Glutathione-S-transferase genotypes influence the risk of chemotherapy-related toxicities and prognosis in Korean patients with diffuse large B-cell lymphoma

Prognostic relevance of sarcopenia, geriatric, and nutritional assessments in older patients with diffuse large B-cell lymphoma: results of a multicentric prospective cohort study

This prospective study aimed to investigate the prognostic effect of sarcopenia, geriatric, and nutritional status in older patients with diffuse large B-cell lymphoma (DLBCL). Ninety-five patients with DLBCL older than 70 years who were treated with immunochemotherapy were included. The lumbar L3 skeletal muscle index (L3-SMI) was measured by computed tomography at baseline, and sarcopenia was defined as low L3-SMI. Geriatric assessment included G8 score, CIRS-G scale, Timed Up and Go test, and instrumental activity of daily living. Nutritional status was assessed using the Mini Nutritional Assessment and the body mass index, and several scores used in the literature incorporating nutritional and inflammatory biomarkers, namely the Nutritional and inflammatory status (NIS), Geriatric Nutritional Risk Index, Prognostic Nutritional Index, and Glasgow Prognostic Score.Fifty-three patients were considered sarcopenic. Sarcopenic patients displayed higher levels of inflammation markers and lower levels of prealbumin than non-sarcopenic patients. Sarcopenia was associated with NIS, but was not associated with severe adverse events and treatment disruptions. They were, however, more frequent among patients with elevated NIS. Sarcopenia did not appear in this study as a prognostic factor for progression-free survival (PFS) or overall survival (OS). However, NIS emerged as predictive of the outcome with a 2-year PFS rate of 88% in the NIS ≤ 1 group and 49% in the NIS > 1 group and a significant effect in a multivariate analysis for both PFS (p = 0.049) and OS (HR = 9.61, CI 95% = [1.03-89.66], p = 0.04). Sarcopenia was not associated with adverse outcomes, but was related to NIS, which appeared to be an independent prognostic factor.

LASSO Model Better Predicted the Prognosis of DLBCL than Random Forest Model: A Retrospective Multicenter Analysis of HHLWG

Background. Diffuse large B-cell lymphoma (DLBCL) is a heterogeneous non-Hodgkin’s lymphoma with great clinical challenge. Machine learning (ML) has attracted substantial attention in diagnosis, prognosis, and treatment of diseases. This study is aimed at exploring the prognostic factors of DLBCL by ML. Methods. In total, 1211 DLBCL patients were retrieved from Huaihai Lymphoma Working Group (HHLWG). The least absolute shrinkage and selection operator (LASSO) and random forest algorithm were used to identify prognostic factors for the overall survival (OS) rate of DLBCL among twenty-five variables. Receiver operating characteristic (ROC) curve and decision curve analysis (DCA) were utilized to compare the predictive performance and clinical effectiveness of the two models, respectively. Results. The median follow-up time was 43.4 months, and the 5-year OS was 58.5%. The LASSO model achieved an Area under the curve (AUC) of 75.8% for the prognosis of DLBCL, which was higher than that of the random forest model (AUC: 71.6%). DCA analysis also revealed that the LASSO model could augment net benefits and exhibited a wider range of threshold probabilities by risk stratification than the random forest model. In addition, multivariable analysis demonstrated that age, white blood cell count, hemoglobin, central nervous system involvement, gender, and Ann Arbor stage were independent prognostic factors for DLBCL. The LASSO model showed better discrimination of outcomes compared with the IPI and NCCN-IPI models and identified three groups of patients: low risk, high-intermediate risk, and high risk. Conclusions. The prognostic model of DLBCL based on the LASSO regression was more accurate than the random forest, IPI, and NCCN-IPI models.

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.

