Thymidylate synthase (TYMS) is an important enzyme for 5-fluorouracil (5-FU) metabolism in metastatic colorectal cancer (mCRC) patients. The search for this enzyme in circulating tumor cells (CTCs) can be a powerful tool to follow-up cancer patients. mCRC patients were enrolled before the beginning of 5-FU-based chemotherapy. The blood was filtered on Isolation by Size of Epithelial Tumor Cells (ISET), and the analysis of TYMS expression in CTCs was made by immunocytochemistry. Additionally, we verified TYMS staining in primary tumors and metastases from the same patients. There were included 54 mCRC patients and 47 of them received 5-FU-based chemotherapy. The median CTCs number was 2 per mL. We were not able to analyze immunocytochemistry in 13 samples (9 patients with absence of CTCs and 4 samples due to technical reasons). Therefore, TYMS expression on CTCs was analyzed in 34 samples and was found positive in 9 (26.5%). Six of these patients had tumor progression after treatment with 5-FU. We found an association between CTC TYMS staining and disease progression (DP), although without statistical significance (P 5 0.07). TYMS staining in primary tumors and metastases tissues did not have any correlation with disease progression (P 5 0.67 and P 5 0.42 respectively). Patients who had CTC count above the median (2 CTCs/mL) showed more TYMS expression (P 5 0.02) correlating with worse prognosis. Our results searching for TYMS staining in CTCs, primary tumors and metastases suggest that the analysis of TYMS can be useful tool as a 5-FU resistance predictor biomarker if analyzed in CTCs from mCRC patients.Colorectal cancer (CRC) was the third most commonly diagnosed cancer in both men and women in the last 3 years in the United States. 1-3 For metastatic patients, the strategy for treatment is mostly 5-Fluorouracil-based chemotherapy, which shows high efficacy in a subset of patients. However, even those patients can experience disease progression due to 5-FU resistance. 4 TYMS is a constitutive enzyme that catalyzes the reductive methylation of deoxyuridine monophosphate (dUMP) by CH 2 H 4 folate to produce deoxythymidine monophosphate (dTMP) and H 2 folate leading to DNA replication and repair. 5 An upgrade of resistance to the treatment has been often correlated to increased levels of TYMS in cancer cells. 6 Others have demonstrated that intratumoral TYMS mRNA expression levels (in paraffin-embedded tissues) are independent predictive markers of survival for 5-FU and oxaliplatin combination therapy. 7 Although the presence of high levels of TYMS presents poor outcome, it becomes hard to evaluate since there are heterogeneity among the population, methods and techniques as well. Furthermore, the best way to detect the presence of TYMS and its real value remains unclear 8 as there is not a consensus about the role of TYMS expression in mCRC published in the last 20 years. Thence, analyzing

Circulating tumor cells are important markers of tumor progression and can reflect tumor behavior in metastatic colorectal cancer (mCRC). Identification of proteins that confer resistance to treatment is an important step to predict response and better selection of treatment for patients. Multidrug resistance-associated protein 1 (MRP1) and Multidrug resistance-associated protein 4 (MRP4) play a role in irinotecan-resistance, and Excision Repair Cross-Complementation group 1 (ERCC1) expression can confer resistance to platinum compounds. Here, we included 34 patients with mCRC and most of them received FOLFIRI or FOLFOX chemotherapy (91.1%). CTCs were isolated by ISET V R Technology and identified in 30 patients (88.2%), with a median of 2.0 CTCs/mL (0-31.0). We analyzed the immunocytochemical expression of MRP1, MRP4 and ERCC1 only in patients who had previously detectable CTCs, accordingly to treatment received (n 5 19, 15 and 13 patients, respectively). Among patients treated with irinotecan-based chemotherapy, 4 out of 19 cases with MRP1 positive CTCs showed a worse progression free survival (PFS) in comparison to those with MRP1 negative CTCs (2.1 months vs. 9.1 months; p 5 0.003). None of the other proteins studied in CTCs had significant association with PFS. We analyzed also histological sections of primary tumors and metastases by immunohistochemistry, and found no association with clinicopathological characteristics or with PFS. Our results show MRP1 as a potential biomarker of resistance to treatment with irinotecan when found in CTCs from mCRC patients. This is a small proof-of-principle study and these early findings need to be validated in a larger cohort of patients.Colorectal cancer (CRC) is the third most common tumor in men and the second in women worldwide.

