Therapeutic targeting of CPT-11 induced diarrhea: a case for prophylaxis

The role of the gut microbiome in neuroinflammation and chemotherapy-induced peripheral neuropathy

Chemotherapy-induced peripheral neuropathy (CIPN) is one of the most debilitating adverse effects caused by chemotherapy drugs such as paclitaxel, oxaliplatin and vincristine. It is untreatable and often leads to the discontinuation of cancer therapy and a decrease in the quality of life of cancer patients. It is well-established that neuroinflammation and the activation of immune and glial cells are among the major drivers of CIPN. However, these processes are still poorly understood, and while many chemotherapy drugs alone can drive the activation of these cells and consequent neuroinflammation, it remains elusive to what extent the gut microbiome influences these processes. In this review, we focus on the peripheral mechanisms driving CIPN, and we address the bidirectional pathways by which the gut microbiome communicates with the immune and nervous systems. Additionally, we critically evaluate literature addressing how chemotherapy-induced dysbiosis and the consequent imbalance in bacterial products may contribute to the activation of immune and glial cells, both of which drive neuroinflammation and possibly CIPN development, and how we could use this knowledge for the development of effective treatment strategies.

Optimized rat models better mimic patients with irinotecan-induced severe diarrhea

Irinotecan-induced severe diarrhea (IISD) not only limits irinotecan's application but also significantly affects patients' quality of life. However, existing animal models often inadequately represent the dynamics of IISD development, progression, and resolution across multiple chemotherapy cycles, yielding non-reproducible and highly variable response with limited clinical translation. Our studies aim to establish a reproducible and validated IISD model that better mimics the pathophysiology progression observed in patients, enhancing translational potential. We investigated the impact of dosing regimens (including different dose, infusion time, and two cycles of irinotecan administration), sex, age, tumor-bearing conditions, and irinotecan formulation on the IISD incidence and severity in mice and rats. Lastly, we investigated above factors' impact on pharmacokinetics of irinotecan, intestinal injury, and carboxylesterase activities. In summary, we successfully established a standard model establishment procedure for an optimized IISD model with highly reproducible severe diarrhea incidence rate (100%) and a low mortality rate (11%) in F344 rats. Additionally, the rats tolerated at least two cycles of irinotecan chemotherapy treatment. In contrast, the mouse model exhibited suboptimal IISD incidence rates (60%) and an extremely high mortality rate (100%). Notably, dosing regimen, age and tumor-bearing conditions of animals emerged as critical factors in IISD model establishment. In conclusion, our rat IISD model proves superior in mimicking pathophysiology progression and characteristics of IISD in patients, which stands as an effective tool for mechanism and efficacy studies in future chemotherapy-induced gut toxicity research.

Suppression of neutrophil extracellular traps is responsible for the amelioration of chemotherapeutic intestinal injury by the natural compound PEITC

Intestinal injury is one of the most debilitating side effects of many chemotherapeutic agents, such as irinotecan hydrochloride (CPT-11). Accumulating evidence indicates that neutrophil extracellular traps (NETs) play a critical role in the symptoms of ischemia and inflammation related to chemotherapy. The present study investigated the effects and possible mechanisms of phenethyl isothiocyanate (PEITC) in inhibiting NETs and alleviating chemotherapeutic intestinal injury. CPT-11 induced robust neutrophil activation, as evidenced by increased NETs release, intestinal ischemia, and mRNA expression of inflammatory factors. PEITC prolonged the clotting time of chemotherapeutic mice, improved the intestinal microcirculation, inhibited the expression of inflammatory factors, and protected the tight junctions of the intestinal epithelium. Both in vivo and in vitro experiments revealed that PEITC directly suppresses CPT-11-induced NETs damage to intestinal cells, resulting in significant attenuation of epithelial injury. These results suggest that PEITC may be a novel agent to relieve chemotherapeutic intestinal injury via inhibition of NETs.

Tight-Binding Small-Molecule Carboxylesterase 2 Inhibitors Reduce Intracellular Irinotecan Activation

As the primary enzyme responsible for the activatable conversion of Irinotecan (CPT-11) to SN-38, carboxylesterase 2 (CES2) is a significant predictive biomarker toward CPT-11-based treatments for pancreatic ductal adenocarcinoma (PDAC). High SN-38 levels from high CES2 activity lead to harmful effects, including life-threatening diarrhea. While alternate strategies have been explored, CES2 inhibition presents an effective strategy to directly alter the pharmacokinetics of CPT-11 conversion, ultimately controlling the amount of SN-38 produced. To address this, we conducted a high-throughput screening to discover 18 small-molecule CES2 inhibitors. The inhibitors are validated by dose-response and counter-screening and 16 of these inhibitors demonstrate selectivity for CES2. These 16 inhibitors inhibit CES2 in cells, indicating cell permeability, and they show inhibition of CPT-11 conversion with the purified enzyme. The top five inhibitors prohibited cell death mediated by CPT-11 when preincubated in PDAC cells. Three of these inhibitors displayed a tight-binding mechanism of action with a strong binding affinity.

Synergistic cytotoxicity of irinotecan combined with polysaccharide-based nanoparticles for colorectal carcinoma

Functional polymeric nanoparticles (NPs) with antitumor potential were combined with the topoisomerase I inhibitor, irinotecan (IRT), to enhance cytotoxicity against colorectal cancers. The negatively charged γ-polyglutamic acid (γ-PGA) or fucoidan (FCD) was complexed with the positively charged chitosan (CS) to encapsulate IRT. The size of the γ-PGA/CS/IRT NPs and FCD/CS/IRT NPs were 146.0 ± 8.0 nm and 230.8 ± 2.5 nm, respectively, with polydispersity index ≤0.3. The cellular uptake ability of FCD/CS-FITC NPs was better than that of γ-PGA/CS-FITC NPs, especially in p-selectin positive HCT116 colorectal cancer cells (4.8 ± 0.8 μg/mL vs 11.4 ± 2.2 μg/mL). The IC50 of FCD/CS/IRT NPs was 2.4 times lower than that of γ-PGA/CS/IRT NPs in HCT116 cells (4.8 ± 0.8 μg/mL vs 11.4 ± 2.2 μg/mL), indicating its superior antitumor potential. The combination of irinotecan and fucoidan-based NPs exhibited a synergistic effect (CI <1), resulting in better anticancer activity of FCD/CS/IRT NPs than irinotecan alone. The apoptosis-related proteins, caspase 3, caspase 9, and poly(ADP-ribose) polymerase (PARP), were prominently increased in FCD/CS/IRT NPs-treated HCT116 cells by 2.3 folds, 3.5 folds, and 6.3 folds, respectively. All results support that fucoidan-based irinotecan-loaded nanoparticles possess the ability to effectively enhance cellular uptake and induce synergistic apoptosis of colorectal cancer cells.

Enhanced cytotoxicity to lung cancer cells by mitochondrial delivery of camptothecin

Delivering traditional DNA-damaging anticancer drugs into mitochondria to damage mitochondria is a promising chemotherapy strategy. The impermeability of this mitochondrial inner membrane, however, impedes the delivery of drug molecules that could impact other important biological roles of mitochondria. Herein, the prodrug camptothecin (CPT)-triphenylphosphine (TPP) modified with hyaluronic acid (HA) via electrostatic adsorption (HA/CPT-TPP, HCT) was used to mediate the mitochondrial accumulation of CPT. These nanoparticles (NPs) showed enhanced drug accumulation in cancer cells through tumor targeting. HCT entered acidic lysosomes through endosomal transport, HA was degraded by hyaluronidase (HAase) in acidic lysosomes, and the positively charged CPT-TPP was exposed and accumulated fully in the mitochondria. Subsequently, CPT-TPP significantly disrupted the mitochondrial structure and damaged mitochondrial function, leading to increased reactive oxygen species (ROS) levels and energy depletion. Finally, HCT enhanced lung cancer cell apoptosis via the activation of caspase-3 and caspase-9. Furthermore, greatly increased tumor growth inhibition was observed in nude mice bearing A549 xenograft tumors after the administration of HCT via tail injection. This study demonstrated that the mitochondria-targeted delivery of CPT may be a promising antitumor therapeutic strategy.

