Genetic markers for toxicity of adjuvant oxaliplatin and fluoropyrimidines in the phase III TOSCA trial in high-risk colon cancer patients. Sci Rep. 2014;4:6828. [PMID: 25370899 PMCID: PMC4220280 DOI: 10.1038/srep06828]

Genetic polymorphisms and platinum-induced hematological toxicity: a systematic review

Background

Platinum-based chemotherapy bring severe hematological toxicity that can lead to dose reduction or discontinuation of therapy. Genetic variations have been reported to influence the risk and extent of hematological toxicity; however, the results are controversial and a comprehensive overview is lacking. This systematic review aimed to identify genetic biomarkers of platinum-induced hematological toxicity.

Method

Pubmed, Embase and Web of science database were systematically reviewed for studies that evaluated the association of genetic variants and platinum-related hematological toxicity in tumor patients with no prior history of chemotherapy or radiation, published from inception to the 28th of January 2022. The studies should have specific toxicity scoring system as well as defined toxicity end-point. The quality of reporting was assessed using the Strengthening the Reporting of Genetic Association Studies (STREGA) checklist. Results were summarized using narrative synthesis.

Results

83 studies were eligible with over 682 single-nucleotide polymorphisms across 110 genes. The results are inconsistent and diverse with methodological issues including insufficient sample size, population stratification, various treatment schedule and toxicity end-point, and inappropriate statistics. 11 SNPs from 10 genes (ABCB1 rs1128503, GSTP1 rs1695, GSTM1 gene deletion, ERCC1 rs11615, ERCC1 rs3212986, ERCC2 rs238406, XPC rs2228001, XPCC1 rs25487, MTHFR rs1801133, MDM2 rs2279744, TP53 rs1042522) had consistent results in more than two independent populations. Among them, GSTP1 rs1695, ERCC1 rs11615, ERCC1 rs3212986, and XRCC1 rs25487 present the most promising results.

Conclusion

Even though the results are inconsistent and several methodological concerns exist, this systematic review identified several genetic variations that deserve validation in well-defined studies with larger sample size and robust methodology.

Systematic Review Registration

https://www.crd.york.ac.uk/, identifier CRD42021234164.

An SNP Marker Predicts Colorectal Cancer Outcomes with 5-Fluorouracil-Based Adjuvant Chemotherapy Post-Resection

Colorectal cancer (CRC) is a global health concern, necessitating adjuvant chemotherapy post-curative surgery to mitigate recurrence and enhance survival, particularly in intermediate-stage patients. However, existing therapeutic disparities highlight the need for biomarker-guided adjuvant chemotherapy to achieve better CRC inhibition. This study explores the molecular mechanisms underlying the inhibition of CRC through a genome-wide association study (GWAS) focused on 5-fluorouracil (5-FU)-based adjuvant therapy in intermediate-stage CRC patients, a domain previously unexplored. We retrospectively included 226 intermediate-stage CRC patients undergoing surgical resection followed by 5-FU-based adjuvant chemotherapy. The exploration cohort comprised 31 patients, and the validation cohort included 195 individuals. Genotyping was carried out using either Axiom Genome-Wide TWB 2.0 Array Plate-based or polymerase chain reaction-based methods on genomic DNA derived from collected tissue samples. Statistical analyses involved descriptive statistics, Kaplan-Meier analyses, and Cox proportional hazard analyses. From the GWAS, potential genetic predictors, GALNT14-rs62139523 and DNMBP-rs10786578 genotypes, of 5-FU-based adjuvant therapy following surgery in intermediate-stage CRC patients were identified. Validation in a larger cohort of 195 patients emphasized the predictive significance of GALNT14-rs62139523 genotypes, especially the "A/G" genotype, for improved overall and progression-free survival. This predictive association remained robust across various subgroups, with exceptions for specific demographic and clinical parameters such as age < 58 years old, CEA ≤ 2.5 ng/mL, tumor diameter > 44.0 mm, and tumor-free margin ≥ 50 mm. This study identifies that the GALNT14-rs62139523 "A/G" genotype modulates therapeutic outcomes, establishing it as a promising biomarker for predicting favorable responses to 5-FU-based adjuvant chemotherapy in intermediate-stage CRC patients, although further investigations are needed to detail these mechanisms.

A systematic review and meta-analysis of the impacts of germline pharmacogenomics on severe toxicity and symptom burden in adult patients with cancer

The clinical application of Pharmacogenomics (PGx) has improved patient safety. However, comprehensive PGx testing has not been widely adopted in clinical practice, and significant opportunities exist to further optimize PGx in cancer care. This systematic review and meta-analysis aim to evaluate the safety outcomes of reported PGx-guided strategies (Analysis 1) and identify well-studied emerging pharmacogenomic variants that predict severe toxicity and symptom burden (Analysis 2) in patients with cancer. We searched MEDLINE, EMBASE, CENTRAL, clinicaltrials.gov, and International Clinical Trials Registry Platform from inception to January 2023 for clinical trials or comparative studies evaluating PGx strategies or unconfirmed pharmacogenomic variants. The primary outcomes were severe adverse events (SAE; ≥ grade 3) or symptom burden with pain and vomiting as defined by trial protocols and assessed by trial investigators. We calculated pooled overall relative risk (RR) and 95% confidence interval (95%CI) using random effects models. PROSPERO, registration number CRD42023421277. Of 6811 records screened, six studies were included for Analysis 1, 55 studies for Analysis 2. Meta-analysis 1 (five trials, 1892 participants) showed a lower absolute incidence of SAEs with PGx-guided strategies compared to usual therapy, 16.1% versus 34.0% (RR = 0.72, 95%CI 0.57-0.91, p = 0.006, I2 = 34%). Meta-analyses 2 identified nine medicine(class)-variant pairs of interest across the TYMS, ABCB1, UGT1A1, HLA-DRB1, and OPRM1 genes. Application of PGx significantly reduced rates of SAEs in patients with cancer. Emergent medicine-variant pairs herald further research into the expansion and optimization of PGx to improve systemic anti-cancer and supportive care medicine safety and efficacy.

