Doktorsvörn í lyfjafræði - Raul Oswaldo Perez Garcia

Mánudaginn 16. september 2024 ver Raul Oswaldo Perez Garcia doktorsritgerð sína í lyfjafræði við Lyfjafræðideild Háskóla Íslands. Ritgerðin ber heitið: Þróun á nýrri lyfjameðferð við sjónufreknum. Toward a first drug therapy for the treatment of retinitis pigmentosa. Andmælendur eru dr. Eugen Stulz, prófessor við University of Southhampton og dr. Kerstin Forsberg, prófessor við KTH Royal institute of technology. Umsjónarkennari og leiðbeinandi voru Þorsteinn Loftsson, prófessor við Lyfjafræðideild og Nicolaas Schipper, Head of Manufacture við RISE, Research Institutes of Sweden. Auk þeirra sátu í doktorsnefnd Hákon Hrafn Sigurðsson, prófessor og Per H. Svensson, prófessor.

Elvar Örn Viktorsson, varadeildarforseti Lyfjafræðideildar, stjórnar athöfninni sem fer fram í Hátíðasal Háskóla Íslands og hefst kl. 13.00.

Ágrip

Markmið verkefnisins var að þróa lyf sem byggja á efnasameindinni CN03 til meðhöndlunar á retinitis pigmentosa (RP) og öðrum arfgengum sjónhimnuhrörnunarsjúkdómum. Fyrri rannsóknir höfðu sýnt að CN03 hefur áhrif á PR og aðra skylda sjúkdóma. Fyrst var þróað efnaferli til framleiðslu á CN03. Aðferðin byggir á H-fosfónat efnaferlum. Tókst að framleiða 125 g af CN03 sem hafði >99,9% hreinleika. Þá var myndað torleysanlegt sölt af CN03. Átta saltform af CN03 voru mynduð og af þeim voru 21 kristalform auðkennd, meðal annars með XRPD og NMR. Sölt af kalsíum, benethamíni og benzatíni (þ.e. CN03-Ca, CN03-Bnet og CN03-BZ) höfðu minnstu leysni eða 300, 50 og 10 µg/mL, og var CN03-BZ valið til frekari rannsókna. Að lokum voru þrjár náskyldar hliðstæður CN03 samtengdar og virkni þeirra rannsökuð in vitro. Rannsóknirnar sýndu að SP-CN03 hafði sviðuð líffræðileg áhrif á ljósviðtaka og móðurefnið CN03 án þess að valda marktækum eituráhrifum á fumurnar. Oxo-CN03 var óvirkt. Virkasust af þessum þremur afleiðun var díðíó-CN03. Díðíó-CN03 hafði mestu líffræðilega virkni, olli minnstum eiturverkunum og hafði mjög litla vatnsleysni, allt eiginleikar sem gagnast lyfi til meðferðar á RP og gefa á með inndælingu í glerhlaup augans.

Abstract

The goal of this project was to contribute to the pharmaceutical development of CN03, the lead candidate for drug treatment of retinitis pigmentosa (RP) and other inherited retinal degenerations (IRDs). RP is an inherited neurodegeneration of the retina with with currently no treatments available on the market. The first task was to develop a chemical process to manufacture large quantities of CN03. A synthetic strategy was designed which makes use of H-phosphonate chemistry to construct the required 3′,5′-cyclic RP-phosphorothioate. The internal cyclization and sulfurization of the nucleoside 5′-H-phosphonate monoester to afford the 3′,5′-cyclic phosphorothioate could be steered to obtain the desired RP-diastereomer with 90% selectivity over the thermodynamically favored SP-phosphorothioate. About 125 g of the CN03, purity >99.9%, were prepered. Access to larger amouts of the drug compound enabled further pharmaceutical development. Next, solid forms of CN03 with low aqueous solubility were investigated. This was sought in order to extend the half-life of the drug compound in the eye, which is critical to aid in reducing the frequency of intravitreal injections – the most likely route of administration. Eight salt forms of CN03 were synthesized. A total of 21 crystal modifications were identified with XRPD, some of which were characterized further with NMR. The calcium, benethamine, and benzathine salts of CN03 (i.e., CN03-Ca, CN03-Bnet, and CN03-BZ) possessed sub-milligram solubilities in water, or 300, 50, and 10 µg/mL, respectively. CN03-BZ was identified as the most promising CN03 solid form based on the lowest solubility as well as lowest hygroscopicity. Finally, three closely related analogues of CN03 were prepared and their biological effects studied in in vitro RP model. The phosphate analogue and the SP-phosphorothioate diastereomer (oxo-CN03 and SP-CN03) were expected to promote photoreceptor cell degeneration, while the activity of the corresponding phosphorodithioate (dithio-CN03) was unknown. In vitro studies found that SP-CN03 was not toxic to photoreceptors, but instead preserved photoreceptors to a similar level as CN03 itself. Oxo-CN03 was not significantly more toxic than CN03 or SP-CN03, and as expected provided no neuroprotection. The most promising compound was the novel dithio-CN03, which was identified as the least toxic and provided significantly more protection to photoreceptors than current drug candidate CN03. The solubility of dithio-CN03 as a triethylammonium salt was determined to be 1.8 mM, compared to 13.7 mM for the same salt of CN03, which further establishes dithio-CN03 as a potentially more effective drug compound as part of sustained-release formulations for treatment of RP via intravitreal injections.

Um doktorsefnið

Raul Oswaldo Perez Garcia fæddist í Maracaibo á Venezuela árið 1993 og flutti til Noregs þegar hann var 14 ára. Hann hlaut BA-gráðu í Biochemistry & Biotechnology frá Háskólanum í Stavanger í Noregi árið 2015. Raul stundaði meistaranám í Biochemistry við í Mohali á Indlandi frá 2015 og lauk meistaranámi árið 2017. Hann hefur stundað doktorsnám við RISE Research Institutes of Sweden og við Háskóla Íslands frá árinu 2018, undir handleiðslu dr. Nicolaas Schippers og Þorsteins Loftssonar, prófessors emeritus, við Lyfjafræðideild Háskóla Íslands.