# OM‐85, a Bacterial Lysate, Reduces Pulmonary Nodule Malignant Probability: A Retrospective Study

## TL;DR

A bacterial lysate called OM-85 may help reduce the risk of lung nodules becoming cancerous in patients with chronic bronchitis.

## Contribution

OM-85 is shown to reduce nodule malignancy risk and increase natural killer cells in patients with chronic bronchitis.

## Key findings

- OM-85 reduced nodule size and malignancy risk in patients with chronic bronchitis.
- Treatment increased natural killer (NK) cells in blood and lung nodules.
- Effects were stronger in older patients and those with longer follow-up periods.

## Abstract

The current clinical management of pulmonary nodules relies heavily on CT follow‐up, without early intervention. This retrospective study investigated the efficacy of OM‐85, a standardized lysate of human respiratory bacteria, in the treatment of high‐risk pulmonary nodules detected by computed tomography (CT) in patients with chronic bronchitis.

This study included 72 patients (93 enrolled nodules) who underwent treatment with OM‐85 and a matched control group of 90 patients (111 control nodules). The primary endpoint included reduced size of high‐risk ground glass nodules based on thin‐layer CT scans during follow‐up. Flow cytometry, multiplex immunofluorescence (mIF) analysis, and scRNA‐seq data were employed to determine differences in the immune cell subsets between the treatment and control groups.

Oral OM‐85 treatment significantly reduced lung nodule diameter (p = 0.031), the risk probability of malignancy (p = 0.003), and the likelihood of clinical disease progression (p = 0.0091). The effects of OM‐85 treatment were more pronounced in older patients (> 65‐year‐old) (p = 0.029) and those with longer follow‐up cycles (> 200 days) (p = 0.011). The peripheral blood samples showed a significantly higher proportion of natural killer (NK) cells in the treatment group. Furthermore, mIF staining of the pulmonary nodules and scRNA‐seq data demonstrated a higher percentage of NK cells in the treatment group compared with the control group (p = 0.0003).

OM‐85 reduced the size of high‐risk pulmonary nodules and decreased the risk of malignant probability and disease progression in patients with chronic bronchitis by increasing the proportion of NK cells. Therefore, OM‐85 is a potential drug for the treatment of high‐risk pulmonary nodules in patients with chronic bronchitis.

OM‐85 reduced the size of high‐risk pulmonary nodules and decreased the risk of malignant probability and disease progression by increasing the proportion of NK cells. Therefore, OM‐85 may be a potential agent for the treatment of high‐risk pulmonary nodules.