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 nameand 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 formof contraception and not donate, or retrieve for their own use, ova from the time ofscreening and throughout the study period, and for at least 6 months after the lastdose of study drug. Male patients must agree to use a highly effective form ofcontraception and not freeze or donate sperm from the time of screening andthroughout the study period, and for at least 6 months after the last dose of studydrug

• 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 priorstandard treatment had proven to be ineffective or intolerable, or no standardtreatment is available

Additional Inclusion Criteria for Part 1

• Have at least 1 evaluable tumor lesion according to Response Evaluation Criteria inSolid Tumors (RECIST) version 1.1. Participants with prostate cancer who have boneonly disease may be eligible on a case-by-case basis after discussion with thesponsor

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 acase-by-case basis after discussion with the sponsor

• Willing to provide archival or fresh tumor tissue samples. Patients who are not ableto provide tumor samples or have inadequate samples may be eligible on acase-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 thatconsists 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 aninterventional study

• Prior systemic anticancer treatment including chemotherapy, molecular targetedtherapy, hormonal therapy, immunotherapy, or biological therapy within 3 weeksbefore the first dose of study drug (use of oral fluorouracil [eg, tegafur andcapecitabine] or small molecular targeted therapy within 2 weeks or 5 half-lifeperiods [whichever is shorter] before the first dose; use of mitomycin ornitrosoureas within 6 weeks before the first dose; use of herbal medicine withantitumor indications or nonspecific immunomodulators [eg, thymosin, interferon, andinterleukin] 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 stereotacticradiation therapy without abdominal, within 2 weeks)

• Undergone major surgery (not including diagnostic surgery) within 4 weeks before thefirst dose of study drug or expect major surgery during the study

• Undergone allogeneic hematopoietic stem cell transplantation (HSCT) before the firstdose of study drug, or autologous HSCT within 3 months before the first dose ofstudy drug

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

1. Intranasal, inhaled, topical steroids, or local steroid injections (eg,intra-articular injection)

2. Systemic steroids at physiological doses as replacement therapy (eg,physiological corticosteroid replacement therapy for adrenal or pituitaryinsufficiency)

3. Steroids as premedication for hypersensitivity reactions (eg, CT scanpremedication)

• Received any live vaccine within 4 weeks before the first dose of study drug orintend to receive a live vaccine during the study

• A history of leptomeningeal carcinomatosis

• Brain metastases or spinal cord compression unless asymptomatic or treated andstable off steroids and anti-convulsants for at least 2 weeks before the first doseof study drug

• Uncontrolled or clinically significant cardiovascular disease

• A history of (noninfectious) interstitial lung disease (ILD)/pneumonitis thatrequires steroids, current ILD/pneumonitis, or where suspected ILD/pneumonitiscannot 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 gastrointestinalconditions that may cause bleeding or perforation by the investigator's discretion

• Uncontrolled infection that requires systemic therapy within 1 week before the firstdose

• Known human immunodeficiency virus (HIV) infection

• Active hepatitis B virus (HBV) or hepatitis C virus (HCV) infection. Active HBV isdefined 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 aspositive hepatitis C antibody and HCV RNA level above ULN at the study site

• Unresolved toxicities from previous anticancer therapy, defined as toxicities notyet resolved to NCI CTCAE Grade ≤1, baseline, or the level specified in theinclusion/exclusion criteria with the exception of alopecia (any grade),pigmentation (any grade), and peripheral neuropathy (Grade ≤2). Patients withirreversible toxicity (eg, hearing loss) that is reasonably not expected to beaggravated by the study drug can be enrolled after discussion with the sponsor

• A history of severe hypersensitivity reactions to the drug substances, inactiveingredients in the drug product, or other mAbs

• Women who are breastfeeding or pregnant as confirmed by pregnancy tests performedwithin 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 bythe investigator to be likely to interfere with a patient's ability to sign informedconsent, adversely affect the patient's ability to cooperate and participate in thestudy, or compromise the interpretation of study results Additional ExclusionCriteria for Part 2

• Multiple primary malignancies within 3 years, except adequately resectednon-melanoma skin cancer, curatively treated in situ disease, or other curativelytreated solid tumors