Personalized cancer vaccines, part 2: the tissue you need — and why to secure it early

In short: This is a follow-up to my main piece on personalized cancer vaccines . That one was about which vaccine could fit my biology. This one is about a much more basic thing that almost stopped me before biology even mattered: tissue. A personalized vaccine can need far more tumour material than the test that first diagnosed you — often fresh-frozen, not paraffin — and if your treatment works well, there may be nothing left to biopsy when you finally need it. I am writing this because I wish someone had told me at the first biopsy. Maybe it reaches you before yours.

What happened to me

My tumour tissue was collected once, at diagnosis, by a core-needle biopsy — two small cores. That was enough to diagnose the cancer and to run a large molecular panel. It felt like plenty.

Months later, chasing a personalized vaccine, I asked the laboratory that holds my paraffin blocks to measure what was actually left. The answer, from the pathologist who put the blocks under a microscope: less than a millimetre of tissue per block — an estimated three to five thin sections each. Not enough for what a vaccine centre needs. The safest way to get more, he wrote, would be to re-biopsy.

Except I cannot re-biopsy. My treatment has worked so well that there is no tumour left that is safe or sensible to sample — nothing large enough, active enough, or reachable enough for a needle. The thing that makes my situation hopeful is the same thing that closed the door on new tissue.

That is the trap in one sentence: the tissue you can get early may be the only tissue you will ever get.

Why a vaccine needs so much more tissue than a diagnosis

A routine diagnostic panel is efficient. It reads a defined list of cancer genes, deeply, from a tiny amount of material. That is why a small biopsy is usually “enough”.

A personalized (neoantigen) vaccine asks a bigger question — what makes my tumour look different from every healthy cell in my body? — and answering it can take a lot more:

• Whole-exome sequencing (all the protein-coding genes, not a short list), to find the tumour’s mutations.
• Often whole-transcriptome sequencing (RNA) on top of that, to see which of those mutations are actually switched on — and to catch gene fusions, which is exactly where my own target lives.
• And several centres strongly prefer fresh-frozen tissue rather than paraffin-embedded, because frozen tissue preserves higher-quality DNA and RNA. Paraffin (the standard archival form) works for many tests, but it degrades the material, and some vaccine pipelines will not accept it — or need more of it to compensate.

So the very analysis that designs the vaccine is the most tissue-hungry step in the whole journey, and it often comes last — long after the biopsy, when the material is already spoken for.

Not every vaccine needs the same amount — this is your lever

Here is the useful part, the thing that gives you options even when tissue is short. Different vaccine platforms need very different amounts of tissue, because they get their two ingredients — the immune cells and the target — from different places:

• The cells. Some vaccines (dendritic-cell vaccines) grow immune cells from your blood, through a simple blood draw or an apheresis. No tumour tissue at all for this part.
• The target. If the tumour’s mutations are already known — from sequencing you already have — some centres can build the vaccine from defined peptides (short pieces matching those mutations), which are chemically synthesised. Again, no fresh tissue needed for this part.

Put those together and you get a real distinction:

• Centres that do their own whole-exome + whole-transcriptome sequencing from your tissue need the most material — and if you are short, they may be out of reach.
• Centres that build defined peptides from data you already hold, with cells from your blood, need little or no new tissue — and can stay open even when the block is nearly empty.

Knowing which kind a centre is before you commit money is one of the most important questions you can ask.

What I would ask at the first biopsy, if I could do it again

None of this requires you to have decided on a vaccine. It just keeps the door open, cheaply, at the one moment it is open:

1. Ask for extra cores. One or two more passes, when the needle is already there and the tumour is active, is the whole game. It is far easier than a second procedure later.
2. Ask whether a portion can be kept fresh-frozen, not only fixed in paraffin. This has to be arranged before the procedure — it cannot be done afterwards.
3. Ask that the diagnostic block not be completely consumed by the first test — that some tumour is preserved for later.
4. Ask for a written inventory after each test: how many sections remain, and what percentage is still tumour. “The tissue is good” and “there is enough tissue left” are two different sentences, and I learned that the hard way.
5. If your cancer is driven by a fusion, ask for the exact junction (the exons and coordinates), not just the two gene names — usually the data already exists in the lab’s files.

There is a fuller, calmer version of this checklist in our companion guide, Preserving your tumour tissue — read it before a biopsy if you can.

If you are already past that point

So am I. It is not the end of the road, it just narrows it:

• Use what data you already have. The molecular report from your diagnosis already contains most of what a defined-peptide vaccine needs. You may not need new sequencing at all — only a centre willing to work from it.
• Favour the blood-and-peptide platforms over the tissue-hungry ones. Tell each centre your tissue is limited and ask, plainly, whether they can design from existing data with cells from your blood.
• Bank the next opportunity. If the disease ever progresses and a new, biopsiable lesion appears, that is the moment to collect generously — including fresh-frozen — because it may not come again.
• Do not overpay for a dead end. Ask, in writing, what happens to your money and your data if the limited tissue turns out to be unusable, before you transfer anything.

Why I am publishing this

I have a clear strategy and no guarantees, and I have spent weeks working around a limitation that a single sentence at my first biopsy would have prevented. The tissue was there once. Nobody told me to keep more of it, and by the time I understood why it mattered, the tumour I would have sampled was gone.

If you are earlier in this than I am — if a biopsy is still ahead of you, or the tumour is still there to sample — please ask for more than the minimum. It costs almost nothing now and it can be worth everything later.