Cancer immunotherapy with a gene modified serotype 3 oncolytic virus

Show full item record

Permalink

http://urn.fi/URN:ISBN:978-951-51-1687-1
Title: Cancer immunotherapy with a gene modified serotype 3 oncolytic virus
Author: Hemminki, Otto
Contributor: University of Helsinki, Faculty of Medicine, Institute of Biomedicine, Cancer Gene Th erapy Group, Department of Pathology, Faculty of Medicine
Thesis level: Doctoral dissertation (article-based)
Abstract: In 2012 WHO announced cancer as the leading cause of death. Every day 20 000 people die due to cancer, and the rate is estimated to double before year 2030. While treatments have progressed, there are still few good treatment options for advanced cancer. Thus, there is an urgent need for new treatments. Immunotherapy with gene modified oncolytic adenoviruses provides novel promising means of treating cancer. These treatments incorporate two basic concepts. Firstly, adenoviruses are modified so that they replicate only in cancer cells, which makes the treatments safer. Secondly, the virus induced cancer cell oncolysis elicits a danger signal that awakens the immune system to fight the cancer. Viruses can be further armed with different genes that can stimulate the immune system even more. Most of these oncolytic viruses are based on adenovirus serotype 5, as indicated in thousands of publications. However, the primary receptor for serotype 5 is down-regulated in advanced cancer. On the contrary, adenovirus serotype 3 receptor is known to be abundant in advanced cancer making it an interesting subject of research. While a different serotype per see offers an alternative immune response, serotype 3 incorporates also other interesting features that might further potentiate its utility. Our first goal was to create serotype 3 based oncolytic adenoviruses for the treatment of human cancer. The goal was achieved, making this virus, to our knowledge, the first non- adenovirus 5 based oncolytic adenovirus in the world used in humans. The publications, study I and II, are now part of this thesis. The virus was designed to have a human telomerase reverse transcriptase (hTERT) promoter diverting the replication of the virus into cancer cells. This virus, Ad3-hTERT-E1A, was successfully cloned, rescued and produced in large scale, which was followed by rigorous preclinical testing of the virus. Rigorous preclinical testing of the virus followed. Several in vitro and in vivo experiments were performed, including sequencing, qPCR, electron microscopy and neutralizing antibody assays, while the most convincing data was gained from the cell cultures and the animal models. We found the serotype 3 effective in all major cancer types in vitro. In vivo, the serotype 3 virus was found at least as potent as serotype 5 based control viruses in several murine models of human cancer. Before clinical treatments, biodistribution and toxicity experiments were performed. In toxicity studies, adenovirus 3 was found less toxic than the serotype 5 based control viruses in an immune competent murine model. The histology of all major organs and basic blood values were analyzed. The preclinical data suggested strong efficacy with good safety. In study II, we publish the data of the first 25 patients treated with the Ad3-hTERT-E1A virus. All patients had advanced solid tumors refractory to standard therapies. Th e safety of the treatment was good with up to 4x10 12 virus particles given intravenously and/or intratumorally. Overall, all patients experienced mild (grade 1-2) self-limiting flu-like adverse events. No severe adverse events were noted attributable to the treatments. After treatment, many patients showed signs of efficacy. Of the 15 patients with elevated tumor markers before the treatment, 73% responded with a decrease or no change in the markers. Even a few complete responses were reported, while some patients also showed a clear decrease in the tumor mass according to imaging. Also the clinical data suggested strong efficacy with good safety, proposing a need for a randomized study. Our next goal was to evaluate better ways in