Management of Side Effects in the Personalized Medicine Era: Chemotherapy-Induced Peripheral Neurotoxicity

Pharmacogenomics is a powerful tool to predict individual response to treatment, in order to personalize therapy, and it has been explored extensively in oncology practice. Not only efficacy on the malignant disease has been investigated but also the possibility to predict adverse effects due to drug administration. Chemotherapy-induced peripheral neurotoxicity (CIPN) is one of those. This potentially severe and long-lasting/permanent side effect of commonly administered anticancer drugs can severely impair quality of life (QoL) in a large cohort of long survival patients. So far, a pharmacogenomics-based approach in CIPN regard has been quite delusive, making a methodological improvement warranted in this field of interest: even the most refined genetic analysis cannot be effective if not applied correctly. Here we try to devise why it is so, suggesting how THE "bench-side" (pharmacogenomics) might benefit from and should cooperate with THE "bed-side" (clinimetrics), in order to make genetic profiling effective if applied to CIPN.

Predictive Biomarkers of Oxaliplatin-Induced Peripheral Neurotoxicity

Oxaliplatin (OXA) is a platinum compound primarily used in the treatment of gastrointestinal cancer. OXA-induced peripheral neurotoxicity (OXAIPN) is the major non-hematological dose-limiting toxicity of OXA-based chemotherapy and includes acute transient neurotoxic effects that appear soon after OXA infusion, and chronic non-length dependent sensory neuronopathy symmetrically affecting both upper and lower limbs in a stocking-and-glove distribution. No effective strategy has been established to reverse or treat OXAIPN. Thus, it is necessary to early predict the occurrence of OXAIPN during treatment and possibly modify the OXA-based regimen in patients at high risk as an early diagnosis and intervention may slow down neuropathy progression. However, identifying which patients are more likely to develop OXAIPN is clinically challenging. Several objective and measurable early biomarkers for OXAIPN prediction have been described in recent years, becoming useful for informing clinical decisions about treatment. The purpose of this review is to critically review data on currently available or promising predictors of OXAIPN. Neurological monitoring, according to predictive factors for increased risk of OXAIPN, would allow clinicians to personalize treatment, by monitoring at-risk patients more closely and guide clinicians towards better counseling of patients about neurotoxicity effects of OXA.

Pharmacogenomic-Guided Therapy in Colorectal Cancer

Approximately 20 drugs have been shown to be effective for the treatment of colorectal cancer (CRC). These drugs are from several classes of agents and include cytotoxic drugs, therapeutics that target cell signaling pathways at the extracellular and/or intracellular levels, and combination therapies that contain multiple targeted agents and/or cytotoxic compounds. Targeted therapeutics can include monoclonal antibodies, fusion proteins, and small molecule drugs. The first introduced into clinical use was 5-fluorouracil in the early 1960s and remains the foundation for most CRC treatments in both adjuvant therapy and in advanced (metastatic) treatment regimens. As with other cancers, the consideration of biomarkers has the potential to improve CRC therapy through patient stratification. The biomarkers can include germline genetic markers, tumor-specific genetic markers, immune markers, and other biomarkers that can predict antitumor efficacy or the likelihood of toxicity prior to administration of a specific drug. Consistent with the benefit of considering biomarkers in treatment, many newer targeted therapies are developed and approved simultaneously with a companion diagnostic test to determine efficacy. This review will focus on biomarkers that have demonstrated clinical utility in CRC treatment; however, it is noted that many additional biomarkers have been theorized to contribute to drug response and/or toxicity based on known biological pathways but thus far have not attained widespread use in the clinic. The importance of pretreatment biomarker testing is expected to increase as future drug development will likely continue to focus on the concurrent development of companion diagnostics.

Oxaliplatin-Induced Neuropathy: Genetic and Epigenetic Profile to Better Understand How to Ameliorate This Side Effect

In the most recent decades, oxaliplatin has been used as a chemotherapeutic agent for colorectal cancer and other malignancies as well. Oxaliplatin interferes with tumor growth predominantly exerting its action in DNA synthesis inhibition by the formation of DNA-platinum adducts that, in turn, leads to cancer cell death. On the other hand, unfortunately, this interaction leads to a plethora of systemic side effects, including those affecting the peripheral and central nervous system. Oxaliplatin therapy has been associated with acute and chronic neuropathic pain that induces physicians to reduce the dose of medication or discontinue treatment. Recently, the capability of oxaliplatin to alter the genetic and epigenetic profiles of the nervous cells has been documented, and the understanding of gene expression and transcriptional changes may help to find new putative treatments for neuropathy. The present article is aimed to review the effects of oxaliplatin on genetic and epigenetic mechanisms to better understand how to ameliorate neuropathic pain in order to enhance the anti-cancer potential and improve patients’ quality of life.

The Road so Far in Colorectal Cancer Pharmacogenomics: Are We Closer to Individualised Treatment?

