Blood test may predict BCG treatment failures

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A simple blood test, much like that used to detect tuberculosis, might identify as many as half of bladder cancer patients likely to fail intravesical bacillus Calmette-Guérin (BCG) immunotherapy, according to a recent small study of high-risk non-muscle-invasive bladder cancer patients.

About a third of high-risk non-muscle-invasive bladder cancer patients experience BCG treatment failure. But physicians treating these patients do not have access to a proven way to predict who will benefit versus fail before administering BCG treatment.

Being able to identify treatment failures before beginning BCG is important on many fronts, according to study author Professor Florian Kern, MD, of Brighton and Sussex Medical School, Brighton, United Kingdom.

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“These patients will ultimately have lost valuable time while on BCG immunotherapy. They might have had side effects, as well, and their hopes will be dashed several months into the treatment course. A treatment that works better for them will have been delayed. This might shorten overall survival,” Dr. Kern told Urology Times.

Dr. Kern and colleagues administered the blood test to analyze in vitro tuberculin-responsiveness of CD4+ T cells before BCG immunotherapy in 42 patients with high-risk non-muscle-invasive bladder cancer. They correlated results with recurrence-free patient survival 6 months after BCG induction.

The blood test, which measures release of the pro-inflammatory molecule Interleukin-2 (IL-2) from immune cells, is like the test used to detect immune response to tuberculin, widely used in tuberculosis testing.

The authors found a tuberculin-induced, secreted IL-2 concentration of more than 250 pg/mL best predicted recurrence-free survival in bladder cancer patients, with 79% sensitivity, 86% specificity, and overall correct classification in 78.6% of cases.

Next: Test correctly predicted therapy outcome in almost 80% of casesThe test seemed to immediately identify about 50% of the patients who would not have benefited from BCG treatment. Overall, the test correctly predicted therapy outcome in almost 80% of cases, according to the study, which was published in Cancer Immunology Research (Aug. 17, 2018 [epub ahead of print]).

Detecting these patients before starting BCG therapy will allow providers and patients to make more informed choices about treatment, the authors concluded.

Read: Sicker MIBC patients no more likely to undergo bladder sparing

“The simplicity of our new test makes it very attractive as a clinical test. There are several tests for tuberculosis that are ultimately based on the same test principle and have been rolled out across the world in recent times,” Dr. Kern said in a press release.

However, it’s not yet time for urologists and others to withhold BCG, which is today’s standard treatment for preserving the bladder in these patients post resection.

“This was a pilot study. We are hoping to do a bigger confirmatory study soon to prove that the test is reliable,” Dr. Kern said. “Once the results are confirmed, the test may be rolled out widely. At this time, however, these are results that require confirmation before they are applied to clinical management.”