An Expert Review of Pharmacogenomics of Sickle Cell Disease Therapeutics: Not Yet Ready for Global Precision Medicine

Pharmacogenomics of Drugs Used in β-Thalassemia and Sickle-Cell Disease: From Basic Research to Clinical Applications

In this short review we have presented and discussed studies on pharmacogenomics (also termed pharmacogenetics) of the drugs employed in the treatment of β-thalassemia or Sickle-cell disease (SCD). This field of investigation is relevant, since it is expected to help clinicians select the appropriate drug and the correct dosage for each patient. We first discussed the search for DNA polymorphisms associated with a high expression of γ-globin genes and identified this using GWAS studies and CRISPR-based gene editing approaches. We then presented validated DNA polymorphisms associated with a high HbF production (including, but not limited to the HBG2 XmnI polymorphism and those related to the BCL11A, MYB, KLF-1, and LYAR genes). The expression of microRNAs involved in the regulation of γ-globin genes was also presented in the context of pharmacomiRNomics. Then, the pharmacogenomics of validated fetal hemoglobin inducers (hydroxyurea, butyrate and butyrate analogues, thalidomide, and sirolimus), of iron chelators, and of analgesics in the pain management of SCD patients were considered. Finally, we discuss current clinical trials, as well as international research networks focusing on clinical issues related to pharmacogenomics in hematological diseases.

Opportunity for pharmacogenetics testing in patients with sickle cell anemia

Background: Patients with sickle cell disease (SCD) are exposed to numerous drugs over their lifespan, and many of these drugs have Clinical Pharmacogenetics Implementation Consortium (CPIC) guidelines for personalized dosing. The authors' aim was to ascertain the number of drugs with CPIC guidelines prescribed to SCD patients. Materials & methods: A search of Indiana University Health affiliated hospitals' electronic medical record identified 957 patients with a diagnosis of SCD. Drugs or drug classes with CPIC actionable guidelines ordered as inpatient and outpatient prescriptions were collected from SCD patients. Results: During the 16-year period, 892 (93%) patients received at least one drug that could have been dosed according to CPIC guidelines. Conclusion: Preemptive pharmacogenetics testing should be considered in SCD patients in order to utilize these data throughout the patient's life.

Emerging drugs for the treatment of sickle cell disease: a review of phase II/III trials

INTRODUCTION

The substitution of glutamic acid by valine on the ß-globin gene produces the hemoglobin S variant responsible for sickle cell disease (SCD), a disorder that affects millions of people worldwide and leads to acute and cumulative organ damage. Even though life expectancy has significantly improved where the best medical care is available, there are still few therapeutic options for SCD and those are limited by their availability, cost, and individual toxicities.

AREAS COVERED

This review summarizes the clinical data on current treatments for SCD and emerging therapies studied in the acute setting as well as potential disease-modifying agents, with an emphasis on the FDA-approved agents.

EXPERT OPINION

Hydroxyurea has been a gold standard for two decades, showing benefits in acute complications and overall survival in sickle cell anemia, although data is lacking for certain genotypes such as hemoglobin SC. As progress is made in our understanding of the pathophysiological networks characterizing SCD, numerous pathways appear to be targetable, with L-glutamine, Crizanlizumab and Voxelotor now approved by the FDA. Pursuing a multi-agent approach could alter the disease course in a more effective fashion and provide an alternative option to curative therapies, but longer clinical studies are needed.

Effects of arginase genetic polymorphisms on nitric oxide formation in healthy pregnancy and in preeclampsia

BACKGROUND AND AIMS

Preeclampsia is associated with reduced nitric oxide (NO) bioavailability. Arginase is related to NO synthesis, but relatively unexplored in preeclampsia. However, no previous study has examined whether variations in ARG1 and ARG2 genes affect NO bioavailability and the risk of preeclampsia. Here, we compared the alleles and genotypes of single nucleotide polymorphisms (SNPs) in ARG1 (rs2781659; rs2781667; rs2246012; rs17599586) and ARG2 (rs3742879; rs10483801) in healthy pregnant women and preeclampsia, and examined whether these SNPs affect plasma nitrite concentrations (a marker of NO formation) in these groups.