In recent decades, survival rates in colorectal cancer have improved greatly due to pharmacological treatment. However, many patients end up developing adverse drug reactions that can be severe or even life threatening, and that affect their quality of life. These remain a limitation, as they may force dose reduction or treatment discontinuation, diminishing treatment efficacy. From candidate gene approaches to genome-wide analysis, pharmacogenomic knowledge has advanced greatly, yet there is still huge and unexploited potential in the use of novel technologies such as next-generation sequencing strategies. This review summarises the road of colorectal cancer pharmacogenomics so far, presents considerations and directions to be taken for further works and discusses the path towards implementation into clinical practice.

Pharmacogenomic Assessment of Patients with Colorectal Cancer and Potential Treatments

Evolving intensiveness of colorectal cancer (CRC) treatment, including chemotherapeutics and targeted agents associations, in adjuvant and metastatic CRC (MCRC) settings, increased overall survival (OS) with individual variability of toxicity. Pharmacogenomic guidelines recommended pre-treatment identification of at-risk patients suggesting dose adjustment of fluoropyrimidines based on dihydropyrimidine dehydrogenase (DPYD), and irinotecan on UDP glucuronosyl-transferase 1 family polypeptide A1 (UGT1A1) genetic variants, but they are poorly applied in clinical practice. This review highlighted clinically validated pharmacogenetic markers, to underline the need of their implementation in the multidisciplinary molecular board for individual CRC patients in clinical practice. Five clinically relevant DPYD variants with different prevalence impair enzymatic effectiveness and significantly increase toxicity: c.1236 G>A (c.1129–5923 C>G, HapB3), 4.1–4.8%; c.1679 T>G (DPYD*13), c.1905+1G>A (DPYD*2A), c.2846 A>T, c.2194 A>T (DPYD*6) 1% each. c.1679T>G and c.1905+1G>A are most deleterious on DPD effectiveness, moderately reduced in c.1236/HapB3 and c.2846A>T. Cumulatively, these variants explain approximately half of the estimated 10–15% fluoropyrimidine-related gastrointestinal and hematological toxicities due to DPD. Prevalent UGT1A1 gene [TA]₇TAA promoter allelic variant UGT1A1*28, characterized by an extra TA repeat, is associated with low transcriptional and reduced enzymatic effectiveness, decreased SN38 active irinotecan metabolite glucuronidation, vs wild-type UGT1A1*1 [A(TA)6TAA]. Homozygote UGT1A1*28 alleles patients are exposed to higher hematological and gastrointestinal toxicities, even more than heterozygote, at >150 mg/m² dose. Dose reduction is recommended for homozygote variant. Wild-type UGT1A1*28 alleles patients could tolerate increased doses, potentially affecting favorable outcomes. Implementation of up-front evaluation of the five validated DPYD variants and UGT1A1*28 in the multidisciplinary molecular tumor board, also including CRC genetic characterization, addresses potential treatments with fluoropyrimidines and irinotecan associations at proper doses and schedules, particularly for early CRC, MCRC patients fit for intensive regimens or unfit for conventional regimens, requiring treatment modulations, and also for patients who experience severe, unexpected toxicities. Integration of individual evaluation of toxicity syndromes (TS), specifically limiting TS (LTS), an innovative indicator of toxicity burden in individual patients, may be useful to better evaluate relationships between pharmacogenomic analyses with safety profiles and clinical outcomes.

Biomarkers in Colorectal Cancer: Current Research and Future Prospects

Colorectal cancer (CRC) is a leading cause of death worldwide, despite progress made in detection and management through surgery, chemotherapy, radiotherapy, and immunotherapy. Novel therapeutic agents have improved survival in both the adjuvant and advanced disease settings, albeit with an increased risk of toxicity and cost. However, metastatic disease continues to have a poor long-term prognosis and significant challenges remain due to late stage diagnosis and treatment failure. Biomarkers are a key tool in early detection, prognostication, survival, and predicting treatment response. The past three decades have seen advances in genomics and molecular pathology of cancer biomarkers, allowing for greater individualization of therapy with a positive impact on survival outcomes. Clinically useful predictive biomarkers aid clinical decision making, such as the presence of KRAS gene mutations predicting benefit from epidermal growth factor receptor (EGFR) inhibiting antibodies. However, few biomarkers have been translated into clinical practice highlighting the need for further investigation. We review a range of protein, DNA and RNA-based biomarkers under investigation for diagnostic, predictive, and prognostic properties for CRC. In particular, long non-coding RNAs (lncRNA), have been investigated as biomarkers in a range of cancers including colorectal cancer. Specifically, we evaluate the potential role of lncRNA plasmacytoma variant translocation 1 (PVT1), an oncogene, as a diagnostic, prognostic, and therapeutic biomarker in colorectal cancer.

Efficacy and toxicity of adjuvant chemotherapy on colorectal cancer patients: how much influence from the genetics?

We studied the predictive value for response and toxicity of functional polymorphisms in genes involved in the oxaliplatin/fluorouracil pathway in colorectal cancer patients. One hundred and twenty-seven (127) patients were treated with curative intended surgery followed by adjuvant chemotherapy with FOLFOX (fluorouracil, leucovorin and oxaliplatin) regimen. The median age was 65.53 (27-80) years (66.9% male, 59.1% rectum). The median follow-up was 8.5 years (IQR, 4.1-9.4). At the end of follow-up, 59 patients (46.5%) had relapsed or died in the whole study population. We did find that XRCC1GG genotype is associated with a higher risk of developing haematologic toxicity. Furthermore, we report a significant association of the TS 3'UTR 6 bp/6 bp polymorphism and the XRCC1 rs25487 with a higher risk of developing anaemia and diarrhoea, respectively. On the other hand, none of the studied polymorphisms showed clinically relevant association with disease-free survival and overall survival or early failure to adjuvant FOLFOX therapy.

