demethoxyzolpidem), or who have received anthracyclines and suffered severe cardiotoxicity, or who discontinued doxorubicin liposome therapy due to serious adverse events.

3. Participants who received radiotherapy or chemotherapy (paclitaxel, cyclosporine, dextropropylenol, cytarabine, streptozotocin, etc.) within 4 weeks prior to first dose administration, or received other antitumor therapy such as endocrine therapy, herbal therapy, or local radiation therapy for pain relief within 2 weeks prior to first dose administration, except for the following: Nitrosourea or mitomycin C within 6 weeks prior to the first administration of the investigational drug.

Oral fluorouracil-based and small-molecule targeted drugs for 2 weeks prior to the first administration of the investigational drug or within 5 half-lives of the drug (whichever is longer).

4. Participants with brain parenchymal metastases or meningeal metastases with clinical symptoms that, in the judgment of the investigator, are not suitable for enrollment (those who have received prior treatment (radiation or surgery) for systemic, radical brain metastases, have maintained imaging- confirmed stability for at least 28 days, and have discontinued systemic steroid therapy for > 14 days without clinical symptoms will be allowed for enrollment).

5. Participants who have not recovered to < Grade 1 (according to CTCAE 5.0) or to pre-treatment baseline levels from all prior treatment-induced adverse events prior to the first dose (except for adverse events without safety risks as judged by the investigator, such as alopecia, Grade 2 peripheral neurotoxicity, and stabilized hypothyroidism under hormone replacement therapy).

6. Participants who are taking (or are not able to discontinue until at least 1 week before the first dose of the study) any drug known to strongly inhibit or strongly induce CYP3A4, CYP2D6 or P-gp.

7. Participants with a history of serious cardiovascular and cerebrovascular diseases, including but not limited to: Serious heart rhythm or conduction abnormalities, such as ventricular arrhythmia that requires clinical intervention, degree II-III atrioventricular block, etc. Cardiac function: left ventricular ejection fraction (LVEF) ≤ 50%, corrected QT interval (QTcF) > 470 ms.

Thromboembolic events requiring therapeutic anticoagulation within 3 months before the first administration, or participants with venous filters.

Participants with Class III~IV cardiac insufficiency according to the New York Heart Association (NYHA) criteria.

Acute coronary syndrome, congestive heart failure, aortic dissection, stroke or other Grade 3 and above cardiovascular and cerebrovascular events within 6 months before the first administration.

Clinically uncontrollable hypertension (systolic blood pressure > 160 mmHg or diastolic blood pressure > 100 mmHg), and patients with a history of hypertension were allowed to enroll as long as their blood pressure was controlled below this limitation through antihypertensive therapy.

Any factors that increase the risk of QTc prolongation or arrhythmia, such as heart failure, hypokalemia, congenital long QT syndrome, or use of any concomitant drug that are known to or may prolong the QT interval.

8. Participants who have received last dose of any other investigational drug product or treatments within 28 days prior to the first administration of the investigational drug.

9. Participants who have undergone major organ surgery (excluding needle biopsy，tracheotomy, gastrostomy, etc.) or had significant trauma within 28 days before the first administration of investigational drug or need to undergo elective surgery during the study period.

10. Participants with a serious unhealable wound/ulcer/fracture within 28 days before the first administration of the investigational drug.

11. Participants with an active infection within 1 week prior to the first administration of the investigational drug and currently require intravenous anti-infection therapy.

12. Third space effusion that cannot be clinically controlled and is not suitable for enrollment as judged by the investigator.

13. Known history of drug abuse.

14. Participants with mental disorders or poor compliance.

15. HIV infection, active HBV infection (HBV DNA > ULN), or active HCV infection (HCV RNA > ULN).

16. Women who are pregnant or breastfeeding. 17. Participants who cannot tolerate venous blood sampling. 18. The investigator believes that the participant has a history of other serious systemic diseases or is not suitable for participating in this clinical study for other reasons.

HER-2 positive (IHC 3+, or IHC 2+ with ISH +) or HER-2 low expression (IHC 2+ with ISH -, or IHC 1+) participants with unresectable or metastatic advanced solid tumors (confirmed by histopathology or cytology analysis) who have failed or are intolerant (disease progression, or intolerance to chemotherapy, targeted therapy, etc.) to standard treatment, or currently have no available treatment regimen.