Interestingly, many cancer "neoantigens" (for example, MAGEB1) are also expressed in meiotic cells in the testis. This is because they're usually epigenetically suppressed in healthy tissues, but cancer cells have messed up epigenomes.

That's very true.

I would disagree that synthesizing long polypeptides is easier than synthesizing long mRNAs

That's not what I said: I said it's not harder and seems better. I'm aware of the chemistry involved and stand by that. Contrary to your implication, oligonucleotide synthesis also requires protecting groups.

ctDNA can in theory be used to sequence the cancer.

I don't think that's a good idea. It's not the same and would be hard to separate from other cfDNA.

Moderna has just put an individualized cancer vaccine into a phase III Do you think that trial is a bad idea?

What Moderna is doing is sequencing cancer cells and healthy cells, and using some algorithm to guess what mRNA vaccine would work. I think they're not quite there yet: the hazard ratio with a checkpoint inhibitor isn't much better than the checkpoint inhibitor alone, and I always discount the reported performance in small trials a bit. (And looking at the stock price, Wall Street seems to agree.) Note also that it's specifically for certain types of melanoma, and comes after several failed cancer mRNA vaccine trials. That limitation to melanoma types indicates to me that their algorithm and its personalization are probably rather limited.

It's not that I'm opposed to Moderna doing their trial per se, but I am a bit concerned that their patents could ultimately result in a net reduction in progress.

There are a few issues with that.

1. The cost would probably be a significant fraction of the development of a new monoclonal antibody treatment, making this currently probably limited to billionaires.

2. Personalized drug development on that scale isn't something that can simply be purchased, and if billionaires tried, governments would probably block them, because voters would consider that unfair, and because cancer researchers can't simply be increased in proportion to budgets. There are only so many people with the relevant skills and inclinations.

3. Better methods for development wouldn't just reduce costs, but would also reduce time taken. There would need to be a billionaire, diagnosed with cancer without a good treatment, who would clearly die from it, but not for a couple years.

4. Better methods and understanding wouldn't just reduce costs and time, they'd also reduce risks. Targeting a receptor that's actually important normally but wasn't fully understood could kill someone before the cancer.

That's true; I misremembered that part when I wrote it. I'll just remove that.

You're mistaken about lemon markets: the initial fraction of lemons does matter. The number of lemon cars is fixed, and it imposes a sort of tax on transactions, but if that tax is low enough, it's still worth selling good cars. There's a threshold effect, a point at which most of the good items are suddenly driven out.

Tubes for this would be more expensive but could be used for piping hydrogen. Pipes for moving hydrogen would be much smaller and at high pressure.

Gas pipelines have lower losses at high pressure, which is why natural gas pipelines are typically >40 bar.

Those Mach numbers are for the relevant speed in air. I would have written that differently, but that's how the cited paper worded things.

Mostly-sealing against part of the tube before cutting it is less problematic than dealing with a large pressure difference.

Aerodynamic support and propulsion in hydrogen is less expensive than magnetic propulsion and support in a vacuum-filled tube. Building an unpressurized tube is cheaper than a tube that doesn't buckle under compressive forces. And so on.

Downside is it doesn't work. There are several reasons it doesn't work, but one is: What happens to the vaporized rock? Were you thinking it just goes up a 20km deep hole without condensing on the walls?