Study: Current Dose Level of Irinotecan Appears "Unacceptably Toxic"

Spanish researchers report that the current dose level of the newer chemotherapy drug irinotecan "appears unacceptably toxic" and are recommending that a lower dose be used for advanced colorectal cancer patients put on the drug after 5-FU chemotherapy.

The drug has been shown to prolong the life of some colorectal cancer patients whose disease has recurred or progressed following 5-FU-based therapy, but it also produces in many patients a variety of side effects including severe diarrhea, anemia and a blood disorder called neutropenia.

In their study of dosing levels, the researchers reported that the response rates obtained among 35 patients studied did not appear to be adversely impacted by cutting back the current irinotecan dose of 350 mg to 250 mg.

One-third of the patients in the study were unable to tolerate doses greater than 250 mg, the researchers reported in the American Journal of Clinical Oncology, and 10 of the 35 patients (28 percent) presented toxicity at 250 mg and 2 patients tolerated only 200 mg.

"The current irinotecan dose of 350 mg appears unacceptably toxic and, hence, a lower dose needs to be considered," the researchers concluded. "The response rates obtained are similar to the results observed in phase III studies, and its activity appears not to be adversely affected with this treatment scheme."

Other Sources: American Journal of Clinical Oncology