Molecular Genetics External Quality Assessment Pilot Scheme for Irinotecan-Related UGT1A1 Genotyping in China

The Correlation Between UGT1A1 Gene Phenotypes and the Clinical Prognosis of Advanced Colorectal Cancer After FOLFIRI Therapy

Objective: This study aimed to investigate the correlations between the different phenotypes of the uridine diphosphate glucuronyl transferase (UGT) 1A1 gene and the treatment of advanced colorectal cancer with the FOLFIRI regimen. Materials and Methods: A total of 240 advanced colorectal cancer patients with stage IV colon cancer or recurrence after radical surgery between January 2014 and December 2018 were included in a retrospective study. All participants were treated with the FOLFIRI regimen until the disease progressed or an intolerable level of toxicity occurred. Results: In this study, three phenotypes of the UGT1A1 gene promoter were found: the homozygous wild type (TA6/6 type, 78.3%), the heterozygous mutant type (TA6/7 type, 19.6%), and the homozygous mutant type (TA7/7 type, 2.1%). Compared with TA6/7 and TA6/6, the risk of nonresponse to FOLFIRI chemotherapy increased by 16%, but the difference was not significant. The risk of death increased by 24%, and there was no significant difference. There was a risk of hematologic and nonhematologic adverse reactions occurring in TA6/7 and TA6/6, and the total risk of adverse reactions increased by 9.3773 times among patients with more than two metastatic organs. Compared with patients with TA6/6, the risk of toxic side-effects increased by 42.8066 times (p = 0.0259) for patients with TA6/7. Among patients who received FOLFIRI chemotherapy for more than four cycles, the proportion with TA6/7 was greater than that with TA6/6. Compared with those with TA6/6, patients with TA6/7 showed a higher risk of hematologic toxicity (22.3246 times, p = 0.0035). Conclusion: The TA6/7 in patients with advanced colorectal cancer had more than two metastatic organs, and received FOLFIRI chemotherapy for more than four cycles compared with TA6/6 patients. Furthermore, the risk of hematologic and nonhematologic adverse reactions significantly increased, and the risk of digestive-tract and hematologic toxicity was more significant.

Quality control materials for pharmacogenomic testing in the clinic

Pharmacogenomics has significantly added to our understanding of drug responses in clinical pharmacology, changing the paradigm of treatment decisions. Interrogations of both inherited and somatic variations for therapeutic purposes are increasingly being adopted in clinics, where quality control (QC) materials are required. However, for many pharmacogenomic tests, the acquisition of well-characterized QC materials is often difficult or impossible. In this review, several sources of appropriate QC materials for therapy-associated genetic testing are discussed. Among them, the novel methods for producing renewable controls that resemble patient samples are highlighted. Owing to technological complexity, more efforts are needed to develop proper controls for next-generation sequencing-based assay.

National Prociency Testing Result of CYP2D6*10 Genotyping for Adjuvant Tamoxifen Therapy in China

Tamoxifen has been successfully used for treating breast cancer and preventing cancer recurrence. Cytochrome P450 2D6 (CYP2D6) plays a key role in the process of metabolizing tamoxifen to its active moiety, endoxifen. Patients with variants of the CYP2D6 gene may not receive the full benefit of tamoxifen treatment. The CYP2D6*10 variant (the most common variant in Asians) was analyzed to optimize the prescription of tamoxifen in China. To ensure referring clinicians have accurate information for genotype-guided tamoxifen treatment, the Chinese National Center for Clinical Laboratories (NCCL) organized a national proficiency testing (PT) to evaluate the performance of laboratories providing CYP2D6*10 genotyping. Ten genomic DNA samples with CYP2D6 wild-type or CYP2D6*10 variants were validated by PCR-sequencing and sent to 28 participant laboratories. The genotyping results and pharmacogenomic test reports were submitted and evaluated by NCCL experts. Additional information regarding the number of samples tested, the accreditation/certification status, and detecting technology was also requested. Thirty-one data sets were received, with a corresponding analytical sensitivity of 98.2% (548/558 challenges; 95% confidence interval: 96.7–99.1%) and an analytic specificity of 96.5% (675/682; 95% confidence interval: 97.9–99.5%). Overall, 25/28 participants correctly identified CYP2D6*10 status in 10 samples; however, two laboratories made serious genotyping errors. Most of the essential information was included in the 20 submitted CYP2D6*10 test reports. The majority of Chinese laboratories are reliable for detecting the CYP2D6*10 variant; however, several issues revealed in this study underline the importance of PT schemes in continued external assessment and provision of guidelines.