Surufatinib for advanced or metastatic chemotherapy-refractory thymic epithelial tumor: A single-arm, single-center, phase II study.

Abstract

8119 Background: Thymic epithelial tumors (TETs), though relatively rare, represent the most common anterior mediastinal malignancy in adults. Platinum-based regimens are the standard first-line therapy; however, treatment options for subsequent lines remain poorly defined. Surufatinib, an oral tyrosine kinase inhibitor targeting VEGFR1/2/3, FGFR1, and CSF-1R, exerts both anti-angiogenic and immune-modulating effects. This study aimed to evaluate the efficacy and safety of surufatinib in patients (pts) with type B2/B3 thymoma (TM) or thymic carcinoma (TC), providing a potential new therapeutic strategy for TETs following anthracycline/taxane-based therapy. Here, we report the initial results. Methods: This was a single-arm, prospective phase II study. Eligible pts had histologically or cytologically confirmed, unresectable or radiotherapy-ineligible, advanced recurrent or metastatic B2/B3 TM or TC, with progression following at least one prior platinum-based chemotherapy regimen. Pts were aged >18 years and had at least one measurable lesion per RECIST 1.1 criteria. Treatment consisted of surufatinib 300 mg orally once daily in a 4-week cycle. Tumor assessments were conducted every 8 weeks. The primary endpoint was the objective response rate (ORR). Secondary endpoints included progression-free survival (PFS), disease control rate (DCR), and overall survival (OS). Results: As of December 25, 2025, 20 pts were enrolled and evaluated. The median age was 55.5 years (range: 35–69), with 55% being male. Pathological subtypes included B2 TM (30%), B3 TM (15%), and thymic squamous cell carcinoma (TSCC, 55%). Eighteen pts (90%) presented with >5 metastatic sites. Ten pts (50%) achieved a partial response, and ten pts (50%) achieved stable disease. The ORR was 50%, and the DCR was 100%. With a median follow-up of 9.50 months, the median PFS was 11.9 months, and the 9-month PFS rate was 73.5%. Median OS was not reached, with an 18-month OS rate of 91.7%. The most common treatment-related adverse events (TRAEs) of any grade were hypertension (70%), diarrhea (40%), elevated bilirubin (40%), and elevated transaminases (25%). Grade 3 TRAEs included hypertension (15%), diarrhea (5%), and elevated transaminases (5%). No treatment-related deaths were reported. Conclusions: Surufatinib monotherapy demonstrated promising antitumor activity and a manageable safety profile in patients with previously treated, advanced recurrent or metastatic TETs, supporting further investigation in this population. Clinical trial information: ChiCTR2600116776.