SINGAPORE-A randomized trial in 650 patients has confirmed the safety and efficacy of a new second-line treatment for metastatic colorectal cancer (CRC), researchers reported at the ESMO Asia 2017 Congress (Abstract LBA3_PR).
Oral fluorinated pyrimidines have been investigated to replace IV 5FU in CRC. Capecitabine combined with oxaliplatin (XELOX) has demonstrated comparable efficacy and safety to FOLFOX for the management of metastatic and adjuvant CRC. However, the combined capecitabine and irinotecan (XELIRI) regimen failed to replace FOLFIRI due to concerns over safety and efficacy (J Clin Oncol 2007;25(30):4779-4786).
A modified XELIRI (mXELIRI) regimen was subsequently developed with reduced doses of irinotecan (200 mg/m2 on day 1) and capecitabine (1,600 mg/m2 on days 1-14). In combination with bevacizumab, it has shown favorable tolerability and efficacy comparable to XELOX plus bevacizumab in the first- and second-line settings (Ann Oncol 2013;24(6):1580-1587, Oncologist 2014;19(11):1131-1132).
XELIRI ProjecT (AXEPT)
Following these two trials, the Asian XELIRI ProjecT (AXEPT) was designed. This multicenter, open-label, randomized phase III trial assessed the efficacy and safety of mXELIRI versus FOLFIRI, with or without bevacizimab, as second-line treatment for patients with metastatic CRC. It was designed to demonstrate non-inferiority of the capecitabine containing regimen in terms of overall survival, with 95 percent confidence interval (CI) upper limit of the hazard ratio (HR) pre-specified as less than 1.3.
The trial enrolled 650 patients aged 20 years or older with histologically confirmed unresectable colorectal adenocarcinoma. Patients had been withdrawn from first-line chemotherapy for mCRC due to intolerable toxicity, disease progression, or relapse fewer than 180 days after the final dose of adjuvant chemotherapy. Patients were randomly assigned in a 1:1 ratio to receive either mXELIRI with or without bevacizumab every 3 weeks or FOLFIRI with or without bevacizumab every 2 weeks.
Patients were stratified according to the following factors:
* country (Japan vs. South Korea vs. China);
* Eastern Cooperative Oncology Group performance status (0-1 vs. 2);
* number of metastatic sites (one vs. more than one);
* prior oxaliplatin treatment (yes vs. no); and
* concurrent bevacizumab treatment (with vs. without).
After a median follow-up of 15.8 months, the median overall survival was 16.8 and 15.4 months in the mXELIRI and FOLFIRI arms, respectively (HR 0.85, 95% CI 0.71-1.02, non-inferiority test p<0.0001). Similarly, there was no statistical difference in terms of median progression-free survival between the two arms: 8.4 months (95% CI, 7.1-9.1) for patients treated with mXELIRI compared with 7.2 months (95% CI, 6.6-8.5) for those treated with FOLFIRI (HR=0.95; 95% CI, 0.81-1.11; p=0.5078).
The incidence of grade 3/4 adverse events was significantly lower in the mXELIRI arm than the FOLFIRI arm (167 [53.9%] vs. 224 [72.3%] of 310 patients; p<0.0001). The most common grade 3/4 adverse event was neutropenia (52 [16.8%] and 133 [42.9%] patients in the mXELIRI and FOLFIRI arms, respectively; p<0.0001). The incidences of grade 3/4 diarrhea were low in both arms (7.1% and 3.2%, respectively; p=0.0443). The efficacy and safety results were similar across all pre-specified subgroups.
"The AXEPT trial demonstrates that modified XELIRI with or without bevacizumab has a non-inferior efficacy to FOLFIRI with or without bevacizumab and is well-tolerated," noted lead author Tae Won Kim, MD, PhD, Professor of the Department of Oncology, Asan Medical Centre, Seoul, Korea. "The modified XELIRI regimen could be an alternative to the standard FOLFIRI regimen as a second-line backbone therapy for metastatic colorectal cancer."
Expert Opinions
Commenting on the study, Rodrigo Dienstmann, MD, principal investigator of the Oncology Data Science (ODysSey) Group, Vall d'Hebron Institute of Oncology, Barcelona, Spain, and research scientist at the Computational Oncology Group, Sage Bionetworks, Seattle, stated: "Capecitabine is given orally and is more convenient for patients compared to infusional 5FU. However, at the maximum doses the combination of capecitabine and irinotecan (XELIRI) can be quite toxic.
"The main objective of AXEPT was to assess whether a reduced dose intensity of the chemotherapy (the modified XELIRI regimen) would not negatively impact overall survival," he continued. "As the trial met the primary endpoint, we can say that mXELIRI is non-inferior to standard FOLFIRI (with or without bevacizumab). The toxicity profile was quite favorable for the modified regimen, with less neutropenia. The investigators observed slightly more diarrhea, as expected, but still acceptable. This study supports the use of mXELIRI in the second-line setting, with the potential to increase patient convenience."
Regarding the need for further research, Dienstmann stated: "Quality-of-life data will be critical to understanding the value of this regimen. We also need biomarker analysis, such as the impact of RAS status and emerging biomarkers on response to chemotherapy with or without bevacizumab and prognosis. This would help clinicians who have to optimize the sequence of chemotherapy/targeted therapy in metastatic CRC.
"Pharmacogenetic studies can also be insightful. There are known genetic variations within the UGT1A1 gene across Asian and non-Asian populations, which may impact on irinotecan toxicity profile. In addition, some early studies have found a favorable safety profile with modified XELIRI given every 2 weeks and this deserves further study."