Rodent models for anticancer toxicity studies: contributions to drug development and future perspectives

Antineoplastic treatment induces a type of gastrointestinal toxicity known as mucositis. Findings in animal models are usually easily reproducible, and standardized treatment regimens are often used, thus supporting translational science. Essential characteristics of mucositis, including intestinal permeability, inflammation, immune and oxidative responses, and tissue repair mechanisms, can be easily investigated in these models. Given the effects of mucositis on the quality of life of patients with cancer, and the importance of experimental models in the development of more effective new therapeutic alternatives, this review discusses progress and current challenges in using experimental models of mucositis in translational pharmacology research. Teaser Experimental models for studying gastrointestinal mucositis have provided a wealth of information improving the understanding of antineoplastic toxicity.

Transporter and metabolic enzyme-mediated intra-enteric circulation of SN-38, an active metabolite of irinotecan: A new concept

SN-38, an active metabolite of irinotecan (CPT-11), is thought to circulate enterohepatically via organic anion-transporting polypeptides (OATPs), UDP-glucuronyl transferases (UGTs), multidrug resistance-related protein 2 (MRP2), and breast cancer resistance protein (BCRP). These transporters and enzymes are expressed in not only hepatocytes but also enterocytes. Therefore, we hypothesized that SN-38 circulates between the intestinal lumen and the enterocytes via these transporters and metabolic enzymes. To test this hypothesis, metabolic and transport studies of SN-38 and its glucuronide (SN-38G) were conducted in Caco-2 cells. The mRNA levels of UGTs, MRP2, BCRP, and OATP2B1 were confirmed in Caco-2 cells. SN-38 was converted to SN-38G in Caco-2 cells. The efflux of intracellularly generated SN-38G across the apical (digestive tract) membranes was significantly higher than the efflux across the basolateral (blood, portal vein) membranes of Caco-2 cells cultured on polycarbonate membranes. SN-38G efflux to the apical side was significantly reduced in the presence of MRP2 and BCRP inhibitors, suggesting that SN-38G is transported across the apical membrane by MRP2 and BCRP. Treatment of Caco-2 cells with OATP2B1 siRNA increased the SN-38 residue on the apical side, confirming that OATP2B1 is involved in the uptake of SN-38 into enterocytes. No SN-38 was detected on the basolateral side with or without siRNA treatment, suggesting that the enterohepatic circulation of SN-38 is limited, contrary to previous reports. These results suggest that SN-38 is absorbed into the enterocytes via OATP2B1, glucuronidated by UGTs to SN-38G, and excreted into the digestive tract lumen by MRP2 and BCRP. SN-38G can be deconjugated by β-glucuronidase from intestinal bacteria in the digestive tract lumen to regenerate SN-38. We named this new concept of local drug circulation "intra-enteric circulation." This mechanism may allow SN-38 to circulate in the intestine and cause the development of delayed diarrhea, a serious side effect of CPT-11.

Recent advances in SN-38 drug delivery system

DNA topoisomerase I plays a key role in lubricatingthe wheels of DNA replication or RNA transcription through breaking and reconnecting DNA single-strand. It is widely known that camptothecin and its derivatives (CPTs) have inhibitory effects on topoisomerases I, and have obtained some clinical benefits in cancer treatment. The potent cytotoxicity makes 7-ethyl-10-hydroxycamptothecin (SN-38) become a brilliant star among these derivatives. However, some undesirable physical and chemical properties of this compound, including poor solubility and stability, seriously hinder its effective delivery to tumor sites. In recent years, strategies to alleviate these defects have aroused extensive research interest. By focusing on the loading mechanism, basic nanodrug delivery systems with SN-38 loaded, like nanoparticles, liposomes and micelles, are demonstrated here. Additionally, functionalized nanodrug delivery systems of SN-38 including prodrug and active targeted nanodrug delivery systems and delivery systems designed to overcome drug resistance are also reviewed. At last, challenges for future research in formulation development and clinical translation of SN-38 drug delivery system are discussed.

Effect of irinotecan administration on amiloride-sensitive sodium taste responses in mice

Taste alteration is a frequently reported side effect in patients receiving the chemotherapeutic agent, irinotecan. However, the way in which irinotecan causes taste disturbance and the type of taste impairment that is affected remain elusive. Here, we used the two-bottle preference test to characterize behavioral taste responses and employed immunohistochemical analyses to clarify the types and mechanisms of taste alteration induced, in mice, by irinotecan administration. Irinotecan administration resulted in a reduced intake of sodium taste solution but had no effect on sweet taste responses, as determined in the two-bottle preference test. In the presence of amiloride, which inhibits the function of the epithelial sodium channel (ENaC) in the periphery, the intake of sodium taste solution was comparable between the irinotecan-treated and control groups. Immunohistochemical analyses revealed that α-ENaC immunoreactivity detected in taste bud cells decreased slowly after irinotecan administration, and that administration of irinotecan had little effect on the number of cells expressing the cellular proliferation marker, Ki67, within or around taste buds. Our results imply that irinotecan administration may be responsible for altered behavioral sodium taste responses originating from ENaC function in the periphery, while being accompanied by the reduction of α-ENaC expression at the apical membrane of taste receptor cells without disturbing taste cell renewal.

Silymarin as a preventive or therapeutic measure for chemotherapy and radiotherapy-induced adverse reactions: a comprehensive review of preclinical and clinical data

PURPOSE

Thus far, silymarin has been examined in several studies for prevention or treatment of various chemotherapy or radiotherapy-induced adverse reactions. In this review, we try to collect all available human, animal, and pre-clinical data in this field.

METHODS

The search was done in Scopus, PubMed, Medline, and systematic reviews in the Cochrane database, using the following keywords: "Cancer," "Chemotherapy," "Radiotherapy," "Mucositis," "Nephrotoxicity," "Dermatitis," "Ototoxicity," "Cardiotoxicity," "Nephrotoxicity," "Hepatotoxicity," "Reproductive system," "Silybum marianum," "Milk thistle," and "Silymarin" and "Silybin." We included all relevant in vitro, in vivo, and human studies up to the date of publication.

RESULTS

Based on 64 included studies in this review, silymarin is considered a safe and well-tolerated compound, with no known clinical drug interaction. Notably, multiple adverse reactions of chemotherapeutic agents are effectively managed by its antioxidant, anti-apoptotic, anti-inflammatory, and anti-immunomodulatory properties. Clinical trials suggest that oral silymarin may be a promising adjuvant with cancer treatments, particularly against hepatotoxicity (n = 10), nephrotoxicity (n = 3), diarrhea (n = 1), and mucositis (n = 3), whereas its topical formulation can be particularly effective against radiodermatitis (n = 2) and hand-foot syndrome (HFS) (n = 1).

CONCLUSION

Further studies are required to determine the optimal dose, duration, and the best formulation of silymarin to prevent and/or manage chemotherapy and radiotherapy-induced complications.