Pharmacogenetics in diffuse large B-cell lymphoma treated with R-CHOP: Still an unmet challenge

DLBCL is the most common lymphoma representing approximately one third of all non-Hodgkin lymphomas and about 40% of patients do not benefit of the standard first-line immune-chemotherapeutic treatment (i.e., R-CHOP - rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisone) that is administered as upfront therapy to substantially all patients independently from the stage of disease and other prognostic parameters. The administration of other pharmacological treatments is in fact limited to selected patients, unfitting for R-CHOP. Although clinical prognostic scores, i.e. International Prognostic Index (IPI), and molecular classifiers based on the cell of origin are available, at present no biomarkers predictive of R-CHOP response has been identified and validated. Constitutional polymorphisms of genes involved in the mechanism of action of drugs included in R-CHOP have been suggested by many authors to play a role in the efficacy and in some case in the toxicity of this treatment. Thus, it is conceivable that in the future, after proper validation, some polymorphisms can be used as pharmacogenetic biomarkers of therapeutic outcome in this disease setting. This review discusses the status of the art on molecular biomarkers predictive of DLBCL prognosis and deals with the relevant issue of the variability in response to DLBCL drug treatment. Overall, this review focuses on single nucleotide polymorphisms (SNPs) that, based on a candidate gene approach or on a GWAS analysis, have been suggested to play a role in response to R-CHOP. In particular, SNPs discovered by a candidate gene approach are related to gene involved in drug transport (i.e. ATP-binding cassette transporters), drug metabolism, drug detoxification enzymes, oxidative stress, apoptosis, DNA repair, immunity and angiogenesis. Data from a GWAS analysis performed in DLBCL patients treated with R-CHOP, identified two SNPs associated with clinical outcomes related to genes involved in pivotal cellular processes and in transcriptional regulation and cell cycle progression, respectively. Ongoing prospective pharmacogenetic clinical trials, including a GWAS study we performed, have also been discussed.

Evaluating the role of GSTP1 genetic polymorphism (rs1695, 313A>G) as a predictor in cyclophosphamide-induced toxicities

The association between Glutathione S-transferase Pi 1(GSTP1) genetic polymorphism (rs1695, 313A>G) and cyclophosphamide-induced toxicities has been widely investigated in previous studies, however, the results were inconsistent. This study was performed to further elucidate the association.A comprehensive search was conducted in PubMed, Embase, Web of Science, China National Knowledge Infrastructure, and Wan Fang database up to January 5, 2020. Risk ratios (RRs) and 95% confidence intervals (95% CIs) were used to estimate the association between GSTP1 rs1695 polymorphism and cyclophosphamide-induced hemotoxicity, gastrointestinal toxicity, infection, and neurotoxicity.A total of 13 studies were eventually included. Compared with the GSTP1 rs1695 AA genotype carriers, patients with AG and GG genotypes had an increased risk of cyclophosphamide-induced gastrointestinal toxicity (RR, 1.61; 95% CI, 1.18-2.19; P = .003) and infection (RR, 1.57; 95% CI, 1.00-2.48; P = .05) in the overall population. In the subgroup analyses, there were significant associations between GSTP1 rs1695 polymorphism and the risk of cyclophosphamide-induced myelosuppression (RR, 2.10; 95% CI, 1.60-2.76; P < .00001), gastrointestinal toxicity (RR, 1.77; 95%CI, 1.25-2.53; P = .001), and infection (RR, 2.01; 95% CI, 1.14-3.54; P = .02) in systemic lupus erythematosus (SLE) or lupus nephritis syndrome patients, but not in cancer patients.Our results confirmed an essential role for the GSTP1 rs1695 polymorphism in the prediction of cyclophosphamide-induced myelosuppression, gastrointestinal toxicity, and infection in SLE or lupus nephritis syndrome patients. More studies are necessary to validate our findings in the future.

Structural variation at the CYP2C locus: Characterization of deletion and duplication alleles

The human CYP2C locus harbors the polymorphic CYP2C18, CYP2C19, CYP2C9, and CYP2C8 genes, and of these, CYP2C19 and CYP2C9 are directly involved in the metabolism of ~15% of all medications. All variant CYP2C19 and CYP2C9 star (*) allele haplotypes currently cataloged by the Pharmacogene Variation (PharmVar) Consortium are defined by sequence variants. To determine if structural variation also occurs at the CYP2C locus, the 10q23.33 region was interrogated across deidentified clinical chromosomal microarray (CMA) data from 20,642 patients tested at two academic medical centers. Fourteen copy number variants that affected the coding region of CYP2C genes were detected in the clinical CMA cohorts, which ranged in size from 39.2 to 1,043.3 kb. Selected deletions and duplications were confirmed by MLPA or ddPCR. Analysis of the clinical CMA and an additional 78,839 cases from the Database of Genomic Variants (DGV) and ClinGen (total n = 99,481) indicated that the carrier frequency of a CYP2C structural variant is ~1 in 1,000, with ~1 in 2,000 being a CYP2C19 full gene or partial-gene deletion carrier, designated by PharmVar as CYP2C19*36 and *37, respectively. Although these structural variants are rare in the general population, their detection will likely improve metabolizer phenotype prediction when interrogated for research and/or clinical testing.

