Developing genetically engineered oncolytic viruses for cancer gene therapy

It has been estimated that up to half of people living in industrial societies will get cancer. Almost all cancer deaths are caused by metastatic disease and only few metastatic solid tumors can be cured with available therapies. Therefore, novel therapeutic modalities are needed. Genetically engineered oncolytic viruses such as adenoviruses and vaccinia viruses are a promising therapeutic approach given their capacity to specifically replicate in and kill tumor cells as well as to reach distant metastasis. Oncolytic viruses have demonstrated good safety, tolerability and promising signs of anti-tumor efficacy in several clinical trials, but the efficacy of the therapy needs improvement to reach its full clinical potential. Adenoviruses are one of the most studied vectors in oncolytic virotherapy. Two major obstacles limiting the efficacy have been insufficient transduction of the tumor cells and the recognition of the virus by the immune system, which rapidly clears the virus from systemic circulation, hampering the overall efficacy. This study shows that novel capsid modifications can increase the transduction efficacy and oncolytic potency of the virus, and that embedding oncolytic virus in a silica implant might help to circumvent the problem of clearance by prompting only modest immune responses against the virus. Recently, arming oncolytic viruses with immunomodulatory molecules has been a major focus in virotherapy. Immunotherapy means inducing the patient´s immune system to recognize and attack the tumor and has been recently linked with oncolytic virotherapy, as the replication of the virus in the tumor can be immunogenic per se and also release cancer epitopes available for antigen-presenting cells. Host immune responses have been shown to be a key player in oncolytic virotherapy as the balance between anti-viral and anti-tumoral immunity determines the efficacy of the therapy. Oncolytic vaccinia virus possesses unique immunogenicity and mechanisms of action that are distinct from other treatment modalities, and its self-perpetuating nature provides an ideal platform for therapeutic transgenic insertion. Therefore we engineered novel oncolytic vaccinia viruses with granulocyte-macrophage colony-stimulating factor (GMCSF) or CD40-ligand and studied their ability to increase the therapeutical outcome and anti-tumor immune responses in preclinical animal models. In the final part of the thesis the life cycle of oncolytic vaccinia virus was studied in more detail as we were able to show that the life cycle was compromised in a feline squamous cell carcinoma cell line. This finding might be important for a deeper understanding of the vaccinia virus-host cell interactions.Syöpäsairaudet ovat vakava maailmanlaajuinen ongelma, johon sairastuu elämänsä aikana arviolta joka toinen mies ja joka kolmas nainen. Vaikka syövän diagnostiikka, ennaltaehkäisy ja nykyiset hoitomuodot ovat parantuneet huomattavasti, erityisesti eräpesäkkeitä muodostavissa syöpäsairauksissa on ennuste usein huono ja parantavaa hoitoa ei ole. Tämän väitöskirjatutkimuksen tavoitteena oli kehittää onkolyyttisiin vaccinia- ja adenoviruksiin perustuvia syöpähoitoja. Viruksia on usein muokattu siten, että ne kopioituvat ensisijaisesti syöpäsoluissa rikkoen syöpäsoluja oman elinkiertonsa päätteeksi. Väitöskirjatyössäni tutkittiin mahdollisuuksia muokata viruksen syöpäsoluun tarttuvaa reseptoria eri tavoin, ja muokkausten huomattiinkin tehostavan viruksen siirtymistä syöpäsolun sisälle huomattavasti. Tutkimme myös mahdollisuutta annostella virus osana elimistössä hajoavaa silika-implanttia, jonka huomattiinkin vapauttavan virusta verenkiertoon hitaammin ja vähentävän siten myös neutralisoivien vasta-aineiden muodostumista. Immunologisten tekijöiden on osoitettu olevat tärkeitä onkolyyttisten virusten tehokkuuden määräytymisessä. Viruksen lisääntyminen kasvaimissa voimistaa immuunivastetta lisäämällä sytokiinien tuotantoa ja vapauttamalla kasvimen antigeenejä immuunijärjestelmän tunnistettavaksi. Viruksia voidaan käyttää vektoreina kuljettaen hoidon kannalta oleellisia geenejä soluihin, joten niiden varustaminen terapeuttisilla siirtogeeneillä saattaa parantaa viruksen kasvaimelle haitallista vaikutusta, säilyttäen kuitenkin turvallisuutensa syöpäkudokseen rajoitetun lisääntymisensä myötä. Väitöskirjatyössäni tutkittiin mahdollisuutta muokata viruksia tuottamaan kahta erilaista immuunijärjestelmää aktivoivaa proteiinia; granulosyytti-makrofagikasvutekijää (GMCSF) sekä CD40-ligandia. Hoitojen toimivuutta testattiin ensin syöpäsoluissa in vitro ja hyviksi havaitut mallit testattiin eläinkokeiden avulla käyttämällä eläinmalleina hiiriä ja hamstereita. Eläinkokeiden tavoitteena oli tutkia miten hoidot toimivat elävässä elimistössä: miten eläimen immuunijärjestelmä vaikuttaa hoitojen tehoon, miten verenkiertoon annostellut hoidot kulkeutuvat elimistössä, miten hoidot tehoavat ja onko niillä sivuvaikutuksia. Sekä GMCSF sekä CD40l aseistetun onkolyyttisen virukens huomatiin herättävän immuunivasteen syöpäsoluissa ja johtavan kasvainten pienenemiseen. Väitöskirjatyön tulokset tuovat kliinisesti merkittävää tietoa teholtaan parannettujen onkolyyttisten virusten kehitystyöhön