The role of gut microbial β-glucuronidase in drug disposition and development

Gut microbial β-glucuronidase (gmGUS) is involved in the disposition of many endogenous and exogenous compounds. Preclinical studies have shown that inhibiting gmGUS activity affects drug disposition, resulting in reduced toxicity in the gastrointestinal tract (GIT) and enhanced systemic efficacy. Additionally, manipulating gmGUS activity is expected to be effective in preventing/treating local or systemic diseases. Although results from animal studies are promising, challenges remain in developing drugs by targeting gmGUS. Here, we review the role of gmGUS in host health under physiological and pathological conditions, the impact of gmGUS on the disposition of phenolic compounds, models used to study gmGUS activity, and the perspectives and challenges in developing drugs by targeting gmGUS.

Mitochondria-Targeted Delivery of Camptothecin Based on HPMA Copolymer for Metastasis Suppression

Poor anti-metastasis effects and side-effects remain a challenge for the clinical application of camptothecin (CPT). Mitochondria can be a promising target for the treatment of metastatic tumors due to their vital roles in providing energy supply, upregulating pro-metastatic factors, and controlling cell-death signaling. Thus, selectively delivering CPT to mitochondria appears to be a feasible way of improving the anti-metastasis effect and reducing adverse effects. Here, we established a 2-(dimethylamino) ethyl methacrylate (DEA)-modified N-(2-hydroxypropyl) methacrylamide (HPMA) copolymer–CPT conjugate (P-DEA-CPT) to mediate the mitochondrial accumulation of CPT. The mitochondria-targeted P-DEA-CPT could overcome multiple barriers by quickly internalizing into 4T1 cells, then escaping from lysosome, and sufficiently accumulating in mitochondria. Subsequently, P-DEA-CPT greatly damaged mitochondrial function, leading to the reactive oxide species (ROS) elevation, energy depletion, apoptosis amplification, and tumor metastasis suppression. Consequently, P-DEA-CPT successfully inhibited both primary tumor growth and distant metastasis in vivo. Furthermore, our studies revealed that the mechanism underlying the anti-metastasis capacity of P-DEA-CPT was partially via downregulation of various pro-metastatic proteins, such as hypoxia induction factor-1α (HIF-1α), matrix metalloproteinases-2 (MMP-2), and vascular endothelial growth factor (VEGF). This study provided the proof of concept that escorting CPT to mitochondria via a mitochondrial targeting strategy could be a promising approach for anti-metastasis treatment.

Opportunities and challenges for co-delivery nanomedicines based on combination of phytochemicals with chemotherapeutic drugs in cancer treatment

The therapeutic limitations such as insufficient efficacy, drug resistance, metastasis, and undesirable side effects are frequently caused by the long duration monotherapy based on chemotherapeutic drugs. multiple combinational anticancer strategies such as nucleic acids combined with chemotherapeutic agents, chemotherapeutic combinations, chemotherapy and tumor immunotherapy combinations have been embraced, holding great promise to counter these limitations, while still taking including some potential risks. Nowadays, an increasing number of research has manifested the anticancer effects of phytochemicals mediated by modulating cancer cellular events directly as well as the tumor microenvironment. Specifically, these natural compounds exhibited suppression of cancer cell proliferation, apoptosis, migration and invasion of cancer cells, P-glycoprotein inhibition, decreasing vascularization and activation of tumor immunosuppression. Due to the low toxicity and multiple modulation pathways of these phytochemicals, the combination of chemotherapeutic agents with natural compounds acts as a novel approach to cancer therapy to increase the efficiency of cancer treatments as well as reduce the adverse consequences. In order to achieve the maximized combination advantages of small-molecule chemotherapeutic drugs and natural compounds, a variety of functional nano-scaled drug delivery systems, such as liposomes, host-guest supramolecules, supramolecules, dendrimers, micelles and inorganic systems have been developed for dual/multiple drug co-delivery. These co-delivery nanomedicines can improve pharmacokinetic behavior, tumor accumulation capacity, and achieve tumor site-targeting delivery. In that way, the improved antitumor effects through multiple-target therapy and reduced side effects by decreasing dose can be implemented. Here, we present the synergistic anticancer outcomes and the related mechanisms of the combination of phytochemicals with small-molecule anticancer drugs. We also focus on illustrating the design concept, and action mechanisms of nanosystems with co-delivery of drugs to synergistically improve anticancer efficacy. In addition, the challenges and prospects of how these insights can be translated into clinical benefits are discussed.

Decreased Tissue Omega-6/Omega-3 Fatty Acid Ratio Prevents Chemotherapy-Induced Gastrointestinal Toxicity Associated with Alterations of Gut Microbiome

Gastrointestinal toxicity (GIT) is a debilitating side effect of Irinotecan (CPT-11) and limits its clinical utility. Gut dysbiosis has been shown to mediate this side effect of CPT-11 by increasing gut bacterial β-glucuronidase (GUSB) activity and impairing the intestinal mucosal barrier (IMB). We have recently shown the opposing effects of omega-6 (n-6) and omega-3 (n-3) polyunsaturated fatty acids (PUFA) on the gut microbiome. We hypothesized that elevated levels of tissue n-3 PUFA with a decreased n-6/n-3 PUFA ratio would reduce CPT-11-induced GIT and associated changes in the gut microbiome. Using a unique transgenic mouse (FAT-1) model combined with dietary supplementation experiments, we demonstrate that an elevated tissue n-3 PUFA status with a decreased n-6/n-3 PUFA ratio significantly reduces CPT-11-induced weight loss, bloody diarrhea, gut pathological changes, and mortality. Gut microbiome analysis by 16S rRNA gene sequencing and QIIME2 revealed that improvements in GIT were associated with the reduction in the CPT-11-induced increase in both GUSB-producing bacteria (e.g., Enterobacteriaceae) and GUSB enzyme activity, decrease in IMB-maintaining bacteria (e.g., Bifidobacterium), IMB dysfunction and systemic endotoxemia. These results uncover a host–microbiome interaction approach to the management of drug-induced gut toxicity. The prevention of CPT-11-induced gut microbiome changes by decreasing the tissue n-6/n-3 PUFA ratio could be a novel strategy to prevent chemotherapy-induced GIT.

Discovery of a naturally occurring broad-spectrum inhibitor against gut bacterial β-glucuronidases from Ginkgo biloba

Gut bacterial β-glucuronidases (GUS) play an important role in deconjugation of various O-glucuronides, which are tightly linked with the drug-induced intestinal toxicity. Increasing evidence has indicated that inhibition of bacterial GUS could alleviate GUS-associated intestinal toxicity, but the potent and broad-spectrum inhibitors against multiple bacterial GUS have been rarely reported. This study aimed to find potent and broad-spectrum GUS inhibitors from Ginkgo biloba. It was found that amentoflavone displayed relatively strong inhibition on three GUS including CpGUS, SpasGUS and EcGUS. Further investigations demonstrated that amentoflavone could inhibit GUS-mediated PNPG hydrolysis in a dose-dependent manner with IC₅₀ values of 2.36 μM, 2.88 μM and 3.43 μM for CpGUS, SpasGUS and EcGUS, respectively. Inhibition kinetic studies showed that amentoflavone functioned as a non-competitive inhibitor against all tested GUS with K_i values of less than 2 μM. Docking simulations indicated that amentoflavone could tightly bind on allosteric sites of three GUS mainly via hydrogen bonding interactions, and the number of hydroxyl groups of amentoflavone played crucial roles in these interactions. Collectively, our findings suggested that amentoflavone was a potent broad-spectrum inhibitor against bacterial GUS, which can be used as a promising lead compound for developing novel agents to alleviate GUS-associated intestinal toxicity.

