A prospective, single-arm, phase II trial of adebrelimab plus nab-paclitaxel and carboplatin in patients with unresectable advanced metastatic or recurrent thymic carcinomas.

8109 Background: With the limited efficacy of chemotherapy (carboplatin/paclitaxel) for advanced thymic carcinomas (TCs), better treatments are in need. In this study (ChiCTR2300072705), we evaluated the efficacy and safety of adebrelimab in combination with nab-paclitaxel and carboplatin as first-line treatment for unresectable advanced metastatic or recurrent TCs. Methods: In this study, patients with unresectable UICC stage III or IV, recurrent, or metastatic TCs without any previous anti-tumor therapy were enrolled. Patients were treated with adebrelimab (20 mg/kg) plus nab-paclitaxel (260 mg/m 2 ) and carboplatin (AUC 5) every 3 weeks for up to 4-6 cycles, followed by adebrelimab (20 mg/kg) every 3 weeks for up to 2 years until progression or unacceptable toxicity. The primary endpoint was the objective response rate (ORR). Secondary endpoints included progression free survival (PFS), disease control rate (DCR), overall survival (OS), and safety. A Simon two-stage design was applied. If more than 4 out of the first 18 pts achieved a response, the cohort would expand to include 33 pts, and the outcome would be considered positive if more than 10 pts achieved a response. Results: Between August 2023 and September 2024, 18 pts were enrolled in the first stage. All pts were included in the efficacy and safety analysis. The median age was 58.0 years old (range 29-71). At data cutoff (Dec 1, 2024), 9 pts (50.0%) were undergoing treatment. Discontinuations occurred in 5 pts (27.8%) primarily due to disease progression, 2 (11.1%) due to adverse events (AEs), 2 (11.1%) due to patient’s decision. Three (16.7%) of 18 pts had complete response, 9 (50.0%) had partial response, and 6 (33.3%) had stable disease. The ORR was 66.7% (12/18) and DCR was 100%. The median PFS was 10.2 months (95% CI, 8.8 - 11.6 months). AEs of any grade and of grade ≥3 severity occurred in 100% (18/18) and 61.1% (11/18) of pts, respectively. The most common treatment related AEs were white blood cell count decreased, neutrophil count decreased, and lymphocyte count decreased. The immune-related AEs of grade ≥3 severity occurred in 16.7% (3/18) of pts, including immune-mediated myositis, rash and lipase increased. None of the pts died from the treatment. Conclusions: In previously untreated advanced TCs, preliminary results showed that adebrelimab plus nab-paclitaxel and carboplatin is effective and safe. It provides a new treatment option in pts with advanced TCs. Clinical trial information: ChiCTR2300072705 .