Predicting mucositis risk associated with cytotoxic cancer treatment regimens: rationale, complexity, and challenges

PURPOSE OF REVIEW

The goals of this review are to describe the complexity of factors influencing the risk of cancer regimen-related mucosal injury (CRRMI), to evaluate the contribution of the innate immune response to CRRMI risk, to compare the concordance of genome analytics in describing mechanism and risk, and to determine if common biological pathways are noted when CRRMI is compared to a disease with a similar phenotype.

RECENT FINDINGS

The pathogenesis of and risk for CRRMI are complex and influenced by multiple intrinsic and extrinsic factors. It is incumbent on analyses to recognize the likelihood that the interplay and cross-talk of synergistically expressed factors is critical and that the contributing weights of these factors is not uniform from patient to patient. Genomically derived analyses imply final common pathways are implicit in phenotype expression.

SUMMARY

The identification of specific factors (both genomic and otherwise) which contribute to CRRMI risk represents an important opportunity to apply principles of precision medicine to the management of regimen-related toxicities.

Association Study Among Candidate Genetic Polymorphisms and Chemotherapy-Related Severe Toxicity in Testicular Cancer Patients

Testicular cancer is one of the most commonly occurring malignant tumors in young men with fourfold higher rate of incidence and threefold higher mortality rates in Chile than the average global rates. Surgery is the initial line of treatment for testicular cancers, and is generally followed by chemotherapy, usually with combinations of bleomycin, etoposide, and cisplatin (BEP). However, the adverse effects of chemotherapy vary significantly among individuals; therefore, the present study explored the association of functionally significant allelic variations in genes related to the pharmacokinetics/pharmacodynamics of BEP and DNA repair enzymes with chemotherapy-induced toxicity in BEP-treated testicular cancer patients. We prospectively recruited 119 patients diagnosed with testicular cancer from 2010 to 2017. Genetic polymorphisms were analyzed using PCR and/or qPCR with TaqMan^®probes. Toxicity was evaluated based on the Common Terminology Criteria for Adverse Events, v4.03. After univariate analyses to define more relevant genetic variants (p < 0.2) and clinical conditions in relation to severe (III–IV) adverse drug reactions (ADRs), stepwise forward multivariate logistic regression analyses were performed. As expected, the main severe ADRs associated with the non-genetic variables were hematological (neutropenia and leukopenia). Univariate statistical analyses revealed that patients with ERCC2 rs13181 T/G and/or CYP3A4 rs2740574 A/G genotypes are more likely to develop alopecia; patients with ERCC2 rs238406 C/C genotype may develop leukopenia, and patients with GSTT1-null genotype could develop lymphocytopenia (III–IV). Patients with ERCC2 rs1799793 A/A were at risk of developing severe anemia. The BLMH rs1050565 G/G genotype was found to be associated with pain, and the GSTP1 G/G genotype was linked infection (p < 0.05). Multivariate analysis showed an association between specific ERCC1/2 genotypes and cumulative dose of BEP drugs with the appearance of severe leukopenia and/or febrile neutropenia. Grades III–IV vomiting, nausea, and alopecia could be partly explained by the presence of specific ERCC1/2, MDR1, GSTP1, and BLMH genotypes (p < 0.05). Hence, we provide evidence for the usefulness of pharmacogenetics as a tool for predicting severe ADRs in testicular cancer patients treated with BEP chemotherapy.