Beta-Glucuronidase Inhibition by Constituents of Mulberry Bark

Intestinal bacterial β-glucuronidases, the key enzymes responsible for the hydrolysis of various glucuronides into free aglycone, have been recognized as key targets for treating various intestinal diseases. This study aimed to investigate the inhibitory effects and mechanisms of the Mulberry bark constituents on E. coli β-glucuronidase (EcGUS), the most abundant β-glucuronidases produced by intestinal bacteria. The results showed that the flavonoids isolated from Mulberry bark could strongly inhibit E. coli β-glucuronidase, with IC₅₀ values ranging from 1.12 µM to 10.63 µM, which were more potent than D-glucaric acid-1,4-lactone. Furthermore, the mode of inhibition of 5 flavonoids with strong E. coli β-glucuronidase inhibitory activity (IC₅₀ ≤ 5 µM) was carefully investigated by a set of kinetic assays and in silico analyses. The results demonstrated that these flavonoids were noncompetitive inhibitors against E. coli β-glucuronidase-catalyzed 4-nitrophenyl β-D-glucuronide hydrolysis, with Ki values of 0.97 µM, 2.71 µM, 3.74 µM, 3.35 µM, and 4.03 µM for morin (1: ), sanggenon C (2: ), kuwanon G (3: ), sanggenol A (4: ), and kuwanon C (5: ), respectively. Additionally, molecular docking simulations showed that all identified flavonoid-type E. coli β-glucuronidase inhibitors could be well-docked into E. coli β-glucuronidase at nonsubstrate binding sites, which were highly consistent with these agents' noncompetitive inhibition mode. Collectively, our findings demonstrated that the flavonoids in Mulberry bark displayed strong E. coli β-glucuronidase inhibition activity, suggesting that Mulberry bark might be a promising dietary supplement for ameliorating β-glucuronidase-mediated intestinal toxicity.

A Pilot Study of Silymarin as Supplementation to Reduce Toxicities in Metastatic Colorectal Cancer Patients Treated With First-Line FOLFIRI Plus Bevacizumab

Irinotecan, a topoisomerase inhibitor, is a common cytotoxic agent prescribed for metastatic colorectal cancer (mCRC) patients. Diarrhea is the most common adverse event (AE). The underlying mechanism of irinotecan-induced diarrhea is intestinal mucosal damage caused by SN-38 (active metabolite of irinotecan) hydrolyzed from SN-38G (inactive metabolite) by bacterial β-glucuronidase (βG). According to an animal study, silymarin reduces the activity of bacterial βG without impairing antitumor efficacy. We conducted a prospective open-label pilot study to evaluate the effect of silymarin as supplementation in reducing toxicities of mCRC patients undergoing irinotecan-based chemotherapy. We enrolled and randomized 70 mCRC patients receiving first-line FOLFIRI (5-fluorouracil/leucovorin/irinotecan) plus bevacizumab. In each treatment cycle, the study group was administered silymarin capsules (150 mg) three times daily for 7 days. The study group experienced less AEs in diarrhea (5.7% vs. 14.6%, p = 0.002) and nausea (27.0% vs. 40.2%, p = 0.005) in comparison with the control group, but no significant differences in hepatic toxicities were observed. In conclusion, simultaneous administration of silymarin is a potential effective supplementation for reducing toxicities in mCRC patients undergoing first-line FOLFIRI plus bevacizumab, especially in diarrhea and nausea.

Discovery of hCES2A inhibitors from Glycyrrhiza inflata via combination of docking-based virtual screening and fluorescence-based inhibition assays

An integrated strategy via combination of chemical profiling, docking-based virtual screening and fluorescence-based high-throughput inhibitor screening assays was used to efficiently identify natural hCES2A inhibitors from herbal medicines.

Tailored-dose chemotherapy with gemcitabine and irinotecan in patients with platinum-refractory/resistant ovarian or primary peritoneal cancer: a phase II trial

OBJECTIVE

We investigated the efficacy and toxicity of tailored-dose chemotherapy with gemcitabine and irinotecan for platinum-refractory/resistant ovarian or primary peritoneal cancer.

METHODS

We enrolled patients with ovarian or primary peritoneal cancer who received ≥2 previous chemotherapeutic regimens but developed progressive disease during platinum-based chemotherapy or within 6 months post-treatment. All patients received gemcitabine (500 mg/m²) and irinotecan (50 mg/m²) on days 1 and 8 every 21 days at the starting dose. The dose was increased or decreased by 4 levels in subsequent cycles based on hematological or non-hematological toxicities observed. The primary endpoint was progression-free survival (PFS), and secondary endpoints were disease control rate (DCR), overall survival (OS), and adverse events.

RESULTS

We investigated 25 patients who received 267 cycles (median 8 cycles/patient) between October 2008 and May 2011. Tailored-dose gemcitabine was administered up to the 5th cycle as follows: 1,000 mg/m² in 1 (4%), 750 mg/m² in 16 (64%), 500 mg/m² in 6 (24%), and 250 mg/m² in 2 patients (8%). The median PFS and OS were 6.2 months (95% confidence interval [CI]=2.7-10.7) and 16.8 months (95% CI=9.4-30.7), respectively. The DCR was 76%, and PFS was >6 months in 12 of 25 patients (48%). Grade 3 hematological toxicities included leukopenia (9.4%), neutropenia (11.2%), anemia (9.8%), and thrombocytopenia (1.1%). Grade 3/4 non-hematological toxicities did not occur except for fatigue in one patient.

CONCLUSIONS

Tailored-dose chemotherapy with gemcitabine and irinotecan was effective and well tolerated in patients with platinum-refractory/resistant ovarian or primary peritoneal cancer.

TRIAL REGISTRATION

UMIN Clinical Trials Registry Identifier: UMIN000004449.

Development and In Vitro Evaluation of Long Circulating Liposomes for Targeted Delivery of Gemcitabine and Irinotecan in Pancreatic Ductal Adenocarcinoma

The classically used nontargeted chemotherapeutic approach to pancreatic cancer has a dual drawback of suboptimal drug delivery at the target site and the systemic side effects produced by the unfettered exposure of the drug to healthy tissue. This study has the objective of developing novel poly(2-ethyl-2-oxazoline) (PETOX)-based long circulating liposomes loaded with gemcitabine and irinotecan for the treatment of pancreatic ductal adenocarcinoma, with a juxtaposition to PEGylated and uncoated liposomes. A PETOX-cholesteryl chloroformate lipopolymer conjugate (PETOX-ChC) with a carbonate linkage was prepared and characterized by ¹H NMR, FTIR, and DSC. Liposomes were prepared using the thin film hydration technique followed by freeze-thaw and membrane extrusion methods. Liposome characterization includes particle size determination, zeta potential determination using a zetameter, and structural elucidation using ³¹P NMR and cryo-TEM. The PETOXylated liposomes showed a particle size of 180.1 ± 2.2 nm and a zeta potential of - 33.63 ± 1.23 mV. The liposomal combination therapy of gemcitabine and irinotecan was found to have an IC₅₀ value 39 times lower in comparison to the drug combination in solution, while the PEGylated and PETOXylated liposomes showed IC₅₀ values 1.6 times lower and 2 times lower than that of uncoated liposomes, respectively, against Mia PaCa II pancreatic cancer cell line. The PEGylated and PETOXylated liposomes showed 4.1 and 5.4 times slower macrophagial uptake in vitro in comparison to the uncoated liposomes respectively. The PEGylated liposomes showed 11% higher in vitro macrophagial uptake in comparison to PETOXylated liposomes.

