Molecular alterations in pediatric brainstem gliomas

BackgroundDiffuse intrinsic pontine gliomas (DIPGs) have a dismal prognosis. Previously, diagnosis was based on a typical clinical presentation and magnetic resonance imaging findings. After the start of the era of biopsies, DIPGs bearing H3 K27 mutations have been reclassified into a novel entity, diffuse midline glioma, based on the presence of this molecular alteration. However, it is not well established how clinically diagnosed DIPG overlap with H3 K27-mutated diffuse midline gliomas, and whether rare long-term survivors also belong to this group. MethodsWe studied tumor samples obtained at diagnosis or upon autopsy from 23 children, including two long-term survivors. Based on clinical, radiological, and histological findings, all tumors were previously diagnosed as DIPGs. All samples were analyzed for genetic alterations by next-generation sequencing (NGS) and for protein expression by immunohistochemistry (IHC). ResultsH3 K27 was mutated in NGS or IHC in 20 patients, excluding both long-term survivors. One of these long-term survivors harbored a mutation in IDH1, formerly considered to be an alteration absent in pediatric diffuse brainstem gliomas. Other altered genes in NGS included TP53 (10 patients), MET and PDGFRA (3 patients each), VEGFR and SMARCA4 (2 patients each), and PPAR, PTEN and EGFR in 1 patient, respectively. IHC revealed cMYC expression in 15 of 24 (63%) of all samples, exclusively in the biopsies. ConclusionsEighty-seven percent of the tumors formerly diagnosed as DIPGs could be reclassified as H3 K27-mutated diffuse midline gliomas. Both long-term survivors lacked this alteration. Contrary to former conceptions, IDH1 mutations may occur also in pediatric brainstem gliomas.Peer reviewe

Angiogenesis in Pediatric Malignancies - From Molecular Markers to Therapeutic Applications

