The CF33, Vaxinia and Oncarlytics Deal, page-1071

If I recall correctly, there are two methods of action going on in the body when dosed with CF33:

1. As you've described, the CF33 virus invades the tumour cells, replicates in the host cells until, in many cases, explodes the host cell which releases the replicated virus to find hunt out other tumour cells.
2. The immune system recognises CF33 as a virus and starts to hunt it down. When it finds it floating around the body it clears it. When the immune system finds a tumour cell infected by the CF33 derived virus, the immune system kills the infected tumour cell which in turn eliminates all the CF33 derived virus in the tumour. I believe it's this second action that results the "immune system’s ability to actually recognise these tumor cells, creating a memory against the tumor antigens, which can help prevent cancer recurrence" (@Watmighthavben).

The downside to the immune system eliminating CF33 is that the body may clear all the CF33 before it has had a chance to hunt down all the tumour cells.

So, the theory is the more CF33 dosed in a patient, the greater the likelihood it can traverse the body to hunt down all cancerous cells. Results to date show it is possible for CF33 to hunt down all tumour cells in a patient, even with a low to moderate dose however for a patient with a lot of distant metastatic tumours they may require a higher dose to overcome the immune response to CF33; which is why they continue to dose escalate to find the maximum possible dose they can give a patient to give the virus the best possible chance to clear the cancer. Also, worth bearing in mind the body eventually clears all drugs* whether chemo, monoclonal anti-body therapy or oncolytic virus therapy, so it's not really a concern that CF33 will be cleared because it is highly likely a high enough dose can be given because the safety profile is looking like it will allow a huge dose to be given.

* perhaps the only exception to the "all drugs will be cleared" is Imugene's B Cell platform which invokes a vaccination response which causes the body to create more of the drug as B Cells, however that's a topic for another thread on another day.