Association of DNA repair gene variants with colorectal cancer: risk, toxicity, and survival

Background

Single nucleotide polymorphisms (SNPs) in DNA repair genes have a potential clinical value in predicting treatment outcomes. In the current study, we examined the association of SNPs in the genes XRCC1-rs25487, ERCC1-rs11615, ERCC2-rs238406, and ERCC2-rs13181 with colorectal cancer (CRC) risk, relapse-free survival (RFS), overall survival (OS), and toxicity during chemotherapy.

Methods

SNPs were analysed in 590 CRC cases and 300 controls using TaqMan technology. The association of SNPs with CRC risk and toxicity during chemotherapy was analysed using Chi2 test. The Kaplan–Meier method and log-rank test was used to measure the effects of the SNPs on RFS and OS.

Results

The CC genotype of ERCC2-rs238406 and the ERCC2-rs13181 C allele were associated with a significantly increased risk of CRC. The ERCC1-rs11615 genotype T/T was associated with stomatitis in adjuvant chemotherapy (p = 0.03). Also, more patients with the ERCC2-rs13181 C allele needed dose reduction compared to patients with the A/A genotype (p = 0.02). In first line chemotherapy, more patients with the ERCC1-rs11615 C allele suffered from nausea compared to those with the T/T genotype (p = 0.04) and eye reactions and thrombocytopenia were more common in patients with the ERCC2-rs13181 C allele compared to the A/A genotype (p = 0.006 and p = 0.004, respectively). ERCC2- rs238406 C/C was also associated with a higher frequency of thrombocytopenia (p = 0.03). A shorter 5-year OS was detected in stage I & II CRC patients with the ERCC2- rs238406 C allele (p = 0.02). However, there was no significant association between the SNPs and 5-year RFS.

Conclusions

Both SNPs in ERCC2 were associated with risk of CRC as well as toxicity during first line treatment. In addition, ERCC2- rs238406 was linked to OS in early stage CRC. The ERCC1-rs11615 variant was associated with toxicity during adjuvant chemotherapy. The results add support to previous findings that SNPs in ERCC1 and ERCC2 have a prognostic and predictive value in clinical management of CRC.

Long-term efficacy of capecitabine plus oxaliplatin chemotherapy on stage III colon cancer: A meta-analysis

BACKGROUND

Many clinical studies for the long-term survival or efficacy of capecitabine plus oxaliplatin (XELOX) in colon cancer have already been studied, but its clinical benefit is controversial.

AIM

To evaluate the long-term efficacy of XELOX regimen in comparison with other adjuvant chemotherapy protocols in colon cancer.

METHODS

By searching the PubMed, EMBASE and Cochrane databases, a total of 12 randomized controlled trials involving 6698 stage III colon cancer cases (XELOX protocol: n = 3298 cases; other adjuvant chemotherapy protocol: n = 3268 cases) were included. The parameter outcomes included the overall survival and the disease-free survival. The quality control of selected literature was based on the Jadad scale and the GRADE system.

RESULTS

In comparison to other adjuvant chemotherapy regimen, XELOX regimen showed a better overall survival (odds ratio = 1.29, 95% confidence interval: 1.15-1.44, P < 0.0001) and a better disease-free survival (odds ratio = 1.32, 95% confidence interval: 1.18-1.46, P < 0.0001) for colon cancer patients, suggesting the XELOX regimen can be a good option for postoperative treatment of stage III colon cancer.

CONCLUSION

The XELOX regimen can be a preferred option for adjuvant treatment of stage III colon cancer after surgery.

Sex-Related Differences in Impact on Safety of Pharmacogenetic Profile for Colon Cancer Patients Treated with FOLFOX-4 or XELOX Adjuvant Chemotherapy

Polymorphisms contribute to inter-individual differences and show a promising predictive role for chemotherapy-related toxicity in colon cancer (CC). TOSCA is a multicentre, randomized, non-inferiority, phase III study conducted in high-risk stage II/stage III CC patients treated with 6 vs 3 months of FOLFOX-4 or XELOX adjuvant chemotherapy. During this post-hoc analysis, 218 women and 294 men were genotyped for 17 polymorphisms: TYMS (rs34743033, rs2853542, rs11280056), MTHFR (rs1801133, rs1801131), ERCC1 (rs11615), XRCC1 (rs25487), XRCC3 (rs861539), XPD (rs1799793, rs13181), GSTP1 (rs1695), GSTT1/GSTM1 (deletion +/−), ABCC1 (rs2074087), and ABCC2 (rs3740066, rs1885301, rs4148386). The aim was to assess the interaction between these polymorphisms and sex, on safety in terms of time to grade ≥3 haematological (TTH), grade ≥3 gastrointestinal (TTG) and grade ≥2 neurological (TTN) toxicity. Interactions were detected on TTH for rs1801133 and rs1799793, on TTG for rs13181 and on TTN for rs11615. Rs1799793 GA genotype (p = 0.006) and A allele (p = 0.009) shortened TTH in men. In women, the rs11615 CC genotype worsened TTN (co-dominant model p = 0.008, recessive model p = 0.003) and rs13181 G allele improved the TTG (p = 0.039). Differences between the two sexes in genotype distribution of rs1885301 (p = 0.020) and rs4148386 (p = 0.005) were found. We highlight that polymorphisms could be sex-specific biomarkers. These results, however, need to be confirmed in additional series.

