OBJECTIVETo evaluate the safety and preliminary efficacy of dose-modified regimen of 5-fluorouracil plus oxaliplatin and irinotecan (mFOLFOXIRI) for patients with advanced colorectal cancer (CRC).

METHODSData of 312 CRC patients confirmed by pathology receiving triplet drug alone or combined with target therapy between October 2012 and December 2016 at the Sixth Affiliated Hospital of Sun Yat-sen University were retrospectively analyzed. CRC patients who had previously completed adjuvant therapy (or neoadjuvant therapy) within 6 months or palliative chemotherapy were excluded, meanwhile those with poor general condition (ECOG score > 2) or grade 2 neuropathy and allergy to oxaliplatin were excluded as well. Regimen of mFOLFOXIRI: oxaliplatin 85 mg/m² dissolved in 5% glucose solution 500 ml by intravenous infusion for 2 h; irinotecan 150 to 165 mg/m² dissolved in 0.9% sodium chloride 250 ml by intravenous infusion for 90 min; following intravenous infusion of leucovorin 400 mg/m² for 2 h, day 1; 5-FU 2800 mg/m², 48-h continuous intravenous infusion; once every 2 weeks. Therapy could be combined with a targeted drug, bevacizumab 5 mg/kg every two weeks; cetuximab 500 mg/m² every two weeks. Side effect was graded using the National Cancer Institute Common Terminology Criteria for Adverse Events (NCI CTCAE 4.0.3). The objective response rate was evaluated according to the Response Evaluation Criteria in Solid Tumors (RECIST 1.1) after administering at least four cycles of chemotherapy.

RESULTSThe median age was 52 years (range 16-73) in the whole group; 113 patients (36.2%) had locally advanced CRC, and 199 (63.8%) had metastatic CRC. Most patients (274/312, 87.8%) did not receive any treatment earlier. There were a total of 1651 chemotherapy cycles in the whole group, with a median of 6(1-19) cycles. Of these 1651 cycles, 124 cycles of chemotherapy(7.5%) were dose-adjusted; 176 cycles of chemotherapy(10.7%) were delayed for median 5(3-13) days; 124 cycles(7.5%) required dose decrease. The overall relative dose intensity was >90%; the specific drug dose intensity was 93.6%(2620 mg×m⁻²×d⁻¹) for fluorouracil, 97.8%(83 mg×m⁻²×d⁻¹) for oxaliplatin, and 94.2%(155 mg×m⁻²×d⁻¹) for irinotecan. Twenty-three patients (7 of intestinal perforation, 7 of intestinal obstruction, 1 of grade 4 hematologic toxicity, and 8 of grade 3 fatigue) refused subsequent chemotherapy due to intolerable toxicity. Main grade 3 or 4 adverse events in patients were neutropenia in 69 cases (22.1%), fatigue in 35 cases (11.2%), and anemia in 28 cases (8.9%). Twenty serious adverse events (6.4%) occurred, including 13 patients of febrile neutropenia (4.2%), 7 patients of intestinal perforation (2.2%, 4 patients in upper rectum, 2 in sigmoid colon, and 1 in transverse colon cancer), and 9 of them had subsequent sepsis (2.9%). All the patients with intestinal perforation underwent emergency operation. No treatment-related deaths occurred. In 199 patients with metastatic CRC, because 22 patients did not receive image evaluation, the preliminary efficacy of 177 patients was actually evaluated. A total of 113 objective response events were observed. The overall response rate was 63.8%(113/177), partial response rate was 61.6%(109/177), clinically complete response rate was 2.3%(4/177), stable disease was 29.9% (53/177), progressive disease was 6.2%(11/177), and the disease control rate was 93.8%(166/177). In 127 patients receiving triplet drug, objective response rate was 40.9% for those with less than four cycles and 81.1% for those with more than four cycles (P<0.001).

CONCLUSIONThe mFOLFOXIRI regimen with reduced dose can be safely used in advanced CRC and has achieved promising results in terms of short-term efficacy.