Safety and biodistribution of a double-deleted oncolytic vaccinia virus encoding CD40 ligand in laboratory Beagles

Peer reviewe

Incomplete but Infectious Vaccinia Virions Are Produced in the Absence of Oncolysis in Feline SCCF1 Cells

Vaccinia virus is a large, enveloped virus of the poxvirus family. It has broad tropism and typically virus replication culminates in accumulation and lytic release of intracellular mature virus (IMV), the most abundant form of infectious virus, as well as release by budding of extracellular enveloped virus (EEV). Vaccinia viruses have been modified to replicate selectively in cancer cells and clinically tested as oncolytic agents. During preclinical screening of relevant cancer targets for a recombinant Western Reserve strain deleted for both copies of the thymidine kinase and vaccinia growth factor genes, we noticed that confluent monolayers of SCCF1 cat squamous carcinoma cells were not destroyed even after prolonged infection. Interestingly, although SCCF1 cells were not killed, they continuously secreted virus into the cell culture supernatant. To investigate this finding further, we performed detailed studies by electron microscopy. Both intracellular and secreted virions showed morphological abnormalities on ultrastructural inspection, suggesting compromised maturation and morphogenesis of vaccinia virus in SCCF1 cells. Our data suggest that SCCF1 cells produce a morphologically abnormal virus which is nevertheless infective, providing new information on the virus-host cell interactions and intracellular biology of vaccinia virus.Peer reviewe

Calcium Gluconate in Phosphate Buffered Saline Increases Gene Delivery with Adenovirus Type 5

Peer reviewe

Immunological data from cancer patients treated with Ad5/3-E2F-Delta 24-GMCSF suggests utility for tumor immunotherapy

Oncolytic viruses that selectively replicate in tumor cells can be used for treatment of cancer. Accumulating data suggests that virus induced oncolysis can enhance anti-tumor immunity and break immune tolerance. To capitalize on the immunogenic nature of oncolysis, we generated a quadruple modified oncolytic adenovirus expressing granulocyte-macrophage colony-stimulating factor (GMCSF). Ad5/3-E2F-Delta 24-GMCSF (CGTG-602) was engineered to contain a tumor specific E2F1 promoter driving an E1 gene deleted at the retinoblastoma protein binding site ("Delta 24"). The fiber features a knob from serotype 3 for enhanced gene delivery to tumor cells. The virus was tested preclinically in vitro and in vivo and then 13 patients with solid tumors refractory to standard therapies were treated. Treatments were well tolerated and frequent tumor-and adenovirus-specific T-cell immune responses were seen. Overall, with regard to tumor marker or radiological responses, signs of antitumor efficacy were seen in 9/12 evaluable patients (75%). The radiological disease control rate with positron emission tomography was 83% while the response rate (including minor responses) was 50%. Tumor biopsies indicated accumulation of immunological cells, especially T-cells, to tumors after treatment. RNA expression analyses of tumors indicated immunological activation and metabolic changes secondary to virus replication.Peer reviewe

Inter- and Intra-Observer Variability and the Effect of Experience in Cine-MRI for Adhesion Detection

Cine-MRI for adhesion detection is a promising novel modality that can help the large group of patients developing pain after abdominal surgery. Few studies into its diagnostic accuracy are available, and none address observer variability. This retrospective study explores the inter- and intra-observer variability, diagnostic accuracy, and the effect of experience. A total of 15 observers with a variety of experience reviewed 61 sagittal cine-MRI slices, placing box annotations with a confidence score at locations suspect for adhesions. Five observers reviewed the slices again one year later. Inter- and intra-observer variability are quantified using Fleiss’ (inter) and Cohen’s (intra) κ and percentage agreement. Diagnostic accuracy is quantified with receiver operating characteristic (ROC) analysis based on a consensus standard. Inter-observer Fleiss’ κ values range from 0.04 to 0.34, showing poor to fair agreement. High general and cine-MRI experience led to significantly (p < 0.001) better agreement among observers. The intra-observer results show Cohen’s κ values between 0.37 and 0.53 for all observers, except one with a low κ of −0.11. Group AUC scores lie between 0.66 and 0.72, with individual observers reaching 0.78. This study confirms that cine-MRI can diagnose adhesions, with respect to a radiologist consensus panel and shows that experience improves reading cine-MRI. Observers without specific experience adapt to this modality quickly after a short online tutorial. Observer agreement is fair at best and area under the receiver operating characteristic curve (AUC) scores leave room for improvement. Consistently interpreting this novel modality needs further research, for instance, by developing reporting guidelines or artificial intelligence-based methods