Is a pharmacogenomic panel useful to estimate the risk of oxaliplatin-related neurotoxicity in colorectal cancer patients?

Oxaliplatin-induced peripheral neurotoxicity (OXPN) is a dose-limiting toxicity in colorectal cancer (CRC) patients. Single nucleotide polymorphisms (SNPs) in genes involved in drug transport may lead to higher intracellular oxaliplatin accumulation in the dorsal root ganglia and thus increased risk of OXPN. In this study, a panel of 5 SNPs, namely ABCC2 (-24C > T/rs717620 and c.4544 G > A/rs8187710), ABCG2 (c.421 C > A/rs2231142), ABCB1 (c.3435 C > T/rs1045642) and SLC31A1 (c.-36 + 2451 T > G/rs10981694), was evaluated to assess their association with grade 2-3 OXPN in metastatic CRC patients. SNPs were considered according to a dominant model (heterozygous + homozygous). Germline DNA was available from 120 patients who received oxaliplatin between 2010 and 2016. An external cohort of 80 patients was used to validate our results. At the univariable logistic analyses, there were no significant associations between SNPs and incidence of OXPN. Taking into account the strength of observed association between OXPN and the SNPs, a clinical risk score was developed as linear predictor from a multivariable logistic model including all the SNPs together. This score was significantly associated with grade 2-3 OXPN (p = 0.036), but the external calibration was not satisfactory due to relevant discrepancies between the two series. Our data suggest that the concomitant evaluation of multiple SNPs in oxaliplatin transporters is an exploratory strategy that may deserve further investigation for treatment customization in CRC patients.

Colorectal Cancer Biomarkers in the Era of Personalized Medicine

The 5-year survival probability for patients with metastatic colorectal cancer has not drastically changed over the last several years, nor has the backbone chemotherapy in first-line disease. Nevertheless, newer targeted therapies and immunotherapies have been approved primarily in the refractory setting, which appears to benefit a small proportion of patients. Until recently, rat sarcoma (RAS) mutations remained the only genomic biomarker to assist with therapy selection in metastatic colorectal cancer. Next generation sequencing has unveiled many more potentially powerful predictive genomic markers of therapy response. Importantly, there are also clinical and physiologic predictive or prognostic biomarkers, such as tumor sidedness. Variations in germline pharmacogenomic biomarkers have demonstrated usefulness in determining response or risk of toxicity, which can be critical in defining dose intensity. This review outlines such biomarkers and summarizes their clinical implications on the treatment of colorectal cancer. It is critical that clinicians understand which biomarkers are clinically validated for use in practice and how to act on such test results.

Predictive biomarkers of chemotherapy-induced peripheral neuropathy: a review

Chemotherapy-induced peripheral neuropathy (CIPN) is a common side effect of taxane treatment during chemotherapy. Identifying predictive biomarkers of CIPN would allow physicians to alter treatment given to patients according to a personal risk of developing this condition. The current literature on CIPN biomarkers is reviewed, identifying biomarkers which have been found to be significantly related to CIPN. Three genetic biomarkers are identified (ARHGEF10 rs9657362, CYP2C8 rs11572080/rs10509681 and FGD4 rs10771973) which have been found to act as predictive CIPN biomarkers in multiple studies. Possible mechanisms underlying the relationship between these single nucleotide polymorphisms and CIPN development are explored. The biomarkers identified in this study should be investigated further to generate predictive biomarkers that may be used in a clinical setting.

Host genetic profiling to increase drug safety in colorectal cancer from discovery to implementation

Adverse events affect the pharmacological treatment of approximately 90% of colorectal cancer (CRC) patients at any stage of the disease. Chemotherapy including fluoropyrimidines, irinotecan, and oxaliplatin is the cornerstone of the pharmacological treatment of CRC. The introduction of novel targeted agents, as anti-EGFR (i.e. cetuximab, panitumumab) and antiangiogenic (i.e. bevacizumab, ziv-aflibercept, regorafenib, and ramucirumab) molecules, into the oncologist's toolbox has led to significant improvements in the life expectancy of advanced CRC patients, but with a substantial increase in toxicity burden. In this respect, pharmacogenomics has largely been applied to the personalization of CRC chemotherapy, focusing mainly on the study of inhered polymorphisms in genes encoding phase I and II enzymes, ATP-binding cassette (ABC)/solute carrier (SLC) membrane transporters, proteins involved in DNA repair, folate pathway and immune response. These research efforts have led to the identification of some validated genetic markers of chemotherapy toxicity, for fluoropyrimidines and irinotecan. No validated genetic determinants of oxaliplatin-specific toxicity, as peripheral neuropathy, has thus far been established. The contribution of host genetic markers in predicting the toxicity associated with novel targeted agents' administration is still controversial due to the heterogeneity of published data. Pharmacogenomics guidelines have been published by some international scientific consortia such as the Clinical Pharmacogenomics Implementation Consortium (CPIC) and the Dutch Pharmacogenetics Working Group (DPWG) strongly suggesting a pre-treatment dose adjustment of irinotecan based on UGT1A1*28 genotype and of fluoropyrimidines based on some DPYD genetic variants, to increase treatment safety. However, these recommendations are still poorly applied at the patient's bedside. Several ongoing projects in the U.S. and Europe are currently evaluating how pharmacogenomics can be implemented successfully in daily clinical practice. The majority of drug-related adverse events are still unexplained, and a great deal of ongoing research is aimed at improving knowledge of the role of pharmacogenomics in increasing treatment safety. In this review, the issue of pre-treatment identification of CRC patients at risk of toxicity via the analysis of patients' genetic profiles is addressed. Available pharmacogenomics guidelines with ongoing efforts to implement them in clinical practice and new exploratory markers for clinical validation are described.

