This week: immunologist Alex Marson walked Huberman through CRISPR-based immune engineering — editing T cells to recognise and destroy specific cancers. Meanwhile, the Essentials vault dropped the sauna protocol episode with the heat-shock protein data, and a Lancet Oncology meta-analysis landed on immunotherapy response prediction.

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The episode that will age best this week is Alex Marson on Huberman. Marson runs a lab at UCSF that uses CRISPR to edit human T cells — reprogramming the immune system's soldiers to recognise targets they'd otherwise ignore. The conversation is technical but the implication is immediate: the era of personalised immune engineering has started. The bottleneck is no longer the science. It's the targeting.

⏱ ~5 min read

Two facts from the same week. One: immunotherapy — unleashing the immune system against cancer — works spectacularly in about 30% of patients with certain solid tumours. In the other 70%, the same treatment does little or nothing. Two: a 20-minute sauna session triggers a heat-shock protein response that primes immune surveillance in ways that overlap with what immunotherapy drugs try to achieve pharmacologically.

The thread this week: the immune system already knows how to kill cancer. The problem is getting it to look in the right direction.

~30%
The approximate overall response rate to checkpoint inhibitor immunotherapy across solid tumours.

Checkpoint inhibitors — drugs like pembrolizumab (Keytruda) and nivolumab (Opdivo) — work by removing the molecular brakes that cancer cells install on T cells. When they work, they can produce durable remissions lasting years. The problem: they only work in roughly 30% of patients with most solid tumour types. The other 70% don't respond, and predicting who will respond before treatment is one of oncology's biggest open problems.

Marson walked Huberman through why the response rate is so variable. The key factor: tumour mutational burden (TMB) — the number of mutations a tumour carries. More mutations mean more abnormal proteins on the cell surface, which gives T cells more targets to recognise. High-TMB tumours (melanoma, lung cancer in smokers) respond well to checkpoint inhibitors because there are many targets. Low-TMB tumours (pancreatic, prostate) respond poorly because the T cells can't distinguish cancer cells from normal tissue.

The CRISPR approach Marson's lab is developing bypasses this limitation. Instead of relying on the immune system to find targets naturally, they identify tumour-specific mutations in each patient, engineer T cell receptors that recognise those specific mutations, and infuse the edited T cells back. It's personalised immunotherapy — custom-built for each patient's tumour.

The immune system isn't failing. It's aiming at an empty field. Give it the right coordinates and it kills with precision that no drug can match.

Dr. Alex Marson on Huberman Lab · March 9, 2026

CRISPR meets the immune system — the most precise weapon oncology has ever had
Alex Marson on editing T cells, the targeting problem in immunotherapy, and why autoimmune disease is the same engineering challenge in reverse.
Dr. Alex Marson · Huberman Lab · March 9, 2026

Marson is a physician-scientist at UCSF and the Gladstone Institutes. His lab develops CRISPR tools for editing primary human T cells — the immune cells that do the actual killing. The conversation with Huberman is dense but revelatory: if you understand why the immune system sometimes misses cancer, you understand why autoimmune disease happens (it's the same targeting system, miscalibrated in the opposite direction).

🎙️ Listen → Huberman Lab, Dr. Alex Marson, March 9, 2026

Marson gives you the engineering. The sauna data gives you the biology. Together they illuminate the immune system's dual nature.

The sauna Essentials episode Huberman dropped the same week connects to Marson's conversation through heat-shock proteins (HSPs). Regular sauna use — 20 minutes at 80–100°C, 2–4 times per week — upregulates HSP70 and HSP90, which serve as molecular chaperones that help the immune system recognise damaged and abnormal cells. HSPs literally present cellular debris to immune surveillance, flagging cells for inspection.

The overlap with immunotherapy is direct. One of the reasons tumours evade immune detection is that they downregulate the surface molecules (MHC class I) that present their abnormal proteins to T cells. HSPs can partially compensate by acting as alternative presentation pathways. This doesn't replace immunotherapy — but it suggests that regular heat stress may support the immune surveillance system that immunotherapy tries to unleash.

Marson's CRISPR work and the sauna HSP data sit at different ends of the same spectrum. One is high-tech, personalised, and expensive. The other is ancient, accessible, and free. Both work by the same principle: helping the immune system see what it needs to kill. The difference is precision. CRISPR gives each T cell a GPS coordinate. HSPs give the whole surveillance team better glasses.

The Lancet Oncology meta-analysis published the same week reinforced the targeting problem from the data side: tumour mutational burden remains the strongest single predictor of checkpoint inhibitor response, but it explains only about 30% of the variance. The other 70% involves tumour microenvironment factors, immune cell infiltration patterns, and patient-specific variables that current models don't capture. The future of oncology isn't better drugs. It's better targeting.

The immune system is the most sophisticated defence network in biology. The question isn't whether it can kill cancer. It's whether we can show it where to look.

P.S. If you could choose one upgrade to your immune system — better cancer surveillance, faster infection response, or elimination of one autoimmune tendency — which would you pick? Hit reply. Best answers go in a future issue.

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