I think a lot of breakthroughs are significant in understanding but can end up being untenable are treatment or it takes a very long time. But to answer the last question: my brother works in cancer research and it goes both ways.

E.g. I would argue one of the most significant developments in cancer treatment is genome sequencing. It allows you to specifically treat the cancer a person has instead of the (mostly false) perception previously of discovering some panacea in the rainforest that cures all cancers. But the genome was sequenced 20 years ago. At the time there was a perception that that was going to be a step change in custom treatment and solving genetic disease. In reality we are just now reaching the $100 genome and if anything it only served to elucidate how much we didn't know about genetics back in 2000. But slow and steady work means we do indeed sequence people's specific cancer and customize treatment for that. So there was a leap: the Human Genome Project. But afterwards it took a lot of slow and steady progress to get to where we are at.

He thinks mRNA vaccines are going to be the same. A leap forward, and now we are looking at slow and steady progress to getting custom mRNA vaccines to effectively cure cancers on a person-to-person basis.