Potentially Cheap Bacteria-Based Immunotherapy For Cancer Passes Phase I Clinical Trial

An immunotherapy based on injecting dead bacteria into tumors has been successful in three animal species and has shown few side effects in humans. Image Credit: Kateryna Kon/Shutterstock.com

Immunotherapy, encouraging the body's immune system to attack threats, is increasingly being used to treat a wide variety of cancers. However, existing immunotherapies can be prohibitively expensive for some. An alternative, with the potential to be dramatically cheaper, could save millions of lives if proved safe and effective. A Phase I trial suggests the first of those is true, offering encouraging signs for the second.

In 2011, Dr Aude Fahrer of the Australian National University published a hypothesis paper floating the idea of injecting tumors with dead bacteria cells. The bacteria, although no longer a threat to the body, would attract the immune system's attention, Fahrer proposed. Once there, T-cells would attack the cancer.

Fahrer is now senior author of a paper in the Journal for ImmunoTherapy of Cancer that reports on the success of this technique in mice, dogs, and horses, along with a small clinical trial.

"We've treated eight patients as part of this trial," Fahrer said in a statement. "They were all late-stage patients, but in one case in particular we were able to significantly improve the patient's quality of life. The treatment reduced the amount of liquid around their lungs and was able to shrink one of their cancers.” A substantial minority of the treated animals were cured, while others made partial recoveries.

One success out of eight might not seem an outstanding hit rate, but these were patients for whom nothing else had worked. The paper proposes the therapy is more likely to work if applied early. Meanwhile, side-effects were low, aside from localized pain.

"Once the immune cells multiply they can travel around the body, so it would not only attack the cancer at the injection site, but any metastases - where the cancer has spread to another part of the body." Faher said

"The best things about this new treatment are that it requires few dosages, is simple to administer, and has low side effects,” Fahrer added. “It is also extremely low cost. We are looking at around $20 a dose, whereas the cost of other immunotherapies can run to $40,000. This makes the treatment accessible for patients in developing countries." 

This idea is not entirely new – Dr William Coley was injecting dead bacteria into tumors more than a century ago. Coley's work showed some success, Fahrer told IFLScience, and some retrospective analysis suggests it may have worked as well as modern immunotherapy. However, no one, Coley included, understood the mechanism, which inhibited progress and the idea was passed over in favor of radiotherapy.

Coley needed to inject his patients every 2-3 days for months to achieve his results, but the researchers on the new trial used Mycobacteria, an unusual bacteria that Fahrer told IFLScience; “Is neither gram positive nor gram negative”. More importantly, it is released slowly from the solution used, so a single injection lasts six weeks. “Mycobacteria is widely used in the standard adjuvant for animal use,” Fahrer added, so it is not hard to come by.

The team is very committed to keeping the costs down. By publishing the work as a hypothesis paper, it has been made unpatentable, and she the trial was run for AU$38,000 ($27,000 US). A second trial, costing three times as much and combining the work with existing therapies, is about to start. Like the first one, it will be run largely on small donations. Fahrer has published her work in open access publications and hopes others will run similar small trials.

“It should be applicable for any solid tumor,” Fahrer told IFLScience, “Although it may be difficult to apply for brain cancers.”

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