Clinical Outcomes of Drug-Eluting Bead Transarterial Chemoembolization Loaded with Raltitrexed for the Treatment of Unresectable or Recurrent Hepatocellular Carcinoma

Objectives Although raltitrexed shows therapeutic effects in many types of malignant tumors, the therapeutic effects and safety of drug-eluting bead transarterial chemoembolization (DEB-TACE) loaded with raltitrexed for the treatment of hepatocellular carcinoma (HCC) are rare. This study aimed to investigate the safety and efficacy of DEB-TACE with raltitrexed-loaded CalliSpheres beads (CB) in patients with unresectable or recurrent HCC. Methods Between May 2018 and October 2021, 41 patients with unresectable or recurrent HCC treated by DEB-TACE loaded with raltitrexed were retrospectively enrolled. The primary end points were overall survival and progression-free survival. The response evaluation criteria in solid tumors (RECIST) criteria and modified RECIST criteria (mRECIST) were used to assess the tumor response after the DEB-TACE procedure. Results A total of 79 DEB-TACE procedures were successfully performed, and the technical success rate was 100%. The overall response rate and disease control rate assessed by mRECIST criteria were 76.9% and 88.5%, 62.5% and 70.8%, and 35.3% and 47.1%, respectively, at 1, 3, and 6 months postprocedure. The mean progression-free survival and overall survival were 21.6 ± 3.6 and 43.7 ± 5.8 months, respectively. The 6-, 24-, and 36-month overall survival rates were 86.8%, 62.7%, and 57.1%, respectively. Minor complications were observed in 21 patients (51.2%), with no treatment-related mortality or severe adverse events. The most common treatment-related complications were abdominal pain (48.8%) and nausea (29.3%). Conclusion DEB-TACE with raltitrexed-loaded CB suggests a feasible, safe, and efficacious palliative regimen in unresectable or recurrent HCC patients.


Introduction
Hepatocellular carcinoma (HCC) is a common leading cause of cancer-related mortality worldwide [1,2]. Only about 20% of patients are diagnosed with early-stage HCC and can be treated with curative treatments, while most patients are diagnosed with late-stage HCC and its prognosis remains poor. Transarterial chemoembolization (TACE), an efficacious palliative treatment, has been performed clinically to improve survival for patients with unresectable HCC [3,4]. Rougier et al. performed TACE with raltitrexed-mixed lipiodol followed by an intraarterial infusion with oxaliplatin [5].
Nowadays, there is still no standard regimen of chemotherapy for the TACE procedure. Doxorubicin, fluorouracil, and oxaliplatin were the most common drugs used during TACE. A number of adverse effects are still observed in these drugs; thus, alternative agents are needed [6]. Raltitrexed is a quinazoline antifolate thymidylate synthase inhibitor [7] and shows therapeutic effects and safety in a number of malignant tumors, such as breast and colorectal cancers [8][9][10], as well as HCC [11]. Currently, drug-eluting bead TACE (DEB-TACE) has been used for many kinds of malignant tumors [12][13][14]. However, the clinical outcomes of raltitrexed-based DEB-TACE for the treatment of HCC are rare. Yang et al. [15] investigated the efficacy of DEB-TACE loaded with epirubicin and raltitrexed, rather than as a single agent, making it difficult to distinguish its efficacy from other drugs. is study was conducted to investigate the safety and efficacy of DEB-TACE with raltitrexed-loaded CalliSpheres beads (CB) in patients with unresectable or recurrent HCC.

Patients.
is was a retrospective cohort study conducted in a single center and was approved by the institutional review board of the university. Written informed consent for the DEB-TACE protocol was obtained from all enrolled patients. Patients were recruited from our department between May 2018 and October 2021 and were diagnosed with primary HCC, including both unresectable and recurrent HCC (Figure 1). Contrast-enhanced computed tomography (CT) and/or magnetic resonance imaging (MRI) were performed before DEB-TACE and during the follow-up period. For research analysis, the following preoperative clinical data were collected from the medical record systems: sex, age, Child-Pugh class, alanine aminotransferase (ALT), aspartate aminotransferase (AST), alpha-fetoprotein (AFP), platelets (PLT), tumor size, tumor number, extrahepatic metastasis, and prothrombin time (PT).
Inclusion criteria included age 18-80 years; a life expectancy >3 months; Barcelona Clinic Liver Cancer (BCLC) stages A, B, or C; and Child-Pugh class A or B. Exclusion criteria included allergy to study drugs; liver metastasis cancer; severe cardiovascular comorbidities; and coagulopathy or bleeding diathesis. e DEB-TACE treatment for HCC patients is discussed and individually tailored according to the BCLC staging system [16]. e final choice of the DEB-TACE strategy needs to consider factors such as the treatment willingness and economic ability of the patients and their families.

