Pharmacogenomic Assessment of Patients with Colorectal Cancer and Potential Treatments

Evaluation of pharmacogenomic evidence for drugs related to ADME genes in CPIC database

OBJECTIVES

Clinical Pharmacogenetics Implementation Consortium (CPIC) is a platform that advances the pharmacogenomics (PGx) practice by developing evidence-based guidelines. The purpose of this study was to analyze the CPIC database for ADME related genes and their corresponding drugs, and evidence level for drug-gene pairs; and to determine the presence of these drug-gene pairs in the highest mortality diseases in the United States.

METHODS

CPIC database was evaluated for drug-gene pairs related to absorption, distribution, metabolism, and excretion (ADME) properties. National Vital Statistics from Centers for Disease Control and Prevention was used to identify the diseases with the highest mortality. CPIC levels are assigned to different drug-gene pairs based on varying levels of evidence as either A, B, C, or D. All drug-gene pairs assigned with A/B, B/C, or C/D mixed levels were excluded from this study. A stepwise exclusion process was followed to determine the prevalence of various ADME drug-gene pairs among phase I/II enzymes or transporters and stratify the drug-gene pairs relevant to different disease conditions most commonly responsible for death in the United States.

RESULTS

From a total of 442 drug-gene pairs in the CPIC database, after exclusion of 86 drug-gene pairs with levels A/B, B/C, or C/D, and 211 non-ADME related genes, 145 ADME related drug-gene pairs resulted. From the 145 ADME related drug-genes pairs, the following were the distribution of levels: Level A: 43 (30%), Level B: 22 (15%), Level C: 59 (41%), Level D: 21 (14%). The most prevalent ADME gene with CPIC level A classification was cytochrome P450 2C9 (CYP2C9) (26%) and overall, the most prevalent ADME gene in the CPIC database was CYP2D6 (30%). The most prevalent diseases related to the CPIC evidence related drugs were cancer and depression.

CONCLUSIONS

We found that there is an abundance of ADME related genes in the CPIC database, including in the high mortality disease states of cancer and depression. There is a differential level of pharmacogenomic evidence in drug-gene pairs enlisted in CPIC where levels A and D having the greatest number of drug-gene pairs. CYP2D6 was the most common ADME gene with CPIC evidence for drug-gene pairs. Pharmacogenomic applications of CPIC evidence can be leveraged to individualize patient therapy and lower adverse effect events.

Microbiota-Host-Irinotecan Axis: A New Insight Toward Irinotecan Chemotherapy

Irinotecan (CPT11) and its active metabolite ethyl-10-hydroxy-camptothecin (SN38) are broad-spectrum cytotoxic anticancer agents. Both cause cell death in rapidly dividing cells (e.g., cancer cells, epithelial cells, hematopoietic cells) and commensal bacteria. Therefore, CPT11 can induce a series of toxic side-effects, of which the most conspicuous is gastrointestinal toxicity (nausea, vomiting, diarrhea). Studies have shown that the gut microbiota modulates the host response to chemotherapeutic drugs. Targeting the gut microbiota influences the efficacy and toxicity of CPT11 chemotherapy through three key mechanisms: microbial ecocline, catalysis of microbial enzymes, and immunoregulation. This review summarizes and explores how the gut microbiota participates in CPT11 metabolism and mediates host immune dynamics to affect the toxicity and efficacy of CPT11 chemotherapy, thus introducing a new concept that is called "microbiota-host-irinotecan axis". Also, we emphasize the utilization of bacterial β-glucuronidase-specific inhibitor, dietary interventions, probiotics and strain-engineered interventions as emergent microbiota-targeting strategies for the purpose of improving CPT11 chemotherapy efficiency and alleviating toxicity.

