Researchers discovered that a specific type of beneficial bacteria called Lactiplantibacillus plantarum FLPL05, found in people who live very long lives in China, might help fight melanoma (a serious type of skin cancer). In laboratory tests with mice, this bacteria reduced tumor growth by more than half and boosted the immune system’s ability to fight cancer cells. The bacteria worked even better when combined with a common chemotherapy drug, suggesting it could become a helpful addition to cancer treatment. While these results are promising, more research in humans is needed before this bacteria can be used as a medical treatment.

The Quick Take

  • What they studied: Whether a beneficial bacteria found in long-living people could help treat melanoma (a dangerous skin cancer) by strengthening the immune system and killing cancer cells.
  • Who participated: Laboratory mice with melanoma tumors and immune cells grown in dishes. No human participants were involved in this study.
  • Key finding: The bacteria reduced tumor growth by 55-78% in mice and made the immune system 1.5 to 2.8 times better at fighting cancer cells. When combined with chemotherapy, it worked even better and caused fewer side effects.
  • What it means for you: This research suggests a natural bacteria might one day help cancer patients, but it’s still in early laboratory stages. Don’t consider this a treatment yet—much more testing in humans is needed before it could be used in clinics.

The Research Details

Scientists tested a special bacteria called L. plantarum FLPL05 in two ways: first, they gave it to mice with melanoma tumors and watched how the cancer grew or shrank; second, they mixed cancer cells with immune cells in laboratory dishes and added the bacteria to see what happened. They measured many things, including tumor size, immune cell activity, and how cancer cells died. The bacteria came from studying very healthy, long-living people in China, which made researchers curious about whether it had special cancer-fighting properties.

The researchers used different amounts of the bacteria to see if higher doses worked better (called a dose-response study). They also tested whether the bacteria worked well alongside 5-fluorouracil, a common chemotherapy drug used to treat cancer. This helped them understand if the bacteria could be a helpful partner to existing cancer treatments rather than a replacement.

Testing in mice and laboratory dishes is an important first step before trying anything in humans. It helps scientists understand how something works and whether it’s safe enough to study further. This type of research is valuable because it explores natural sources (like bacteria from healthy populations) that might have health benefits we haven’t discovered yet.

This study was published in a peer-reviewed scientific journal, meaning other experts reviewed it before publication. However, because it only tested the bacteria in mice and laboratory conditions (not in humans), the results may not work the same way in people. The study appears well-designed with multiple measurements and tests, but human studies would be needed to confirm these findings are real and safe for cancer patients.

What the Results Show

The bacteria significantly slowed tumor growth in mice. When given different doses, the bacteria reduced tumor size by 55.7% at lower doses and up to 77.7% at higher doses—meaning the effect got stronger with more bacteria. The mice that received the bacteria also had healthier immune systems, with larger spleens and thymus glands (organs that make immune cells).

The bacteria made immune cells much more active. When scientists tested immune cells from treated mice, they responded 1.47 to 1.79 times stronger to immune challenges compared to untreated mice. This suggests the bacteria ‘woke up’ the immune system to fight the cancer more effectively.

The bacteria killed cancer cells through multiple pathways. It activated special proteins that trigger cancer cells to self-destruct (apoptosis), increased protective immune molecules called Th1 cytokines, and changed immune cells called macrophages into cancer-fighting versions. The bacteria also prevented cancer cells from spreading by blocking their ability to change shape and invade other tissues.

When combined with chemotherapy (5-fluorouracil), the bacteria made the treatment work better while reducing a common side effect called splenomegaly (enlarged spleen). The bacteria blocked cancer cells from spreading to other parts of the body by stopping a process called epithelial-mesenchymal transition, which is how cancer cells learn to migrate. It also reduced the growth of new blood vessels that feed tumors, cutting off the cancer’s food supply. In laboratory dishes mixing cancer and immune cells, the bacteria triggered immune cells to release cancer-killing substances and directly caused cancer cell death.

This research builds on growing evidence that beneficial bacteria (probiotics) can support immune function and potentially help fight disease. Previous studies showed that certain probiotics can boost immunity, but this is one of the first to specifically test a bacteria from long-living populations against melanoma. The findings align with earlier research showing that immune system activation is important for cancer treatment, and they suggest that natural sources like probiotics might offer new approaches to support conventional cancer therapies.

This study only tested the bacteria in mice and laboratory dishes, not in humans, so results may not translate directly to people. The study didn’t include a large number of different mouse strains or cancer types, so we don’t know if results would be similar in other situations. The researchers didn’t test long-term effects or potential side effects in detail. Additionally, the exact dose that would be safe and effective in humans is unknown, and we don’t know if the bacteria would work as well in people with different genetics or health conditions.

The Bottom Line

This research is preliminary and should not be used as a treatment recommendation. Current evidence suggests: (1) This bacteria shows promise in laboratory studies and warrants further research (moderate confidence); (2) People with melanoma should continue following their doctor’s recommended treatments, which have proven effectiveness in humans (high confidence); (3) Taking probiotics containing this specific bacteria is not a substitute for medical cancer treatment (high confidence). Anyone interested in probiotics should discuss options with their healthcare provider.

Melanoma patients and their families should know about this research as a potential future option, but it’s not ready for use yet. Researchers studying cancer immunotherapy should find this interesting. People interested in preventive health and probiotics may find the connection to long-living populations intriguing, but shouldn’t expect this bacteria to prevent cancer based on current evidence. Healthcare providers treating cancer should monitor this research as it develops.

In mice, effects appeared within the study period (timeline not specified in abstract), but human studies would likely take 3-5 years minimum before any potential clinical use. Even if human trials begin soon, it would be 5-10+ years before this could potentially become an approved medical treatment. Don’t expect this to be available as a cancer treatment in the near future.

Want to Apply This Research?

  • Users interested in immune health could track daily probiotic intake and general wellness markers (energy levels, digestion, sleep quality) using a simple daily checklist, noting any changes over 4-8 weeks. This creates a personal baseline while research continues.
  • Users could add a reminder to take a standard probiotic supplement daily (if recommended by their doctor) and log it in the app. They could also track immune-supporting habits like sleep, exercise, and stress management alongside probiotic use to see correlations with their wellness.
  • Create a long-term wellness dashboard tracking probiotic consistency, immune-related symptoms (like frequency of colds), energy levels, and digestive health over months. Users could share this data with their healthcare provider to discuss whether probiotics are helping their personal health goals.

This research describes laboratory and animal studies only—not human clinical trials. These findings do not represent a proven treatment for melanoma or any human disease. Melanoma is a serious medical condition requiring professional medical care. Anyone with melanoma should work with qualified oncologists and dermatologists for evidence-based treatment. Do not use this bacteria or any probiotic as a substitute for conventional cancer treatment without explicit approval from your medical team. While probiotics are generally considered safe for most people, they may not be appropriate for immunocompromised individuals. Always consult with a healthcare provider before starting any new supplement, especially if you have cancer or are undergoing cancer treatment. This article is for educational purposes only and should not be interpreted as medical advice.