A Predictive Model for Evaluating Responsiveness to Pemetrexed reatment in Patients with Advanced Colorectal Cancer

Purpose: To highlight the potential factors that could predict the response rate of patients with metastaticcolorectal cancer (mCRC) treated with pemetrexed combined chemotherapy after first- or second-linechemotherapy using the FOLFOX regimen. Materials and
Methods: Between January 2007 and July 2014, 54patients diagnosed and pathologically-confirmed with advanced colorectal cancer in Jiangsu Cancer Hospitaland Research Institute, were enrolled. They received pemetrexed at a dose of 500mg/m2 by 10 minute infusionon day 1, repeated every 3 weeks. Doses were modified depending on nadir counts of blood cells. Combinedchemotherapeutic agents included irinotecan, lobaplatin, carboplatin, oxaliplatin, gemcitabine, cis-platinum orbevacizumab. Multiple variables (age, sex, hemoglobin, platinum drugs combined, metastasis sites, LDH, ALP,CEA>40 ug/ml) reported earlier were selected.We used logistic regression analysis to evaluate relationshipsbetween these and tumor response.
Results: On multivariable analysis, we found that age was significant inpredicting the responsiveness to pemetrexed (p<0.05) combined with oxaliplatin. We did not find any otherfactors which were significantly associated with the response rate to chemotherapy with pemetrexed andirinotecan.
Conclusions: By multivariate analysis, we found that age had significant impact on the responsivenessof pemetrexed when combined with oxaliplatin. Additional research based on genomic properties of host andtumors are needed to clarify markers for better selection of patients who could benefit from pemetrexed combinedchemotherapy.