Efficacy and Safety Evaluation and Follow-Up.
e primary end points were overall survival and progression-free survival. Tumor responses were assessed using the response evaluation criteria in solid tumors (RECIST) [17,18] and the modified RECIST (mRECIST) [19]. Patients were followed up by computed tomography (CT) or magnetic resonance imaging (MRI) scans at 1, 3, and 6 months after the procedure and every 2-3 months thereafter (Figures 2(d)-2(f)). A telephone follow-up was performed for all patients, with the last follow-up date of August 27, 2022. Safety and toxicity were the secondary end points. Adverse events were assessed according to the National Cancer Institute Common Toxicity Criteria (version 3.0) [20].

Statistical Analysis.
A statistical analysis was performed using SPSS version 24.0 (IBM, Armonk, NY, USA). Overall survival was analyzed using the Kaplan-Meier analysis, followed by the log-rank test. e prognostic factors for overall survival and progression-free survival were determined by performing univariate and multivariate analyses. Statistically significant variables (p < 0.20) in the univariate analysis were entered into the multivariate Cox regression model. e outcomes were reported using hazard ratios and associated 95% confidence intervals (CI). A p < 0.05 was set as statistically significant.

Patient Characteristics.
In total, 41 patients were enrolled in this study, including 31 males and 10 females (mean age 58.4 ± 11.4 years, range 36-80 years). Detailed baseline demographics and disease characteristics are shown in Table 1. Extrahepatic metastases were present in 15 patients (36.6%). e portal vein or inferior vena cava invasion was found in 9 patients (22.0%). A total of 27 patients (65.9%) received synchronous treatments before or after the DEB-TACE procedure, including targeted therapy (n � 16), immunotherapy (n � 2), and both targeted and immunotherapy (n � 9).

DEB-TACE Treatments.
A total of 79 DEB-TACE procedures were performed in 41 patients, and the mean was 1.9 ± 1.3 procedures. Twenty-one patients completed at least Canadian Journal of Gastroenterology and Hepatology 3 two cycles of DEB-TACE. All DEB-TACE procedures were successfully performed, with a technical success rate of 100%. Except for 27 DEB-TACE procedures with a CB of 100-300 μm, the remaining 72 DEB-TACE procedures were performed by using CB of 300-500 μm in diameter. All patients received a bottle of beads. Additional embolization was performed by gelatin sponge particles of 350-560 μm during 11 procedures or polyvinyl alcohol particles of 350-560 μm during 5 procedures or embolization microsphere of 300-500 μm during 2 DEB-TACE procedures. irteen patients (31.7%) received other interventional treatments, of which 11 patients underwent c-TACE, 2 patients underwent 125 I seed implantation in the portal vein, and 4 patients received thermal ablation (Table 2).

Safety and Toxicity.
Minor complications occurred in 21 patients (51.2%), with no treatment-related mortality or severe adverse events. e most common treatment-related complications were abdominal pain (48.8%) and nausea (29.3%). All reported toxicities were grades 1 and 2, which were mild and manageable. Table 4 shows the results of univariate and multivariate analyses. Moreover, Cox's proportional hazard model suggested that AFP>400 ng/ mL was an independent predictive factor for progressionfree survival (HR � 0.234, 95% CI: 0.063-0.869, p � 0.030) and overall survival (HR � 0.326, 95% CI: 0.107-0.994, p � 0.049). Targeted therapy or immunotherapy was not the independent risk factors for overall survival (Figure 4).

