5-fluorouracil modulated by leucovorin, methotrexate and mitomycin: highly effective, low-cost chemotherapy for advanced colorectal cancer

Eubacterium coprostanoligenes alleviates chemotherapy-induced intestinal mucositis by enhancing intestinal mucus barrier

Chemotherapy-induced mucositis represents a severe adverse outcome of cancer treatment, significantly curtailing the efficacy of these treatments and, in some cases, resulting in fatal consequences. Despite identifying intestinal epithelial cell damage as a key factor in chemotherapy-induced mucositis, the paucity of effective treatments for such damage is evident. In our study, we discovered that Eubacterium coprostanoligenes promotes mucin secretion by goblet cells, thereby fortifying the integrity of the intestinal mucus barrier. This enhanced barrier function serves to resist microbial invasion and subsequently reduces the inflammatory response. Importantly, this effect remains unobtrusive to the anti-tumor efficacy of chemotherapy drugs. Mechanistically, E. copr up-regulates the expression of AUF1, leading to the stabilization of Muc2 mRNA and an increase in mucin synthesis in goblet cells. An especially significant finding is that E. copr activates the AhR pathway, thereby promoting the expression of AUF1. In summary, our results strongly indicate that E. copr enhances the intestinal mucus barrier, effectively alleviating chemotherapy-induced intestinal mucositis by activating the AhR/AUF1 pathway, consequently enhancing Muc2 mRNA stability.

Cytosolic localization and in vitro assembly of human de novo thymidylate synthesis complex

De novo thymidylate synthesis is a crucial pathway for normal and cancer cells. Deoxythymidine monophosphate (dTMP) is synthesized by the combined action of three enzymes: serine hydroxymethyltransferase (SHMT1), dihydrofolate reductase (DHFR) and thymidylate synthase (TYMS), with the latter two being targets of widely used chemotherapeutics such as antifolates and 5‐fluorouracil. These proteins translocate to the nucleus after SUMOylation and are suggested to assemble in this compartment into the thymidylate synthesis complex. We report the intracellular dynamics of the complex in cancer cells by an in situ proximity ligation assay, showing that it is also detected in the cytoplasm. This result indicates that the role of the thymidylate synthesis complex assembly may go beyond dTMP synthesis. We have successfully assembled the dTMP synthesis complex in vitro, employing tetrameric SHMT1 and a bifunctional chimeric enzyme comprising human thymidylate synthase and dihydrofolate reductase. We show that the SHMT1 tetrameric state is required for efficient complex assembly, indicating that this aggregation state is evolutionarily selected in eukaryotes to optimize protein–protein interactions. Lastly, our results regarding the activity of the complete thymidylate cycle in vitro may provide a useful tool with respect to developing drugs targeting the entire complex instead of the individual components.

Treatment of stage IV colorectal carcinoma in elderly patients

Colorectal adenocarcinoma ranks second as a cause of death due to cancer in the Western world. In Europe, 40% of patients with colorectal cancer are over 70 years old and the incidence increased through the 1980's. Without any treatment the median survival after the detection of liver metastases is approximately 9 months, depending on the extent of disease at the time of diagnosis but not on the patients age. In the elderly there are only few data apt to define the standard regimen in the advanced disease, but results seem similar to those observed in younger patients. As a result of exclusion criteria and screening, elderly patients entering clinical trials are usually a select group, with good performance status, access to transportation, and limiting numbers of coexisting conditions. This paper examines the factors pertinent to the small number of clinical trials designed for metastatic colorectal cancer in this group of persons.

Phase II study of a triplet regimen in advanced colorectal cancer using methotrexate, oxaliplatin and 5-fluorouracil

Building upon the concept of schedule-specific biochemical modulation of 5-fluorouracil (FU), which alternates bolus and continuous infusion (CI) FU, we have incorporated oxaliplatin (l-OHP) following the bolus part of the regimen to explore the activity of this new combination. Patients with advanced, untreated, measurable colorectal cancer received sequential methotrexate (MTX) (days 1 and 15) → l-OHP+FU (days 2 and 16) (200, 85 and 600 mg m⁻², respectively) followed by 3 weeks of CI FU (200 mg m⁻² day⁻¹) given from day 29 to 50, modulated by weekly leucovorin (LV) (20 mg m⁻²). After 1 week of rest, the second cycle was started. The treatment was continued until progression or patient's refusal. According to the intention-to-treat analysis on all 46 patients accrued, the response rate was 42% (95% CL=28–55%), with three complete responses and 16 partial responses. The median overall survival was 15.9 months and the median progression-free survival 6.9 months. Toxicity was very mild, with the bolus part of the regimen more toxic than the infusional part (24 vs 7% of grade III–IV, respectively). This new combination of MTX → l-OHP−FU followed by FU CI is well tolerated, feasible and produces activity results similar to other more simple, but more toxic, regimens. Pros and cons of the different fluoropyrimidines–l-OHP combinations are discussed.

Protracted infusional 5-fluorouracil plus high-dose folinic acid combined with bolus mitomycin C in patients with gastrointestinal cancer: a phase I/II dose escalation study

The aim of this study was to define the maximum tolerated dose (MTD) of bolus mitomycin C (MMC) in combination with 24 h-continuous infusion of 5-flourouracil (FU) plus folinic acid, and to assess the toxicity and activity in patients with previously treated colorectal and gastric cancer. Escalating doses of MMC starting from 6 mg m(-2) in 2 mg m(-2)-steps to a maximum of 10 mg m(-2) were applied on days 1 and 22, given to fixed doses of 5-FU (2.600 mg m(-2)) as 24 h infusion and folinic acid 500 mg m(-2) prior to 5-FU weekly for 6 weeks. At least three patients were treated at each dose level. A total of 16 patients have been included in the phase I study. At the highest dose level (MMC 10 mg m(-2)), grade III thrombocytopenia, dyspnoea, mucositis and diarrhoea were observed in one patient each (17 %). In the phase II study 45 patients, 33 with colorectal cancer and 12 with gastric cancer, 23 patients after failure of first- and 22 patients after at least second-line or subsequent chemotherapy have been treated. Seven partial responses (PR) were registered (16%), one (3%; CI(95%), 0-16) in colorectal and six (50%; CI(95%), 21-79%) in gastric cancer patients. In all, 17 (38%) achieved disease stabilisation, 15 colorectal (45%, CI(95%), 28-64%) and two gastric cancer patients (17%; CI(95%), 2-48%). The median progression-free survival was 3.1 months (range, 0.9-9.1) in colorectal and 4.6 months (range, 0.7-12.4) in gastric cancer. The median overall survival time was 6.6 months (range, 1.9-15.6) in colorectal and 7.1 months (range, 1.7-20.8) in patients with gastric cancer. This regimen was considered to be safe and well tolerated for pretreated patients with gastrointestinal adenocarcinoma. In gastric cancer,MMC plus infusional 5-FU/folinic acid may be a potential second-line regimen with promising antitumour activity.