Fenbendazole and TP53

This page covers the p53-dependent part of the fenbendazole question.

The short version is:

Fenbendazole tends to work better when the tumour still has functional p53.

That does not mean it becomes irrelevant in p53-mutant cancer. It means one of its best-known mechanisms is weakened when tumour p53 is mutated or absent.

Why TP53 type matters here

The key preclinical finding is that fenbendazole appears much more effective in tumour cell lines with somatic wild-type p53 than in cell lines with mutant or null p53.

This makes the relevant question a somatic tumour question, not a SNP or a germline one:

• Does the tumour still have functional p53?

• Or is the tumour p53-mutant or p53-null?

This is why Somatic TP53 is the page that directly informs this issue.

The p53-dependent mechanism

In the tumour with p53-intact setting, fenbendazole appears to promote tumour cell death, partly by activating p53-linked apoptotic signalling.

If the tumour has:

• wild-type p53 the p53-dependent apoptotic route is more available

• mutant p53 then that apoptosis route is impaired

• If p53 is null, then that apoptosis route is unavailable.

What this does not mean

It does not mean fenbendazole is automatically useless in p53-mutant or null cancer cells.

Fenbendazole has other proposed mechanisms that are not fully dependent on p53, including:

• microtubule disruption

• effects on glucose handling

• proteasome-related effects

So the better way to say it is:

• p53-intact tumours may retain more of fenbendazole's key mechanism set

• p53-mutant or p53-null tumours may lose a key part of that mechanism set

Practical interpretation

If someone asks, "Why did fenbendazole seem to help one person more than another?" then tumour TP53 (somatic) status is one plausible part of that answer.

It is not the only variable, but it is an important one.

Best next step when reviewing a report

Check:

1. whether the result is from a tumour/somatic report

2. whether a TP53 variant code is listed

3. whether pathology suggests p53 null or aberrant staining

Then use TP53 Mutation Types Reference to sort the mutation bucket.
Visit and bookmark: helpful questions and prompts when receiving TP53 test results

Bottom line

Fenbendazole appears most favourable, mechanistically, when the tumour still has functioning p53.

If the tumour p53 is mutant or null, the p53-dependent pathway is weakened. That does not negate all other Fenben anti-cancer mechanisms, but it does make the biology less aligned.

Key references

Dogra et al. Scientific Reports fenbendazole study
https://pmc.ncbi.nlm.nih.gov/articles/PMC6085345/