Discussion
e highest incidence of HCC is shown in Southeast Asia, and the major risk factor is hepatitis B virus infection [21]. Curative treatment is recommended as the first-choice treatment for patients with early HCC. In particular, liver transplant is considered in HCC patients within the Milan criteria, and radical surgical resection and ablation are curative treatments in HCC patients who are not suitable for liver transplant [22]. However, most patients are diagnosed with intermediate or advanced stage HCC and cannot be treated with curative treatments. In this case, palliative locoregional treatments (e.g., TACE and hepatic arterial infusion chemotherapy) and systemic drugs such as targeted therapy and immunotherapy can be considered. TACE is recommended as the first-line therapy for HCC patients with BCLC tumor stage B [23]. TACE is also a valid treatment option in patients with single  Canadian Journal of Gastroenterology and Hepatology 5 HCC not suitable for curative treatment [22]. Oxaliplatin in combination with doxorubicin or fluorouracil is usually performed during the TACE procedure. However, these drugs are not suitable for patients with previous cardiotoxicity or high cardiologic risk factors [24], indicating a need for a new kind of agent. Raltitrexed is a thymidylate synthase inhibitor [9], which is effective in many types of tumor types [8]. Raltitrexed may theoretically serve as a substitute for fluorouracil due to the lack of cardiac toxicity [6,24].
Nowadays, DEB-TACE has been used for many kinds of malignant tumors [25][26][27]. By injecting drug-eluting beads directly into the tumor-feeding artery, DEB-TACE shows significant advantages over conventional chemotherapy, which not only embolizes the tumor to promote tumor necrosis but also improves the antitumor effect and alleviates the side effects of the drugs by slowly releasing the drug. However, very few studies have reported the efficacy and safety of DEB-TACE loaded with raltitrexed for the   Figure 4: Cumulative overall survival rates and Kaplan-Meier analysis of subgroups. AFP>400 ng/mL and portal vein invasion were the independent risk factors for overall survival by the log-rank test of multivariate analysis. Targeted therapy or immunotherapy was not the independent risk factor for overall survival. treatment of advanced HCC. Zhao et al. [5] reported that raltitrexed plus oxaliplatin-based TACE is a safe and efficacious regimen in unresectable HCC. Yang et al. [15] reported that DEB-TACE loaded with epirubicin and raltitrexed improves the clinical outcomes and survival rate in patients with intermediate and advanced HCC. Both studies investigated the role of raltitrexed in combination with other drugs such as oxaliplatin and epirubicin, rather than as a single agent, making it difficult to distinguish its efficacy from other drugs. In this study, the technical success rate of DEB-TACE was 100%. e mean progression-free survival and overall survival were 21.6 ± 3.6 months and 43.7 ± 5.8 months, respectively. It is reported that raltitrexed-based TACE shows a superior objective response rate than that of doxorubicin and fluorouracil-based TACE in patients with unresectable HCC. Consistent with previous studies, we also observed a higher overall response rate determined by mRECIST criteria than the RECIST criteria [5]. e complete response was almost zero if assessed by RECIST, which was similar to the previous report [11]. Besides, most patients showed a significant decrease in tumor enhancement after the DEB-TACE procedure, indicating that mRECIST may be more suitable for locoregional therapy.
Safety was also evaluated to study whether DEB-TACE loaded with raltitrexed was tolerable and safe in patients with unresectable or recurrent HCC. ese data suggested that the most common treatment-related complications were abdominal pain (48.8%) and nausea (29.3%), similar to a previous study [5]. ere was no treatment-related mortality or severe adverse events. All reported toxicities were grades 1 and 2, which were manageable and reversible.
Despite the advances in pharmacological and locoregional therapies, HCC is still considered to be one of the most lethal malignancies. e survival outcomes of unresectable HCC are still poor after the failure of firstline therapy due to poor knowledge of its biology and limited therapeutic options. Sorafenib is the first tyrosine kinase inhibitor used for advanced HCC patients and has been the approved treatment option for several years [28]. However, its efficacy is limited by the development of drug resistance [28]. In this study, sorafenib (n � 8), lenvatinib (n � 7), and apatinib (n � 10) were used. However, targeted therapy or immunotherapy was not an independent risk factor for progression-free survival or overall survival.
e possible explanation is that the small sample size and the inconsistent use of targeted drugs affected the results of the statistical analysis. A combination of biologic therapy with immune checkpoint inhibitors seems to be promising for a new therapeutic strategy for patients with unresectable HCC [29]. However, the safety and efficacy are still not well established for the subset of patients, including those with preexisting inflammatory bowel disease, autoimmune disease, or nonalcoholic steatohepatitis [29].Furthermore, regorafenib, as a second-line agent, showed promising results and may represent a valuable and relatively safe therapeutic option in intermediate/advanced HCC patients after sorafenib failure [30].
is study had several shortcomings. is was a retrospective study conducted in a single center, and the sample size was too small to allow for statistically powered subgroup analysis. Multiple targeted agents and immunotherapy were used, which are likely to have an impact on efficacy outcomes and Cox regression analysis. It is necessary to study DEB-TACE in combination with different targeted agents or immunotherapy. ere were selection bias and confounding factors in this study, such as combined targeted therapies, immunotherapy, ablation, and other therapies.

Conclusion
Our preliminary results suggest that DEB-TACE with raltitrexed-loaded CB is safe and tolerable in patients with unresectable HCC; further clinical studies are warranted to compare to an additional cohort receiving targeted and/or immunotherapy.
Data Availability e clinical data were obtained from the Interventional Department of the First Affiliated Hospital of Zhengzhou University. e data used to support the findings of this study are available from the corresponding author upon request.

Ethical Approval
All procedures performed in the studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki Declaration and its later amendments or comparable ethical standards.