HAIC Plus Systemic Therapy as De-escalation Therapy Strategy for Biliary Tract Cancer

Biliary tract cancer (BTC), including cholangiocarcinoma and gallbladder cancer (GBC), is a group of malignancies with highly heterogeneous, highly aggressiveness, and poor prognosis. Surgery is recognized as the only curative treatment for BTC, however, only about 20% BTC patients are eligible for curative resection since most patients with BTC are diagnosed at an advanced stage. The median overall survival (OS) in patients with unresectable BTC is typically less than 6 months. For patients with unresectable BTC, gemcitabine plus cisplatin (GemCis) had been recommended as the standard first-line treatment for many years. However, the objective response rate (ORR) of this regimen is only 26.1%, and the survival benefit remains limited, with a median OS of less than one year. In recent years, two phase III trials (TOPAZ-1 and KEYNOTE-966) have demonstrated that combining immune checkpoint inhibitors (durvalumab or pembrolizumab) with the GemCis regimen could further prolong survival in patients with BTC, achieving a median OS of 12.9 months and 12.7 months, respectively. Based on this evidence, many guidelines worldwide had recommended GemCis plus durvalumab or pembrolizumab as the preferred standard first-line treatment for patients with unresectable BTC. However, survival benefits from this combination therapy remain relatively limited, and tumor response is suboptimal, with an ORR of only 26.7%-29%. Hepatic arterial infusion chemotherapy (HAIC) enables continuous infusion of chemotherapeutic agents via the hepatic artery, significantly increasing local drug concentration at the tumor site, maximizing antitumor efficacy, and achieving a higher ORR (50%-60%) with substantial reduction in tumor burden. In recent years, HAIC has been increasingly used in the treatment of unresectable BTC, with its efficacy supported by many clinical studies. Firstly, HAIC provides survival benefits comparable to surgery in patients with multifocal intrahepatic cholangiocarcinoma (iCCA), and significantly outperforms systemic therapy. In 2022, a retrospective study enrolled 141 patients who received HAIC and 178 patients who underwent surgical resection from 12 centers. The results showed the median OS was 20.3 months in the HAIC group and 18.9 months in the resection group (P = 0.32), indicating comparable survival outcomes between HAIC and surgery. Given the risks of post-hepatectomy complications, HAIC may serve as an effective alternative treatment strategy for multifocal iCCA. Furthermore, for locally advanced unresectable iCCA, the results in a study in 2024 comparing HAIC with GemCis regimen chemotherapy revealed that although patients in the HAIC group had a higher tumor burden (proportion of multifocal disease: 73.4% vs. 55.3%, P = 0.023), the median OS in HAIC group remained significantly superior to that in the GemCis group (27.7 months vs. 11.8 months, P \< 0.001). Secondly, HAIC has also been demonstrated to be effective in treating perihilar cholangiocarcinoma (pCCA). In 2017, a single-arm, prospective phase II trial conducted in our center showed HAIC with oxaliplatin and fluorouracil yielded an ORR of 67.6%, a median progression-free survival (PFS) of 12.2 months, and a median OS of 20.5 months in treating perihilar cholangiocarcinoma (pCCA). Furthermore, HAIC also has clinical potential in treating advanced GBC. In 2021, a retrospectively study in our center enrolled 26 patients with advanced GBC who received HAIC with oxaliplatin and fluorouracil, of whom 23.1% had failed prior systemic therapy and 34.6% had contraindications to systemic treatment. The results showed that HAIC achieved a median PFS of 10 months and a median OS of 13.5 months, with an ORR of 69.2% and a disease control rate (DCR) of 92.3%. In recent years, many studies have demonstrated that HAIC combined with systemic therapy could yield significant survival benefits in patients with unresectable BTC. A phase II clinical trial in 2022 evaluated the efficacy of HAIC with floxuridine plus systemic gemcitabine and oxaliplatin (GEMOX) in unresectable iCCA. The results showed that the combination therapy achieved a median PFS of 11.8 months and a median OS of 25 months, with a 6-month DCR of 84%, and 58% of patients achieved partial response (PR). Additionally, the association of benefit of combining HAIC with systemic chemotherapy and stage of BTC has been reported, and that patients with locally advanced cholangiocarcinoma may not derive such benefit from this combination. In 2025, a phase II clinical trial conducted in our center evaluated the efficacy and safety of HAIC (bevacizumab, oxaliplatin, and fluorouracil) combined with toripalimab as a first-line treatment for unresectable BTC. The results showed a median PFS of 13.2 months and a median OS of 19 months, with an ORR as high as 84.38%. Some patients achieved successful conversion resection following this combination therapy, and postoperative pathology confirmed pathological complete res