Bei der onkolytischen Virotherapie handelt es sich um eine Immuntherapie bei der onkolytische Viren in der Lage sind gezielt Krebszellen zu infizieren, sich darin massenhaft zu vermehren und dadurch diese zu zerstören. Im Zuge dieser viralen Onkolyse wird eine starke anti-tumorale Immunantwort induziert, die überall im Körper befindliche Tumorzellnester nachhaltig bekämpfen kann.
Die Virotherapie macht sich eine Schwachstelle der Tumorzellen zu Nutze: Krebszellen sind wehrlos gegen Viren. Gesunde Zellen schütten Interferone aus, Botenstoffe, die das Immunsystem aufrütteln und letztlich dafür sorgen, dass die Viren in Schach gehalten werden. Das Interferonsystem fehlt Krebszellen, andernfalls würden sie auf sich aufmerksam machen. Sie machen sich für das Immunsystem unsichtbar, indem sie die gegen sie gerichtete Immunantwort unterdrücken.
Hier eine kurze Zusammenfassung auf Englisch:
Virotherapy is a treatment using biotechnology to convert viruses into therapeutic agents.
There are three main branches of virotherapy:
1. anti-cancer oncolytic viruses
An oncolytic virus is a virus that preferentially infects and kills cancer cells… Oncolytic viruses are thought not only to cause direct destruction of the tumour cells, but also to stimulate host anti-tumour immune system response (see 3)
2. viral vectors for gene therapy
Viral vectors are tools commonly used by molecular biologists to deliver genetic material into cells... Adeno-associated virus (AAV) is one of the vectors most commonly used today.
3. viral immunotherapy.
Immunotherapy is the treatment of disease by activating or suppressing the immune system.
Oncolytic viruses (Ovs) are therapeutically useful anticancer viruses that will selectively infect and damage / kill cancerous tissues without causing harm to normal tissues.
In contrast to gene therapy where a virus is used as a mere carrier for transgene delivery, oncolytic virus therapy uses the virus itself as an active drug reagent.
OVs can also stimulate the immune system. The delivery of OVs into the tumor wakes up the immune system so that it can facilitate a strong and durable response against the tumor itself.
Oncolytic viruses are selected or designed to launch a multipronged attack on cancer cells: after reaching a tumor, they
- enter, selectively replicate and lyse the infected cell,
- spread to neighboring cells and release local inflammatory signals, including tumor antigens. These switch on immune surveillance, potentially triggering both adaptive and innate systemic immune responses against the cancer.
A combination with immune checkpoint inhibitors or chemotherapy may enhance the efficacy of oncolytic virus therapy. Arming oncolytic viruses with immunostimulatory gene(s) or cancer therapeutic genes may also be beneficial.
Checkpoint inhibitors are antibodies who block the negative regulators of T cell function thereby increasing T-cell activation. When these checkpoints are blocked, the “brakes” on the immune system are released and T cells are able to kill cancer cells better. Examples of checkpoint inhibitors currently approved are:
- ipilimumab (Yervoy®, Bristol-Myers Squibb) blocks a checkpoint protein called CTLA-4,
- pembrolizumab (Keytruda®; Merck / MSD) and nivolumab (Opdivo®, Bristol-Myers Squibb), target another checkpoint protein called PD-1,
- atezolizumab (Tecentriq®, Roche), targets one called PD-L1
To date, two genetically engineered oncolytic viruses have been approved for marketing as drugs.
- One is Oncorine(Shanghai Sunway Biotech) , an E1B-deleted adenovirus, which was approved in China for head and neck cancer and esophagus cancer in 2005.
- The other is T-Vec (IMLYGIC, Amgen) which was approved for melanoma by the FDA in the USA in October 2015 and was subsequently approved in Europe in January 2016 and in Australia in May 2016. T-Vec is a double-mutated HSV-1 with deletions in the c34.5 and a47 genes, and the human granulocyte-macrophage colony-stimulating factor (GM-CSF) gene inserted into the deleted c34.5 loci .
Other oncolytic viruses are coming through the pipeline including SillaJen/Transgene’s Pexa-Vec, Targovax’ mesothelioma candidate ONCOS-102. Another virus – Viralytics’ Cavatak – showed promise in a phase I trial as a combination with Keytruda in melanoma, piquing Merck’s interest and prompting a $394m takeover deal earlier this year.
Meanwhile, AbbVie and Johnson & Johnson have both struck deals this year with biotechs in this field: Turnstone Biologics and BeneVir Biopharm respectively – suggesting the oncolytic virus sector is heating up.
Meanwhile, AbbVie and Johnson & Johnson have both struck deals this year with biotechs in this field: Turnstone Biologics and BeneVir Biopharm respectively – suggesting the oncolytic virus sector is heating up.
Virus manufacturing for viro- and gene-therapy is probably the most complex and resource-intensive process in biologics manufacturing
- scaling up often requires switching virus expression hosts from adherent to suspension cell lines
- purification methods must be equally scalable, strict quality control assays are mandatory to ensure that product quality remains unchanged
- down-stream processing and formulation conditions must be matched carefully to the features of each virus
- Quality Assurance and Quality Control (QA/QC) are at the heart of GMP production
This is a boost for contract development and manufacturing organizations (CDMOs) like Vibalogics.
- Private Equity Groups have been shaping this industry. They seem to have continued confidence in the sector, increasing the value of their individual bets.
- Large CDMOs have snapped up smaller ones with expertise in these fields so they have an offering as biotechs look for contractors to help them develop and manufacture their products.
Mehr / further reading / sources:
- https://www.medizin.uni-tuebingen.de/uktmedia/EINRICHTUNGEN/Kliniken/Medizinische+Klinik/Innere+Medizin+VIII/PDF_Archiv/2018_Beil_Lauer_OH118_finale+Druckversion-port-10443-p-92950.pdf
- https://www.spektrum.de/news/mit-viren-gegen-krebs/1579542
- https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3888062/
- https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5932159/
- https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6234197/
- https://onlinelibrary.wiley.com/doi/full/10.1111/cas.13027
- http://www.hsj.gr/medicine/oncolytic-viruses-a-gene-therapy-for-treatment-of-cancer-in-companion-animals.php?aid=23108
- https://jitc.biomedcentral.com/articles/10.1186/s40425-018-0458-z
- https://www.phrma.org/report/list-of-2018-medicines-in-development-for-cell-and-gene-therapy
- https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5417845/
- https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5084676/
- http://www.genetherapynet.com/gene-therapy-products-on-the-market.html
- https://www.creative-biolabs.com/oncolytic-virus/oncolytic-virus-therapy-clinical-trials-overview.htm
- https://en.wikipedia.org/wiki/Virotherapy
- https://labiotech.eu/sponsored/manufacturing-gene-therapy-bottleneck/
- https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4822647/
- https://www.nature.com/articles/1209045
- https://www.biopharma-reporter.com/Article/2019/05/09/Vibalogics-invests-in-drug-product-virus-manufacturing
- https://www.fiercepharma.com/manufacturing/viral-vector-cdmo-vibalogics-latest-private-equity-target
- http://www.pmlive.com/pharma_intelligence/Cancer_immunotherapy_Whats_on_the_horizon_1245525
- https://www.evaluate.com/vantage/articles/news/oncolytics-prepares-tap-us-investors
- https://www.pharmazeutische-zeitung.de/von-der-doppelhelix-bis-zur-gentherapie/