Jiawei Xianglian Decoction (JWXLD), a Traditional Chinese Medicine (TCM), Alleviates CPT-11-Induced Diarrhea in Mice

Irinotecan (CPT-11) is used for therapy of various cancers. However, it has several serious adverse reactions such as diarrhea which is caused by SN-38, the active form of CPT-11. This study aimed to evaluate the effectiveness of Jiawei xianglian decoction (JWXLD), which has been widely used for the treatment of diarrhea in China. In this study, a mouse model with delayed diarrhea was generated by CPT-11. Real-time PCR and enzyme-linked immunosorbent assay (ELISA) were performed to explore intestinal microflora and inflammatory cytokine. Hematoxylin and eosin (H&E) staining was used to analyze tissue morphology. We found that 0.12, 0.23, and 0.46 g JWXLD significantly reduced the severity of CPT-11-induced diarrhea. The levels of Lactobacillus (Lacto) and Bifidobacterium (Bifid) were significantly downregulated by CPT-11, and these effects can be reversed by JWXLD treatment. Furthermore, JWXLD was observed to decrease the activity of β-glucuronidase (β-GD). Histopathological data showed that CPT-11 induced severe intestinal mucosal injury, which was characterized as grade 6, and JWXLD significantly alleviated the injury. In addition, CPT-11 increased the productions of tumor necrosis factor-alpha (TNF-α), tumor necrosis factor-beta (TNF-β), interleukin-6 (IL-6), and interleukin-1 (IL-1), but decreased interleukin-15 (IL-15), interleukin-7 (IL-7), and uridine diphosphate-glucuronosyltransferase 1A1 (UGT1A1). In conclusion, JWXLD can counteract these effects caused by CPT-11 treatment. JWXLD could alleviate CPT-11-induced diarrhea.

A new recombinant MS-superoxide dismutase alleviates 5-fluorouracil-induced intestinal mucositis in mice

Intestinal mucositis is a common side effect of anticancer regimens that exerts a negative impact on chemotherapy. Superoxide dismutase (SOD) is a potential therapy for mucositis but efficient product is not available because the enzyme is degraded following oral administration or induces an immune reaction after intravascular infusion. Multi-modified Stable Anti-Oxidant Enzymes^® (MS-AOE^®) is a new recombinant SOD with better resistance to pepsin and trypsin. We referred it as MS-SOD to distinguish from other SODs. In this study we investigated its potential to alleviate 5-FU-induced intestinal injury and the mechanisms. An intestinal mucositis model was established in C57/BL6 mice by 5-day administration of 5-FU (50 mg/kg every day, ip). MS-SOD (800 IU/10 g, ig) was given once daily for 9 days. 5-FU caused severe mucositis with intestinal morphological damage, bodyweight loss and diarrhea; MS-SOD significantly decreased the severity. 5-FU markedly increased reactive oxygen species (ROS) and inflammatory cytokines in the intestine which were ameliorated by MS-SOD. Furthermore, MS-SOD modified intestinal microbes, particularly reduced Verrucomicrobia, compared with the 5-FU group. In Caco2 cells, MS-SOD (250–1000 U/mL) dose-dependently decreased tBHP-induced ROS generation. In RAW264.7 cells, MS-SOD (500 U/mL) had no effect on LPS-induced inflammatory cytokines, but inhibited iNOS expression. These results demonstrate that MS-SOD can scavenge ROS at the initial stage of injury, thus play an indirect role in anti-inflammatory and barrier protein protection. In conclusion, MS-SOD attenuates 5-FU-induced intestinal mucositis by suppressing oxidative stress and inflammation, and influencing microbes. MS-SOD may exert beneficial effect in prevention of intestinal mucositis during chemotherapy in clinic.

Identify old drugs as selective bacterial β-GUS inhibitors by structural-based virtual screening and bio-evaluations

Irinotecan (CPT-11) is a cytotoxic drug that has wide applicability and usage in cancer treatment. Despite its success, patients suffer dose-dependent diarrhea, limiting the drug's efficacy. No effective therapy is available for this unmet medical need. The bacterial β-glucuronidase (β-GUS) plays pivotal role in CPT-11-induced diarrhea (CID) via activating the non-toxic SN-38G to toxic SN-38 inside intestine. By using structural-based virtual screening, three old drugs (N-Desmethylclozapine, Aspartame, and Gemifloxacin) were firstly identified as selective bacterial β-GUS inhibitors. The IC₅₀ values of the compounds in the enzyme-based and cell-based assays range from 0.0389 to 3.6040 and 0.0105 to 5.3730 μM, respectively. The compounds also showed good selectivity against mammalian β-GUS and no significant cytotoxicity in bacteria. Molecular docking and molecular dynamics simulations were performed to further investigate the binding modes of compounds with bacterial β-GUS. Binding free energy decomposition revealed that the compounds formed strong interactions with E413 in catalytic trail from primary monomer and F365' on the bacterial loop from the other monomer of bacterial β-GUS, explaining the selectivity against mammalian β-GUS. The old drugs identified here may be used as bacterial β-GUS inhibitors for CID or other bacterial β-GUS-related disorders.

Evaluation of human primary intestinal monolayers for drug metabolizing capabilities

BACKGROUND

The intestinal epithelium is a major site of drug metabolism in the human body, possessing enterocytes that house brush border enzymes and phase I and II drug metabolizing enzymes (DMEs). The enterocytes are supported by a porous extracellular matrix (ECM) that enables proper cell adhesion and function of brush border enzymes, such as alkaline phosphatase (ALP) and alanyl aminopeptidase (AAP), phase I DMEs that convert a parent drug to a more polar metabolite by introducing or unmasking a functional group, and phase II DMEs that form a covalent conjugate between a functional group on the parent compound or sequential metabolism of phase I metabolite. In our effort to develop an in vitro intestinal epithelium model, we investigate the impact of two previously described simple and customizable scaffolding systems, a gradient cross-linked scaffold and a conventional scaffold, on the ability of intestinal epithelial cells to produce drug metabolizing proteins as well as to metabolize exogenously added compounds. While the scaffolding systems possess a range of differences, they are most distinguished by their stiffness with the gradient cross-linked scaffold possessing a stiffness similar to that found in the in vivo intestine, while the conventional scaffold possesses a stiffness several orders of magnitude greater than that found in vivo.

RESULTS

The monolayers on the gradient cross-linked scaffold expressed CYP3A4, UGTs 2B17, 1A1 and 1A10, and CES2 proteins at a level similar to that in fresh crypts/villi. The monolayers on the conventional scaffold expressed similar levels of CYP3A4 and UGTs 1A1 and 1A10 DMEs to that found in fresh crypts/villi but significantly decreased expression of UGT2B17 and CES2 proteins. The activity of CYP3A4 and UGTs 1A1 and 1A10 was inducible in cells on the gradient cross-linked scaffold when the cells were treated with known inducers, whereas the CYP3A4 and UGT activities were not inducible in cells grown on the conventional scaffold. Both monolayers demonstrate esterase activity but the activity measured in cells on the conventional scaffold could not be inhibited with a known CES2 inhibitor. Both monolayer culture systems displayed similar ALP and AAP brush border enzyme activity. When cells on the conventional scaffold were incubated with a yes-associated protein (YAP) inhibitor, CYP3A4 activity was greatly enhanced suggesting that mechano-transduction signaling can modulate drug metabolizing enzymes.

CONCLUSIONS

The use of a cross-linked hydrogel scaffold for expansion and differentiation of primary human intestinal stem cells dramatically impacts the induction of CYP3A4 and maintenance of UGT and CES drug metabolizing enzymes in vitro making this a superior substrate for enterocyte culture in DME studies. This work highlights the influence of mechanical properties of the culture substrate on protein expression and the activity of drug metabolizing enzymes as a critical factor in developing accurate assay protocols for pharmacokinetic studies using primary intestinal cells.