Dihydropyrimidine dehydrogenase (DPYD) gene c.1627A>G A/G and G/G genotypes are risk factors for lymph node metastasis and distant metastasis of colorectal cancer

BACKGROUND

Dihydropyrimidine dehydrogenase (DPD) acts as the key enzyme catabolizing pyrimidines, and may affect the tumor progression. DPYD gene mutations affect DPD activity. The relationship between DPYD IVS14+1G>A, c.1627A>G, c.85T>C and lymph node metastasis (LNM) and distant metastasis (DM) of colorectal cancer (CRC) was investigated.

METHODS

A total of 537 CRC patients were enrolled in this study. DPYD polymorphisms were analyzed by polymerase chain reaction (PCR)-Sanger sequencing. The relationship between DPYD genotypes and clinical features of patients, metastasis of CRC was analyzed.

RESULTS

About DPYD c.1627A>G, A/A (57.7%) was the most common genotype, followed by A/G (35.6%), G/G (6.7%) genotypes. In c.85T>C, T/T, T/C, and C/C genotypes are accounted for 83.6%, 16.0%, and 0.4%, respectively. Logistic regression analysis revealed that DPYD c.1627A>G A/G and G/G genotypes in the dominant model (A/G + G/G vs. A/A) were significant risk factors for the LNM (p = 0.029, OR 1.506, 95% CI = 1.048-2.165) and DM (p = 0.039, OR 1.588, 95% CI = 1.041-2.423) of CRC. In addition, DPYD c.1627A>G polymorphism was more common in patients with abnormal serum carcinoembryonic antigen (CEA) (>5 ng/ml) (p = 0.003) or carbohydrate antigen 24-2 (CA24-2) (>20 U/ml) level (p = 0.015).

CONCLUSIONS

The results suggested that DPYD c.1627A>G A/G, G/G genotypes are associated with increased risk of LNM and DM of CRC.

Pharmacogenetics: Knowledge assessment amongst Syrian pharmacists and physicians

Background

Pharmacogenetics targets genetic variations that influence drug response. It is relatively a new science that has not been vastly employed in most developing countries including Syria. Therefore we aimed at evaluating the depth of knowledge in pharmacogenetics and the attitude towards it amongst Syrian pharmacists and physicians.

Methods

We carried out an internet-based questionnaire consisted of 26 questions, sent through specialized websites and private groups with a large number of pharmacists and physicians members. The survey was available online for a period of 1 month.

Results

The total number of respondents was 154, mostly female pharmacists. Our statistical analysis showed a strong positive association between profession (in favour of pharmacists) and pharmacogenetics knowledge p = 0.049; however, no correlation with experience p = 0.811 was found. A significant difference was reported between the knowledge of pharmacists and physicians p = 0.001 concerning drugs that need pharmacogenetics testing before being prescribed. The majority of respondents had no information about applying genetic tests in Syria before prescribing medications nor did they possess the knowledge regarding drugs that show differential responses in patients according to their unique genotypes. In our study, the percentage knowledge assessment score was low in general (mean ± Standard deviation, SD) (46% ± 13.9%). The majority of the respondents agreed that pharmacists should provide counselling to patients on the subject of pharmacogenetics. Respondents’ opinions varied concerning making pharmacogenetics learning a priority.

Conclusion

Lack of pharmacogenetics knowledge was found amongst respondents in general. Our findings raise concerns about the lack of awareness amongst physicians, which may hinder the implementation of this crucial field in Syria. We suggest an emphasis on the role of education, training, and conducting genotyping research on the Syrian population.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12913-021-07040-9.

Complete Pathologic Response of Multiple Liver Metastases and Clinical Complete Response of Rectal Cancer in a Patient with Ataxia-Telangiectasia Mutated Gene Mutations After XELOXIRI Plus Bevacizumab: A Case Report

Background

Doublet or triplet chemotherapy plus or minus targeted drugs can achieve a high objective response rate (ORR) and are currently considered to be the backbone of conventional therapy for liver metastatic colorectal cancer (mCRC). However, current biomarkers (such as UGT1A1 and DPYD) are limited to the prediction of toxicity and there are no effective biomarkers to predict chemotherapy response. Therefore, personalized cancer chemotherapy underpinned by genomic alterations in mCRC has received increasing attention.

