53P - Envafolimab and chidamide in combination with GEMOX as first-line treatment for advanced and metastatic biliary tract cancer (B-Enefits/SCOG-B001): A single-arm, exploratory, phase II trial: Interim report

Background

Biliary tract cancer (BTC) is a rare malignant tumor with poor prognosis. Envafolimab is a light-chain deficient PD-L1 antibody. Chidamide is a subtype-selective histone deacetylase (HDAC) inhibitor. Here we conducted a single-arm, multicenter, prospective phase Ⅱclinical study (ChiCTR2400080783) to evaluate the efficacy and safety of Envafolimab and Chidamide in combination with GEMOX as first-line treatment.

Methods

Patients with advanced BTCs receive treatment of Envafolimab (400 mg, on day 1) and Chidamide (20 mg orally for twice a week, on day 0, 3, 7, and 10), and GEMOX (gemcitabine 1000 mg/m², on day 1 and 8, and oxaliplatin 100 mg/m², on day 1) every 3 weeks for 8 cycles, followed by maintenance treatment with Envafolimab, Chidamide, and gemcitabine until PD, unacceptable toxicity, or patient refusal. The primary end points are safety and ORR. The secondary end points include PFS, OS, DCR, QoL and nutrition score.

Results

From Feb 2023 to Jun 2024, a total of 32 patients were enrolled; 22 were evaluable, including 16 patients of cholangiocarcinoma and 6 patients of gallbladder cancer. The median age was 64 years (range 33 - 78) and 16 (72.73%) patients had extrahepatic metastasis. After a median follow-up of 8.50 months, the ORR and DCR by RECIST1.1 were 50.00% and 77.27%, respectively, and median PFS and OS were not reached. Grade≥3 TRAEs occurred in 59.09% of patients, the most common TRAEs being anemia (54.55%), decreased platelet count (59.09%) and leukopenia (45.45%). No treatment-related deaths occurred.

Conclusions

Preliminary data suggest that Envafolimab and Chidamide in combination with GEMOX may be an effective treatment regimen with a manageable safety profile in patients with advanced BTCs.

Clinical trial identification

ChiCTR2400080783.

Editorial acknowledgement

Legal entity responsible for the study

The authors.

Funding

Beijing Health Alliance Charitable Foundation.

Disclosure

All authors have declared no conflicts of interest.