METHODS

Genotypes for the ARG1 and ARG2 SNPs were determined by Taqman probe and plasma nitrite by an ozone-based chemiluminescence assay.

RESULTS

Regarding ARG1 SNPs, the GG genotype and G allele frequencies for rs2781659, and the C allele frequencies for rs2246012 were higher in preeclampsia compared to healthy pregnant women. Moreover, the GG genotype for rs2781659 and the TT genotype for rs2781667 were associated with higher plasma nitrite in healthy pregnant. We found no association of ARG2 polymorphisms with preeclampsia or nitrite levels in the study groups.

CONCLUSIONS

Our results suggest that SNPs of ARG1 increase the risk of preeclampsia and modulate plasma nitrite levels in healthy pregnant women.

Clinical implementation of pharmacogenetics and model-informed precision dosing to improve patient care

Providing maximal therapeutic efficacy without toxicity is a universal goal of rational drug therapy. However, substantial between-patient variability in drug response often impedes such successful treatments and brings the necessity of tailoring drug dose to individual needs for more precise therapy. In many cases plenty of patient characteristics, such as body size, genetic makeup and environmental factors, need to be taken into consideration to find the optimal dose in clinical practice. A pharmacokinetics and pharmacodynamics (PK/PD) model-informed approach offers integration of various patient information to provide an expectation of drug response and derive practical dose estimates to support clinicians' dosing decisions. Such an approach was pioneered in the late 1970s, but its broad clinical acceptance and implementation have been hampered by the lack of widespread computer technology, including user-friendly software tools. This has significantly changed in recent years. With the advent of electronic health records (EHRs) and the ubiquity of user-friendly software tools, we now experience a convergence of clinical information, pharmacogenetics, systems pharmacology and pharmacometrics, and technology. Advanced pharmacometrics research is now more appliable and implementable to improve health care. This article presents examples of successful development and implementation of pharmacogenetics-guided and PK/PD model-informed decision support to facilitate precision dosing, including the development of an EHR-embedded decision support tool. Through the integration of clinical decision support tools in EHRs, clinical pharmacometrics support can be brought directly to the clinical team and the bedside.

The association of HBG2, BCL11A, and HBS1L-MYB polymorphisms to thalidomide response in Chinese β-thalassemia patients

Thalidomide has been shown to reactivate fetal hemoglobin (HbF) production and reduce the need for blood transfusions in β-thalassemia patients. However, some patients show a minor response or no response to thalidomide. In view of its potential side effects, targeted prescription of thalidomide is imperative. We initially aimed to explore the relevance of HBG2 (rs7482144), BCL11A (rs11886868, rs4671393, rs766432 and rs1427407) and HBS1L-MYB (rs9399137, rs4895440 and rs4895441) single nucleotide polymorphisms (SNPs) in thalidomide response. Eight SNPs were investigated by PCR and DNA sequencing, and their roles in thalidomide response in Chinese β-thalassemia patients were assessed. Results demonstrated that minor alleles of four SNPs were associated with an increased main response risk (rs7482144: P = 0.015; rs9399137: OR = 4.911, P = 0.029; rs4895440: OR = 4.522, P = 0.040; and rs4895441: OR = 4.522, P = 0.040). For patients with non-transfusion-dependent thalassemia (NTDT), with an increase in the minor allele numbers of rs7482144 (P = 0.011), rs9399137 (P = 0.013), rs4895440 (P = 0.011) and rs4895441 (P = 0.011), Hb increments after treatment were increased significantly as well. The cumulative effects of patients carrying any combination of one or three significant minor alleles included a gradually increased main response risk compared to those without the significant minor alleles (P = 0.040-0.018, OR = 8.556-11.000). Furthermore, Hb increments after treatment correlated with cumulative numbers of minor alleles in the four significant SNPs among patients with NTDT (P = 0.001). It was demonstrated that SNPs in HBG2 and HBS1L-MYB contributed significantly to thalidomide response in Chinese patients with β-thalassemia and that the cumulative number of minor SNP alleles may serve as good predictors of treatment response in this population.

Emerging drugs in randomized controlled trials for sickle cell disease: are we on the brink of a new era in research and treatment?

