Controlling transduction and replication of oncolytic adenoviruses

Despite progress in conventional cancer treatment regimes, metastatic disease essentially remains incurable and new treatment alternatives are needed. Virotherapy is a relatively novel approach in cancer treatment. It harnesses the natural ability of oncolytic viruses to kill the cells they proliferate in and to spread to neighboring cells, thereby amplifying the therapeutic effect of the initial input dose. The use of replicating, oncolytic viruses for cancer treatment necessitates introduction of various genetic modifications to the viral genome, thereby restraining replication exclusively to tumor cells and eventually obtaining selective eradication of the tumor without side effects to healthy tissue. Furthermore, various modifications can be applied to the viral capsid in hope of gaining effective transduction of target tissue. In other words, the entry of viruses into tumor tissue can be augmented by allowing the virus to utilize non-native receptors for entry. Genetic capsid modifications may also help to avoid some major hurdles in systemic delivery that ultimately lead to the rapid clearance of the virus from the blood and virus induced toxicity. In addition to genetic modifications that alter the phenotype of the virus, some pharmacologic agents may be utilized to enhance the virus entry to target site. Liver kupffer cells (KC) are responsible for the majority of viral clearance after systemic viral delivery and they play a major role in adenovirus induced acute toxicity. The therapeutic window could possibly be widened by transiently depleting KCs, allowing smaller viral input doses and diminishing KC related toxicity. The transductional efficacy of various capsid modified viruses was analyzed in vitro and in vivo in murine orthotopic breast cancer model. The effect of capsid modifications on the oncolytic efficacy, i.e. the ability of the viruses to kill cancer cells, was evaluated in vitro and in vivo in murine cancer models. We concluded that capsid modifications result in transductional enhancement, and that enhanced transduction translates into more potent oncolysis in vitro and in vivo. When KC depleting agents were used in vivo prior to viral injections, enhanced tumor transduction was seen, but this effect was not translated into enhanced antitumor activity. Transcriptional regulation of replicative oncolytic viruses is a prerequisite for virotherapy. Tumor or tissue specific promoters can be used to control the transcription of adenoviral early genes to gain cancer specific viral replication. Specific deletions in viral regions essential for virus replication in normal cells can further increase the safety by allowing viral genome replication in cancer cells featuring specific mutations. Genetically modified viruses were shown to be able to kill putative cancer stem cells that are thought to be responsible for post treatment relapses and metastasis. Further, pharmacologic intervention reduced viral replication and thereby might offer an additional safety switch in case viral replication related side effects are encountered.Huolimatta perinteisten syöpähoitojen parantumisesta levinnyttä syöpää ei voida parantaa, ja uusia tehokkaita hoitomuotoja tarvitaan. Onkolyyttisten eli syöpäsoluja tappavien adenovirusten käyttö on uusi lähestymistapa syövän hoidossa. Se perustuu adenovirusten kykyyn tappaa solut, joissa ne monistavat perimänsä ja tuottavat uusia viruspartikkeleita. Adenovirusten levitessä kasvaimessa naapurisoluihin niiden terapeuttinen vaikutus teoriassa moninkertaistuu. Virusten käyttö syövän hoidossa edellyttää viruksen perimän muokkaamista, jotta sen monistuminen rajoittuu syöpäsoluihin ja sivuvaikutuksilta normaalisoluissa vältytään. Lisäksi adenovirusten kykyä päästä kohdesoluihin voidaan parantaa muokkaamalla kuorta, jonka sisällä viruksen perimä on. Muokkaamalla viruksen kuorta voidaan myös osittain välttää immuunipuolustukseen liittyvä viruksen nopea poistaminen verenkierrosta ja samoin immuunipuolustukseen liittyvä mahdollinen akuutti toksisuus. Erilaisilla adenoviruksen perimän muokkauksilla voidaan vaikuttaa siihen, missä soluissa adenoviruksen perimä monistuu ja uusia viruksia syntyy. Perimän monistumiselle ehdottoman tärkeiden geenien luentaa voidaan kontrolloida erityisillä promoottorialueilla, jotka toimivat ja siten sallivat geenien luennan vain syöpäsoluissa. Perimästä voidaan myös poistaa lyhyitä alueita sellaisista geeneistä, joiden toiminta on edellytys adenoviruksen perimän monistumiselle normaalisoluissa. Syöpäsoluissa on yleensä sellaisia muutoksia, jotka sallivat tällä tavalla muokattujen adenovirusten perimän monistamisen, tavallisissa soluissa ei. Adenovirusten pääsyä kohdesoluihin voidaan kontrolloida myös kemiallisilla yhdisteillä. Ihmisen maksan kupfferinsolut ovat makrofageja, jotka vastaavat adenovirusten nopeasta poistamisesta verenkierrosta ja saattavat samalla aiheuttaa akuuttia toksisuutta. Tietyt yhdisteet estävät Kupfferinsoluja poistamasta adenoviruksia verenkierrosta, ja siten niin sanottua terapeuttista ikkunaa voidaan laajentaa. Toisin sanoen vaikuttamalla Kupfferinsoluihin adenoviruksia voidaan antaa vähemmän ja silti saavuttaa tyydyttävä taso adenoviruksen pääsyssä kohdesoluihin verenkierrosta. Myös adenovirusten leviämiseen kohdesolusta toiseen voidaan vaikuttaa. Viruksen perimän monistumiseen ja uusien virusten leviämiseen voi liittyä haittavaikutuksia etenkin ihmisissä, joiden immuunipuolustus on heikentynyt. Tietyt yhdisteet estävät adenovirusten pääsyä uusiin kohdesoluihin, pysäyttäen siten niiden lisääntymisen ihmisessä. Tutkimuksessamme totesimme onkolyyttisten adenovirusten kuoren muokkauksen parantavan niiden pääsyä syöpäsoluihin ja syöpäsolujen tappamistehokkuutta sekä in vitro soluviljelmissä, että in vivo hiiren rintasyöpämalleissa. Erilaiset turvallisuutta lisäävät perimän muokkaukset eivät merkittävästi huonontaneet virusten tehokkuutta ja muokatut virukset kykenivät tappamaan jopa niin sanottuja syövän kantasoluja, joiden uskotaan olevan syöpien synnyn ja hoidettujen syöpien uusiutumisen taustalla. Lisäksi totesimme, että erilaisilla yhdisteillä voidaan lisätä adenovirusten pääsyä kohdesoluihin ja toisaalta hallita virusten leviämistä ihmisessä mahdollisten viruksen monistumiseen liittyvien haittavaikutusten ilmetessä