Glutathione-S-transferase-theta genotypes and the risk of cyclophosphamide toxicity in dogs

The antineoplastic agent cyclophosphamide (CP) has dose-limiting side effects including sterile haemorrhagic cystitis (SHC), bone marrow (BM) suppression and gastrointestinal (GI) toxicity in dogs. The metabolites acrolein and phosphoramide that mediate these toxicities are glutathione-S-transferase (GST) substrates, and low functioning GST alleles are associated with CP toxicity in humans. The aim of this study was to determine whether variants in 2 canine GST genes, GSTT1 and GSTT5, were over-represented in dogs that developed CP toxicity. Dogs undergoing pulse or metronomic CP chemotherapy were recruited (n = 101) and genotyped for 6 GSTT1 polymorphisms and 1 GSTT5 6-bp deletion that leads to non-functional enzyme. Median cumulative CP dosages for dogs with SHC (1350 mg/m² ) were significantly higher than for dogs with GI/BM toxicity (871 mg/m² ) or no toxicity (991 mg/m² ; P = .0012). Dogs with SHC were more likely to have had metronomic (84.2%, 16 of 19 SHC cases) vs pulse (15.8%, 3 of 19 SHC cases) CP dosing (P < .0001). All dogs with BM or GI toxicity (n = 30) had pulse chemotherapy. GSTT1 and GSTT5 variant allele frequencies were not significantly different in CP-treated dogs with SHC or GI/BM toxicity compared to dogs without documented adverse effects. Work is underway to identify which canine GSTs detoxify acrolein and phosphoramide, so that better tools are available to predict the risk of CP toxicity in dogs.

Sex Differences in Cancer: Epidemiology, Genetics and Therapy

The incidence and mortality of various cancers are associated with sex-specific disparities. Sex differences in cancer epidemiology are one of the most significant findings. Men are more prone to die from cancer, particularly hematological malignancies. Sex difference in cancer incidence is attributed to regulation at the genetic/molecular level and sex hormones such as estrogen. At the genetic/molecular level, gene polymorphism and altered enzymes involving drug metabolism generate differences in cancer incidence between men and women. Sex hormones modulate gene expression in various cancers. Genetic or hormonal differences between men and women determine the effect of chemotherapy. Until today, animal studies and clinical trials investigating chemotherapy showed sex imbalance. Chemotherapy has been used without consideration of sex differences, resulting in disparity of efficacy and toxicity between sexes. Based on accumulating evidence supporting sex differences in chemotherapy, all clinical trials in cancer must incorporate sex differences for a better understanding of biological differences between men and women. In the present review, we summarized the sex differences in (1) incidence and mortality of cancer, (2) genetic and molecular basis of cancer, (3) sex hormones in cancer incidence, and (4) efficacy and toxicity of chemotherapy. This review provides useful information for sex-based chemotherapy and development of personalized therapeutic strategies against cancer.

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.

Identifying novel genes and biological processes relevant to the development of cancer therapy-induced mucositis: An informative gene network analysis

Mucositis is a complex, dose-limiting toxicity of chemotherapy or radiotherapy that leads to painful mouth ulcers, difficulty eating or swallowing, gastrointestinal distress, and reduced quality of life for patients with cancer. Mucositis is most common for those undergoing high-dose chemotherapy and hematopoietic stem cell transplantation and for those being treated for malignancies of the head and neck. Treatment and management of mucositis remain challenging. It is expected that multiple genes are involved in the formation, severity, and persistence of mucositis. We used Ingenuity Pathway Analysis (IPA), a novel network-based approach that integrates complex intracellular and intercellular interactions involved in diseases, to systematically explore the molecular complexity of mucositis. As a first step, we searched the literature to identify genes that harbor or are close to the genetic variants significantly associated with mucositis. Our literature review identified 27 candidate genes, of which ERCC1, XRCC1, and MTHFR were the most frequently studied for mucositis. On the basis of this 27-gene list, we used IPA to generate gene networks for mucositis. The most biologically significant novel molecules identified through IPA analyses included TP53, CTNNB1, MYC, RB1, P38 MAPK, and EP300. Additionally, uracil degradation II (reductive) and thymine degradation pathways (p = 1.06-08) were most significant. Finally, utilizing 66 SNPs within the 8 most connected IPA-derived candidate molecules, we conducted a genetic association study for oral mucositis in the head and neck cancer patients who were treated using chemotherapy and/or radiation therapy (186 head and neck cancer patients with oral mucositis vs. 699 head and neck cancer patients without oral mucositis). The top ranked gene identified through this association analysis was RB1 (rs2227311, p-value = 0.034, odds ratio = 0.67). In conclusion, gene network analysis identified novel molecules and biological processes, including pathways related to inflammation and oxidative stress, that are relevant to mucositis development, thus providing the basis for future studies to improve the management and treatment of mucositis in patients with cancer.

