Colorectal cancer (CRC), the fifth most common malignancy in men and the fourth most common malignancy in women in China, had 376 300 newly sufferers, with 191 000 deaths in 2015 1. It is reported that hepatic metastasis is present in 15–25% of patients at the time of diagnosis, and another 15–25% suffered from metastasis after radical resection 2. Surgical resection is currently the main treatment option for colorectal liver metastases (CRLM), resulting in cure or increased survival. However, there are still patients with liver metastases in whom surgical removal may not be suitable 3, or may have a high recurrence rate after resection 4.
Transarterial chemoembolization (TACE) can specifically increase drug concentration in the lesion with little systemic toxicity by directly administrating chemotherapeutic drugs and embolic agents into the liver metastases 5,6. Increasing evidence has shown that TACE plays a significant role in the therapy of patients with CRLM, with a satisfactory tumor response rate and progression-free survival 7. Various chemotherapeutic drugs are used in TACE, among which 5-fluorouracil (5-FU), platinum, and antitumor antibiotics are the most commonly used. However, 5-FU-based regimens require complex dosing schedules and are associated with multiple adverse events, limiting their applications in TACE.
Raltitrexed exerts cytotoxic activity by specific inhibition of thymidylate synthase, whereas oxaliplatin is a third-generation platinum antineoplastic agent generally used in combination with 5-FU, exerting an antitumor effect by disrupting DNA replication. Previous studies have shown that raltitrexed exerts effects similar to those of 5-FU in the treatment of advanced CRC 8–10. Furthermore, the RALOX regimen (raltitrexed plus oxaliplatin) has been reported to have superior efficacy compared with FOLFOX4 (5-FU, leucovorin, plus oxaliplatin) 11–14. A systematic review of raltitrexed-based first-line chemotherapy in advanced CRC showed that the overall response rate was 40%, with 43.9% for RALOX and 34.1% for RALIRI (raltitrexed plus irinotecan) arms, and the median overall survival (OS) and progression-free survival for all arms were 14.6 and 6.7 months, respectively 15. These studies suggested that raltitrexed-based chemotherapy was effective in the treatment of advanced CRC.
Hepatic artery infusion with raltitrexed plus oxaliplatin schedule has also been investigated in patients with CRLM. One retrospective study evaluated the efficacy and safety of combined hepatic arterial infusion with raltitrexed and oxaliplatin in patients who presented isolated hepatic metastases of CRC after failure of irinotecan and oxaliplatin treatment. The median time to progression (TTP) was 10.5 months and the median survival time was 27.5 months, indicating that the combination regimen of hepatic artery infusion combined with raltitrexed and oxaliplatin is feasible and promising in these patients 16. However, Fiorentini and colleagues found that there is no significant difference in the median survival time and progression-free survival observed between the RALOX-treated and FOLFOX-treated groups 17. As the clinical benefits of raltitrexed-based TACE in patients with CRLM are still inconsistent, the present study aimed to evaluate the efficacy and safety of TACE using raltitrexed plus oxaliplatin lipiodol emulsion in Chinese CRLM patients.
Participants and methods
This study was a prospective, multicenter, single-arm trial. Raltitrexed-based TACE was tested for its efficacy and safety in patients with CRLM. The study protocol was approved by the Ethics Committee of Zhongshan Hospital Fudan University. Informed consent was obtained from all patients. The study was registered with ClinicalTrials.gov (ID: NCT01959061).
A total of 90 patients were enrolled. The criteria for eligibility were histologically confirmed CRC with liver metastases, age 18–75 years, Eastern Cooperative Oncology Group performance status 0–2, Child–Pugh A or B with life expectancy of at least 3 months, adequate hematological, hepatic, and renal function, and no other antitumor therapy within 4 weeks before enrollment. Exclusion criteria included pregnant or lactating women; patients with severe organ dysfunction or failure; patients with severe cardiovascular disease or mental disease; and patients with extra-liver metastases. The reasons for treatment termination included progressive disease as evaluated every two cycles according to the mRECIST criteria, patient-terminated treatment voluntarily, unacceptable serious adverse events (allergic reactions; severe nausea or vomiting; myelosuppression of the fourth degree; Child–Pugh C), or poor compliance.
Intervention and follow-up
TACE treatment were regularly applied every 28 days for 4 cycles with raltitrexed 4 mg and oxaliplatin 100 mg; followed by a super-selective embolization proceeded by administering the mixture containing 50 mg oxaliplatin and 5–20 mllipiodol emulsion. A diagnostic angiography was performed in all patients to determine the feeding artery for tumor before TACE treatment. Treatment response was evaluated every two cycles according to the mRECIST criteria. Treatment was continued until progressive disease. The follow-up for disease progression and survival monitoring was performed every 3 months after completion of the treatment and up to 12 months.
At the beginning and the end of the treatment, routine examinations including blood clotting function, liver and kidney function, and tumor markers (carcinoembryonic antigen, cancer antigen 199, α-fetoprotein) were measured. Routine blood test and computed tomography were performed at each follow-up.
The primary endpoint was TTP. The secondary endpoints included OS and disease control rate (DCR). Adverse events were assessed according to the National Cancer Institute Common Toxicity Criteria (NCI-CTC), version 4.0.
Data analysis was carried out using the software packages, SAS9.2 for Windows (SAS Institute Inc., Cary, North Carolina, USA). There were three sets of analyses: full analysis set (FAS), per-protocol set (PPS), and safety analysis set (SAS). Continuous data were expressed as the mean±SD or median (maximum, minimum). Categorical and ordinal data were expressed as frequency. Survival data were analyzed using the Kaplan–Meier method to evaluate the median OS and the median TTP. A two-sided P value of 0.05 or less was considered statistically significant.
