Value of plasma SN-38 levels and DPD activity in irinotecan-based individualized chemotherapy for advanced colorectal cancer with heterozygous type UGT1A1*6 or UGT1A1*28

UGT1A1 genotype-guided irinotecan dosing during neoadjuvant chemoradiotherapy for locally advanced rectal cancer: A prospective analysis of SN-38 concentration

Irinotecan plays a crucial role in the neoadjuvant chemoradiotherapy (nCRT) of rectal cancer, but its optimal dosing is still unclear. In this study, we included 101 eligible patients with the UGT1A1*28 genotype of UGT1A1*1*1 (74.3%) and UGT1A1*1*28 (25.7%) and UGT1A1*6 genotypes of GG (63.4%), GA (32.7%), and AA (3.9%). All patients received preoperative radiotherapy (50 Gy/25 fractions) with concurrent irinotecan (UGT1A1*1*1: 80 mg/m2 ; UGT1A1*1*28: 65 mg/m2 ) and capecitabine (CapIri). SN-38 concentrations were measured at 1.5, 24, and 49 h post-administration. Patients were divided into four groups (Q1-Q4) based on the SN-38 concentration. The complete-response (CR) rate was the primary endpoint. The analysis demonstrated that the 49 h SN-38 concentration was relatively optimal for predicting efficacy and toxicity. The Q4 group had a significantly higher CR rate than the Q1 group (p = .019), but also higher rates of adverse events (p = .009). We screened the recommended 49 h SN-38, with a 0.5-1.0 ng/mL concentration range. We also validated the correlation between UGT1A1*6 polymorphism and SN-38 concentration, along with the clinical efficacy of irinotecan. In conclusion, our study identified the relatively optimal timepoint and concentration range for monitoring SN38 concentrations and revealed the clinical significance of UGT1A1*6 and UGT1A1*28 polymorphisms in guiding irinotecan administration, offering meaningful insights for personalised irinotecan dosing.

Bilirubin metabolism and UDP-glucuronosyltransferase 1A1 variants in Asians: Pathogenic implications and therapeutic response

In the Asian general population, at least six single-nucleotide variants (SNVs) in the UDP-glucuronosyltransferase (UGT) 1A1 gene have been identified: -3279T>G, -53A(TA)₆ TAA>A(TA)₇ TAA, 211G>A, 686C>A, 1091C>T, and 1456T>G. Each of these six SNVs was observed in at least four ethnic groups of the 12 Asian populations studied. In East Asian populations, the descending frequency of these six SNVs was as follows: -3279G>[-53A(TA)₇ TAA, 211A]>(686A, 1091T)>1456G. Because of the presence of linkage disequilibrium and the expulsion phenomenon, when the SNVs -3279G, -53A(TA)₇ TAA, 211A, and 686A were simultaneously involved, 15 instead of the estimated 81 genotypes were observed. Those carrying 686AA or 1456GG developed Gilbert's syndrome or Crigler-Najjar syndrome type 2. Both -53A(TA)₇ TAA/A(TA)₇ TAA and 211AA are the main causes of Gilbert's syndrome in East Asian populations. In East Asian populations, the 211AA genotype is the main cause of neonatal hyperbilirubinemia, whereas -53A(TA)₇ TAA/A(TA)₇ TAA exerts a protective effect on hyperbilirubinemia development in neonates fed with breast milk. Both 211A and -53A(TA)₇ TAA are significantly associated with adverse drug reactions induced by irinotecan (one of the most widely used anticancer agents) in Asians. However, at least three common SNVs (-3279G, -53A(TA)₇ TAA, and 211A) should be comprehensively analyzed. This study investigated the clinical significance of these six SNVs and demonstrated that examining UGT1A1 variants in Asian populations is considerably challenging.

Characteristics and Clinical Implication of UGT1A1 Heterozygous Mutation in Tumor

BACKGROUND

The literature recommends that reduced dosage of CPT-11 should be applied in patients with UGT1A1 homozygous mutations, but the impact of UGT1A1 heterozygous mutations on the adverse reactions of CPT-11 is still not fully clear.

METHODS

A total of 107 patients with UGT1A1 heterozygous mutation or wild-type, who were treated with CPT-11 from January 2018 to September 2021 in Peking University Third Hospital, were retrospectively enrolled. The adverse reaction spectra of patients with UGT1A1*6 and UGT1A1*28 mutations were analyzed. Adverse reactions were evaluated according to National Cancer Institute Common Terminology Criteria for Adverse Events (NCI-CTCAE) 5.0. The efficacy was evaluated according to Response Evaluation Criteria in Solid Tumors (RECIST) 1.1. The genotypes of UGT1A1*6 and UGT1A1*28 were detected by digital fluorescence molecular hybridization.

