Vpliv genetskih polimorfizmov rs12201199, rs2278294 in rs2228075 na aktivnost izbranih encimov v presnovi tiopurinov in odmerjanje 6-merkaptopurina

Klančnik, Nika (avtor), Šmid, Alenka (mentor), Urbančič, Dunja (komentor)

Tiopurini, med katerimi je ključen 6-merkaptopurin, predstavljajo temelj zdravljenja pediatrične akutne limfoblastne levkemije, pri čemer je zaradi njihovega ozkega terapevtskega okna ter tveganja za toksičnost ali neučinkovitost optimizacija odmerjanja ključnega pomena. Za tiopurine je značilen razvejan metabolizem. Spremenjena aktivnost encimov, ki sodelujejo pri njihovi pretvorbi, med njimi tiopurin S-metiltransferaza in inozin-5'-monofosfat dehidrogenaza, je odgovorna za del variabilnega odziva na tiopurine. Namen magistrske naloge je bil preučiti vpliv genetskih polimorfizmov rs12201199 v genu TPMT ter rs2278294 in rs2228075 v genu IMPDH1 na encimsko aktivnost, odmerjanje 6-merkaptopurina in pojav neželenih učinkov med vzdrževalnim zdravljenjem akutne limfoblastne levkemije. V raziskavo smo vključili dve neodvisni skupini: 160 posameznikov zdrave slovenske populacije za vrednotenje encimske aktivnosti in 42 pediatričnih bolnikov z akutno limfoblastno levkemijo za retrospektivno analizo kliničnih podatkov. Aktivnosti encimov tiopurin S-metiltransferaze in inozin-5'-monofosfat dehidrogenaze v hemolizatih smo izmerili s tekočinsko kromatografijo visoke ločljivosti ter izvedli genotipizacijo preučevanih različic s hidrolizirajočimi sondami. Rezultati so pokazali, da ima v zdravi slovenski populaciji statistično značilen vpliv na encimsko aktivnost različica rs12201199, kjer so nosilci variantnega genotipa izkazovali nižjo aktivnost tiopurin S-metiltransferaze, a je učinek ob izključitvi posameznikov z alelom TPMT*3 postal statistično neznačilen. Polimorfizma v genu IMPDH1 nista statistično značilno vplivala na aktivnost encima inozin-5'-monofosfat dehidrogenaza. Pri analizi podatkov bolnikov z akutno limfoblastno levkemijo nismo zabeležili statistično značilnih razlik v relativnem kumulativnem odmerku 6-merkaptopurina ali indikatorjih hepatotoksičnosti glede na preučevane genotipe. Podrobnejši pregled diferencialne krvne slike je razkril trende pri polimorfizmih rs2278294 in rs2228075, kjer so imeli posamezniki s prisotnim vsaj enim variantnim alelom višji delež nevtrofilcev in nižji delež limfocitov. Odsotnost končne statistične značilnosti pripisujemo omejeni velikosti preučevane populacije. Z raziskavo smo uspešno prispevali k farmakogenetskemu karakteriziranju slovenske populacije, izraženi trendi pa spodbujajo nadaljnje farmakogenetske raziskave teh polimorfizmov kot potencialnih dodatnih označevalcev za varno in personalizirano optimizacijo terapije s tiopurini.

• Jezik: Slovenski jezik
• Ključne besede: tiopurini, TPMT, IMPDH1, farmakogenetika, akutna limfoblastna levkemija, mielosupresija.
• Vrsta gradiva: Magistrsko delo/naloga
• Tipologija: 2.09 - Magistrsko delo
• Organizacija: FFA - Fakulteta za farmacijo
• Založnik: [N. Klančnik]
• Leto izida: 2026
• PID: 20.500.12556/RUL-188073
• UDK: 615.015:575(043.2)
• COBISS.SI-ID: 291844867
• Datum objave v RUL: 18.09.2026

Sekundarni jezik

• Jezik: Angleški jezik
• Naslov: Influence of genetic polymorphisms rs12201199, rs2278294, and rs2228075 on activities of selected enzymes involved in tiopurine metabolism and dosing of 6-mercaptopurine

Izvleček

Thiopurines, notably 6-mercaptopurine, represent the cornerstone of treatment for pediatric acute lymphoblastic leukemia, where dosage optimization is critical due to their narrow therapeutic window and the risks of severe toxicity or therapeutic failure. Thiopurines have a complex metabolic pathway. Altered activity of the enzymes involved, including thiopurine S-methyltransferase and inosine-5'-monophosphate dehydrogenase, accounts for part of the interindividual variability in response to thiopurines. This thesis aimed to study the impact of genetic polymorphisms rs12201199 in the TPMT gene, and rs2278294 and rs2228075 in the IMPDH1 gene, on enzyme activity, 6-mercaptopurine dosing, and adverse effects during maintenance therapy for acute lymphoblastic leukemia. The study included two independent cohorts: 160 healthy Slovenian individuals for enzyme activity evaluation and 42 pediatric acute lymphoblastic leukemia patients for a retrospective clinical data analysis. Thiopurine S-methyltransferase and inosine-5'-monophosphate dehydrogenase enzyme activities in hemolysates were measured by high-performance liquid chromatography, and genotyping of the studied variants was performed using hydrolysis probes. Results showed that within the healthy Slovenian population, the rs12201199 significantly impacted enzyme activity, with variant genotype carriers exhibiting lower thiopurine S-methyltransferase activity; however, after excluding individuals carrying the TPMT*3 allele, this effect became statistically not significant. IMPDH1 polymorphisms did not exert a statistically significant effect on inosine-5'-monophosphate dehydrogenase activity. In the clinical data analysis of acute lymphoblastic leukemia patients, no significant differences were observed in the relative cumulative 6-mercaptopurine dose or indicators of hepatotoxicity across the studied genotypes. A detailed analysis of the differential blood count revealed trends for the rs2278294 and rs2228075 polymorphisms, where carriers of at least one variant allele exhibited a higher percentage of neutrophils and a lower percentage of lymphocytes. The lack of definitive statistical significance is attributed to the limited size of the study population. This study successfully contributes to the pharmacogenetic characterization of the Slovenian population, and the observed trends warrant further pharmacogenetic research into these polymorphisms as potential additional biomarkers for safe and personalized optimization of thiopurine therapy.

• Ključne besede: thiopurines, TPMT, IMPDH1, pharmacogenetics, acute lymphoblastic leukemia, myelosuppression.