SNPs in predicting clinical efficacy and toxicity of chemotherapy: walking through the quicksand

In the "precision medicine" era, chemotherapy still remains the backbone for the treatment of many cancers, but no affordable predictors of response to the chemodrugs are available in clinical practice. Single nucleotide polymorphisms (SNPs) are gene sequence variations occurring in more than 1% of the full population, and account for approximately 80% of inter-individual genomic heterogeneity. A number of studies have investigated the predictive role of SNPs of genes enrolled in both pharmacodynamics and pharmacokinetics of chemotherapeutics, but the clinical implementation of related results has been modest so far. Among the examined germline polymorphic variants, several SNPs of dihydropyrimidine dehydrogenase (DPYD) and uridine diphosphate glucuronosyltransferases (UGT) have shown a robust role as predictors of toxicity following fluoropyrimidine- and/or irinotecan-based treatments respectively, and a few guidelines are mandatory in their detection before therapy initiation. Contrasting results, however, have been reported on the capability of variants of other genes as MTHFR, TYMS, ERCC1, XRCC1, GSTP1, CYP3A4/3A5 and ABCB1, in predicting either therapy efficacy or toxicity in patients undergoing treatment with pyrimidine antimetabolites, platinum derivatives, irinotecan and taxanes. While formal recommendations for routine testing of these SNPs cannot be drawn at this moment, therapeutic decisions may indeed benefit of germline genomic information, when available. Here, we summarize the clinical impact of germline genomic variants on the efficacy and toxicity of major chemodrugs, with the aim to facilitate the therapeutic expectance of clinicians in the odiern quicksand field of complex molecular biology concepts and controversial trial data interpretation.

Pre-treatment evaluation of 5-fluorouracil degradation rate: association of poor and ultra-rapid metabolism with severe toxicity in a colorectal cancer patients cohort

Despite the wide use of 5-fluorouracil-based chemotherapy, development of severe toxicity that follow the treatment is not a rare event. The efforts to establish pretreatment tools for toxicity prediction, led to the development of various pharmacogenetic and biochemical assays, mainly targeted to assess the activity level of dihydropyrimidine dehydrogenase (DPD), the main metabolizing enzyme for 5-fluorouracil. Using peripheral blood mononuclear cells, we developed a biochemical assay, that is not limited to the evaluation of DPD activity, but determines the net result of all the enzymatic transformation of 5FU, in terms of the amount of drug consumed by the cells in a time unit. This parameter, named 5-fluorauracil degradation rate, presents a normal distribution inside the population and highlight the presence of an ultra-rapid metabolizers class of subjects, besides the expected poor metabolizers class. Here we will show that, in a colorectal cancer patient cohort, both poor and ultra-rapid metabolizers have significantly increased the risk of developing severe toxicity (grade3–4). Patient stratification depending on the individual 5-fluorouracil degradation rate allows to identify a 10% of the overall population at high risk of developing severe toxicity, compared to the 1.3% (as assessed in the Italian population) identified by the most commonly employed pharmacogenetic test, including the DPD polymorphism IVS14+1G>A.

The molecular genetics of chemotherapy-induced peripheral neuropathy: A systematic review and meta-analysis

Chemotherapy-induced peripheral neuropathy (CIPN) can adversely affect completion of systemic anti-cancer treatment and cause long-term morbidity. Increasingly pharmacogenetic studies have been performed to explore susceptibility to this important adverse effect. A systematic review was conducted to identify pharmacogenetic studies, assess their quality and findings and undertake meta-analysis where possible. 93 studies were included. Notable methodological issues included lack of standardisation and detail in phenotype definition and acknowledgement of potential confounding factors. Insufficient data was presented in many studies meaning only a minority could be included in meta-analysis showing mainly non-significant effects. Nonetheless, SNPs in CYP2C8, CYP3A4, ARHGEF10, EPHA and TUBB2A genes (taxanes), FARS2, ACYP2 and TAC1 (oxaliplatin), and CEP75 and CYP3A5 (vincristine) are of potential interest. These require exploration in large cohort studies with robust methodology and well-defined phenotypes. Seeking standardisation of phenotype, collaboration and subsequently, individual-patient-data meta-analysis may facilitate identifying contributory SNPs which could be combined in a polygenic risk score to predict those most at risk of CIPN.

Dihydropyrimidine dehydrogenase pharmacogenetics for predicting fluoropyrimidine-related toxicity in the randomised, phase III adjuvant TOSCA trial in high-risk colon cancer patients

Background:

Dihydropyrimidine dehydrogenase (DPD) catabolises ∼85% of the administered dose of fluoropyrimidines. Functional DPYD gene variants cause reduced/abrogated DPD activity. DPYD variants analysis may help for defining individual patients’ risk of fluoropyrimidine-related severe toxicity.