Neurocognitive functioning and genetic variation in patients with primary brain tumours

Impairment of neurocognitive functioning is a common result of cerebral neoplasms and treatment, although there is substantial heterogeneity in the pattern and severity of neurocognitive dysfunction across individuals and tumour types. The effects of many clinical and patient characteristics on neurocognitive functioning have been documented, but little research has been devoted to understanding the effect of genetic variation on neurocognitive outcomes in patients with brain tumours. This Review highlights preliminary evidence that suggests an association between various genes and risk of adverse neurocognitive outcomes in patients with brain tumours. Studies include genes specific to neuronal function, and those associated with more systemic cellular regulation. Related scientific literature in other disease populations is briefly discussed to indicate additional candidate genes. We consider methodological issues central to the study of neurocognitive functioning and genetic associations for patients with brain tumours, and emphasise the need for future research integrating novel investigative techniques.

Informative gene network for chemotherapy-induced peripheral neuropathy

BACKGROUND

Host genetic variability has been implicated in chemotherapy-induced peripheral neuropathy (CIPN). A dose-limiting toxicity for chemotherapy agents, CIPN is also a debilitating condition that may progress to chronic neuropathic pain. We utilized a bioinformatics approach, which captures the complexity of intracellular and intercellular interactions, to identify genes for CIPN.

METHODS

Using genes pooled from the literature as a starting point, we used Ingenuity Pathway Analysis (IPA) to generate gene networks for CIPN.

RESULTS

We performed IPA core analysis for genes associated with platinum-, taxane- and platinum-taxane-induced neuropathy. We found that IL6, TNF, CXCL8, IL1B and ERK1/2 were the top genes in terms of the number of connections in platinum-induced neuropathy and TP53, MYC, PARP1, P38 MAPK and TNF for combined taxane-platinum-induced neuropathy.

CONCLUSION

Neurotoxicity is common in cancer patients treated with platinum compounds and anti-microtubule agents and CIPN is one of the debilitating sequela. The bioinformatic approach helped identify genes associated with CIPN in cancer patients.

The role of gender in patients with diffuse large B cell lymphoma treated with rituximab-containing regimens: a meta-analysis

INTRODUCTION

Diffuse large B cell lymphoma (DLBCL) is the most common subtype of non-Hodgkin lymphoma (NHL). Although gender has not been included in prognostic systems, male gender has been found as a bad prognostic indicator in Hodgkin lymphoma, follicular lymphoma and chronic lymphocytic leukemia. The relationship between gender and prognosis is not clear in patients with DLBCL treated with rituximab-containing regimens. The aim of this meta-analysis is to determine the prognostic/predictive role of gender in patients with DLBCL treated with rituximab-containing regimens.

MATERIAL AND METHODS

We systematically searched for studies investigating the relationships between gender and prognosis in DLBCL treated with rituximab-containing regimens. After careful review, survival data were extracted from eligible studies. A meta-analysis was performed to generate combined hazard ratios for overall survival, disease-free survival (DFS) and event-free survival (EFS).

RESULTS

A total of 5635 patients from 20 studies were included in the analysis. Our results showed that male gender was associated with poor prognosis in terms of overall survival (OS) (hazard ratio (HR) = 1.155; 95% confidence interval (CI): 1.037-1.286; p < 0.009). The pooled hazard ratio for DFS and EFS showed that male gender was not statistically significant (HR = 1.219; 95% CI: 0.782-1.899; p = 0.382, HR = 0.809; 95% CI: 0.577-1.133; p = 0.217).

CONCLUSIONS

The present meta-analysis indicated male gender to be associated with a poor prognosis in patients with DLBCL treated with rituximab-containing regimens.

Management of side effects in the personalized medicine era: chemotherapy-induced peripheral neuropathy

Pharmacogenomics has been establishing itself as a powerful tool to predict individual response to treatment, in order to personalize therapy management; this field has been explored in particular in Oncology. Not only efficacy on the malignant disease has been investigated, but also the possibility to predict adverse effects due to drug administration. Chemotherapy-Induced 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.