finding treatment responders, as size based computed tomography (CT) is known to be suboptimal in evaluating immunotherapeutics where initial swelling of the tumor due to the immune response is common. In study III, we examined the ability of magnetic resonance imaging (MRI) and spectroscopy (MRS) in immunocompetent Syrian hamsters. T2 weighed MRI seemed encouraging in finding responding hamsters as soon as two days after treatment. Similar findings were noted with a patient responding to oncolytic treatments. MRS of taurine, choline and unsaturated fatty acids were found to be promising metabolites when evaluating responders after oncolytic immunotherapy. These results propose MRI and MRS as potential methods in evaluating responding patients. T2 weighed MRI is already widely used in the clinics, thus a clinical trial should be easy to implement. In study IV, we evaluated the first 16 patients treated with a quadruple modified oncolytic serotype 5 adenovirus. Th e fiber knob of this virus is from serotype 3, while the virus also produces an immunostimulatory GM-CSF molecule. Th e two other modifications restrict the replication to cancer cells. The safety profile of the virus resembled that of the oncolytic serotype 3 virus, and also numerous signs of effi cacy were noted. Immunological studies indicated activation of the immune system in responding patients. Rationale for a randomized study exists also for this virus.WHO arvioi 2012 syövän maailman yleisimmäksi kuolinsyyksi ja saman arvion mukaan syöpäkuolemat kaksinkertaistuvat vuoteen 2030 mennessä. Vaikkakin perinteiset syöpähoidot ovat kehittyneet merkittävästi viime vuosikymmeninä, levinneen taudin ennuste on edelleen huono. Täten uusien syöpähoitojen tarve on ilmeinen. Onkolyyttiset virukset ovat yksi mahdollisuus hoitaa levinnyttä syöpää. Viruksia voidaan muokata siten, että niiden lisääntyminen rajoittuu syöpäkudoksiin tehden onkolyyttisistä viruksista turvallisempia kuin luonnon omat virukset. Halutessa viruksiin voidaan myös lisätä geenejä, jolloin ne saadaan tuottamaan esimerkiksi immuunipuolustusta aktivoivia molekyylejä. Immuunipuolustuksen aktivoituminen vaikuttaisikin olevan ensisijaisen tärkeää hyvän hoitovasteen saavuttamiseksi. Adenovirukset ovat osoittautuneet soveltuvan hyvin tähän käyttöön, ja tuhansia julkaisuja erityisesti adenovirus serotyyppi 5:sta on olemassa. Tässä väitöskirjassa tarkastellaan erityisesti adenovirus serotyyppi 3:n ominaisuuksia syövän immunoterapiassa. Tiettävästi tämä on ensimmäinen ei-serotyypin-5 onkolyyttinen virus, jolla on hoidettu potilaita. Väitöskirjan ensimmäinen osatyö perustuu prekliinisiin töihin serotyypin 3 onkolyyttisella viruksella ja toinen painottuu potilashoitojen raportointiin. Kolmannessa osatyössä tarkastelen magneettikuvantamisen ja magneettispektroskopian mahdollisuuksia onkolyyttisissä immunoterapioissa. Neljäs osatyö käsittelee potilaita, joita on hoidettu onkolyyttisellä viruksella, johon asetettu geeni saa aikaan sen, että virus tuottaa immuunipuolustusta aktivoivaa GM-CSF sytokiinia. Yhteenvetona voidaan todeta, että serotyypin 3 onkolyyttinen adenovirus vaikuttaa lupaavalta hoitomuodolta. Hoidetuista potilaista (N=25), joilla tuumorimarkkerit olivat koholla ennen hoitoa (N=15), markkerit laskivat tai pysyivät ennallaan 73 %:lla. Lisäksi muutamilla potilailla havaittiin selkeitä tuumorimassan pienenemisiä kuvantamisessa. Vastaavia havaintoja tehtiin myös potilaissa, joita hoidettiin GM-CSF sytokiinilla varustetulla viruksella. Prekliiniset kuvantamistutkimukset ja yksittäinen potilas antoivat viitettä siitä, että magneetti tai magneettispektroskopia kuvantamisesta voisi olla hyötyä hoitovastetta arvioitaessa.
URI: URN:ISBN:978-951-51-1687-1
http://hdl.handle.net/10138/157665
Date: 2015-11-13
Subject: lääketiede
Rights: This publication is copyrighted. You may download, display and print it for Your own personal use. Commercial use is prohibited.


Files in this item

Total number of downloads: Loading...

Files Size Format View
cancerim.pdf 2.769Mb PDF View/Open

This item appears in the following Collection(s)

Show full item record