Introduction: Sickle cell disease (SCD) is caused by a mutation in the HBB gene which is key for making a component of hemoglobin. The mutation leads to the formation of an abnormal hemoglobin molecule called sickle hemoglobin (HbS). SCD is a chronic, complex disease with a multiplicity of pathophysiological targets; it has high morbidity and mortality.Hydroxyurea has for many years been the only approved drug for SCD; hence, the development of new therapeutics is critical.Areas covered: This article offers an overview of the key studies of new therapeutic options for SCD. We searched the PubMed database and Cochrane Database of Systemic Reviews for agents in early phase clinic trials and preclinical development.Expert opinion: Although knowledge of SCD has progressed, patient survival and quality of life must be improved. Phase II and phase III clinical trials investigating pathophysiology-based novel agents show promising results in the clinical management of SCD acute events. The design of long-term clinical studies is necessary to fully understand the clinical impact of these new therapeutics on the natural history of the disease. Furthermore, the building of global collaborations will enhance the clinical management of SCD and the design of primary outcomes of future clinical trials.

Pharmacoproteomics Profiling of Plasma From β-Thalassemia Patients in Response to Hydroxyurea Treatment

β-Thalassemia is a genetic disorder caused by defects in the β-globin gene resulting in the absence or reduced synthesis of adult hemoglobin (HbA). Hydroxyurea is an effective drug to increase fetal γ-globin (HbF) expression, replacing the missing adult β-globin. The mechanism of HbF induction by hydroxyurea and improvement in clinical symptoms are still poorly understood. In the present study we performed comparative analysis of plasma proteome in pre- and post-hydroxyurea-treated β-thalassemia major transfusion-dependent children (n = 10, mean age = 3.2 years) as well as responders versus nonresponders to hydroxyurea treatment. Plasma was collected before and after 6 months of hydroxyurea treatment, with patients subcategorized on the basis of their response to hydroxyurea. Among 400 identified proteins using a label-free quantitative proteomics approach, 28 proteins were found to be significantly different in pre- versus post-hydroxyurea-treated groups, with transferrin receptor protein-1 being most downregulated and hemopexin and haptoglobin the most upregulated proteins after treatment. In responder versus nonresponder comparison, 26 proteins were found to be differentially expressed, with carbonic anhydrase 1, hemoglobin subunit γ-1, and peroxiredoxin-2 showing the significant changes. The mechanism of hydroxyurea treatment in β-thalassemia patients appears to be complex, requiring a large sample size and a longer period of treatment to reveal its details.

Clinical and genetic factors are associated with pain and hospitalisation rates in sickle cell anaemia in Cameroon

We aimed to investigate the clinical and genetic predictors of painful vaso-occlusive crises (VOC) in sickle cell disease (SCD) in Cameroon. Socio-demographics, clinical variables/events and haematological indices were acquired. Genotyping was performed for 40 variants in 17 pain-related genes, three fetal haemoglobin (HbF)-promoting loci, two kidney dysfunctions-related genes, and HBA1/HBA2 genes. Statistical models using regression frameworks were performed in R^® . A total of 436 hydoxycarbamide- and opioid-naïve patients were studied; median age was 16 years. Female sex, body mass index, Hb/HbF, blood transfusions, leucocytosis and consultation or hospitalisation rates significantly correlated with VOC. Three pain-related genes variants correlated with VOC (CACNA2D3-rs6777055, P = 0·025; DRD2-rs4274224, P = 0·037; KCNS1-rs734784, P = 0·01). Five pain-related genes variants correlated with hospitalisation/consultation rates. (COMT-rs6269, P = 0·027; FAAH-rs4141964, P = 0·003; OPRM1-rs1799971, P = 0·031; ADRB2-rs1042713; P < 0·001; UGT2B7-rs7438135, P = 0·037). The 3·7 kb HBA1/HBA2 deletion correlated with increased VOC (P = 0·002). HbF-promoting loci variants correlated with decreased hospitalisation (BCL11A-rs4671393, P = 0·026; HBS1L-MYB-rs28384513, P = 0·01). APOL1 G1/G2 correlated with increased hospitalisation (P = 0·048). This first study from Africa has provided evidence supporting possible development of genetic risk model for pain in SCD.

