A Study of YL201 in Patients With Advanced Solid Tumors

Inclusion Criteria:

Common Inclusion Criteria (Part 1 and Part 2)

Informed of the trial before the start of the trial and voluntarily sign their name and date on the ICF
Aged ≥18 years
Eastern Cooperative Oncology Group performance status (ECOG PS) of 0 or 1
Adequate organ and bone marrow function
Female patients of childbearing potential must agree to use a highly effective form of contraception and not donate, or retrieve for their own use, ova from the time of screening and throughout the study period, and for at least 6 months after the last dose of study drug. Male patients must agree to use a highly effective form of contraception and not freeze or donate sperm from the time of screening and throughout the study period, and for at least 6 months after the last dose of study drug
Life expectancy of ≥3 months
Able and willing to comply with protocol visits and procedures
Pathologically confirmed diagnosis of an advanced solid tumor for which prior standard treatment had proven to be ineffective or intolerable, or no standard treatment is available

Additional Inclusion Criteria for Part 1

Have at least 1 evaluable tumor lesion according to Response Evaluation Criteria in Solid Tumors (RECIST) version 1.1. Participants with prostate cancer who have bone only disease may be eligible on a case-by-case basis after discussion with the sponsor

Additional Inclusion Criteria for Part 2

Have at least 1 measurable tumor lesion according to RECIST version 1.1. Participants with prostate cancer who have bone only disease may be eligible on a case-by-case basis after discussion with the sponsor
Willing to provide archival or fresh tumor tissue samples. Patients who are not able to provide tumor samples or have inadequate samples may be eligible on a case-by-case basis after discussion with the sponsor

Exclusion Criteria:

Common Exclusion Criteria (Part 1 and Part 2)

Intolerant to prior treatment with a topoisomerase I inhibitor or an ADC that consists of a topoisomerase I inhibitor, including but not limited to topotecan, irinotecan, and Dxd
Concurrent enrollment in another clinical study, unless it is an observational (noninterventional) clinical study or during the follow-up period of an interventional study
Prior systemic anticancer treatment including chemotherapy, molecular targeted therapy, hormonal therapy, immunotherapy, or biological therapy within 3 weeks before the first dose of study drug (use of oral fluorouracil [eg, tegafur and capecitabine] or small molecular targeted therapy within 2 weeks or 5 half-life periods [whichever is shorter] before the first dose; use of mitomycin or nitrosoureas within 6 weeks before the first dose; use of herbal medicine with antitumor indications or nonspecific immunomodulators [eg, thymosin, interferon, and interleukin] within 2 weeks before the first dose)
Prior radiation therapy, including palliative stereotactic radiation with abdominal, within 4 weeks before the first dose of study drug (if palliative stereotactic radiation therapy without abdominal, within 2 weeks)
Undergone major surgery (not including diagnostic surgery) within 4 weeks before the first dose of study drug or expect major surgery during the study
Undergone allogeneic hematopoietic stem cell transplantation (HSCT) before the first dose of study drug, or autologous HSCT within 3 months before the first dose of study drug

Received systemic steroids (>10 mg/day of prednisone or its equivalent) or other immunosuppressive therapy within 2 weeks before the first dose of study drug. The following are exceptions to this criterion:

Intranasal, inhaled, topical steroids, or local steroid injections (eg, intra-articular injection)
Systemic steroids at physiological doses as replacement therapy (eg, physiological corticosteroid replacement therapy for adrenal or pituitary insufficiency)
Steroids as premedication for hypersensitivity reactions (eg, CT scan premedication)
Received any live vaccine within 4 weeks before the first dose of study drug or intend to receive a live vaccine during the study
A history of leptomeningeal carcinomatosis
Brain metastases or spinal cord compression unless asymptomatic or treated and stable off steroids and anti-convulsants for at least 2 weeks before the first dose of study drug
Uncontrolled or clinically significant cardiovascular disease
A history of (noninfectious) interstitial lung disease (ILD)/pneumonitis that requires steroids, current ILD/pneumonitis, or where suspected ILD/pneumonitis cannot be ruled out by imaging at screening
Clinically significant concomitant pulmonary disease
Have a diagnosis of Gilbert's syndrome
Uncontrolled third-space fluid that requires repeated drainage
Active gastric and duodenal ulcers, ulcerative colitis, or other gastrointestinal conditions that may cause bleeding or perforation by the investigator's discretion
Uncontrolled infection that requires systemic therapy within 1 week before the first dose
Known human immunodeficiency virus (HIV) infection
Active hepatitis B virus (HBV) or hepatitis C virus (HCV) infection. Active HBV is defined as hepatitis B core antibody (HBcAb) or hepatitis B surface antigen (HBsAg) positive, and HBV DNA level above ULN at the study site; active HCV is defined as positive hepatitis C antibody and HCV RNA level above ULN at the study site
Unresolved toxicities from previous anticancer therapy, defined as toxicities not yet resolved to NCI CTCAE Grade ≤1, baseline, or the level specified in the inclusion/exclusion criteria with the exception of alopecia (any grade), pigmentation (any grade), and peripheral neuropathy (Grade ≤2). Patients with irreversible toxicity (eg, hearing loss) that is reasonably not expected to be aggravated by the study drug can be enrolled after discussion with the sponsor
A history of severe hypersensitivity reactions to the drug substances, inactive ingredients in the drug product, or other mAbs
Women who are breastfeeding or pregnant as confirmed by pregnancy tests performed within 7 days before the first dose
Any illness, medical condition, organ system dysfunction, or social situation, including but not limited to mental illness or substance/alcohol abuse, deemed by the investigator to be likely to interfere with a patient's ability to sign informed consent, adversely affect the patient's ability to cooperate and participate in the study, or compromise the interpretation of study results Additional Exclusion Criteria for Part 2
Multiple primary malignancies within 3 years, except adequately resected non-melanoma skin cancer, curatively treated in situ disease, or other curatively treated solid tumors