Researchers have recently demonstrated a mechanism by which two important strains of bacteria found in the human gut play a role in boosting the effectiveness of a routinely administered anticancer drug. The authors suggest that an intermediate metabolite released from the bacteria might be exerting these effects and understanding this may lead to the development of new drugs to target cancer.
Co-senior authors Mathias Chamaillard of Lille University and Laurence Zitvogel of the Institut de Cancérologie Gustave Roussy Cancer Campus published their results in the journal Immunity.
It was previously known that the chemo-immunotherapy cyclophosphamide, a routinely prescribed anticancer drug, relies on intestinal bacteria for its effectiveness. The mechanism of action and which beneficial strains of bacteria are involved are shown in the current study.
The authors showed that oral treatment with two bacteria strains, Enterococcus hirae and Barnesiella intestinihominis, leads to antitumor T cell activation in the spleen and T cell infiltration into the tumor in various mouse models.
Translating this finding to the clinic, they analyzed blood from 38 patients with advanced lung and ovarian cancers treated with chemo-immunotherapy. It turned out that memory T cell immune responses specific to E. hirae and B. intestinihominis bacteria strains correlated with progression-free survival.
The next step for the researchers is to identify the intermediate signaling molecules released from these bacteria that are having these beneficial and synergistic effects on T cell behavior and tumor clearance.
"This paradigm opens the way to improve treatment design by either optimizing the use of antibiotics, or implementing supplementation with so-called oncomicrobiotics or their bioactive metabolites, to promote the efficacy of anticancer drugs,” said Chamaillard in a statement.