Although most children with cancer can be cured, every fifth patient still succumb from their disease. The need for new treatments and more refined diagnostic methods are thus understandable. Angiogenesis, the formation of new blood vessels, is an essential phenomenon in many malignancies. The first study in this thesis evaluated the role of two regulators of angiogenesis, vascular endothelial growth factor (VEGF) and angiopoietin-2 (Ang-2), during allogenic hematopoietic stem cell transplantation (HSCT) in 67 children. High levels of VEGF and Ang-2 in plasma samples collected after allogenic HSCT correlated with severe acute graft-versus-host disease (GVHD). High Ang-2 post-HSCT was associated with increased non-relapse mortality and, together with concomitantly high VEGF, correlated with inferior event-free survival. However, methodological challenges should prompt cautious interpretation of these results. The second study summarized results of the anti-angiogenic Angiocomb protocol in the treatment of pediatric diffuse intrinsic pontine gliomas (DIPGs). The survival of study patients (N = 41) did not differ from that of controls (N = 8), but the ability to attend school or daycare and walk was maintained for a longer time after the diagnosis in the study cohort. The Angiocomb protocol was generally well tolerated, with the most frequent adverse event being neutropenia. The third study explored the effect of the Extended Angiocomb protocol in a cohort of 17 heavily pre-treated children with high-risk or end-stage malignancies. Although a significant increase in Karnofsky-Lansky performance scores occurred in patients during therapy, the protocol was more toxic than anticipated. This underlines the importance of careful patient selection and close monitoring during metronomic therapy in heavily pre-treated patients. The fourth study analyzed genetic alterations by next-generation sequencing and protein expression and microvessel density (MVD) by immunohistochemistry in 26 DIPG tumor samples. 87% of the patients had mutations in H3-K27M, excluding two rarely encountered long-term survivors. One of the long-term survivors had an IDH1 mutation, an alteration formerly considered to be absent in DIPGs. Angiogenesis-related genes were altered in 40% of the patients, whereas MVD showed up to 6-fold variation. The clinical significance of these findings requires further studies in the future.Vaikka valtaosa syöpää sairastavista lapsista paranee pysyvästi, viidesosalla potilaista sairaus johtaa edelleen kuolemaan. Ennusteen parantaminen edellyttää uusien hoitojen ohessa tarkempia tutkimusmenetelmiä ja lisää tietoa syöpien biologisista ominaisuuksista. Angiogeneesi eli verisuonten uudismuodostus on tärkeä ilmiö monessa syövässä. Väitöskirjan ensimmäisessä osatyössä tutkittiin kahden angiogeneesiä säätelevän tekijän, VEGF:n ja Ang-2:n, pitoisuuksia 67:n kantasolusiirron saaneen lapsipotilaan veressä. Korkeat VEGF- ja Ang-2-pitoisuudet liittyivät kantasolusiirron komplikaationa kehittyvän akuutin käänteishyljinnän vaikeusasteeseen sekä siirron jälkeiseen suurempaan kuolleisuuteen. Angiogeneettisten merkkiaineiden määrityksiin liittyvät epävarmuustekijät tulisi kuitenkin huomioida tulosten kliinistä merkitystä arvioitaessa. Väitöskirjan toisessa osatyössä selvitettiin osittain angiogeneesin estoon perustuvan Angiocomb-hoidon tehoa ja turvallisuutta diffuuseja aivorunkoglioomia sairastavilla lapsilla. Nämä aivojen syvissä osissa sijaitsevat kasvaimet johtavat vääjäämättä potilaan kuolemaan. Vaikka 41:n tutkimushoitoa saaneen potilaan mediaanielinaika ei pidentynyt aikaisimpiin tutkimuksiin nähden, he pystyivät käymään koulua tai päiväkotia sekä liikkumaan ilman apuvälineitä kauemmin kuin vertailuryhmä. Hoito oli yleisesti ottaen hyvin siedetty. Kolmannessa osatyössä tutkittiin Extended Angiocomb -nimisen hoidon vaikutuksia parantumatonta tai korkean uusiutumisriskin syöpää sairastavien lasten ryhmässä. Vaikka osa tutkimukseen osallistuneesta 17:sta potilaasta näyttikin hyötyvän tästä niin ikään angiogeneesin estoon perustuvasta hoidosta oireiden väliaikaisen lievittymisen valossa, sivuvaikutuksia oli odotettua enemmän. Tulokset korostavat oikean potilasvalinnan ja tarkan hoidon aikaisen seurannan tärkeyttä. Väitöskirjan neljännessä osatyössä analysoitiin diffuusien aivorunkoglioomien geeni- ja proteiinitason poikkeavuuksia sekä kasvainten verisuonitiheyttä. 87 %:lla tutkimukseen osallistuneesta 23:sta potilaasta todettiin huonoon ennusteeseen liittyvä H3K27M-mutaatio tätä osatyötä varten kehitetyn geenipaneelin avulla. Kahdella harvinaisella pitkäaikaisselviytyjällä kyseistä muutosta ei löytynyt. 40 %:lla potilaista oli poikkeavuuksia angiogeneesiin liittyvissä geeneissä ja kasvainten verisuonitiheydessä todettiin huomattavaa vaihtelua, mutta näiden ilmiöiden kliinisen merkityksen arviointi vaatii kuitenkin lisää tutkimusta tulevaisuudessa

Radiation therapy and concurrent topotecan followed by maintenance triple anti-angiogenic therapy with thalidomide, etoposide, and celecoxib for pediatric diffuse intrinsic pontine glioma.

To access publisher's full text version of this article click on the hyperlink at the bottom of the pageDespite major treatment attempts, the prognosis for pediatric diffuse intrinsic pontine gliomas (DIPGs) remains dismal. Gliomas are highly vascularized tumors, suggesting that the prevention of vessel formation by anti-angiogenic treatment might be effective.Forty-one pediatric patients with DIPG were treated according to the Angiocomb protocol, starting with radiotherapy combined with topotecan and followed by anti-angiogenic triple medication consisting of thalidomide, etoposide, and celecoxib. Overall survival, radiological response, quality of life, requirement of corticosteroids, and adverse effects were monitored. Eight patients treated with only radiotherapy were used as controls.For study patients, the 12 and 24 months overall survival was 61% and 17%, respectively. The median overall survival was 12 months (range 4-60 months). Four radiological complete responses were seen, of which two were transient. Radiologically, 56% of the tumors reduced in size and 78% in signal intensity. Study patients were able to visit school or daycare and walk for a significantly longer time compared to controls (Log Rank 0.036 and 0.008, respectively). Adverse effects were generally minor.The Angiocomb protocol created a noticeable share of long-term survivors and was well tolerated, suggesting that anti-angiogenic therapy for patients with DIPG should be studied more in the future