Penile squamous cell carcinoma (PSCC) represents a significant unmet medical need, particularly in low- and middle-income regions where the incidence is higher. For patients with disease recurrence or metastasis following first-line platinum-based chemotherapy, standard second-line therapeutic options offer poor response rates and a dismal median overall survival of 4 to 5 months. Recent findings show that over 80% of PSCC cases express high levels of TROP-2, making it a key therapeutic target. Sacituzumab tirumotecan (sac-TMT; MK-2870) is a novel antibody-drug conjugate (ADC) composed of a humanized anti-TROP2 monoclonal antibody linked to a topoisomerase I inhibitor payload (KL610023). Study Design & Intervention: This is an open-label, multicenter, single-arm Phase 2 trial enrolling 37 adult patients with advanced/metastatic PSCC who experienced disease progression on or after first-line platinum-based chemotherapy. Participants receive sacituzumab tirumotecan at a dose of 4 mg/kg via intravenous (IV) infusion on Days 1 and 15 of every 28-day cycle for up to 8 cycles, or until disease progression, unacceptable toxicity, or consent withdrawal.
Primary Endpoint: Objective Response Rate (ORR), defined as the proportion of participants achieving a confirmed Complete Response (CR) or Partial Response (PR) assessed by the investigator using RECIST v1.1 criteria. Secondary Endpoints:Independent Central Review Objective Response Rate (ORR-ICR) Disease Control Rate (DCR) and Clinical Benefit Rate (CBR at 24 weeks) Duration of Response (DoR) Progression-Free Survival (PFS) and Overall Survival (OS) Safety and toxicity profile (evaluated via CTCAE v5.0) Treatment compliance and post-progression therapies Exploratory Research: Assessment of baseline tumor TROP-2 expression, HPV16 status, ctDNA dynamics, and molecular mechanisms of acquired resistance. Statistical Design: The trial utilizes Simon's two-stage Minimax design (18 participants accrued in Stage 1, expanding to 33 total evaluable participants if $\ge5$ responses are observed). Accounting for a 10% drop-out rate, a total of 37 participants will be enrolled.