David Bowie and the Art of Slow Innovation: A Fast-Second Winner Strategy for Biotechnology and Precision Medicine Global Development

Original ideas and innovation cannot always be ordered like a courier service and delivered fresh to our desk at 9 am. Yet, most creativity-based organizations, careers, and professions, science and biotechnology innovation included, emphasize the speed as the prevailing ideology. But a narrow focus on speed has several and overlooked shortcomings. For example, it does not offer the opportunity to draw from, and stitch together disparate concepts and practices for truly disruptive innovation. Preventing false starts, learning from others' or our own mistakes, and customizing innovations for local community needs are difficult in a speed-hungry innovation ecosystem. We introduce a new strategy, the Fast-Second Winner, specifically in relation to global development of biotechnologies and precision medicine. This à la carte global development strategy envisions a midstream entry into the innovation ecosystem. Moreover, we draw from the works of the late David Bowie who defied rigid classifications as an artist and prolific innovator, and introduce the concept and practice of slow innovation that bodes well with the Fast-Second Winner strategy. A type of slow innovation, the Fast-Second Winner is actually fast and sustainable in the long term, and efficient by reducing false starts in new precision medicine application contexts and geographies, learning from other innovators' failures, and shaping innovations for the local community needs. The establishment of Centers for Fast-Second Innovation (CFSIs), and their funding, for example, by crowdfunding and other innovative mechanisms, could be timely for omics and precision medicine global development. If precision medicine is about tailoring drug treatments and various health interventions to individuals, we suggest to start from tailoring new ideas, and focus not only on how much we innovate but also what and how we innovate. In principle, the Fast-Second Winner can be applied to omics and other biotechnology responsible development in medical practice or any field of applied innovation.

National nursing science priorities: Creating a shared vision

BACKGROUND

Nursing science is essential to advance population health through contributions at all phases of scientific inquiry. Multiple scientific initiatives important to nursing science overlap in aims and population focus.

PURPOSE

This article focused on providing the American Academy of Nursing and nurse scientists in the Unites States with a blueprint of nursing science priorities to inform a shared vision for future collaborations, areas of scientific inquiry, and resource allocation.

METHODS

The Science Committee convened four times and using Delphi methods identified priorities with empirical evidence and expert opinion for prioritization, state of the science, expert interest, and potential target stakeholders.

DISCUSSION

Nursing science priorities for 2017 were categorized into four themes including: (a) precision science, (b) big data and data analytics, (c) determinants of health, and (d) global health.

CONCLUSION

Nurse scientists can generate new knowledge in priority areas that advances the health of the world's populations.

Key Pharmacogenomic Considerations for Sickle Cell Disease Patients

Sickle cell disease (SCD), although a monogenic disease, exhibits a complex clinical phenotype that hampers optimum patient stratification and disease management, especially on hydroxyurea treatment. Moreover, theranostics, the combination of diagnostics to individualize and optimize therapeutic interventions, has not been firmly on the forefront of SCD research and clinical management to date. We suggest that if tailor-made theranostics in SCD is envisaged, pharmacogenomics is anticipated to be the way forward. Herein, we present the current key pharmacogenomic opportunities and challenges in SCD, considering population variation, ethics, and socioeconomic aspects. We focus on pharmacogenomics and pain management, genethics, and cost-effectiveness in SCD. We searched for and synthesized data from PubMed and Google Scholar, and the references from relevant articles, using the keywords "pharmacogenomics," "sickle cell disease," "hydroxyurea," "ethics," "pain management," "morphine metabolism," "opioids," "pharmacogenomics and chronic pain," "cost-effectiveness," and "economic evaluation." Only articles published in English were included. So far, when pharmacogenomics in SCD has been considered, interindividual variability in hydroxyurea response/toxicity has been of primary interest. We underscore the need to extend pharmacogenomic considerations on other therapeutic interventions currently present using a holistic patient-centric approach, and taking disease complications into account as well. Furthermore, we raise awareness toward socioeconomic, ethical, and population differences in the way sickle cell pharmacogenomics might unfold in the future. If pharmacogenomics in SCD is to be used in the clinic in an evidence-based manner, cost-effectiveness and population-specific empirical ethics data are urgently needed.