Prenatal antidepressant exposure associated with CYP2E1 DNA methylation change in neonates

Some but not all neonates are affected by prenatal exposure to serotonin reuptake inhibitor antidepressants (SRI) and maternal mood disturbances. Distinguishing the impact of these 2 exposures is challenging and raises critical questions about whether pharmacological, genetic, or epigenetic factors can explain the spectrum of reported outcomes. Using unbiased DNA methylation array measurements followed by a detailed candidate gene approach, we examined whether prenatal SRI exposure was associated with neonatal DNA methylation changes and whether such changes were associated with differences in birth outcomes. Prenatal SRI exposure was first associated with increased DNA methylation status primarily at CYP2E1(β(Non-exposed) = 0.06, β(SRI-exposed) = 0.30, FDR = 0); however, this finding could not be distinguished from the potential impact of prenatal maternal depressed mood. Then, using pyrosequencing of CYP2E1 regulatory regions in an expanded cohort, higher DNA methylation status--both the mean across 16 CpG sites (P < 0.01) and at each specific CpG site (P < 0.05)--was associated with exposure to lower 3rd trimester maternal depressed mood symptoms only in the SRI-exposed neonates, indicating a maternal mood x SRI exposure interaction. In addition, higher DNA methylation levels at CpG2 (P = 0.04), CpG9 (P = 0.04) and CpG10 (P = 0.02), in the interrogated CYP2E1 region, were associated with increased birth weight independently of prenatal maternal mood, SRI drug exposure, or gestational age at birth. Prenatal SRI antidepressant exposure and maternal depressed mood were associated with altered neonatal CYP2E1 DNA methylation status, which, in turn, appeared to be associated with birth weight.

Emerging evidence on the pathobiology of mucositis

BACKGROUND

Considerable progress has been made in our understanding of the biological basis for cancer therapy-induced mucosal barrier injury (mucositis). The last formal review of the subject by MASCC/ISOO was published in 2007; consequently, an update is timely.

METHODS

Panel members reviewed the biomedical literature on mucositis pathobiology published between January 2005 and December 2011.

RESULTS

Recent research has provided data on the contribution of tissue structure changes, inflammation and microbiome changes to the development of mucositis. Additional research has focused on targeted therapy-induced toxicity, toxicity clustering and the investigation of genetic polymorphisms in toxicity prediction. This review paper summarizes the recent evidence on these aspects of mucositis pathobiology.

CONCLUSION

The ultimate goal of mucositis researchers is to identify the most appropriate targets for therapeutic interventions and to be able to predict toxicity risk and personalize interventions to genetically suitable patients. Continuing research efforts are needed to further our understanding of mucositis pathobiology and the pharmacogenomics of toxicity.

Emerging evidence on the pathobiology of mucositis

BACKGROUND

Considerable progress has been made in our understanding of the biological basis for cancer therapy-induced mucosal barrier injury (mucositis). The last formal review of the subject by MASCC/ISOO was published in 2007; consequently, an update is timely.

METHODS

Panel members reviewed the biomedical literature on mucositis pathobiology published between January 2005 and December 2011.

RESULTS

Recent research has provided data on the contribution of tissue structure changes, inflammation and microbiome changes to the development of mucositis. Additional research has focused on targeted therapy-induced toxicity, toxicity clustering and the investigation of genetic polymorphisms in toxicity prediction. This review paper summarizes the recent evidence on these aspects of mucositis pathobiology.

CONCLUSION

The ultimate goal of mucositis researchers is to identify the most appropriate targets for therapeutic interventions and to be able to predict toxicity risk and personalize interventions to genetically suitable patients. Continuing research efforts are needed to further our understanding of mucositis pathobiology and the pharmacogenomics of toxicity.

Sex differences in the drug therapy for oncologic diseases

There are clear gender-dependent differences in response rates and the probability of side effects in patients treated with chemotherapy. Sex-biased expression levels of metabolic enzymes and transporters in liver and kidney leading to different pharmacokinetics have been described for most common anti-cancer drugs. In women, half-life is often longer, which is associated with improved survival, but also increased toxicity.Some chemotherapy protocols lead to a better response rate in women without increasing toxicity (e.g., cisplatin and irinotecan), while others only increase toxicity, but do not improve response rates in women (e.g., 5-fluorouracil). The increased toxicity often correlates with different pharmacokinetics, but women also show a higher sensitivity to some agents with shorter half-life (e.g., steroids). Organ-specific toxicities like cardiac toxicity after doxorubicin treatment or neurotoxicity associated with ifosfamide are more severe in women due to gender-specific changes in gene expression. Novel therapies like tyrosine kinase inhibitors or monoclonal antibodies show very complex, but clinical significant differences depending on gender. Antibodies often have a longer half-life in women, which is associated with an improved response to therapy.Side effects appear to be highly dependent on different tissue properties, as women have a higher incidence of oral mucositis, but lower rates of gut toxicity. Nausea and vomiting is a greater problem in females during therapy due to the lower activity of anti-emetic drugs. Nausea and vomiting pose a bigger challenge in female patients, as anti-emetic drugs seem to be less effective.

