Yes, the catch-22 mentioned in the article is that the clinical studies are done on late stage patients with usually at that point severely damaged immune syste

Yes, the catch-22 mentioned in the article is that the clinical studies are done on late stage patients with usually at that point severely damaged immune system which of course wouldn’t produce desired effect especially if it is about using virus to cause flooding of the tumor with the immune response cells and not about virus directly attacking cancer cells. Also in the metastatic late stage one can imagine it isn’t really possible to inject each tumor.