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.