A Phase 1 Study to Evaluate the Safety, Pharmacokinetics, and Preliminary Efficacy of MK-6204 (SKB535) for Injection in Participants with Advanced Solid Tumors

Inclusion Criteria:

1. ≥ 18 years of age

2. Have a histologically or cytologically confirmed advanced/metastatic solid tumor bypathology report and have failed or do not have available standard treatments. Thetumor types will be limited to: CRC; Gastric carcinoma or gastroesophageal junction (GEJ) adenocarcinoma; Esophageal carcinoma; Pancreatic cancer; NSCLC; Cervicalcarcinoma; Head and Neck squamous cell carcinoma.

3. Have measurable disease by RECIST 1.1 as assessed by the local siteinvestigator/radiology. Target lesions situated in a previously irradiated area areconsidered measurable if progression has been shown in such lesions.

4. Have a performance status of 0 or 1 on the ECOG Performance Scale.

5. The participant has provided documented informed consent for the study.

6. Participants who agree to provide archival tumor tissue sample or newly obtainedcore, incisional, or excisional biopsy of a tumor lesion not previously irradiated.

7. Participants who have AEs due to previous anticancer therapies must have recoveredto ≤Grade 1 or baseline. Participants with endocrine-related AEs who are adequatelytreated with hormone replacement or participants who have ≤Grade 2 neuropathy areeligible.

Exclusion Criteria:

1. Active severe digestive disease, including but not limited to complete or incompletegastric outlet obstruction, persistent/recurrent vomiting, severe gastrointestinalhemorrhage, gastric or duodenal ulcers, acute gastrointestinal perforation, acutenecrotizing pancreatitis, ulcerative enteritis, congenital megacolon, or Crohn'sdisease.

2. Participants with a history of interstitial lung disease (ILD) or a history ofnoninfectious pneumonitis that required steroids, have current ILD/pneumonitis, orwhere suspected ILD/pneumonitis cannot be ruled out by imaging at screening.

3. Received strong cytochrome P450 (CYP3A4) inhibitors or inducers within 2 weeks priorto the first dose of study intervention or within 5 half-lives of drug elimination,whichever is longer.

4. Received strong breast cancer resistance protein (BCRP) inhibitors within 2 weeksprior to the first dose of study intervention or within 5 half-lives of drugelimination, whichever is longer.

5. Received prior systemic anticancer therapy including investigational agents within 4weeks or 5 half-lives, whichever is shorter, before intervention allocation.

6. Known additional malignancy that is progressing or has required active treatmentwithin the past 2 years.

7. Known active CNS metastases and/or carcinomatous meningitis. Participants withpreviously treated brain metastases may participate provided they are radiologicallystable (i.e., without evidence of progression) for at least 4 weeks as confirmed byrepeat imaging performed during the study screening, are clinically stable and havenot required steroid treatment for at least 14 days before the first dose of studyintervention.