Akkermansia muciniphila attenuates macrophage efferocytosis to enhance anti-PD-1 efficacy in microsatellite-stable colorectal cancer.

In 30 seconds

This study examined whether Akkermansia muciniphila (Akk) could improve anti-PD-1 activity in microsatellite-stable (MSS) colorectal cancer. In mouse models, oral Akk suppressed tumorigenesis and altered the tumor immune environment, including by reducing macrophage efferocytosis and promoting immune activation. The investigators also conducted a phase 1 trial of Akk probiotics plus a PD-1 antibody in patients with metastatic MSS colorectal cancer after at least one prior treatment line. The combination was reported as safe and had an objective response rate of 19%; responders showed enhanced antitumor immunity.

Key findings

• In mouse models, Akk reduced macrophage efferocytosis, with downstream cGAS-STING activation, type I interferon production, and effector CD8+ T-cell activation.
• Akk enhanced the response to anti-PD-1 therapy in MSS colorectal cancer mouse models.
• In the phase 1 trial, Akk probiotics plus a PD-1 antibody achieved an objective response rate of 19% and was reported as safe.
• Responders in the clinical trial exhibited enhanced antitumor immunity.

Why it matters

MSS colorectal cancer commonly shows intrinsic resistance to anti-PD-1 therapy, leaving a substantial unmet need. These findings connect gut microbiome modulation with changes in tumor immune activity and provide early clinical evidence that Akk combined with PD-1 blockade may have activity in metastatic MSS disease. The clinical result is preliminary and requires interpretation in the context of a phase 1 trial.

What to keep in mind

The clinical evidence comes from a phase 1 trial; the abstract does not report a comparator or further details needed to assess the response estimate.