This is a first-in-human (FIH) Phase I, multi-center, open-label, study of QLS5316, in patients with advanced solid tumors. The study aim to evaluating the safety, tolerability, preliminary efficacy, pharmacokinetics (PK), and immunogenicity of QLS5316 as monotherapy.

Inclusion Criteria:

1. Age ≥ 18 years
2. Eastern Cooperative Oncology Group (ECOG) Performance Status: 0-1
3. Life expectancy ≥ 3 months;
4. Measurable disease per RECIST v1.1
5. Adequate organ and marrow function as defined in the protocol
6. Dose escalation and PK expansion stages: Histologically or cytologically confirmed locally advanced or metastatic malignant solid tumors that cannot undergo radical surgery or radiotherapy, who have failed SOC or SOC is not available
7. Cohort expansion stage: Patients with histologically or cytologically confirmed locally advanced or metastatic malignant solid tumors that cannot undergo radical surgery or radiotherapy, including CRC, GC/GEJ, HNSCC (mouth, oropharynx, hypopharynx or larynx), EGFR-sensitive mutant NSCLC and EGFR wild-type NSCLC or other advanced malignant solid tumors who have failed SOC or SOC is not available.

Exclusion Criteria:

1. Prior treatment with antibody-drug conjugates (ADCs) containing topoisomerase I inhibitors, or prior treatment with EGFR and/or c-MET targeted ADCs
2. Untreated or active brain metastasis
3. Presence of Grade ≥ 2 toxicity (according to the Common Terminology Criteria for Adverse Events (CTCAE Version 5.0) ) left over from prior therapy
4. Patients with a history of interstitial lung disease (ILD)/non-infectious pneumonia, or patients whose suspected ILD/non-infectious pneumonia cannot be ruled out by imaging examination at screening; patients with radiation pneumonitis who do not require steroid treatment are allowed to be enrolled;
5. Patients with a history of active tuberculosis, active autoimmune diseases or autoimmune diseases that may recur
6. Patients with a history of severe cardiovascular and cardiovascular diseases
7. Clinically uncontrollable third space effusion
8. Presence of persistent uncontrolled systemic bacterial, fungal or viral infections or severe infections within 4 weeks before the first dose in the study, or active infections requiring systematic antibiotic treatment within 1 week before the first dose in the study;
9. Known hypersensitivity reactions or delayed-type sensitization to some components or analogues of the investigational drug