149P - Toripalimab and chemotherapy as first line combination in advanced thymic carcinoma: A prospective, single-arm, phase II trial

Background

Thymic carcinoma(TC) is the most aggressive subtype of thymic epithelial tumors. According to previous clinical trials, immunotherapy was proved to be effective in second line of treatment. Hence a phase II, prospective clinical trial was conducted by our research team to explore the safety and efficacy of toripalimab (a PD-1 inhibitor) combined with chemotherapy as first line treatment in advanced TC.

Methods

We enrolled patients with histologically diagnosis of Masaoka stage III or IV TC. Patients received toripalimab (240mg, d1, q3w) plus paclitaxel (175mg/m², d1, q3w) and carboplatin (AUC=5, d1, q3w) for 4-6 cycles and continued to receive toripalimab (240mg, d1, q4w) maintenance therapy until disease progression, intolerable toxicity, or withdrawal of consent. The primary endpoint was progression-free survival (PFS). Secondary endpoints were objective response rate (ORR), Disease control rate (DCR), duration of response (DoR), overall survival (OS), time to response (TTR) and safety.

Results

From December 27^th, 2020 to June 6^th, 2024, 24 patients were enrolled. Median age was 55 years (range: 35–69) and 16 (66.7%) patients were male. 11(45.8%) patients were still on toripalimab maintenance treatment at the time of analysis. For 24 patients received radiological evaluation, best overall response of 8 partial response, 16 stable disease were observed. Accordingly, the ORR was 33.3% and DCR was 100.0%. Median PFS was 25.3 months (95% CI: 14.1-36.5), 1-year PFS rate was 72.0%, 2-year PFS rate was 63.0%. The median follow-up duration was 16.18 months (range: 1.57-41.8). Treatment-related adverse event (TRAE) of any-grade occurred in 23 patients. Grade 3-4 TRAE occurred in 10 patients. The most common grade 3-4 TRAE was neutrophil count decrease. Furthermore, we observed that the patients with lower TMB had more CD8+T cells and CD56dim NK subtype. Patients with PD-L1 TPS≥1% had a higher proportion of M1 type macrophages, suggesting a greater potential for activating antitumor immunity.

Conclusions

Toripalimab combined with chemotherapy is effective and well tolerated as first line treatment for patients with advanced thymic carcinoma.

Clinical trial identification

ChiCTR2000039155.

Legal entity responsible for the study

The authors.

Funding

Has not received any funding.

Disclosure

All authors have declared no conflicts of interest.