GRAPHICAL ABSTRACT

Pharmacogenomics, biomarker network, and allele frequencies in colorectal cancer

Colorectal cancer is one of the leading causes of cancer death worldwide. Over the last decades, several studies have shown that tumor-related genomic alterations predict tumor prognosis, drug response, and toxicity. These observations have led to the development of several therapies based on individual genomic profiles. As part of these approaches, pharmacogenomics analyses genomic alterations which may predict an efficient therapeutic response. Studying these mutations as biomarkers for predicting drug response is of a great interest to improve precision medicine. We conduct a comprehensive review of the main pharmacogenomics biomarkers and genomic alterations affecting enzyme activity, transporter capacity, channels, and receptors; and therefore the new advances in CRC precision medicine to select the best therapeutic strategy in populations worldwide, with a focus on Latin America.

A randomized controlled, open-label early phase II trial comparing incidence of FOLFIRI.3-induced diarrhoea between Hangeshashinto and oral alkalization in Japanese patients with colorectal cancer

WHAT IS KNOWN AND OBJECTIVE

We conducted a pilot clinical trial to investigate whether Hangeshashinto (TJ-14) could be substituted for oral alkalization in patients scheduled to undergo chemotherapy by FOLFIRI.3 regimen for colorectal cancer (CRC).

METHODS

Patients with CRC were randomized 1:1 to a TJ-14 (7.5 g/day) group or an oral alkalization (sodium bicarbonate, 1.8 g/day; ursodeoxycholic acid, 300 mg/day) group. The primary endpoint was incident of late-onset diarrhoea. A total of 30 patients were randomized to either the TJ-14 group or the alkalization group.

RESULTS AND DISCUSSION

There was no statistical difference in age, concomitantly used drugs or UGT1A1 genotypes between the groups. In the alkalization group (n = 15), the frequency of grade 0/1/2 and grade 3 diarrhoea was 73% and 27%, respectively. In the TJ-14 group (n = 14), the frequency of grade 0/1/2 and grade 3 diarrhoea was 79% and 21%, respectively. Grade 4 diarrhoea was not observed in either group. There was no statistically significant difference in other adverse events or in response to FOLFIRI.3 between the groups.

WHAT IS NEW AND CONCLUSION

This pilot trial suggests that TJ-14 is a promising alternative treatment option to reduce FOLFIRI.3-induced late-onset diarrhoea, although additional clinical study with a larger number of patients is necessary to confirm these results.

Irinotecan: 25 years of cancer treatment

Twenty-five years ago, the cytotoxic drug irinotecan (IRT) was first approved in Japan for the treatment of cancer. For more than two decades, the IRT prodrug has largely contributed to the treatment of solid tumors worldwide. Nowadays, this camptothecin derivative targeting topoisomerase 1 remains largely used in combination regimen, like FOLFIRI and FOLFIRINOX, to treat metastatic or advanced solid tumors, such as colon, gastric and pancreatic cancers and others. This review highlights recent discoveries in the field of IRT and its derivatives, including analogues of the active metabolite SN38 (such as FL118), the recently approved liposomal form Nal-IRI and SN38-based immuno-conjugates currently in development (such as sacituzumab govitecan). New information about the IRT mechanism of action are presented, including the discovery of a new protein target, the single-stranded DNA-binding protein FUBP1. Significant progress has been made also to better understand and manage the main limiting toxicities of IRT, chiefly neutropenia and diarrhea. The role of drug-induced inflammation and dysbiosis is underlined and strategies to limit the intestinal toxicity of IRT are discussed (use of β-glucuronidase inhibitors, plant extracts, probiotics). The detailed knowledge of the metabolism of IRT has enabled the identification of potential biomarkers to guide patient selection and to limit drug-induced toxicities, but no robust IRT-specific therapeutic biomarker has been approved yet. IRT is a versatile chemotherapeutic agent which combines well with a variety of anticancer drugs. It offers a large range of drug combinations with cytotoxic agents, targeted products and immuno-active biotherapeutics, to treat a variety of advanced solid carcinoma, sarcoma and cancers with progressive central nervous system diseases. A quarter of century after its first launch, IRT remains an essential anticancer drug, largely prescribed, useful to many patients and scientifically inspiring.

Herbal Medicines for Irinotecan-Induced Diarrhea

Irinotecan (CPT-11), a water-soluble derivative of camptothecin, belongs to the class of DNA topoisomerase I inhibitors and has been approved worldwide for the treatment of advanced colorectal cancer, lung cancer, and malignant lymphoma. Although CPT-11-based chemotherapy is widely used, severe gastrointestinal (GI) toxicity, especially late-onset diarrhea, is a common adverse reaction, limiting clinical application of the drug. The incidence of grade 3 or 4 diarrhea is high, with 20-40% of CPT-11-treated patients experiencing this adverse effect. High-dose loperamide and octreotide are generally recommended for treatment of CPT-11-induced diarrhea. However, in clinical practice, loperamide is associated with a significant failure rate and the beneficial effects of octreotide are controversial. An accumulating number of recent studies have suggested that medicinal herbs and their derived phytocompounds may be effective complementary treatments for CPT-11-induced diarrhea. In this mini-review, we briefly summarize currently available literatures regarding the formulae and herbs/natural products used as adjuvants in animal and clinical studies for the treatment of diarrhea caused by CPT-11.

Liposomal Irinotecan for Treatment of Colorectal Cancer in a Preclinical Model

Colorectal cancer (CRC) is the most frequently diagnosed cancer and leading cause of cancer-related deaths worldwide. Because of the use of first-line CRC treatments, such as irinotecan (IRI), is hindered by dose-limiting side effects, improved drug delivery systems may have major clinical benefits for CRC treatment. In this study, we generate and characterize liposomal irinotecan (Lipo-IRI), a lipid-based nanoparticle, which shows excellent bioavailability and pharmacokinetics. Additionally, this formulation allows IRI to be maintained in active form and prolongs its half-life in circulation compared to IRI in solution. Compared with IRI statistically, the level of prostaglandin E2 (PGE2) in colonic tissue decreases, and Bifidobacterium spp. (beneficial intestinal microbiota) content increases in the Lipo-IRI-treated group. Moreover, no damage is observed by the hematoxylin and eosin staining of the normal tissue samples from the Lipo-IRI-treated group. In a xenograft mouse model, CRC tumors shrink markedly following Lipo-IRI treatment, and mice receiving a targeted combination of Lipo-IRI and liposomal doxorubicin (Lipo-Dox) extend their survival rate significantly. Overall, our results demonstrate that this formulation of Lipo-IRI shows a great potential for the treatment of colorectal cancer.

Protective effect of curcumin against irinotecan‑induced intestinal mucosal injury via attenuation of NF‑κB activation, oxidative stress and endoplasmic reticulum stress

