OATP2B1 Deficiency Ameliorates Irinotecan-Induced Gastrointestinal Toxicity

Area of Science:

• Pharmacology
• Gastroenterology
• Molecular Biology

Background:

• Irinotecan (CPT-11) is a vital chemotherapy for metastatic colorectal cancer.
• Severe gastrointestinal toxicity limits CPT-11's clinical use, with mechanisms incompletely understood.
• SN-38 accumulation in intestinal cells is implicated in CPT-11 toxicity.

Purpose of the Study:

• To investigate the role of organic anion transporting polypeptide 2B1 (OATP2B1) in SN-38 intestinal uptake.
• To determine if OATP2B1 is a critical factor in CPT-11-induced gastrointestinal toxicity.

Main Methods:

• Utilized a mouse model with Oatp2b1 deficiency.
• Administered CPT-11 to wild-type and Oatp2b1-deficient mice.
• Assessed gastrointestinal toxicity through diarrhea incidence, intestinal length changes, and histological examination.

Main Results:

• Oatp2b1-deficient mice exhibited significantly milder diarrhea and reduced intestinal injury compared to wild-type mice after CPT-11 treatment.
• Histological analysis confirmed less severe intestinal enterocyte damage in Oatp2b1-deficient mice.
• These protective effects occurred without significant alterations in systemic SN-38 or its glucuronide metabolite levels.

Conclusions:

• OATP2B1 is an intestinal uptake transporter for SN-38.
• OATP2B1 plays a critical role in mediating CPT-11-induced gastrointestinal toxicity.
• Plasma SN-38 levels are not reliable predictors of CPT-11 toxicity; OATP2B1 inhibitors may mitigate side effects.