Prevention of Irinotecan Induced Diarrhea by Probiotics: A Phase III Study

In preventing antibiotic-induced diarrhea in double blind placebo controlled clinical trials it was found protective effect of probiotics containing S. boulardii and Enterococcus faecium. Also in preventing infectious diseases associated with Clostridium difficile, administration of probiotics resulted in a significant decrease in disease recurrence. Duration of rotavirus diarrhea, in children and in immunocompromised HIV-positive patients was significantly shortened after administration of strains of Lactobacilli and S. boulardii respectively.

Meta-analysis of 9 randomized, placebo-controlled trials showed significant reduction in the incidence of antibiotic associated diarrhea in children. Another meta-analysis in which 23 studies were included showed significant reduction in risk of infectious diarrhea. Most of these studies was carried out with the probiotic strain Lactobacillus rhamnosus GG®.

The incidence of diarrhea during treatment of acute leukemia is between 15 to 80%. Severe diarrhea level 3 to 4 is present in 8-20% and is much more common during the induction phase of chemotherapy. In phase II study performed in NCI Slovakia preventive administration of Enterococcus faecium probiotic strain M-74 with selenium was associated with low incidence (14%) and severity (all grade 1) diarrhea, despite the fact that half of the patients received induction therapy. The investigators noted safety of probiotic strain during 370 days of severe neutropenia Gr 3-4.

The incidence of irinotecan induced diarrhea varies between 60-90%, by which the incidence of severe diarrhea is 20-40%. In phase II studies, its incidence was 17% in NCI Slovakia, but irinotecan dose was reduced by 25% in all patients. Diarrhea is an important factor in morbidity and mortality during irinotecan based chemotherapy. Predisposing factors are age over 65 years, ECOG (Eastern Cooperative Oncology Group) PS (Performance status) of 1 and previous abdominopelvic radiation. One of irinotecan metabolites, SN-38 (7-ethyl-10 hydroxycamptothecin), which is glucuronidated in the liver and subsequently expelled into intestine is main cause of diarrhea. Due to the bacterial enzyme beta-D-glucuronidase it is deconjugated in intestinal lumen again. This form causes direct damage to intestinal mucosa associated with malabsorption of water, electrolytes and development of diarrhea.

Reduction of activity of intestinal beta-D-glucuronidase using broad-spectrum antibiotics and/or beta-D-glucuronidase inhibitors is one of the ways to avoid irinotecan induced diarrhea. It is also possible to modulate metabolism of irinotecan using cyclosporine and phenobarbital to reduce biliary excretion of SN-38 and induction of glucuronidation. Promising results were shown using activated charcoal, which has resulted in the absorption of SN-38. Also other methods were tested: oral alkalization, thalidomide, amifostine, but without success. These procedures have been studied only in phase II trials. It is known that some probiotic bacteria, reduce activity of intestinal beta-D-glucuronidase and therefore these bacteria could be applied in the prevention of diarrhea in patients treated by irinotecan based therapy.