Serotype Chimeric Human Adenoviruses for Cancer Gene Therapy

Peer reviewe

Toxicological and bio-distribution profile of a GM-CSF-expressing, double-targeted, chimeric oncolytic adenovirus ONCOS-102-Support for clinical studies on advanced cancer treatment

The purpose of this work was to carry out preclinical toxicity and bio-distribution studies required for regulatory approval of a clinical trial application for Phase I clinical studies of ONCOS-102 (Ad5/3-D24-GM-CSF) for therapy of advanced cancers (NCT01598129). The study design, route of administration and dosage differs from the clinical protocol and in more detail, investigate bio-distribution and toxicological profile of ONCOS-102 treatment in animal model. The study was carried out in 300 hamsters divided into nine test groups-three bio-distribution groups and six groups for analysis of toxicity. Hamsters received ONCOS-102 by intracardial, intraperitoneal or subcutaneous injections. Additionally, one group was administered twice a week with intraperitoneal injections of Cyclophosphamide. The control animals were administered with NaCl solution without ONCOS-102 in the same volume and the same way. No adverse effects of repeated administration of ONCOS-102 including body weight, food consumption, hematology and clinical chemistry parameters, histopathology and bio-accumulation were observed in the course of 6-month administration and following 3-month recovery period. All obtained findings indicate the treatment clinically safe.Peer reviewe

Retrospective, Registry-based, Cohort Investigation of Clinical Outcomes in Patients with Cutaneous Squamous Cell Carcinoma and Basal Cell Carcinoma in Finland

Most cases of keratinocyte cancer can be treated effectively with surgery. However, survival is reduced in patients with advanced disease. This retrospective cohort study evaluated overall survival of patients with invasive keratinocyte cancers, and high-risk features for progression of the disease and mortality in Finnish patients in a real-world setting. A total of 43,143 patients with keratinocyte cancer types of basal cell carcinoma and 10,380 with cutaneous squamous cell carcinoma were identified nationwide. More detailed patient records were available for a subset of patients (basal cell carcinoma n = 5,020 and cutaneous squamous cell carcinoma n = 1,482) from a regional database. Fifty percent of patients with advanced cutaneous squamous cell carcinoma died approximately 4.5 years after diagnosis. Multivariable models suggested that risk factors for keratinocyte cancer progression were male sex, presence of comorbidities, immunosuppression, and pre-cancerous lesions, while risk factors for disease-specific mortality were advanced disease stage with immunosuppression, other malignancies, and consecutive surgical excisions. These results suggest that identifying patient and tumour factors associated with poor disease outcome could be important when determining appropriate treatment and follow-up; however, further studies are necessary.</p