A total of 90 patients were recruited in the present trial. Among the 14 patients who did not complete the treatment, eight dropped out owing to voluntary withdrawal and six were lost to follow-up. None of the enrolled patients used other treatments in the present study including surgical resection and ablation. The baseline characteristics of these patients are shown in Table 1.
During the follow-up of up to 12 months, the median TTP exceeded 9 months both in FAS and in PPS (Table 2). The median OS was 17.8 months (95% confidence interval: 15.5–20.0) in FAS and 19.1 months (95% confidence interval: 16.8–21.2) in PPS, respectively (Table 2).
In the FAS population, the overall DCR was 71 (78.9%), including one patient with a complete response, 21 patients with a partial response, and 49 patients with stable disease. The overall DCR in the PPS population was 71 (93.4%), with the same number of patients who achieved disease control as those in the FAS population (Table 3).
Adverse events are summarized in Table 4. Grade 3 or 4 adverse events on the basis of NCI-CTCAE 4.0 during the period of treatment were reported for 24 (26.7%) out of all 90 patients. The main hematological toxicity was grade III/IV thrombocytopenia and neutropenia, which occurred in 8.9 and 5.6% of patients, respectively.
The present prospective, multicenter, single-arm trial showed that TACE with raltitrexed plus oxaliplatin was effective and safe in patients with CRLM. To the best of our knowledge, this is the first study to explore the efficacy and safety of TACE using raltitrexed plus oxaliplatin lipiodol emulsion in patients with CRLM.
In the present study, a median TTP and OS of 9.1 and 17.8 months were observed, respectively. In addition, the DCR after the treatment with raltitrexed-based TACE was 78.9%. Such good treatment responses may be mediated partially by the advantages of TACE. As is known, TACE can induce an intensively centralized local concentration and minimize the toxicity to normal liver tissue as the therapeutic agents were injected directly to the tumor 7. Moreover, transarterial embolotherapy can blunt the source of tumor nutrition by occlusion of tumor vascular 18. Thus, TACE is a promising therapy with combined antitumor effects (chemotoxicity and blood supply occlusion), resulting in a better response rate and a favorable survival trend.
Although cisplatin, 5-FU, doxorubicin, and mitomycin are commonly used for TACE in patients with CRLM 18, our observed results support that raltitrexed-based TACE may have a superior clinical benefit compared with cisplatin or 5-FU-based strategies for the treatment of CRLM. The median TTP and OS of 9.1 and 17.8 months from our study are higher than those in the study by Albert et al. 19, which reported TTP of 5 months and a median OS of 9 months in 121 CRLM patients receiving TACE with cisplatin, doxorubicin, mitomycin C, and ethiodized oil. Also, the OS length is longer than that of the study by You et al. 20, which showed that chemoembolization with 5-FU and leucovorin resulted in an objective tumor response of 47.5% and OS of 16 months in the treatment of unresectable hepatic metastases from CRC. The superiority of the raltitrexed-based regimen may be explained by several reasons. First, raltitrexed can inhibit the activity of thymidylate synthase in a short infusion with a longer duration of antitumor effects than 5-FU; therefore, it is a good candidate drug for transarterial infusion 21. Second, raltitrexed can inhibit HepG2 proliferation by induction of G0/G1 arrest in vitro, which indicates its potential application in CRLM 22. Finally, raltitrexed can enhance the efficacy of oxaliplatin markedly, which is supported by a recent study that raltitrexed plus oxaliplatin-based TACE yielded a better objective response rate than 5-FU plus oxaliplatin or doxorubicin plus oxaliplatin-based TACE 23.
Our present study also evaluated the safety and tolerability of raltitrexed-based TACE treatment. No unexpected adverse events or toxic deaths were observed. 26.7% of patients developed Grade 3 or 4 adverse events after the treatment. Grade 4 toxicities occurred only for pain and dyspnea, both in only one (2.22%) case. In one phase II clinical trial testing the efficacy and safety of hepatic artery embolization using 5-FU-based regimens, the total incidence of grade 3/4 toxicities was 73.0%, and the most common events were diarrhea (17%) and hepatic toxicity (8%) 24. All these results support that TACE combination with raltitrexed plus oxaliplatin for the treatment of patients with CRLM is safe and tolerable.
Similarly, hepatocellular carcinoma is another major application of TACE and there are emerging promising studies investigating the clinical efficacy and safety of TACE using a raltitrexed-based regime in treating unresectable hepatocellular carcinoma. Their findings suggest that the raltitrexed-based regime in TACE confers some benefits to patients with unresectable HCC. Larger prospective trials are needed to confirm this conclusion.
Although the major limitation of the present study design is that it is a single-arm study, this study was the first prospective and multicenter study to investigate the efficacy and toxicity of TACE with raltitrexed and oxaliplatin in CRLM patients. Another limitation is that we did not collect the details of the type of tumor progression, such as recurrent liver lesions or extrahepatic metastases, which might provide some more interesting information on the outcomes of TACE-treated CRLM patients. Our findings provide the clinical evidence to support the application of TACE with raltitrexed plus oxaliplatin. Further studies, especially well-designed randomized-controlled trials, are needed to confirm our findings.
TACE with raltitrexed plus oxaliplatin is feasible, clinically active, and well tolerated with low-grade toxicity for CRC patients with liver metastases.
Conflicts of interest
There are no conflicts of interest.
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