irinotecan hydrochloride

Overview

Irinotecan hydrochloride (CPT-11) is a semisynthetic derivative of camptothecin and a potent inhibitor of Topoisomerase I (Topo I), the enzyme responsible for relieving torsional stress in DNA during replication and transcription. By stabilizing the covalent Topo I–DNA cleavage complex, irinotecan prevents re-ligation of single-strand DNA breaks, ultimately causing irreversible double-strand breaks and apoptosis in rapidly dividing cells. The drug is a prodrug that requires carboxylesterase-mediated conversion to its active metabolite, SN-38, which carries the majority of its cytotoxic activity. Hepatic and intestinal uridine diphosphate glucuronosyltransferase 1A1 (UGT1A1) further conjugates SN-38 to an inactive glucuronide (SN-38G), a step critical for both detoxification and the pathogenesis of delayed-onset diarrhea—one of its most clinically significant adverse effects.

Irinotecan is approved and widely used as a first- and second-line chemotherapeutic agent, most prominently in advanced and metastatic colorectal cancer (CRC), where it forms the backbone of regimens such as FOLFIRI (fluorouracil, folinic acid, and irinotecan) and FOLFIRINOX (combined with oxaliplatin and gemcitabine in pancreatic cancer contexts). Its clinical utility extends to gastric carcinoma, neuroblastoma, and other solid tumors, often in combination with targeted agents such as cetuximab and bevacizumab, or with cytotoxic partners such as temozolomide and oxaliplatin.

Focus of Latest Publications

Recent publications on irinotecan hydrochloride have focused on improving its therapeutic performance, predicting response, and mitigating toxicity, particularly in colorectal cancer and other solid tumors. Several studies examined irinotecan in combination with delivery systems or adjunct agents designed to enhance efficacy and tolerability. A multistage formulation co-delivering irinotecan hydrochloride with bevacizumab in zein nanoparticles embedded in a thermo-sensitive hydrogel showed sustained release, improved permeability across a 3D intestinal barrier, and cytotoxic activity in colorectal cancer monolayers and spheroids. In another colorectal cancer study, a self-assembled nanomedicine incorporating irinotecan and indole-3-carbinol was reported to increase irinotecan uptake, promote endoplasmic reticulum stress, and improve antitumor activity while counteracting irinotecan-induced steatohepatitis-associated liver metastasis.

Other recent work has addressed biomarkers and mechanisms relevant to irinotecan-based therapy. In pancreatic ductal adenocarcinoma, a ratiometric fluorescent sensor for carboxylesterase 2 activity was shown to correlate strongly with response to irinotecan (CPT-11)-based regimens, including FOLFIRINOX, supporting its potential use for predicting treatment sensitivity before therapy. In colorectal cancer cell lines, irinotecan induced both genotoxic damage and reactive oxygen species production in a dose-dependent manner, with similar effects observed in TP53 wild-type and TP53-null HCT116 cells under the tested non-cytotoxic conditions. These findings suggest a drug-specific oxidative and DNA-damaging profile that may be relevant for combination strategies.

Irinotecan hydrochloride also appeared in studies of local delivery and disease-specific treatment regimens. A sodium alginate sulfate microsphere platform achieved high loading capacity for irinotecan hydrochloride and was proposed as a stabilized embolic system for transarterial chemoembolization, with sustained release and favorable embolization stability in a pig renal artery model. In relapsed or refractory neuroblastoma, the bevacizumab/irinotecan/temozolomide (BIT) regimen was highlighted as a guideline-supported option based on prior clinical evidence. In colorectal cancer, combining irinotecan with FASN inhibition was reported to synergistically reduce xenograft growth and delay tumor relapse, with further potentiation by olaparib maintenance treatment.

Across these publications, irinotecan hydrochloride was consistently studied as part of efforts to improve delivery, personalize treatment, or overcome limitations such as toxicity, resistance, and relapse. The overall theme is that irinotecan remains a clinically important topoisomerase I-targeting therapy, but its recent research emphasis has shifted toward formulation engineering, biomarker-guided selection, and rational combinations that enhance antitumor efficacy while reducing adverse effects.