Bacillus Calmette-Guérin (BCG) plus therapy is an enhanced medical approach primarily used in treating certain bladder cancers. It builds upon established BCG immunotherapy by incorporating additional agents or modified protocols.
BCG Therapy Basics
Bacillus Calmette-Guérin (BCG) is a weakened strain of Mycobacterium bovis, also used in the tuberculosis vaccine. BCG is used as an immunotherapy for non-muscle invasive bladder cancer (NMIBC). This type of cancer is confined to the bladder lining and has not spread into the deeper muscle layers. BCG treatment stimulates the body’s immune system to target and destroy cancer cells within the bladder.
The “Plus” in BCG Treatment
The “plus” in BCG treatment refers to adding other therapeutic agents or enhanced protocols to standard BCG therapy. These additions aim to improve outcomes, address BCG resistance, or manage specific tumor types. Combination therapies often involve chemotherapy drugs like mitomycin C (MMC) or gemcitabine. These combinations increase effectiveness, reduce cancer recurrence, or prevent progression to a more invasive stage.
Combining BCG with mitomycin C has been linked to a decreased risk of bladder cancer recurrence and progression compared to BCG monotherapy. The combination of gemcitabine and BCG has also shown promise, especially in patients previously exposed to BCG. Other approaches involve immunomodulating agents, such as nogapendekin alfa inbakicept-pmln, which mimics the cytokine IL-15 to boost natural killer and T cell activity.
How BCG Plus Works
BCG plus therapy enhances the immune response initiated by BCG. When BCG is introduced into the bladder, it attaches to urothelial cells, including cancer cells, triggering the release of immune-signaling molecules like cytokines and chemokines. This process recruits immune cells like T cells, natural killer cells, granulocytes, and macrophages to the bladder wall, which then activate to destroy tumor cells.
The “plus” component, whether a chemotherapy drug or another immunomodulating agent, augments this immune response or directly impacts cancer cells. For example, chemotherapy drugs like mitomycin C can directly damage cancer cell DNA, leading to cell death, potentially making cancer cells more visible or vulnerable to the immune system. Some agents, like nogapendekin alfa inbakicept-pmln, directly stimulate the proliferation and activation of specific immune cells, amplifying anti-cancer effects. This combined approach aims for a more comprehensive attack on the cancer, potentially overcoming single-agent therapy limitations.
Treatment Experience and Considerations
BCG plus therapy for bladder cancer is administered directly into the bladder through a catheter, a method known as intravesical instillation. Patients receive an initial course of treatment, often once a week for six weeks, referred to as induction therapy. If the treatment is effective, a maintenance therapy schedule may follow, which can involve periodic instillations for several months or even up to three years to help prevent recurrence.
Common side effects often include bladder irritation, leading to a frequent or urgent need to urinate, and a burning sensation during urination. Patients might also experience flu-like symptoms such as chills, mild fever, muscle pain, and fatigue, which resolve within two to three days after each session. While generally manageable, severe side effects are rare but can occur if the bacteria enter the bloodstream, potentially causing a serious infection. The overall outlook with BCG therapy, especially for high-risk non-muscle invasive bladder cancer, shows a 10-year survival rate ranging from 70% to 85%.