RESULTS

There were 43 patients with UGT1A1*6 heterozygous mutation, 26 patients with UGT1A1*28 heterozygous mutation, 8 patients with UGT1A1*6 and UGT1A1*28 double heterozygous mutations, 61 patients with heterozygous mutation at any gene locus of UGT1A1*6 and UGT1A1*28. Logistic regression analysis showed that the presence or absence of vomiting (P=0.013) and mucositis (P=0.005) was significantly correlated with heterozygous mutation of UGT1A1*28, and the severity of vomiting (P<0.001) and neutropenia (P=0.021) were significantly correlated with heterozygous mutation of UGT1A1*6. In colorectal cancer, UGT1A1*6 was significantly correlated to diarrhea (P=0.005), and the other adverse reactions spectrum was similar to that of the whole patient cohort, and efficacy and prognosis were similar between patients with different genotypes and patients treated with reduced CPT-11 dosage or not.

CONCLUSIONS

In clinical use, heterozygous mutations of UGT1A1*6 and UGT1A1*28 are related to the risk and severity of vomiting, diarrhea, neutropenia and mucositis in patients with Pan-tumor and colorectal cancer post CPT-11 therpy. In colorectal cancer, UGT1A1*6 is significantly related to diarrhea post CPT-11 use, efficacy and prognosis is not affected by various genotypes or CPT-11 dosage reduction.

Ultra-performance liquid chromatography-tandem mass spectrometry for simultaneous determination of 12 anti-tumor drugs in human plasma and its application in therapeutic drug monitoring

The effectiveness and safety of anti-tumor drugs are clinically important issues, and their therapeutic drug monitoring (TDM) is recommended. This study aimed to develop an ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method for simultaneous TDM and exploration of clinical pharmacokinetics of anti-tumor drugs, including cyclophosphamide, ifosfamide, cisplatin, methotrexate, pemetrexed disodium, capecitabine, 5-fluorouracil, gemcitabine, doxorubicin, fulvestrant, tamoxifen, and irinotecan. After magnetic solid-phase extraction of plasma samples, the isotope internal standards and 12 anti-tumor drugs were separated using a ZORBAX Eclipse Plus C18 column (50.0 × 2.1 mm, 1.7 µm) with water containing 0.1% formic acid and acetonitrile as the mobile phase in a total run time of 5.0 min. The developed UPLC-MS/MS method was validated based on the Chinese Pharmacopoeia and the US Food and Drug Administration guidelines for bioanalytical method validation, including assessment of specificity, calibration curves, carryover, accuracy, crosstalk, precision, stability, recovery, dilution integrity, incurred sample reanalysis, and matrix effect. The results showed that a simple, fast, reliable, and specific UPLC-MS/MS method was developed and validated, and all the performance characteristics of the method met the requirements. The response function was established for concentration range of 0.10-25.00 μg/mL for gemcitabine, cyclophosphamide, ifosfamide, methotrexate, pemetrexed disodium, capecitabine, 5-fluorouracil, and cisplatin, and 0.05-12.50 μg/mL for doxorubicin, fulvestrant, tamoxifen, and irinotecan, with a coefficient of correlation of>0.9984 for all the compounds. The precision and accuracy of all the analytes were<6.5% and 5.9%, respectively. Hence, it could be used for TDM and exploration of pharmacokinetics of the aforementioned 12 anti-tumor drugs.

A Molecular-Splicing Strategy for Constructing a Near-Infrared Fluorescent Probe for UDP-Glucuronosyltransferase 1A1

UDP-glucuronosyltransferase 1A1 (UGT1A1) is a vital metabolic enzyme responsible for the clearance of endogenous substances and drugs. Hitherto, the development of fluorescent probes for UGTs was severely restricted due to the poor isoform selectivity and on-off or blue-shifted fluorescence response. Herein, we established a novel "molecular-splicing" strategy to construct a highly selective near-infrared (NIR) fluorescent probe, HHC, for UGT1A1, which exhibited a NIR signal at 720 nm after UGT1A1 metabolism. HHC was then successfully used for the real-time imaging of endogenous UGT1A1 in living cells and animals and to monitor the bile excretion function. In summary, an isoform-specific NIR fluorescent probe has been developed for monitoring UGT1A1 activity in living systems, high-throughput screening of novel UGT1A1 inhibitors and visual evaluation of bile excretion function.