Newer prostate cancer agent slows progression in phase II trial

An investigational prostate cancer treatment slows the disease’s progression and may increase survival, especially among men whose cancer has metastasized to the bones, according to a recent analysis.

Researchers say the study, which was published online in Clinical Cancer Research (Nov. 19, 2013), adds long-term survival and safety data for the investigational agent tasquinimod, a new candidate for treating advanced and recurrent prostate cancer.

“While all subgroups in the clinical trial benefited from tasquinimod, those whose cancer metastasized to their bones had the greatest benefit in terms of delaying the time from the start of treatment to when the cancer progressed. This group of men also seemed to have a longer survival benefit when we followed them over several years,” said lead author Andrew J. Armstrong, MD, ScM, of Duke Cancer Institute, Durham, NC.

Tasquinimod is an oral therapy that activates the body’s immune system to fight cancer. Its mechanism is not fully understood, but it appears to affect the function of myeloid-derived suppressor cells, which are found in increased numbers in cancer patients. Tasquinimod is also known to block angiogenesis.

In this phase II clinical trial, researchers studied the use of tasquinimod in men with metastatic castration-resistant prostate cancer. The study enrolled 201 men who were followed for approximately 3 years, with 134 randomly assigned to receive tasquinimod and 67 given placebo.

The authors measured patients’ overall survival, whether their cancer progressed, and the drug’s safety and tolerability. They also conducted studies of biomarkers to better understand how tasquinimod stimulates the immune system.

Dr. Armstrong and his colleagues found that men taking tasquinimod saw no cancer progression for an average of 7.6 months, compared with 3.3 months for placebo. Men whose cancer had already metastasized to their bones and took tasquinimod remained progression-free for 8.8 months, compared with 3.4 months for placebo.

Men taking tasquinimod survived 33.4 months on average, versus 30.4 months with placebo. However, those whose cancer had already metastasized to their bones survived an average of 34.2 months, compared with 27.1 months for placebo, a 7-month difference. This improvement in survival with tasquinimod persisted when statistical adjustments were made for PSA level, PSA doubling time, lactate dehydrogenase levels, and the presence of anemia, each of which were important prognostic factors.

The treatment was considered safe with low to moderate side effects, which included mild gastrointestinal issues, muscle and joint pains, and fatigue.

Based on results from the phase II trial, tasquinimod is now being evaluated in an international phase III trial in castration-resistant metastatic disease.

Dr. Armstrong and one of his co-authors received research funding from Active Biotech, which is developing tasquinimod. Two of Dr. Armstrong’s co-authors are employees and shareholders of Active Biotech.

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