Case Presentation

We present a case of a 28-year-old female rectal cancer patient with multiple liver metastases (clinical risk score, CRS = 5 points). The patient underwent XELOXIRI plus bevacizumab regimen that consisted of irinotecan (150 mg/m2), oxaliplatin (100 mg/m2) on day 1, capecitabine (1700 mg/m2 per day from day 2 to 15), bevacizumab (7.5 mg/kg) on day 1 (on the second cycle), given every three weeks for eight cycles. After multi-disciplinary team (MDT) discussion, the patient underwent right hemihepatectomy, partial liver resection of segment IV and cholecystectomy. Surprisingly, the patient achieved a complete pathologic response (pCR) of the hepatic metastasis and clinical complete response (cCR) of the primary rectal lesion. A paired tumor molecular profile revealed somatic mutations in ataxia-telangiectasia mutated (ATM) genes that may explain why the patient achieved such a dramatic tumor response. Treatment was discontinued after eight cycles of a single oral dose of capecitabine and the patient started a follow-up program of physical and radiological examinations. To monitor the signs of recurrence, we also obtained blood samples to analyze circulating tumor DNA (ctDNA). To date, the patient has remained disease-free.

Conclusion

The XELOXIRI-bevacizumab regimen is a feasible and effective regimen for patients with mCRC. Mutations in the ATM genes may characterize a subset of patients with a better prognosis who are more sensitive to chemotherapy plus biological agents.

Intensive multidisciplinary treatment strategies and patient resilience to challenge long-term survival in metastatic colorectal cancer: a case report in real life and clinical practice

In fit metastatic colorectal cancer (MCRC), multidisciplinary treatment strategy integrating intensive FIr-B/FOx triplet chemotherapy associated to bevacizumab and secondary metastasectomies significantly improved clinical outcomes up to progression-free survival (PFS) 17 months and overall survival (OS) 44 months. A non-elderly woman affected by rectal cancer, lymph nodes involvement, synchronous unresectable liver metastases, was treated with first-line FIr-B/FOx integrated with two-stage liver resections, short course radiotherapy, anterior rectal resection, with a PFS 9 months and progression-free interval (PFI) 4 months off-treatment. After progression characterized by single liver and lymph node inferior mesenteric axis metastases, FIr-B/FOx was re-introduced, liver and lymph node resections were performed, with a PFS 8 months and PFI 3 months. FIr-B/FOx was further proposed due to bilateral lung, and liver metastases with stable disease, PFS 8 months. Patient experienced a limiting toxicity syndrome multiple sites (LTS-ms) with G3 diarrhea, G2 asthenia, nausea, requiring irinotecan reduction and 5-fluorouracil discontinuation, and subsequent oxaliplatin discontinuation, due to infusional hypersensitivity reaction. Overall, integrated first-line medical and surgical treatment strategies gained PFS 26 months. Further lines II-V of treatment obtained a combined PFS 28 months: modulated aflibercept/irinotecan, PFS 8 months; panitumumab, PFS 8 months, proposed due to KRAS/NRAS/BRAF wild-type and EGFR c.2156 G>C (p.G719A) mutation, achieving biomarkers reduction, lung, liver, lymph nodes partial responses; regorafenib, PFS 8 months; trifluridine-tipiracil, PFS 4 months and induced an LTS-ms, with febrile G4 leucopenia, G3 neutropenia, thrombocytopenia, asthenia, G2 anemia, diarrhea, hypotension. After 2 months of palliative care, patient died, at OS 58 months, gained by intensive medical/surgical treatments coupled with patient's resilience. To date, selection of tailored medical treatments, according to clinical (age, performance and comorbidity status) and molecular (RAS/BRAF and pharmacogenomic analyses) evaluations, careful monitoring of individual toxicity syndromes, potential integration of metastasectomies, and furthermore individual resilience as patient life priority need to challenge MCRC long-term survival.