A Phase I Clinical Study to Evaluate the PK Profile, Efficacy, Safety and Immunogenicity of HLX17 vs. Keytruda® in Multiple Resected Solid Tumors

Inclusion Criteria:

1. Participants must have signed and dated an Institutional Review Board/IndependentEthics Committee (IRB/IEC) approved written informed consent form (ICF) inaccordance with regulatory and institutional guidelines.

2. At least 18 years and no older than 75 years (including 75 years old) at the time ofsigning the ICF.

3. 18 kg/m2 ≤ body mass index (BMI) ≤ 30 kg/m2 and 50 kg ≤ body weight ≤ 85 kg.

4. The patient with one of the following resected solid tumors:

• NSCLC patients after complete resection OR

• Melanoma following complete resection OR

• Renal cell carcinoma (RCC) at intermediate-high or high risk of recurrencefollowing nephrectomy, or following nephrectomy and resection of metastaticlesions.

5. Have a performance status of 0 on the Eastern Cooperative Oncology Group (ECOG)Performance Status within 7 days prior to the first dose in this study.

6. Have a life expectancy of at least 12 weeks.

7. Have adequate organ function as indicated by the following laboratory values (noblood transfusions, or treatment with albumin, recombinant human thrombopoietin orcolony-stimulating factor within 14 days prior to the first dose in this study)

8. Female patients must meet one of the following conditions:

9. Menopause (defined as no menstruation for at least 1 year with no confirmedcause other than menopause), or

10. Surgically sterilized (removal of the ovaries and/or uterus), or

11. Fertile, but must:

• be tested negative for serum/urine pregnancy test within 7 days prior tothe randomization, and
• agree to use contraception methods with an annual failure rate of < 1% orto remain abstinent (avoid heterosexual intercourse from signing the ICFto at least 6 months after the last dose of the study drug) (acontraceptive method with an annual failure rate of < 1% includesbilateral tubal ligation, male sterilization, correct use of hormonalcontraceptives that can inhibit ovulation, hormone-releasing intrauterinedevices and copper-containing intrauterine devices or condoms), and
• not breastfeed

9. Male patients must: agree to remain abstinent (avoid heterosexual intercourse) ortake contraception measures as follows: male patients with a pregnant partner or apartner of childbearing potential must remain abstinent or use condoms to preventdrug exposure to the embryo during study treatment and for at least 6 months afterthe last dose of study drug. Periodic abstinence (e.g., contraception based oncalendar day, ovulatory phase, basal body temperature, or postovulatory phase) andexternal ejaculation are ineligible methods of contraception.

Exclusion Criteria:

1. Pregnant or lactating women.

2. History of illicit drug use or alcohol abuse within 12 months prior to randomizationin the investigator's judgment.

3. Participants with NSCLC have two synchronous primary non-small cell lung cancers orother histopathological types (such as mixed adenosquamous carcinoma, small celllung cancer, or neuroendocrine carcinoma)； known positive for EGFR sensitivemutations or ALK fusion. EGFR sensitive mutations include: exon 19 deletion mutation (19DEL) and exon 21 point mutation (21L858R).

4. Participants with MEL have mucosal or ocular melanoma.

5. Participants with RCC have pre-existing brain or bone metastatic lesions, orresidual thrombus in the renal vein or vena cava after nephrectomy.

6. Participants with other primary active malignancies within 5 years or at the sametime prior to randomization.

7. Have received an organ or bone marrow transplantation prior to randomization orscheduled for transplantation during the study.

8. Presence of central nervous system (CNS) metastases and/or carcinomatous meningitis.

9. Symptomatic cerebrovascular disease or known myocardial infarction or poorlycontrolled arrhythmia (including QTc intervals ≥ 450 ms for males and ≥ 470 ms forfemales calculated by Fridericia's formula) within 6 months prior to randomization.

10. Chronic heart failure (Class III to IV based on NYHA classification) or an LVEF (left ventricular ejection fraction) assessed with the doppler echocardiography lessthan 50%.

11. Peripheral neuropathy greater than or equal to Grade 2 (CTCAE).

12. Known human immunodeficiency virus (HIV) infection (or positive anti-HIV duringscreening), or known Hepatitis B (or positive test for HBsAg or HBcAb and positivetest for HBV-DNA during screening), or known Hepatitis C (or positive tests for HCVantibody and HCV-RNA during screening), or known Hepatitis B and C co-infection (orpositive test for HBsAg or HBcAb and positive test for HCV antibody duringscreening), or active pulmonary tuberculosis within 6 months prior to randomization.

13. Known interstitial pneumonia, pneumoconiosis, radiation pneumonitis, drug-relatedpneumonitis, and severe lung function abnormalities that may impede theinvestigators' diagnosis and management of drug-related pulmonary toxicity prior toscreening.

14. Known severe allergic or anaphylactic reactions to pembrolizumab or any othermonoclonal antibody or any components of the investigational medicinal products.

15. Known active or suspected autoimmune diseases. Patients with stable disease who donot require systemic immunosuppressive therapy may also participate.

16. Unstable hyperthyroidism or hypothyroidism at screening.

17. Have received live vaccines within 28 days prior to the first dose in this study (Inactivated viral vaccines for seasonal influenza are allowed).

18. Treatment with systemic corticosteroids (> 10 mg/day prednisone efficacy dosage) orother immunosuppressive drugs within 14 days prior to the first dose or during thestudy. However, participants are allowed to be enrolled under the followingconditions: in the absence of active autoimmune disease, participants are allowed touse topical or inhaled steroids and adrenal hormone replacement therapy at dosagesequivalent to ≤ 10 mg/day of prednisone efficacy.

19. Any active infection requiring systemic therapy within 1 month prior to the firstdose in this study.

20. Participants have planning to undergo surgical treatment during this clinical trial.Tumor puncture or incisional lymph node biopsy is allowed.

21. Have received pembrolizumab or any other immune checkpoints inhibitors (PD-1, PD-L1,CTLA4, etc.) before randomization.

22. Participants have participated in a clinical study with another investigationalmedicinal product prior to randomization, and the interval between the current studyand the previous study is too short: within 1 month prior to the first dose of thecurrent study or within 5 half-lives of the previous investigational medicinalproduct (whichever is longer). Or planning to participate in a clinical study withanother investigational medicinal product before completing all scheduledassessments in this clinical study.

23. Participants have participated in a device clinical study within 1 month prior toscreening, or are participating in another surgical or device clinical study at thetime of screening, or plan to participate in another surgical or device clinicalstudy during this clinical study.

24. The investigator has a clear reason to believe that participation in this studywould be detrimental to the participant.