Efficacy and safety of radiotherapy combined with raltitrexed and irinotecan for treating unresectable recurrent colorectal cancer: a single-arm phase II trial.

Abstract

Local recurrence of colorectal cancer is associated with poor prognosis and quality of life. For patients not eligible for curative surgery, chemoradiation could be a promising therapeutic option, but there is no consensus yet for the concurrent chemotherapy regimen. This study evaluated the effects and safety of intensity-modulated radiation therapy (IMRT) when administered concurrently with raltitrexed and irinotecan to patients with unresectable recurrent colorectal cancer. Eligible patients developed unresectable recurrent colorectal cancer, and were refractory to, or intolerant of, chemotherapy with fluoropyrimidine and oxaliplatin. IMRT was delivered (total dose: 50-60 Gy in 25-30 fractions) concurrently with irinotecan and raltitrexed (200 and 3 mg/m2, respectively, on days 1 and 22). After treatment completion, patients underwent surgery or continued the same regimen of chemotherapy and were assessed by a multidisciplinary team. The primary endpoint was the objective response rate, defined as the proportion of patients with a confirmed complete response or partial response, assessed by radiologist and investigator after the completion of radiotherapy and reconfirmed a month later, in accordance with the Response Evaluation Criteria in Solid Tumors version 1.1. All 30 patients enrolled in this study between January 2019 and July 2020 completed radiotherapy and received a median of five chemotherapy cycles (range, 2-10 cycles). Twelve patients (40.0%) experienced an objective response (two complete responses and ten partial responses) and 17 patients exhibited stable disease [disease control rate (DCR): 96.7%]. The median follow-up was 22 months (range, 4-35 months), by the end of follow-up, six (20.0%) patients had local failure in the irradiation field, four (13.3%) had regional progression outside the irradiation field, 13 (43.3%) had distant metastasis or metastatic progression and nine (30.0%) died. The median progression-free survival (PFS) and local PFS (LPFS) were 13.5 and 23 months, respectively. The incidence of grade 3 or 4 adverse events was 26.7%, the most common of which was neutropenia (13.3%). IMRT with concurrent raltitrexed and irinotecan is a feasible treatment for unresectable recurrent colorectal cancer, which allows good tumor response and local control with acceptable toxicity profile.