Impact of genetic polymorphisms on chemotherapy toxicity in childhood acute lymphoblastic leukemia

The efficacy of chemotherapy in pediatric acute lymphoblastic leukemia (ALL) patients has significantly increased in the last 20 years; as a result, the focus of research is slowly shifting from trying to increase survival rates to reduce chemotherapy-related toxicity. At the present time, the cornerstone of therapy for ALL is still formed by a reduced number of drugs with a highly toxic profile. In recent years, a number of genetic polymorphisms have been identified that can play a significant role in modifying the pharmacokinetics and pharmacodynamics of these drugs. The best example is that of the TPMT gene, whose genotyping is being incorporated to clinical practice in order to individualize doses of mercaptopurine. However, there are additional genes that are relevant for the metabolism, activity, and/or transport of other chemotherapy drugs that are widely use in ALL, such as methotrexate, cyclophosphamide, vincristine, L-asparaginase, etoposide, cytarabine, or cytotoxic antibiotics. These genes can also be affected by genetic alterations that could therefore have clinical consequences. In this review we will discuss recent data on this field, with special focus on those polymorphisms that could be used in clinical practice to tailor chemotherapy for ALL in order to reduce the occurrence of serious adverse effects.

Germline copy number variations and cancer predisposition

We present an overview of the role of germline copy number variations (CNVs) in cancer predisposition. CNVs represent a significant source of genetic diversity, although the mechanisms by which they influence cancer susceptibility still remain largely unknown. Approximately 100 highly penetrant germline mutant genes are now known to cause cancer predisposition inherited in a Mendelian fashion; in this review, we show that nearly half of these genes have also been observed as rare CNVs associated with cancer. However, these highly penetrant alleles seem to account for less than 5% of all familial cancers. We surmise that most of the genetic risk of cancer in the general population must largely involve genes of low or moderate penetrance. In the last 5 years, studies have demonstrated that although common low penetrant CNVs are modest contributors to cancer individually, their combined impact on cancer predisposition must be taken into account in estimating cancer risk.

Central nervous system chemotoxicity during treatment of pediatric acute lymphoblastic leukemia/lymphoma

In the last decades, increasing success rates are being obtained in the chemotherapy of pediatric leukemia and lymphoma. However, the cornerstone of this treatment is still formed by a reduced number of drugs with a highly toxic profile. In particular, central nervous system complications remain a challenging clinical problem, requiring rapid detection and prompt treatment to limit permanent damage. Furthermore, clinicians are often challenged to discriminate between CNS involvement by the disease, toxicity of drugs or infections. This clinically oriented review will help recognize and handle the main neurologic adverse effects induced by chemotherapy in pediatric patients with lymphoblastic leukemia/lymphoma. Different clinical entities and putative drugs involved are discussed in each chapter, with clinical cases illustrating the most relevant and challenging events. In addition, specific clinical-radiological patterns of some of these neurologic events are detailed. Finally, the role of pharmacogenetics, with special focus on those polymorphisms that could help explain the occurrence of neurotoxicity, is also discussed.

An update on ethnic differences in drug metabolism and toxicity from anti-cancer drugs

INTRODUCTION

Based on recent emerging evidence of inter-ethnic differences in drug response and toxicity, ethnic diversity in pharmacokinetics, pharmacogenomics and clinical outcomes are being increasingly investigated. Ultimately, this will promote improved understanding of inter-individual differences in the pharmacokinetics and tolerance of cytotoxic drugs.

AREAS COVERED

This article reviews potential explanations for the observed ethnic differences in treatment outcomes and provides clinical data to support this concept. A literature search was implemented on PubMed and PharmGKB to investigate the areas of ethnic differences in pharmacogenomics, pharmacogenetics and clinical outcomes of cancer therapies.