Common Inflammation-Related Candidate Gene Variants and Acute Kidney Injury in 2647 Critically Ill Finnish Patients

Acute kidney injury (AKI) is a syndrome with high incidence among the critically ill. Because the clinical variables and currently used biomarkers have failed to predict the individual susceptibility to AKI, candidate gene variants for the trait have been studied. Studies about genetic predisposition to AKI have been mainly underpowered and of moderate quality. We report the association study of 27 genetic variants in a cohort of Finnish critically ill patients, focusing on the replication of associations detected with variants in genes related to inflammation, cell survival, or circulation. In this prospective, observational Finnish Acute Kidney Injury (FINNAKI) study, 2647 patients without chronic kidney disease were genotyped. We defined AKI according to Kidney Disease: Improving Global Outcomes (KDIGO) criteria. We compared severe AKI (Stages 2 and 3, n = 625) to controls (Stage 0, n = 1582). For genotyping we used iPLEX(TM) Assay (Agena Bioscience). We performed the association analyses with PLINK software, using an additive genetic model in logistic regression. Despite the numerous, although contradictory, studies about association between polymorphisms rs1800629 in TNFA and rs1800896 in IL10 and AKI, we found no association (odds ratios 1.06 (95% CI 0.89-1.28, p = 0.51) and 0.92 (95% CI 0.80-1.05, p = 0.20), respectively). Adjusting for confounders did not change the results. To conclude, we could not confirm the associations reported in previous studies in a cohort of critically ill patients.Peer reviewe

Favorable Alteration of Tumor Microenvironment by Immunomodulatory Cytokines for Efficient T-Cell Therapy in Solid Tumors

Unfavorable ratios between the number and activation status of effector and suppressor immune cells infiltrating the tumor contribute to resistance of solid tumors to T-cell based therapies. Here, we studied the capacity of FDA and EMA approved recombinant cytokines to manipulate this balance in favor of efficient anti-tumor responses in B16. OVA melanoma bearing C57BL/6 mice. Intratumoral administration of IFN-alpha 2, IFN-gamma, TNF-alpha, and IL-2 significantly enhanced the anti-tumor effect of ovalbumin-specific CD8+ T-cell (OT-I) therapy, whereas GM-CSF increased tumor growth in association with an increase in immunosuppressive cell populations. None of the cytokines augmented tumor trafficking of OT-I cells significantly, but injections of IFN-alpha 2, IFN-gamma and IL-2 increased intratumoral cytokine secretion and recruitment of endogenous immune cells capable of stimulating T-cells, such as natural killer and maturated CD11c+ antigen-presenting cells. Moreover, IFN-alpha 2 and IL-2 increased the levels of activated tumor-infiltrating CD8+ T-cells concomitant with reduction in the CD8+ T-cell expression of anergy markers CTLA-4 and PD-1. In conclusion, intratumoral administration of IFN-alpha 2, IFN-gamma and IL-2 can lead to immune sensitization of the established tumor, whereas GM-CSF may contribute to tumor-associated immunosuppression. The results described here provide rationale for including local administration of immunostimulatory cytokines into T-cell therapy regimens. One appealing embodiment of this would be vectored delivery which could be advantageous over direct injection of recombinant molecules with regard to efficacy, cost, persistence and convenience.Peer reviewe

Heme oxygenase-1 repeat polymorphism in septic acute kidney injury

Acute kidney injury (AKI) is a syndrome that frequently affects the critically ill. Recently, an increased number of dinucleotide repeats in the HMOX1 gene were reported to associate with development of AKI in cardiac surgery. We aimed to test the replicability of this finding in a Finnish cohort of critically ill septic patients. This multicenter study was part of the national FINNAKI study. We genotyped 300 patients with severe AKI (KDIGO 2 or 3) and 353 controls without AKI (KDIGO 0) for the guanine-thymine (GTn) repeat in the promoter region of the HMOX1 gene. The allele calling was based on the number of repeats, the cut off being 27 repeats in the S-L (short to long) classification, and 27 and 34 repeats for the S-M-L2 (short to medium to very long) classification. The plasma concentrations of heme oxygenase-1 (HO-1) enzyme were measured on admission. The allele distribution in our patients was similar to that published previously, with peaks at 23 and 30 repeats. The S-allele increases AKI risk. An adjusted OR was 1.30 for each S-allele in an additive genetic model (95% CI 1.01-1.66; p = 0.041). Alleles with a repeat number greater than 34 were significantly associated with lower HO-1 concentration (p<0.001). In septic patients, we report an association between a short repeat in HMOX1 and AKI risk