BackgroundColorectal cancer (CRC) is the third most prevalent cancer worldwide. New prognostic markers are needed to identify patients with poorer prognosis, and circulating tumor cells (CTCs) seem to be promising to accomplish this.Patients and methodsA prospective study was conducted by blood collection from patients with metastatic CRC (mCRC), three times, every 2 months in conjunction with image examinations for evaluation of therapeutic response. CTC isolation and counting were performed by Isolation by Size of Epithelial Tumor Cells (ISET).ResultsA total of 54 patients with mCRC with a mean age of 57.3 years (31–82 years) were included. Among all patients, 60% (n=32) were carriers of wild-type KRAS (WT KRAS) tumors and 90% of them (n=29) were exposed to monoclonal antibodies along with systemic treatment. Evaluating CTC kinetics, when we compared the baseline (pretreatment) CTC level (CTC1) with the level at first follow-up (CTC2), we observed that CTC1-positive patients (CTCs above the median), who became negative (CTCs below the median) had a favorable evolution (n=14), with a median progression-free survival (PFS) of 14.7 months. This was higher than that for patients with an unfavorable evolution (CTC1− that became CTC2+; n=13, 6.9 months; P=0.06). Patients with WT KRAS with favorable kinetics had higher PFS (14.7 months) in comparison to those with WT KRAS with unfavorable kinetics (9.4 months; P=0.02). Moreover, patients whose imaging studies showed radiological progression had an increased quantification of CTCs at CTC2 compared to those without progression (P=0.04).ConclusionThis study made possible the presentation of ISET as a feasible tool for evaluating CTC kinetics in patients with mCRC, which can be promising in their clinical evaluation.

Background: Definitive chemoradiation (CRT) is the standard treatment for localized squamous cell carcinoma of the anus (SCCA). Because most phase III trials in SCCA have excluded patients with HIV, the evidence on treatment outcomes of these patients is lacking. We performed a systematic review and metaanalysis on the efficacy and toxicity profiles of HIV-positive SCCA patients treated with definitive CRT. Methods: The systematic search was conducted Embase, Medline, Cochrane Libary, Scopus, Lilacs and Opengrey, from inception until September 2017. Eligible studies were clinical trials, prospective or retrospective cohort studies. The main outcome variables were 3-year disease-free survival (DFS) and overall survival (OS) rates and frequency of grade 3 or 4 (G3/4) treatment-related toxicities, according to HIV status. Meta-analyses using pooled risk ratios were performed for binary outcomes from comparative studies from the antiretroviral therapy (HAART) era with the fixed effects model. Results: Out of 3,951 studies, 40 were deemed eligible, with a total of 3,720 patients. One third (N=1,298; 34%) were HIV-positive and their median pre CRT CD4 count was 347 μm/L. HIV-positive patients presented higher risk of G3/4 cutaneous toxicities [risk ratio (RR) =1.34; 95% CI, 1.10-1.64; P=0.004; I 2 =77.7%], worse 3-year DFS rate (RR =1.32; 95% CI, 1.01-1.74; P=0.043; I 2 =52.19%), and 3-year OS rate (RR =1.77; 95% CI, 1.35-2.32; P<0.001; I 2 =6%). Conclusions: Patients with localized SCCA and HIV infection treated with CRT tend to experience higher risk of toxicities and worse DFS and OS rates. Our findings suggest that future trials should be tailored to HIV-positive patients.

Neoadjuvant chemoradiation (NCRT) followed by total mesorectal excision is the standard treatment for locally advanced rectal cancer (LARC). To justify a non-surgical approach, identification of pathologic complete response (pCR) is required. Analysis of circulating tumor cells (CTCs) can be used to evaluate pCR. We hypothesize that monitoring of thymidylate synthase (TYMS) and excision repair protein, RAD23 homolog B (RAD23B), can be used to predict resistance to chemotherapy/radiotherapy. Therefore, the aims of this study were to analyze CTCs from patients with LARC who underwent NCRT plus surgery for expression of TYMS/RAD23B and to evaluate their predictive value. Blood samples from 30 patients were collected prior to NCRT (S1) and prior to surgery (S2). CTCs were isolated and quantified by ISET®, proteins were analyzed by immunocytochemistry, and TYMS mRNA was detected by chromogenic in situ hybridization. CTC counts decreased between S1 and S2 in patients exhibiting pCR (p = 0.02) or partial response (p = 0.01). Regarding protein expression, TYMS was absent in 100% of CTCs from patients with pCR (p = 0.001) yet was expressed in 83% of non-responders at S2 (p < 0.001). Meanwhile, RAD23B was expressed in CTCs from 75% of non-responders at S1 (p = 0.01) and in 100% of non-responders at S2 (p = 0.001). Surprisingly, 100% of non-responders expressed TYMS mRNA at both timepoints (p = 0.001). In addition, TYMS/RAD23B was not detected in the CTCs of patients exhibiting pCR (p = 0.001). We found 83.3% of sensitivity for TYMS mRNA at S1 (p = 0.001) and 100% for TYMS (p = 0.064) and RAD23B (p = 0.01) protein expression at S2. Thus, TYMS mRNA and/or TYMS/RAD23B expression in CTCs, as well as CTC kinetics, have the potential to predict non-response to NCRT and avoid unnecessary radical surgery for LARC patients with pCR.