Phase II Parallel Arm Study of Sacituzumab Govitecan-Hziy in Patients With Advanced Thymoma or Thymic Carcinoma.

Background: Thymic epithelial tumors (TETs), including thymoma and thymic carcinoma, are rare thoracic tumors of the anterior mediastinum. For those with advanced disease, platinum-based chemotherapy is used as first-line treatment. However, there is no standard regimen established for TET at progression after initial therapy, and treatment options for advanced/recurrent TETs are limited. Trop-2, a transmembrane glycoprotein, is overexpressed in solid tumors including thymomas and thymic carcinomas. Sacituzumab govitecan-hziy, a Trop-2-directed antibody-drug conjugate, has shown efficacy and safety in several tumors including breast cancer. The overexpression of Trop-2 in TETs and the clinical efficacy in other malignancies provide rationale for exploring its use in thymoma and thymic carcinoma.

Methods: This open-label, single-arm, parallel cohort, multi-center study assesses the safety and efficacy of sacituzumab govitecan-hziy in patients with advanced thymoma (cohort A) and thymic carcinoma (cohort B) who have received at least 1 prior line of systemic therapy (NCT06248515). The study employs a Simon optimal 2-stage design, enrolling patients with adequate performance status, measurable disease, and adequate organ function. Sacituzumab govitecan-hziy is administered at a fixed dose of 10 mg/kg weekly on days 1 and 8 of 21-day cycles until disease progression or unacceptable toxicity. Follow-up continues every 6 months for 2 years postdiscontinuation. Archival tissue is obtained prior to initiation of study treatment with an optional biopsy at the time of progression. In cases where archival tissue is not available, a fresh biopsy is obtained at baseline. The primary endpoint is investigator-assessed response rate using Response Evaluation Criteria in Solid Tumors v1.1 (RECIST) criteria, with tumor imaging assessments every 2 cycles during the first 3 months and every 3 cycles thereafter. Secondary endpoints comprise adverse events by Common Terminology Criteria for Adverse Events v5.0, median and 6-month progression-free survival, duration of response, and overall survival. For each cohort, 9 patients will be enrolled. If 0 of the 9 achieve a response, no further patients will be enrolled in that cohort. If 1 or more of the first 9 patients has a response, accrual will continue until a total of 17 patients have been enrolled in that cohort.