Previus discussion (from the university press release) https://news.ycombinator.com/item?id=46306894 (498 points | 6 months ago | 140 comments) I'll rehash my comment

They used mice, because they are good for early tries. The researchers had 9 bacterias and only 1 was successful. Experiments in mice are cheaper and have less ethical problems than experiments in humans. (Hey! They even injected the cancer cells in mice and waited a week until it grow. Nobody will approve something like that in humans.)

The title claims that the tumos were eradicated. The title hides that it was a small tumor they injected in the mice and more importantly that it disappeared for two weeks until the experiment ended. It's difficult to guess if it will be useful for humans with bigger tumors because they are harder to detect, and it would work for a interesting enough period like 5 years.

There is also and old comment by octaane https://news.ycombinator.com/item?id=46308732 I'll quote it partially:

> Several things trigger my bullshit meter. Quote:

>> "This dramatically surpasses the therapeutic efficacy of current standard treatments, including immune checkpoint inhibitors (anti-PD-L1 antibody) and liposomal doxorubicin (chemotherapy agents)"

> PD-L1 monoclonal antibodies are only effective against cancers that are PD-L1 positive. [...] Many tumor types are not PD-l1 positive.

> Doxy is an ancient SOC chemo.

> [...]

I disagree that the title "hides" that the title was small and that it disappeared for two weeks. The surviving contingent on the E. americana strain was evaluated for 60 days, and the tumor doesn't look particularly small based on the picture on page 8 of the paper. I think the study size is small (n=5) so we'd like to see more large-scale studies next, but it's already a strong result to show 5/5 (100%) at p < 0.0001 for multiple primary endpoints and the absence of success from comparable bacteria is helpful to frame future research. The absence of long-term side effects and only transient weight-loss followed by 15-day weight gain is also intriguing. I'm not a doctor, oncologist, or cancer researcher, but the methodology looks sound and appropriate to me, as does the title, based on reading the paper.

> and have less ethical problems than experiments in humans

More like, what's a mouse gonna do about it?

Moneyshot:

> The three bacterial strains that successfully induced tumor regression (E. americana, C. portucalensis, and E. ludwigii) were all identified as facultative anaerobic bacteria.

> This finding is consistent with established principles of bacterial cancer therapy, as anaerobic bacteria possess the unique capability to selectively accumulate and colonize within solid tumors due to the characteristically hypoxic and immunosuppressive tumor microenvironment.

> This selective tumor colonization likely enabled efficient intratumoral bacterial proliferation and, in conjunction with activated immune cell responses, contributed significantly to the observed tumor regression phenomena.

Said in other words, the tumours created the ideal environment for anaerobic bacteria to multiply. Eventually causing a reaction from the body’s own immune response (which ignored the tumour but successfully detected the bacterial growth).

So one of the reasons this worked well was that the bacteria acted as a target for the immune cells, and they proliferated inside the tumour thus weakening it.

Don't know about mice, but rats more or less have a 50% tumor/cancer chance if they really do get to live 1+ years. I think for some lines it goes up to 90%+.

The world would be a smarter place if every study and resulting news article were required by law to include something like this at the top.

Cant it be just some immunity reaction induced by the bacteria what would not translate to humans?

I think you overestimate the "interesting enough period". How much would it be worth for some patients to go into remission for a year? or even 6 months? The answer is a lot