Many patients with non-muscle invasive bladder cancer (NMIBC) do not receive the full course of recommended immunotherapy, leading to higher rates of disease progression and bladder removal surgery, the latest research indicates.
A recent study of over 26,000 patients, published in JAMA Network Open, found that while most start the standard treatment, known as Bacillus Calmette-Guérin (BCG), very few complete the long-term “maintenance” phase necessary to reduce the risk of cancer returning.
BCG is a vaccine originally developed for tuberculosis that has served as the standard immunotherapy for non-muscle invasive bladder cancer for decades, helping to prevent both tumor recurrence and progression to invasive disease.
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The authors noted that while 74% of the overall patient group finished the “induction” phase of BCG treatment, which requires receiving at least four doses with intervals no longer than three weeks, only about 18% of the total cohort completed the maintenance phase. For maintenance to be considered adequate, a patient must receive at least two treatments within a three-month period, and this phase must begin within six months from the start of induction.
The results were no better for the subgroup of patients with high-risk carcinoma in situ (CIS) bladder cancer. CIS is an early but high-grade, flat form of non-muscle invasive bladder cancer, with a high chance of recurrence and progression, requiring close monitoring. In this high-risk group, only 21.1% of patients received adequate maintenance therapy.
The benefits of completing the maintenance phase were consistent across all risk groups. For both the high-risk and overall patient populations, finishing the full treatment course led to a substantial reduction in the risk of cancer progressing and the need for bladder removal surgery. The high-risk CIS group who finished adequate maintenance therapy also had a lower incidence of disease returning.
Focusing on the CIS subgroup, the study stratified patients with cancer recurrence based on when their cancer returned. The “BCG-unresponsive” group was defined by 100% maintenance completion but with cancer persisting or returning early, within 12 months. In contrast, the “BCG-exposed” group included those who finished induction and at least some maintenance (whether adequate or not), but saw their cancer return between 12 and 24 months.
The majority of patients were in the BCG-exposed group, which represented 83.1% of all recurrences. Furthermore, of the 384 patients who required a radical cystectomy (total bladder removal), nearly 88% were from the BCG-exposed group.
The results of this study suggest that BCG-exposed patients represent a large and medically underserved population that bears the greatest burden of disease progression.
Researchers highlighted that these patients were not eligible for therapies approved for the BCG-unresponsive population, which creates a significant void in available care.
“These findings may inform clinical trial design, regulatory considerations, and development of bladder-sparing therapies beyond the currently approved treatments,” the researchers noted, highlighting the need to develop better ways to manage this high-risk population.
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