A személyre szabott terápia legújabb lehetőségei a molekuláris onkológiában

Abstract

Összefoglaló. A molekuláris onkológia térnyerésével számos új lehetőség érhető el a daganatos betegek hatékonyabb kezelésére. Ilyen a klinikai vizsgálatokban alkalmazott, a valóban személyre szabott kezelést elősegítő génpanelelemzés, illetve a célzott kezelés szövettípustól független alkalmazása. A személyre szabott terápiák jelentős hányada valamelyik kinázt gátolja. Az összefoglalónkban bemutatjuk a RAS jelátviteli út sejten belüli komplex szabályozását, valamint ismertetjük az útvonal további farmakológiai szempontból kiaknázható célpontjait nemzetközi és saját eredményeink alapján. A kinázokat érintő gyakori mutációk ellenére számos daganattípusban nem áll rendelkezésre személyre szabott terápia. A hagyományos terápiával nem kezelhető agydaganatok példáján keresztül bemutatjuk a tirozin-kinázok várható jövőbeli terápiás jelentőségét. Summary. With the advent of molecular oncology, the identification of mutations in solid tumours is now clinically routine. The growing repertoire of targeted therapeutic agents has supported the rise of a new type of clinical trial in which the selection of the therapeutic agent is no longer restricted to a single option. Instead, a panel of genes is screened to identify the most suitable drug for each patient. Such trials have delivered objective response rates in 5–30% of patients. Most of the signal transduction pathways targeted by these agents involves RAS signaling. Somatic mutations in RAS genes are common in human tumours. Such mutations generally decrease the ability of RAS to hydrolyze GTP, maintaining the protein in a constitutively active GTP-bound form that drives uncontrolled cell proliferation. Recent emerging data suggest that RAS regulation is more complex than the scientific community has appreciated for decades. We discuss a novel type of RAS regulation that involves direct phosphorylation and dephosphorylation of RAS tyrosine residues. The discovery that pharmacological inhibition of the tyrosine phosphoprotein phosphatase SHP2 maintains mutant Ras in an inactive state suggests that SHP2 could be a novel drug target for the treatment of Ras-driven human cancers. In addition to RAS gene mutations, other common oncogenic events have also been identified, including mutation of EGFR (epidermal growth factor receptor) or BRAF (isoform B of rapidly accelerated fibrosarcoma). EGFR has tyrosine kinase activity while BRAF acts as a serine/threonine kinase. In some tumours, mutant forms of these kinases over-activate cell proliferation, leading to uncontrolled tumour cell growth; therefore, it seems rational to develop inhibitor molecules that target these hyper-active oncogenic kinases to reduce tumour cell burden in cancer patients. Fusion protein kinases activated via the RAS pathway represent target proteins with high clinical success rates. Recently approved TRK fusion protein kinase inhibitors have reached response rates in almost 80% of patients regardless of tumour type. Although these drugs can only be administered to patients whose tumours harbour a TRK fusion protein, such success stories pave the way for future development of agents that target similar genetic mutations. Glioblastoma multiforme, a relatively frequent, almost uniformly fatal brain tumour, has ubiquitous alterations in tyrosine-kinase signalling. Nevertheless, to this day, no tyrosine-kinase inhibitors have been approved for its treatment. We have ongoing research projects to uncover associations between initial gene expression levels in untreated glioblastoma samples and treatment-related survival, and we have identified overexpression of druggable tyrosine-kinase receptors in chemotherapy-resistant patients. Our approach will help to identify patients who might benefit from concurrent use of tyrosine kinase inhibitors and conventional cytotoxic therapies.