None of the other issues he pointed out are things that can't/haven't been overcome. Cancer is a pretty big deal, and he didn't exactly say point blank it's not possible. He hemmed and hawed for a minute before saying "I'm less concerned in humans" and "I don't think this is a real kind of danger".Not openly no, but they might suggest that a safety profile will have to be established through trials. Alexey point blank just said no it's not an issue, where as he pointed out a lot of other potential issues and roadblocks in the same interview.