Irinotecan (CPT‑11) is a DNA topoisomerase I inhibitor which is widely used in clinical chemotherapy, particularly for colorectal cancer treatment. However, late‑onset diarrhea is one of the severe side‑effects of this drug and this restricts its clinical application. The present study aimed to investigate the protective effects of curcumin treatment on CPT‑11‑induced intestinal mucosal injury both in vitro and in vivo and to elucidate the related mechanisms involved in these effects. For this purpose, mice were intraperitoneally injected with CPT‑11 (75 mg/kg) for 4 days to establish a model of late‑onset diarrhea. Curcumin (100 mg/kg) was intragastrically administered 8 days before the injection of CPT‑11. Injury to small intestinal tissues was examined by H&E staining. The protein expression of prolyl 4‑hydroxylase subunit beta (P4HB) and peroxiredoxin 4 (PRDX4) was detected by immunohistochemistry, as well as western blot analysis. IEC‑6 cell viability was detected by MTT assay. Flow cytometry was performed to examine the cell apoptotic rate, mitochondrial membrane potential and reactive oxygen species (ROS) generation. Immunofluorescence was used to observe the localization of nuclear factor (NF)‑κB. The levels of cleaved caspase‑3, glucose‑regulated protein, 78 kDa (GRP78), P4HB, PRDX4 and CHOP were detected by western blot analysis. The results revealed that in vivo, curcumin effectively attenuated the symptoms of diarrhea and abnormal intestinal mucosa structure induced by CPT‑11 in nude mice. Treatment with curcumin also increased the expression of P4HB and PRDX4 in the tissue of the small intestine. In vitro, curcumin, exhibited little cytotoxicity when used at concentrations <2.5 µg/ml for 24 h in IEC‑6 cells. At this concentration, curcumin also improved cell morphology, inhibited apoptosis, maintained mitochondrial membrane potential and reduced the elevated levels of ROS induced by CPT‑11 (20 µg/ml). Furthermore, curcumin abolished NF‑κB signal transduction and protected the cells from CPT‑11‑induced apoptosis by upregulating the expression of molecular chaperones, such as GRP78, P4HB and PRDX4, and suppressing the levels of the apoptosis‑related proteins, CHOP and cleaved caspase‑3. On the whole, our data indicate that curcumin exerted protective effects against CPT‑11‑induced intestinal mucosa injury. The protective effects of curcumin are mediated by inhibiting the activation of NF‑κB, and suppressing oxidative stress and endoplasmic reticulum stress.

Synergistic antitumor efficacy of hybrid micelles with mitochondrial targeting and stimuli-responsive drug release behavior

The term synergism means that the overall therapeutic benefits should be greater than the sum of the effects of individual agents and that the optimal therapeutic efficacy can be achieved at reduced doses. Micellar systems usually fail to deliver multiple drugs to target sites at synergistic doses and thus are not able to maximize the antitumor efficacy. In the current study, we demonstrate a strategy to coordinate the release of camptothecin (CPT) and α-tocopheryl succinate (TOS) from hybrid micelles for nucleus and mitochondrion interferences. TOS is decorated with cationic triphenylphosphonium (TPP) to promote the targeting capability of TOS-TPP to mitochondria. The combination of CPT and TOS-TPP shows strong synergistism with a combination index of 0.186. Hyaluronic acid (HA) is conjugated with CPT or TOS-TPP via disulfide linkages for tumor cell targeting and intracellular reduction-triggered release. Both conjugates either separately self-assemble into M_C and M_T micelles, or are blended at different ratios to form M_C-T hybrid micelles. In response to elevated intracellular glutathione levels, the coordinated release of CPT and TOS-TPP from M_C-T results in a combination index of 0.26 and the dose-reduction indexes of CPT and TOS are 7.7 and 3.4, respectively. Compared with M_C and M_T, M_C-T micelles with 5 fold lower doses exhibit higher intracellular reactive oxygen species (ROS) levels, comparable tumor growth inhibition and animal survival, indicating no hematologic and intestinal toxicities. Moreover, the HA conjugates of M_C-T are linked to polylactide via acid-labile linkages and electrospun into short fibers (M_C-T@SF) as an injectable depot to release M_C-T in response to the acidic tumor microenvironment. At a predetermined synergistic ratio, M_C-T@SF with 5 fold lower doses achieves antitumor profiles comparable to those of individual micelle-loaded short fibers. Therefore, the hybrid micelles and micelle-releasing short fibers represent a feasible strategy to synergistically enhance the therapeutic efficacy and enable significant reduction in effective doses of chemotherapeutic agents.

Effects of Δ9-tetrahydrocannabinol on irinotecan-induced clinical effects in rats

Because of the great interest for research on the potential use of cannabis preparations as co-medication for alleviation of toxic effects in cancer management, we investigated the influence of Δ⁹-tetrahydrocannabinol (Δ⁹-THC) to modulate irinotecan (CPT-11)-induced toxicity. Male Wistar rats were treated either with a single irinotecan intraperitoneal dose, 100 mg/kg body-weight (b.w.), or with irinotecan in combination with THC (7 mg/kg b.w., p.o., administered repeatedly for 1, 3 and 7 days). Serial blood samples were obtained up to seven days after dosing and were analyzed for complete blood count and biochemical parameters (liver enzymes, creatinine, inflammatory markers, and lipid status). Serial urine samples were collected in the first 24 h to monitor the time-course of THC metabolite 11-nor-9-carboxy-Δ⁹-THC (THC-COOH) excretion with concomitant irinotecan treatment or without. Both irinotecan and irinotecan + Δ⁹-THC administration caused moderate leukopenia but a greater decrease in leukocyte count was observed in the irinotecan + Δ⁹-THC treated compared to the single irinotecan suggesting higher cytotoxic effects in combined treatment. Irinotecan treatment induced elevation of aspartate aminotransferase (AST) in rats without diarrheal symptoms and without an increase in circulating pro-inflammatory mediators. Interestingly, the elevation of AST was not observed in the irinotecan + Δ⁹-THC group. The median creatinine-corrected urinary THC-COOH concentration was higher in the irinotecan + THC group compared to the THC-only group in a time-dependent manner, suggesting a possible early interaction between cannabinoids and irinotecan. Further studies are needed to investigate the role of cannabinoids particularly on hematological toxicity, irinotecan metabolism and their role as a possible modifiable factor among irinotecan-treated hosts.

Prolonged Deleterious Influences of Chemotherapeutic Agent CPT-11 on Resident Peritoneal Macrophages and B1 Cells

CPT-11 is a first-line chemotherapeutic agent for the treatment of colorectal cancer in clinic. Previous studies including ours have demonstrated that CPT-11 is, however, toxic to the intestinal epithelium and resident peritoneal macrophages. By interacting with B1 cells, the resident peritoneal macrophages play critical roles in the maintenance of gastrointestinal homeostasis. It remains therefore elusive whether these peritoneal innate immune cells could be rebuilt spontaneously or artificially after being impaired by CPT-11 administration. In this study, we found that mouse resident peritoneal macrophages, namely the large peritoneal macrophages (LPMs) with a CD11b⁺F4/80^hiGATA6⁺ phenotype, and B1 (CD19⁺CD23⁻) cells were depleted by intraperitoneal (i.p.) CPT-11 treatment within 1 week, but reappeared from day 14 after CPT-11 treatment. However, the recovery processes of these innate immune cells were slow, as their counts could not be fully recovered even 2 months later, when compared with that of vehicle-treated control group. Interestingly, in the peritoneal cavity of the mice treated with CPT-11, the cell counts of LPMs and B1 cells were significantly increased after adoptive transfer with syngeneic peritoneal exudate cells (PECs) from healthy mice. Adoptive transfer with bone marrow cells also slightly increased, although not significantly, the cell counts of LPMs and B1 cells in CPT-11-treated mice. The survival rate of bacterial infected mice was significantly reduced by i.p. CPT-11 treatment in comparison with vehicle-treated or untreated control groups. Besides, oral administration of CPT-11 also had a delayed toxicity on the resident peritoneal macrophages. Our results suggest that CPT-11 has prolonged deleterious effects on peritoneal innate immune cells but adoptive transfer with PECs may accelerate their recovery processes, highlighting the potential of adoptive cell transfer as an avenue to counteract the adverse effects of this chemotherapeutic agent.

