Farmakogenetiska studier av tiopuriner - för skräddarsydd behandling vid inflammatorisk tarmsjukdom och barnleukemi | Application
Farmakogenetiska studier av tiopuriner - för skräddarsydd behandling vid inflammatorisk tarmsjukdom och barnleukemi
Registration number: LIO-8176
Medel för Gästforskare 2006
Application started by: Curt Peterson, 2006-09-14
Professional title at the time of application: Professor/överläkare
Work place at the time of application: Laboratoriemedicinskt centrum, Avdelningen för klinisk kemi och klinisk farmakologi
Last updated / corrected by: Agneta Linghag, 2009-01-20
Application received by: Region Östergötland
Granted and completedGranted and completed
Applicant: Curt Peterson
Professor/överläkare, Avdelningen för klinisk farmakologi

Forskningsområde

Genetik

Ansökan avser:

Medel för GästforskareVi arbetar med att kunna skräddarsy behandling med tiopuriner (azatioprin Imurel, 6-merkaptopurin Puri-nethol och 6-tioguanin Lanvis) efter individens farmakogenetiska konstitution. Medlen är viktiga vid behandling av inflammatoriska tarmsjukdomar (Mb Crohn, ulcerös kolit) och barnleukemi.Medlen är mycket gamla och patenten är utgångna sedan länge varför inget företag driver några studier längre. Icke desto mindre är de mer använda idag än någonsin. De anses verka främst genom bildning av fosforylerade metaboliter som kan inkorporeras i DNA. En alternativ metabolisk väg är metylering via tiopurinmetyltransferas (TPMT), som är ett polymorft enzym dvs vissa individer har en genetisk defekt som leder till brist på enzymet och dessa löper risk för allvarliga t o m dödliga biverkningar pga ökad bildning av fosforylerade metaboliter. I Sverige har 10 -15% av befolkningen en brist i heterozygot form och ca 0,5% saknar helt enzymet.
De tre tiopurinerna bildar samma terminala fosforylerade metaboliter men har olika användningsområden: azatioprin mot inflammatorisk tarmsjukdom, 6-merkaptopurin mot barnleukemi och 6-tioguanin mot akut myeloisk leukemi hos äldre. Frågan är om detta endast är tradition eller har biokemiska förklaringar. Vi avser att utröna skillnader och likheter i medlens verkningsmekanismer samt analyserar prover från patienter från hela Sverige (feno- och genotypning av TPMT inför behandling, metabolitbestämningar under behandling) i syfte att individualsiera behandlingen.

Rapport

During the autumn of 2007 Dr Sally Coulthard worked as a visiting scientist from Newcastle University in Prof Curt Peterson’s Laboratory at Linkoping University.
The purpose of the visit was to consolidate collaboration between the two groups both of whom have established reputations in thiopurine research and exchange techniques and ideas.
The main area of research to be focussed on was the cytotoxicity of the thiopurines which include three drugs, 6-thioguanine (6-TG), 6-mercaptopurine (6-MP) and azathioprine. 6-TG and 6-MP are primarily used in the treatment of childhood acute lymphoblastic leukaemia (ALL) and the latter as an immunosuppressant.
The primary cytotoxic effect of 6-TG is through incorporation of 6-thioguanine nucleotides into newly synthesized DNA (TGN), whereas 6-MP also inhibits de novo purine synthesis (DNPS) through the production of methyl-thioinosine monophosphate (MeTIMP), not formed in cells exposed to 6-TG. Conversion of 6-MP to MeTIMP is dependent on thiopurine methyltransferase (TPMT) activity.
Methylthioadenosine phosphorylase, (MTAP) is an enzyme ubiquitously expressed in most tissues except the colon. It is responsible for the salvage of methylthioribose-1-phosphate and adenine from methylthioadenosine. Many cancer patients have deletion or inactivation of this gene, which is situated on chromosome 9p in the tumour cells, but not the normal cells. Deletion or inactivation of this gene renders the cell dependent on DNPS for purine production. It has been suggested by several authors that tumour cells that lack this enzyme would be more sensitive to inhibitors of DNPS compared to the surrounding normal cells and studies using drugs such as methotrexate have shown that indeed MTAP non-expressing cells are more susceptible to inhibitors of DNPS.
Experiments started in Newcastle have shown that Jurkat-TO T-ALL cells (which do not express MTAP), are more sensitive to Jurkat-MTAP cells (Jurkat cells transfected with MTAP cDNA) to inhibitors of DNPS including 6-MP. As azathioprine was not tested one of the goals was therefore to test azathioprine in this model system with the expectation that there would be no difference in sensitivity as a product of azathioprine metabolism is hypoxanthine which would “rescue” the non-MTAP expressing cells from the cytotoxicity of this drug. This was carried out with the expected results.
Experiments were also planned in which MTAP expression would be reduced by siRNA to MTAP. The cells in which this was done were those previously transfected with TPMT cDNA (HEK293-TPMT) which would allow manipulation of expression of this enzyme at the same time as manipulating the MTAP expression levels. This was successfully optimized and publishable results generated. Metabolite measurements after thiopurine treatment of the Jurkat-TO, Jurkat-MTAP and HEK293-TPMT +/- MTAP expression at EC50 values were also measured producing publishable results.
The transfection experiments and the measurement on the metabolites described above will be used together with the data generated by Dr Coulthard in Newcastle on the Jurkat-TO Jurkat-MTAP cells for the preparation of an article to be submitted as a joint publication.

Decision

Decision date: 2006-12-21

Brief description of each costApplied sumDecision SEKDecision comment
Gästforskare
40000 kr x 1,53 = 61200183 600183 600 
Resekostnader
Newcastle - Linköping t o r5 0005 000 
Hyreskostnader
3 x 3500 kr (liten lägenhet Linnégatan)10 50010 500 
Medarbetare 1
Sven Almer, 53000 x 1,53 = 81090 kr/mån243 270120 900 
Medarbetare 2
Malin Lindqvist, täcks av huvudmannens
projektanslag
00 
Drift
täcks av huvudmannens projektanslag00 
sum442 370320 000 

Grant providers for application

Region Östergötland
Fund group: Medel för Gästforskare

Contributes with 320000 SEK


Farmakogenetiska studier av tiopuriner - för skräddarsydd behandling vid inflammatorisk tarmsjukdom och barnleukemi | Application, from Region Östergötland
http://researchweb.org/is/en/lio/ansokan/8176