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Fulltext Economic evaluations of personalized medicine: existing challenges and current developments

Shabaruddin FH, Fleeman ND, Payne K

Pharmgenomics Pers Med, 2015;8:115-26.
PMID: 26309416 DOI: 10.2147/PGPM.S35063

Personalized medicine, with the aim of safely, effectively, and cost-effectively targeting treatment to a prespecified patient population, has always been a long-time goal within health care. It is often argued that personalizing treatment will inevitably improve clinical outcomes for patients and help achieve more effective use of health care resources. Demand is increasing for demonstrable evidence of clinical and cost-effectiveness to support the use of personalized medicine in health care. This paper begins with an overview of the existing challenges in conducting economic evaluations of genetics- and genomics-targeted technologies, as an example of personalized medicine. Our paper illustrates the complexity of the challenges faced by these technologies by highlighting the variations in the issues faced by diagnostic tests for somatic variations, generally referring to genetic variation in a tumor, and germline variations, generally referring to inherited genetic variation in enzymes involved in drug metabolic pathways. These tests are typically aimed at stratifying patient populations into subgroups on the basis of clinical effectiveness (response) or safety (avoidance of adverse events). The paper summarizes the data requirements for economic evaluations of genetics and genomics-based technologies while outlining that the main challenges relating to data requirements revolve around the availability and quality of existing data. We conclude by discussing current developments aimed to address the challenges of assessing the cost-effectiveness of genetics and genomics-based technologies, which revolve around two central issues that are interlinked: the need to adapt available evaluation methods and identifying who is responsible for generating evidence for these technologies.
Fulltext Inconsistency in race and ethnic classification in pharmacogenetics studies and its potential clinical implications

Zhang F, Finkelstein J

Pharmgenomics Pers Med, 2019;12:107-123.
PMID: 31308725 DOI: 10.2147/PGPM.S207449

Introduction: Racial and ethnic categories are frequently used in pharmacogenetics literature to stratify patients; however, these categories can be inconsistent across different studies. To address the ongoing debate on the applicability of traditional concepts of race and ethnicity in the context of precision medicine, we aimed to review the application of current racial and ethnic categories in pharmacogenetics and its potential impact on clinical care.
Methods: One hundred and three total pharmacogenetics papers involving the CYP2C9, CYP2C19, and CYP2D6 genes were analyzed for their country of origin, racial, and ethnic categories used, and allele frequency data. Correspondence between the major continental racial categories promulgated by National Institutes of Health (NIH) and those reported by the pharmacogenetics papers was evaluated.
Results: The racial and ethnic categories used in the papers we analyzed were highly heterogeneous. In total, we found 66 different racial and ethnic categories used which fall under the NIH race category "White", 47 different racial and ethnic categories for "Asian", and 62 different categories for "Black". The number of categories used varied widely based on country of origin: Japan used the highest number of different categories for "White" with 17, Malaysia used the highest number for "Asian" with 24, and the US used the highest number for "Black" with 28. Significant variation in allele frequency between different ethnic subgroups was identified within 3 major continental racial categories.
Conclusion: Our analysis showed that racial and ethnic classification is highly inconsistent across different papers as well as between different countries. Evidence-based consensus is necessary for optimal use of self-identified race as well as geographical ancestry in pharmacogenetics. Common taxonomy of geographical ancestry which reflects specifics of particular countries and is accepted by the entire scientific community can facilitate reproducible pharmacogenetic research and clinical implementation of its results.
Fulltext ABCB1 genetic variants in leukemias: current insights into treatment outcomes

Ankathil R

Pharmgenomics Pers Med, 2017;10:169-181.
PMID: 28546766 DOI: 10.2147/PGPM.S105208

Despite improvements in treatment of different types of leukemia, not all patients respond optimally for a particular treatment. Some treatments will work better for some, while being harmful or ineffective for others. This is due to genetic variation in the form of single-nucleotide polymorphisms (SNPs) that affect gene expression or function and cause inherited interindividual differences in the metabolism and disposition of drugs. Drug transporters are one of the determinants governing the pharmacokinetic profile of chemotherapeutic drugs. The ABCB1 transporter gene transports a wide range of drugs, including drugs used in leukemia treatment. Polymorphisms in the ABCB1 gene do affect intrinsic resistance and pharmacokinetics of several drugs used in leukemia treatment protocols and thereby affect the efficacy of treatment and event-free survival. This review focuses on the impact of three commonly occurring SNPs (1236C>T, 2677G>T/A, and 3435C>T) of ABCB1 on treatment response of various types of leukemia. From the literature available, some of the genotypes and haplotypes of these SNPs have been found to be potential determinants of interindividual variability in drug disposition and pharmacologic response in different types of leukemia. However, due to inconsistencies in the results observed across the studies, additional studies, considering novel genomic methodologies, comprehensive definition of clinical phenotypes, adequate sample size, and uniformity in all the confounding factors, are warranted.
Association of the Reduced Function Met420del Polymorphism of SLC22A1 with Metformin-Induced Gastrointestinal Intolerance in Ethiopian Patients with Type 2 Diabetes Mellitus

Degaga A, Sirgu S, Huri HZ, Sim MS, Loganadan NK, Kebede T, et al.

Pharmgenomics Pers Med, 2024;17:183-191.
PMID: 38715682 DOI: 10.2147/PGPM.S457374

BACKGROUND: Despite its widespread use and favored profile, there are extensive variations in the treatment outcome of metformin therapy. Furthermore, studies reported that the inter-individual variability in the occurrence of metformin treatment associated side effects were related to the differences in individual genetic profiles. Thus, this study aimed to evaluate whether the reduced function methionine deletion at codon 420 (Met420del) variant of SLC22A1 (rs72552763) is associated with metformin induced gastrointestinal intolerance in Ethiopian patients with type 2 diabetes mellitus (T2DM).
PATIENTS AND METHODS: A retrospective observational study was conducted on 47 T2DM patients on metformin treatment for <3 years to assess the association of SLC22A1 (rs72552763) polymorphism with metformin induced gastrointestinal intolerance. Accordingly, 24 metformin tolerant and 23 metformin intolerant individuals with T2DM were recruited. Genotyping of rs72552763 was performed using TaqMan® Drug Metabolism Enzyme Genotyping Assay and its association to metformin induced gastrointestinal intolerance was assessed based on switching to a new class of glucose lowering agents or failure to up titrate dose due to metformin induced gastrointestinal intolerance. Chi-square, logistic regression and Mann-Whitney statistical tests were used as appropriate. Statistical significance was set at p < 0.05.
RESULTS: In our study, no significant association was observed between rs72552763 and metformin induced gastrointestinal intolerance. We found that the female gender and physical inactivity were risk factors for metformin gastrointestinal intolerance.
CONCLUSION: Our study found that the Met420del variant of SLC22A1 (rs72552763) was not associated with metformin induced gastrointestinal intolerance in Ethiopian patients with T2DM. This is the study first to investigate the association of rs72552763 with metformin intolerance in the Ethiopian population with T2DM. However, the findings need to be cautiously interpreted given the relatively small sample size. In addition, a more complete investigation of SLC22A1 variants would be required to fully assess the effect of the gene on metformin induced gastrointestinal intolerance as several variants with a more severe loss of function have been described.