EXPERT OPINION

There has been a relative paucity of clinical evidence linking genetic polymorphisms of genes encoding drug-metabolizing enzymes to the pharmacokinetics, pharmacodynamics and tolerance of anti-cancer drugs. Future research should focus on studies using large sample sizes, in the hope that they will provide results of high clinical significance. Due to the potential for ethnic differences to impact on both toxicities and benefits of systemic cancer therapies, the development of new therapeutic agents should include patients from diverse geographical ancestries in each phase of drug development.

Chemotherapy-induced peripheral neurotoxicity in the era of pharmacogenomics

Development of advanced and high-throughput methods to study variability in human genes means we can now use pharmacogenomic analysis not only to predict response to treatment but also to assess the toxic action of drugs on normal cells (so-called toxicogenomics). This technological progress could enable us to identify individuals at high and low risk for a given side-effect. Pharmacogenomics could be very useful for stratification of cancer patients at risk of developing chemotherapy-induced peripheral neurotoxicity, one of the most severe and potentially permanent non-haematological side-effects of modern chemotherapeutic agents. However, study data reported so far are inconsistent, which suggests that methodological improvement is needed in clinical trials to obtain reliable results in this clinically relevant area.

Evaluation of current and upcoming therapies in oral mucositis prevention

Cancer chemotherapy has evolved from a few therapeutic agents in three drug classes to more than 50 drugs in over ten drug classes. With generally cytotoxic mechanisms of action, there is continued research interest in preventing and managing adverse events of chemotherapy. Although treatment-induced symptom management has made significant progress, most therapies lead to intolerable reactions that result in a dose reduction or discontinuation of therapy. Mucositis is a common adverse event that can occur after administration of systemic chemotherapy and/or radiation therapy leading to inflammatory lesions anywhere from the oral cavity to the GI tract. Although pathophysiologically similar, gastrointestinal mucositis and oral mucositis (OM) differ in terms of symptom presentation and offending therapies. The focus of the article will be on OM; gastrointestinal mucositis will be mentioned when therapy efficacy is relevant to OM. OM prophylaxis has been a subject of interest for at least the past 30 years, yet progress has been limited due to a lack of understanding of the condition. With the recent introduction of palifermin (Kepivance™), novel therapies continue to be developed that may significantly reduce the incidence, duration and/or severity of OM. In addition, outcomes including an improvement in patient quality of life, increasing treatment dose intensity or reducing healthcare costs may result from successful management of OM prophylaxis. This article will review currently available OM prophylactic therapies. Agents in preclinical or clinical development and natural supplements will also be discussed.

Copy number variants in pharmacogenetic genes

Variation in drug efficacy and toxicity remains an important clinical concern. Presently, single nucleotide polymorphisms (SNPs) only explain a portion of this problem, even in situations where the pharmacological trait is clearly heritable. The Human CNV Project identified copy number variations (CNVs) across approximately 12% of the human genome, and these CNVs were considered causes of diseases. Although the contribution of CNVs to the pathogenesis of many common diseases is questionable, CNVs play a clear role in drug-related genes by altering drug metabolizing and drug response. In this review, we provide a comprehensive evaluation of the clinical relevance of CNVs to drug efficacy, toxicity, and disease prevalence in world populations, and discuss the implication of using CNVs as a diagnostic tool in clinical intervention.

Male gender is an adverse prognostic factor in B-cell lymphoma patients treated with immunochemotherapy

Male gender is an adverse prognostic factor in Hodgkin's lymphoma, but no such association has yet been established in non-Hodgkin lymphomas. Here, we have evaluated whether gender has prognostic impact on the survival of patients with B-cell non-Hodgkin lymphoma in the postrituximab era of lymphoma therapies. The study populations consisted of 217 diffuse large B-cell lymphoma (DLBCL) and 110 follicular lymphoma (FL) patients treated with immunochemotherapy. Hundred and sixty chemotherapy-treated DLBCL patients served as a control group. According to Kaplan-Meier analyses, female patients had a significantly better progression-free survival than men both in DLBCL (4 yr PFS 75% vs. 60%; P= 0.013) and in FL (4 yr PFS 68% vs. 52%, P=0.036) patients treated with immunochemotherapy. In chemotherapy-treated DLBCL patients, no difference in survival between the genders was found. The results support the idea that women seem to respond better to rituximab.