Local treatment of a pleural mesothelioma tumor with ONCOS-102 induces a systemic antitumor CD8(+) T-cell response, prominent infiltration of CD8(+) lymphocytes and Th1 type polarization

Peer reviewe

Gene expression analysis of tumors demonstrates an induction of Th1 type immune response following intratumoral administration of ONCOS-102 in refractory solid tumor patients

2014-11-0

Phase I study with ONCOS-102 for the treatment of solid tumors - an evaluation of clinical response and exploratory analyses of immune markers

Peer reviewe

31st Annual Meeting and Associated Programs of the Society for Immunotherapy of Cancer (SITC 2016) : part two

Background The immunological escape of tumors represents one of the main ob- stacles to the treatment of malignancies. The blockade of PD-1 or CTLA-4 receptors represented a milestone in the history of immunotherapy. However, immune checkpoint inhibitors seem to be effective in specific cohorts of patients. It has been proposed that their efficacy relies on the presence of an immunological response. Thus, we hypothesized that disruption of the PD-L1/PD-1 axis would synergize with our oncolytic vaccine platform PeptiCRAd. Methods We used murine B16OVA in vivo tumor models and flow cytometry analysis to investigate the immunological background. Results First, we found that high-burden B16OVA tumors were refractory to combination immunotherapy. However, with a more aggressive schedule, tumors with a lower burden were more susceptible to the combination of PeptiCRAd and PD-L1 blockade. The therapy signifi- cantly increased the median survival of mice (Fig. 7). Interestingly, the reduced growth of contralaterally injected B16F10 cells sug- gested the presence of a long lasting immunological memory also against non-targeted antigens. Concerning the functional state of tumor infiltrating lymphocytes (TILs), we found that all the immune therapies would enhance the percentage of activated (PD-1pos TIM- 3neg) T lymphocytes and reduce the amount of exhausted (PD-1pos TIM-3pos) cells compared to placebo. As expected, we found that PeptiCRAd monotherapy could increase the number of antigen spe- cific CD8+ T cells compared to other treatments. However, only the combination with PD-L1 blockade could significantly increase the ra- tio between activated and exhausted pentamer positive cells (p= 0.0058), suggesting that by disrupting the PD-1/PD-L1 axis we could decrease the amount of dysfunctional antigen specific T cells. We ob- served that the anatomical location deeply influenced the state of CD4+ and CD8+ T lymphocytes. In fact, TIM-3 expression was in- creased by 2 fold on TILs compared to splenic and lymphoid T cells. In the CD8+ compartment, the expression of PD-1 on the surface seemed to be restricted to the tumor micro-environment, while CD4 + T cells had a high expression of PD-1 also in lymphoid organs. Interestingly, we found that the levels of PD-1 were significantly higher on CD8+ T cells than on CD4+ T cells into the tumor micro- environment (p < 0.0001). Conclusions In conclusion, we demonstrated that the efficacy of immune check- point inhibitors might be strongly enhanced by their combination with cancer vaccines. PeptiCRAd was able to increase the number of antigen-specific T cells and PD-L1 blockade prevented their exhaus- tion, resulting in long-lasting immunological memory and increased median survival

Serotype Chimeric Human Adenoviruses for Cancer GeneTherapy

Cancer gene therapy consists of numerous approaches where the common denominator is utilization of vectors for achieving therapeutic effect. A particularly potent embodiment of the approach is virotherapy, in which the replication potential of an oncolytic virus is directed towards tumor cells to cause lysis, while normal cells are spared. Importantly, the therapeutic effect of the initial viral load is amplified through viral replication cycles and production of progeny virions. All cancer gene therapy approaches rely on a sufficient level of delivery of the anticancer agent into target cells. Thus,enhancement of delivery to target cells, and reduction of delivery to non-target cells, in an approach called transductional targeting, is attractive. Both genetic and non-genetic retargeting strategies have been utilized. However, in the context of oncolytic viruses, it is beneficial to have the specific modification included in progeny virions and hence genetic modification may be preferable. Serotype chimerism utilizes serotype specific differences in receptor usage, liver tropism and seroprevalence in order to gain enhanced infection of target tissue. This review will focus on serotype chimeric adenoviruses for cancer gene therapy applications