Methods:

The TOSCA Italian randomised trial enrolled colon cancer patients for 3 or 6 months of either FOLFOX-4 or XELOX adjuvant chemotherapy. In an ancillary pharmacogenetic study, 10 DPYD variants (*2A rs3918290 G>A, *13 rs55886062 T>G, rs67376798 A>T, *4 rs1801158 G>A, *5 rs1801159 A>G, *6 rs1801160 G>A, *9A rs1801265 T>C, rs2297595 A>G, rs17376848 T>C, and rs75017182 C>G), were retrospectively tested for associations with ⩾grade 3 fluoropyrimidine-related adverse events (FAEs). An association analysis and a time-to-toxicity (TTT) analysis were planned. To adjust for multiple testing, the Benjamini and Hochberg’s False Discovery Rate (FDR) procedure was used.

Results:

FAEs occurred in 194 out of 508 assessable patients (38.2%). In the association analysis, FAEs occurred more frequently in *6 rs1801160 A allele carriers (FDR=0.0083). At multivariate TTT analysis, significant associations were found for *6 rs1801160 A allele carriers (FDR<0.0001), *2A rs3918290 A allele carriers (FDR<0.0001), and rs2297595 GG genotype carriers (FDR=0.0014). Neutropenia was the most common FAEs (28.5%). *6 rs1801160 (FDR<0.0001), and *2A rs3918290 (FDR=0.0004) variant alleles were significantly associated with time to neutropenia.

Conclusions:

This study adds evidence on the role of DPYD pharmacogenetics for safety of patients undergoing fluoropyrimidine-based chemotherapy.

Chemotherapy-induced peripheral neurotoxicity: management informed by pharmacogenetics

The increasing availability of sophisticated methods to characterize human genetic variation has enabled pharmacogenetic data to be used not only to predict responses to treatment (in the context of so-called personalized medicine), but also to identify patients at high or low risk of specific treatment-related adverse effects. Over the past two decades, extensive attempts have been made to understand the genetic basis of chemotherapy-induced peripheral neurotoxicity (CIPN), one of the most severe non-haematological adverse effects of cancer treatment. Despite substantial efforts, however, the identification of a genetic profile that can detect patients at high risk of CIPN still represents an unmet need, as the information obtained from pharmacogenetic studies published so far is inconsistent at best. Among the reasons for these inconsistencies, methodological flaws and the poor reliability of existing tools for assessing CIPN features and severity are particularly relevant. This Review provides a critical update of the pharmacogenetics of CIPN, focusing on the studies published since 2011. Strategies for improving the reliability of future pharmacogenetic studies of CIPN are also discussed.

HLA-G 3'UTR Polymorphisms Predict Drug-Induced G3-4 Toxicity Related to Folinic Acid/5-Fluorouracil/Oxaliplatin (FOLFOX4) Chemotherapy in Non-Metastatic Colorectal Cancer

Polymorphisms in drug-metabolizing enzymes might not completely explain inter-individual differences in toxicity profiles of patients with colorectal cancer (CRC) that receive folinic acid/5-fluorouracil/oxaliplatin (FOLFOX4). Recent data indicate that the immune system could contribute to FOLFOX4 outcomes. In light of the immune inhibitory nature of human leukocyte antigen-G (HLA-G), a non-classical major histocompatibility complex (MHC) class I molecule, we aimed to identify novel genomic markers of grades 3 and 4 (G3-4) toxicity related to FOLFOX4 therapy in patients with CRC. We retrospectively analyzed data for 144 patients with stages II-III CRC to identify HLA-G 3′ untranslated region (3′UTR) polymorphisms and related haplotypes and evaluate their impact on the risk of developing G3-4 toxicities (i.e., neutropenia, hematological/non-hematological toxicity, neurotoxicity) with logistic regression. The rs1610696-G/G polymorphism was associated with increased risk of G3-4 neutropenia (OR = 3.76, p = 0.015) and neurotoxicity (OR = 8.78, p = 0.016); rs371194629-Ins/Ins was associated with increased risk of neurotoxicity (OR = 5.49, p = 0.027). HLA-G 3′UTR-2, which contains rs1610696-G/G and rs371194629-Ins/Ins polymorphisms, was associated with increased risk of G3-4 neutropenia (OR = 3.92, p = 0.017) and neurotoxicity (OR = 11.29, p = 0.009). A bootstrap analysis confirmed the predictive value of rs1610696 and rs371194629, but the UTR-2 haplotype was validated only for neurotoxicity. This exploratory study identified new HLA-G 3′UTR polymorphisms/haplotypes as potential predictive markers of G3-4 toxicities in CRC.

Biological and predictive role of ERCC1 polymorphisms in cancer

Excision repair cross-complementation group 1 (ERCC1) is a key component in DNA repair mechanisms and may influence the tumor DNA-targeting effect of the chemotherapeutic agent oxaliplatin. Germline ERCC1 polymorphisms may alter the protein expression and published data on their predictive and prognostic value have so far been contradictory. In the present article we review available evidence on the clinical role and utility of ERCC1 polymorphisms and, in the absence of a 'perfect' trial, what we call the 'sliding doors' trial, we present the data of ERCC1 genotyping in our local patient population. We found a useful predictive value for oxaliplatin-induced risk of anemia.

Adjuvant FOLFOX treatment for stage III colon cancer: how many cycles are enough?

Purpose

Adjuvant FOLFOX (5-fluorouracil and oxaliplatin) chemotherapy benefits stage III colon cancer patients. However, it still results in side effects and increased cost. Reducing cycles had been thought to decrease these problems. This retrospective study aimed to find the appropriate number of treatment cycles that are sufficient for treating these patients.

