This study is an open-label first-in-human phase I clinical study to evaluate the safety and tolerability of HLX42.

The first stage: This study is an open-label first-in-human phase I clinical study to evaluate the safety and tolerability of HLX42 with escalated doses in the treatment of patients with advanced/metastatic solid tumors. In this study, a 3 + 3 dose escalation method will be adopted, and the patients will be administered with HLX42 at different doses via intravenous infusion. The DLT observation period lasts for 3 weeks after the first administration of HLX42.

The second stage: This is a randimazation, open label, 2 arms, muticentral clinical study, about 30 patients in each arm, the total sample size is about 60. Eligible subjects will be randomized in a 1:1 ratio: Group A: HLX42 2.5 mg/kg; Group B: HLX42 2.0 mg/kg. Stratification: tumor tissue type(adenocarcinoma or squamous carcinoma), EGFR-sensitive mutation status (mutant or wild-type or missing).

Inclusion Criteria:

1. ≥ 18 years and ≤ 75 years at the time of signing the ICF, male or female;
2. Patients with histologically or cytologically confirmed advanced/metastatic malignant solid tumors, who are refractory to or intolerable with standard treatment, or for which no standard treatment is available(stage 1); Patients with histologically or cytologically confirmed advanced/metastatic malignant NSCLC, who are refractory to or intolerable with standard treatment, or for which no standard treatment is available(stage 2);
3. At least one measurable lesion as per RECIST 1.1；
4. An ECOG performance status score of 0-1；
5. Life expectancy > 3 months;
6. Adequate organ functions as confirmed by laboratory tests within 7 days prior to the first administration of the investigational product;
7. For patients with hepatocellular carcinoma, Child-Pugh score must be A;

Exclusion Criteria:

1. History of other malignant tumors within 2 years prior to the first administration, except for cured cervical carcinoma in situ or cutaneous basal cell carcinoma;
2. The histopathological type is large cell carcinoma, adenosquamous carcinoma, other types (including but not limited to sarcomatoid carcinoma, lymphoepithelioma-like carcinoma, NUT carcinoma, etc.), or contains neuroendocrine pathological components, etc. (stage 2)；
3. History of (non-infectious) ILD requiring the use of steroids, current ILD, or suspected ILD that cannot be ruled out by imaging at screening;
4. Subjects who are allergic to protein preparations/ monoclonal antibodies/ any component in the formulation of the investigational product;
5. Subjects with known previous serious eye disorders;
6. Active systemic infectious diseases requiring intravenous antibiotics within 2 weeks prior to the first administration of the investigational product;
7. Any poorly-controlled cardiovascular and cerebrovascular clinical symptoms or diseases;
8. Patients who have been assessed as unsuitable for inclusion by the investigator, due to brain metastases, spinal cord compression, or cancerous meningitis with clinical symptoms, or uncontrolled brain or spinal cord metastases that have been evidenced;
9. Patients who have received long-term systemic steroids treatment (equivalent to prednisone > 10 mg/day) or immunosuppressive agents of any other forms, which should be discontinued at least 2 weeks prior to the first infusion of the investigational product;
10. Patients who have used potent CYP2D6/CYP3A inhibitors or inducers within 2 weeks prior to the first administration;
11. Patients who have history of immunodeficiency, including HIV infection or other acquired or congenital immunodeficiencies, or history of organ transplantation;
12. Patients with active HBV or HCV infection or HBV/HCV co-infection;
13. Pregnant or lactating women;
14. Subjects who are not suitable for participating in this clinical study due to any clinical or laboratory abnormalities or other reasons as assessed by the investigator.