Bacteria-based cancer therapies originated in the 1860s with Coley’s streptococcal injections. Coley treated thousands of patients with Coley’s toxins, crude bacterial formulations with occasional dramatic results.
Coley injected 1,000 cancer patients with bacteria or products while leading the Bone Tumour Service at Memorial Hospital. His approach was later dismissed, as injecting patients with bacteria was viewed as dangerous and outdated. Coley’s early ideas were being reimagined through the lens of modern science. His work was eventually overshadowed by radiation therapy and chemotherapy skepticism.
Scientists now use specially engineered bacteria to exploit the tumor microenvironment for targeted internal treatment. Bacteria kill cancer cells by releasing toxins or stimulating localized immune attacks.
These bacteria can be programmed to deliver tumor protein fragments, training the immune system to destroy cancer. However, even weakened live bacteria may cause infections or disrupt the microbiome. Some methods use a single bacterial strain, while others combine species for enhanced efficacy. The complexity of immune responses and individual patient differences complicate universal strategies.
Recent studies reveal that engineered E. coli can safely deliver therapeutic agents directly into tumors. Bacterial components stimulate the immune system effectively without using the whole organism. Bacterial therapies synergize effectively with immunotherapy, offering potential solutions for cancers resistant to conventional treatments. The greatest hope is in treating hard-to-reach tumors resistant to chemotherapy and radiation. Bacteria-based research targets deadly colon, ovarian, and breast cancers.
Tumor-targeting therapies that spare healthy tissue may lower treatment side effects and enhance patient survival rates and quality of life. Bacteria-based cancer therapy is progressing quickly, and human clinical trials are upcoming to evaluate its safety and long-term effectiveness.
Refined bug drugs may become mainstream cancer treatment in a decade. Dismissed pseudoscience is now validated in advanced global laboratories. Researchers are exploring the intricate interactions among bacteria, tumors, and the immune system to effectively use organisms to target cancer.
Reference: Stebbing J. Bug drugs: bacteria-based cancer therapies are finally overcoming barriers. The Conversation. Published March 17, 2025. Accessed March 22, 2025