The role of gut microbiota in the modulation of drug action: a focus on some clinically significant issues

INTRODUCTION

A healthy gut microbiota is necessary for the normal operation of several body functions, including gastrointestinal sensitivity and motility, lipid and glucid metabolism, immune surveillance, and host behavior. In addition, intestinal bacteria contribute to determining the pharmacological properties of several drugs by producing different drug metabolizing enzymes. Areas covered: Four enzymatic processes are discussed: prodrug activation; drug inactivation; drug deconjugation; and hydrolysis of natural glycosides with further metabolism of released aglycones. For each of these processes, a literature search has been undertaken on certain paradigmatic examples that have significant clinical implications: aminosalicylates and anthranoid laxatives; digoxin; irinotecan and non-steroidal anti-inflammatory drugs (NSAIDs); rutin, diosmin, and baicalin. Expert commentary: The modulation of certain reactions catalyzed by gut bacterial enzymes may offer new opportunities to improve the clinical efficacy of drugs such as aminosalicylates, and natural glycosides by increasing their metabolic transformation, and of digoxin by reducing its inactivation, or to decrease the lower intestinal toxicity of irinotecan, and NSAIDs by inhibiting the hydrolytic cleavage of their conjugates. Randomized clinical trials are awaited to clarify whether new intervention strategies may modulate these processes and provide clinical benefits such as improved therapeutic outcomes and drug safety profiles.

Shengjiang Xiexin Decoction Alters Pharmacokinetics of Irinotecan by Regulating Metabolic Enzymes and Transporters: A Multi-Target Therapy for Alleviating the Gastrointestinal Toxicity

Shengjiang Xiexin decoction (SXD), a classic traditional Chinese medical formula chronicled in Shang Han Lun, is used in modern clinical practice to decrease gastrointestinal toxicity induced by the chemotherapeutic drug irinotecan (CPT-11). In this study, the effect of SXD on the pharmacokinetics of CPT-11 and its active metabolites (SN-38 and SN-38G), and the underlying mechanisms were further examined. An ultra-high-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) method was developed and validated for the simultaneous quantification of CPT-11, SN-38, and SN-38G in the plasma, bile, liver, intestine, and intestinal contents of control and SXD-pre-treated rats after intravenous administration of CPT-11. SXD pretreatment increased the area under the curve (AUC) and the initial plasma concentration (C₀) of CPT-11 but decreased the plasma clearance (CL). The AUC and the maximum plasma concentration (C_max) of SN-38 decreased, whereas the C_max of SN-38G increased. Compared with that of the control group, the biliary excretion of CPT-11, SN-38, and SN-38G was inhibited. The CPT-11, SN-38, and SN-38G concentrations in the liver, intestine, and intestinal contents were different between the two groups. Furthermore, the hepatic expression of multidrug resistance-associated protein-2 (Mrp-2), P-glycoprotein (P-gp), and carboxylesterase 2 (CES2) was significantly down-regulated by SXD, while the hepatic and jejunal uridine diphosphate (UDP)-glucuronosyltransferase 1A1 (UGT1A1) expression was elevated. The hydrolysis of CPT-11 to SN-38 by CES and the glucuronidation of SN-38 to SN-38G by UGT were affected by liver and jejunum S9 fractions from rats pre-treated with SXD. Therefore, this study demonstrated for the first time that SXD could alter the pharmacokinetics of CPT-11 and its metabolites to alleviate CPT-11-induced diarrhea. And the underlying mechanism of drug interaction between CPT-11 and SXD involves decreasing hepatic Mrp-2 and P-gp expression and altering the activities of CES and UGT.

Chemotherapy-induced gastrointestinal toxicity is associated with changes in serum and urine metabolome and fecal microbiota in male Sprague-Dawley rats

Purpose

Chemotherapy-induced gastrointestinal toxicity (CIGT) is a complex process that involves multiple pathophysiological mechanisms. We have previously shown that commonly used chemotherapeutics 5-fluorouracil, oxaliplatin, and irinotecan damage the intestinal mucosa and increase intestinal permeability to iohexol. We hypothesized that CIGT is associated with alterations in fecal microbiota and metabolome. Our aim was to characterize these changes and examine how they relate to the severity of CIGT.

Methods

A total of 48 male Sprague–Dawley rats were injected intraperitoneally either with 5-fluorouracil (150 mg/kg), oxaliplatin (15 mg/kg), or irinotecan (200 mg/kg). Body weight change was measured daily after drug administration and the animals were euthanized after 72 h. Blood, urine, and fecal samples were collected at baseline and at the end of the experiment. The changes in the composition of fecal microbiota were analyzed with 16S rRNA gene sequencing. Metabolic changes in serum and urine metabolome were measured with 1 mm proton nuclear magnetic resonance (¹H-NMR).

Results

Irinotecan increased the relative abundance of Fusobacteria and Proteobacteria, while 5-FU and oxaliplatin caused only minor changes in the composition of fecal microbiota. All chemotherapeutics increased the levels of serum fatty acids and N(CH₃)₃ moieties and decreased the levels of Krebs cycle metabolites and free amino acids.

Conclusions

Chemotherapeutic drugs, 5-fluorouracil, oxaliplatin, and irinotecan, induce several microbial and metabolic changes which may play a role in the pathophysiology of CIGT. The observed changes in intestinal permeability, fecal microbiota, and metabolome suggest the activation of inflammatory processes.

Electronic supplementary material

The online version of this article (doi:10.1007/s00280-017-3364-z) contains supplementary material, which is available to authorized users.

Irinotecan-Induced Gastrointestinal Dysfunction Is Associated with Enteric Neuropathy, but Increased Numbers of Cholinergic Myenteric Neurons

Gastrointestinal dysfunction is a common side-effect of chemotherapy leading to dose reductions and treatment delays. These side-effects may persist up to 10 years post-treatment. A topoisomerase I inhibitor, irinotecan (IRI), commonly used for the treatment of colorectal cancer, is associated with severe acute and delayed-onset diarrhea. The long-term effects of IRI may be due to damage to enteric neurons innervating the gastrointestinal tract and controlling its functions. Balb/c mice received intraperitoneal injections of IRI (30 mg/kg⁻¹) 3 times a week for 14 days, sham-treated mice received sterile water (vehicle) injections. In vivo analysis of gastrointestinal transit via serial x-ray imaging, facal water content, assessment of gross morphological damage and immunohistochemical analysis of myenteric neurons were performed at 3, 7 and 14 days following the first injection and at 7 days post-treatment. Ex vivo colonic motility was analyzed at 14 days following the first injection and 7 days post-treatment. Mucosal damage and inflammation were found following both short and long-term treatment with IRI. IRI-induced neuronal loss and increases in the number and proportion of ChAT-IR neurons and the density of VAChT-IR fibers were associated with changes in colonic motility, gastrointestinal transit and fecal water content. These changes persisted in post-treatment mice. Taken together this work has demonstrated for the first time that IRI-induced inflammation, neuronal loss and altered cholinergic expression is associated with the development of IRI-induced long-term gastrointestinal dysfunction and diarrhea.

Sacituzumab govitecan: an antibody-drug conjugate

INTRODUCTION

Despite advances in the diagnosis and treatment of patients with cancer, patients with metastatic cancer have limited therapeutic options after initial lines of therapy. Understanding tumor biology has translated into the identification of actionable targets that resulted in therapeutics. Antibody-drug conjugates (ADC) are capitalizing on this explosion of scientific information. ADCs allow an antibody to a unique target to be conjugated via an innovative linker, to a highly toxic drug which is delivered to its target. Sacituzumab govitecan is an ADC that combines the active molecule in irinotecan, SN-38, to an antibody targeting trop2. Areas covered: In this review, the authors introduce the reader to the ADC sacituzumab govitecan providing the reader with details about its pharmacokinetics, pharmacodynamics, efficacy and safety. The authors also give their expert analysis about its potential future use. Expert opinion: Sacituzumab govitecan is a novel and well-tolerated therapeutic showing promising results in difficult to treat cancers. Further studies are underway to optimize the group of patients that would benefit from it. Given its excellent performance, we are cautiously optimistic it will be approved by the FDA.