Patients and methods

A total of 213 stage III colon cancer patients receiving adjuvant FOLFOX therapy were retrospectively recruited. Demographic data were collected for analysis. Survival analyses were performed between all cases of patients receiving above and below a certain cycle number. If a significant difference was reached at that cycle number, multivariate Cox Regression was performed with those factors resulting in p < 0.2 to assess the independent prognostic factors.

Results

The 5-year overall survival rate of patients was 77.9 %, and the 3-year disease-free survival was 76.7 %. For overall survival, a significant benefit was noted for treatment of at least 8 cycles, for disease-free survival, significant differences were apparent from patient data of those who underwent from 7 to 12 treatment cycles. Multivariate survival analysis of that patient data at cycle 8 for overall survival and cycle 7 for disease free survival revealed cycle number as the only independent prognostic factor (p = 0.04, 0.048).

Conclusion

Cycle number of adjuvant FOLFOX is a significant prognostic factor for stage III colon cancer patients. At least 8 cycles are needed to have an overall survival benefit, and 7 to disease-free survival.

Predictive value of GSTP1 Ile105Val polymorphism in clinical outcomes of chemotherapy in gastric and colorectal cancers: a systematic review and meta-analysis

PURPOSE

Gastric and colorectal cancers remain the major causes of cancer-related death with a bad prognosis. Up to now, platinum combined with fluoropyrimidines has been most commonly used in chemotherapy regimens of gastric and colorectal cancers. Recently, a series of studies have been conducted to investigate the associations of biomarkers, such as GSTP1 Ile105Val polymorphism, with the chemotherapy efficacy in gastric and colorectal cancers; however, the results were not consistent and inconclusive. Here, we performed a systematic review and meta-analysis to summarize the associations of GSTP1 Ile105Val polymorphism with the chemotherapy efficacy in gastric and colorectal cancers.

METHODS

A systematic review was conducted to search relevant studies in English databases (PubMed, ISI Web of Science, and EMBASE) up to November 30, 2015. The pooling ORs or HRs were used to assess the strength of the associations of GSTP1 Ile105Val polymorphism with clinical outcomes such as tumor response, toxicity, progression-free survival (PFS), and overall survival (OS).

RESULTS

Forty-one papers containing 8169 cases were finally included in the present meta-analysis study. Of which, 28 articles were performed in colorectal cancers, one in gastrointestinal carcinoma (gastric and colon cancer), 11 in gastric cancers, and one in colorectal and gastroesophageal cancers. After pooling all the eligible studies, we identified significant associations of GSTP1 Ile105Val polymorphism with chemotherapy-related tumor response (G vs. A: OR 1.697, 95 % CI 1.191-2.418; GG vs. AA: OR 2.804, 95 % CI 1.414-5.560; AG vs. AA: OR 1.540, 95 % CI 1.011-2.347; GG vs. AAAG: OR 2.139, 95 % CI 1.256-3.641), PFS (GG vs. AA, HR 0.640, 95 % CI 0.455-0.900; AGGG vs. AA: HR 0.718, 95 % CI 0.562-0.919), and OS (AG vs. AA: HR 0.857, 95 % CI 0.746-0.986; GG vs. AA: HR 0.679, 95 % CI 0.523-0.882; AGGG vs. AA: HR 0.663, 95 % CI 0.542-0.812) in gastric and colorectal cancers and no significant association was found between the polymorphism with toxicity.

CONCLUSIONS

GSTP1 Ile105Val polymorphism was associated with tumor response, PFS, and OS in gastric and colorectal cancers after chemotherapy.

Nucleotide excision repair and response and survival to chemotherapy in colorectal cancer patients

Several new chemotherapeutic agents have become available for the treatment of colorectal cancer, which has led to increased complexity in treatment planning. Treatment decision making for individual patients could be facilitated if guided by predictive and prognostic markers. As most cytotoxic drugs induce DNA damage, the DNA damage repair pathways hold potential for yielding such biomarkers. Here, we review the current evidence of a possible involvement of the nucleotide excision repair pathway in the efficacy of chemotherapeutic agents used in the treatment of colorectal cancer. Although a large number of studies have been conducted, they are generally of moderate size and heterogeneous in design. Up to date no firm conclusions can be drawn to translate these results into the clinic. We recommend further comprehensive investigations of the nucleotide excision repair pathway in large patient studies that include both discovery and validation cohorts.

Cancer survivorship: long-term side-effects of anticancer treatments of gastrointestinal cancer

PURPOSE OF REVIEW

Surveillance of patients with a history of cancer is a frequent practice in oncology. However, it is often aimed at the early diagnosis of relapse and tends to underestimate the evaluation and care of factors impairing quality of life (QoL). Among these, long-term toxicities of anticancer treatments are one of the major threats to a complete physical and psychosocial recovery. We aimed to review the relevant literature on long-term side-effects of treatment in gastrointestinal cancers.

RECENT FINDINGS

We focused on esophageal, gastric, pancreatic, liver and colorectal cancers. A significant fraction of patients treated for these cancers suffer with some form of late toxicity from surgery, radiotherapy or chemotherapy. Prompt evaluation and management is of the utmost importance in reducing the impact of these symptoms on QoL.

SUMMARY

The knowledge of the reviewed data should encourage a multidisciplinary approach to surveillance and convince clinicians of the comprehensive role of survivorship care.