The human immune system can recognize and eliminate not only germs but also cancer cells.
This is why treatments with weakened germs can help the immune system in its fight against cancer.
In a new study, researchers have genetically modified the tuberculosis vaccine BCG in a way that it stimulates the immune system more specifically.
The new vaccine VPM1002 offers much greater protection against tuberculosis.
The researchers found that therapy with VPM1002 could successfully prevent the recurrence of tumors in almost half of the patients with bladder cancer.
The results could lead to the early approval of the drug for the treatment of cancer of the bladder so that as many patients as possible can profit from this quickly.
The research was conducted by a team at the Max Planck Institute for Infection Biology in Berlin.
At the end of the 19th century, doctors observed that the tumor in some cancer patients shrank if the patients suffered from bacterial infection with a high fever.
These findings sparked interest in immunotherapy for cancer. Immunomodulatory treatments can specifically stimulate the immune system.
As a result, the body’s own immune system is supported in its fight against the tumor, leading to a reduction in the size of the tumor.
The tuberculosis vaccine Bacille Calmette-Guérin (BCG) that was introduced back in the 1920s contains weakened pathogens of bovine tuberculosis, which can also be transmitted to humans.
Tests in the 1970s showed that BCG is also effective against bladder cancer, one of the most common tumor diseases in Europe.
Immunotherapies for solid tumors often have little success, though the use of BCG for bladder tumors developed into a standard therapy.
During this treatment, the bladder is repeatedly flushed with the weakened germ over a period of six weeks.
This triggers an immune response that, although not aimed specifically at the tumor, does presumably activate the body’s own killer cells that in turn recognize and specifically kill the altered tumor cells.
Nevertheless, the share of patients who have managed to fully overcome cancer after BCG therapy is low.
Furthermore, flushing with BCG has serious side-effects such as fever, incontinence or flu-like symptoms, so that many patients discontinue the therapy prematurely.
However, the tumor returns in 30% to 40% of such treated patients. In these cases, the bladder has to be removed completely, though highly unwanted, but as an ultimate resort.
In the study, the team developed the BCG vaccine further. They modified the weakened tuberculosis bacteria in a way that it can be recognized better by the immune system.
According to the team, the new vaccine VPM1002 is absorbed like BCG by the immune system’s phagocytes, which can then subsequently identify their targets—tuberculosis bacteria and cancer cells—much better.
Improved protection against infection with tuberculosis bacteria has already been proven using VPM1002.
Patients suffering from cancer of the bladder, where cancer had returned after removal of the tumor and a subsequent standard BCG therapy, were then treated in a Phase II study.
The team found over 49% of the patients treated with VPM1002 were free from tumors in the bladder after 60 weeks. Tumor-free patients avoid the removal of the bladder.
The results have encouraged the developers to apply for early regulatory approval as soon as possible.
As a result, patients suffering from cancer of the bladder who no longer respond to conventional therapies, can profit from the new drug as quickly as possible and therefore, if responding to VPM1002 therapy, avoid removal of the bladder.
Talks are now planned with the European Medicines Agency to bring about its Europe-wide approval as quickly as possible.
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