Upon joining the study, eligibility is confirmed based on specific criteria such as having locally advanced, unresectable, or metastatic disease. The disease must be one of the selected HER2-expressing tumor types, including biliary tract, bladder, cervical, endometrial, epithelial ovarian, pancreatic cancers, or rare tumors with HER2 expression.

Eligibility also requires progression following prior treatment or lack of satisfactory alternative treatment options. Prior HER2 targeting therapy is allowed, and HER2 expression must be confirmed by local or central assessment.

The treatment involves the administration of trastuzumab deruxtecan (also known as DS-8201a), which is a solution for infusion given intravenously. The specific dosage and frequency of administration are determined by the study protocol and the healthcare provider overseeing the treatment.

Throughout the study, regular monitoring and assessments are conducted to evaluate the treatment’s efficacy and safety. This includes measuring the objective response rate (ORR) according to RECIST version 1.1, as assessed by the investigator.

Secondary assessments include the duration of response, disease control rate, progression-free survival, overall survival, and the occurrence of adverse events. Pharmacokinetics and immunogenicity of the treatment are also evaluated.

Follow-up involves continued monitoring of the patient’s health status and any long-term effects of the treatment. This phase ensures that any late-onset side effects are identified and managed appropriately.