New information has recently been published updating early clinical trials results for two new promising prostate cancer drugs, galeterone (TOK-011 from Tokai Pharmaceuticals) and tasquinimod (TASQ, from Active Biotech and Ispen). Both drugs have been described in the December 20th, 2012 issue of the Prostate Cancer Foundation NewsPulse.
Galeterone: Resistance to therapy is a growing concern in treating cancer as cancer cells mutate to avoid the effects of a given therapy. This is a major problem in androgen-deprivation (ADT) prostate cancer treatment (hormone therapy) when men become resistant (refractory) and testosterone levels rise thus fueling the proliferation of cancer cells. Galeterone, an oral drug also known as TOK-011, is unique in that it is the first and only single-agent therapeutic that combines three distinct approaches to attack prostate cancer and which thereby may help to prevent resistance to ADT. Galeterone’s development and review has received a “fast-track designation” by the U.S. Food and Drug Administration. Androgen is mainly produced in the testicles (90%) and to a lesser degree by the adrenal glands and even the prostate tumor itself. The male androgen testosterone fuels prostate cancer and triple-action galeterone thwarts prostate cancer cell proliferation by targeting the primary driver of treatment-resistance disease—androgen receptor signaling—in various ways. Galeterone works by blocking testosterone synthesis (specifically by blocking the enzyme CYP17 lyase), blocking testosterone’s ability to bind to its androgen receptor (the prostate cell molecule that responds to the androgen) and finally, by limiting overall androgen receptor levels in the body. A Phase I dose-finding study in 49 chemotherapy-naïve patients produced PSA reductions of greater than 50 percent (50%) in 11 patients (or 22%). Another 26 percent of patients had PSA declines ranging between 30 to 50 percent. Galeterone is now entering a Phase II trial in which Tokai plans to enroll 196 patients, the first of whom has already begun treatment. This trial will use a slightly reformulated version of galeterone that has improvements in its uptake and absorption in the body. In addition, the Phase II trial will not only include men who are chemotherapy-naïve, but also men whose disease has progressed while taking Zytiga (abiraterone acetate), another androgen-inhibiting drug. All patients will be evaluated to determine galeterone’s effects upon PSA levels and their overall safety profiles. An interesting article about how galeterone was co-developed was published in the Baltimore Sun in September, 2014.
Tasquinimod: Tasquinimod, or TASQ (ABR-215050), is an oral experimental treatment for men with metastatic, treatment-resistant prostate cancer. Chemically, TASQ is a quinoline-3-carboxamide with three-pronged immunomodulatory (activates the body’s immune system to fight cancer), anti-angiogenic (prevents the formation of new blood vessels to feed tumor cells) and anti-metastatic (inhibiting tumor growth) activity. Specifically, TASQ modulates the expression of thrombospondin-1 in human prostate tumors. After completing Phase I and II clinical trials, Active Biotech and Ispen, the drug’s developers, announced successful enrollment of 1,200 patients in 250 clinics for a global, randomized, double-blind, placebo-controlled Phase III clinical trial evaluating TASQ in men with metastatic, hormone-refractory prostate cancer. The end points of the Phase III study will be progression-free (PFS) and overall survival. Dr. Andrew Armstrong, principal investigator from the Duke University Medical Center, describes the Phase II results as published in the Journal of Clinical Oncology in September, 2011. They showed a median overall survival benefit of three months (33.4 vs. 30.4 months) in favor of TASQ versus placebo. In patients with bone metastases, median overall survival was 34.2 versus 27.1 months. Six month progression-free proportion of patients for TASQ and placebo treatment groups were 69% and 37%, respectively with a median progression-free survival of 7.6 vs. 3.3 months. TASQ treatment also had an effect on biomarkers relevant for prostate cancer progression and was generally well tolerated. In the Phase III clinical trial, researchers will further investigate the drugs overall efficacy, with an ultimate goal of receiving approval from the Food and Drug Administration for the treatment of men with metastatic castrate-resistant disease (CRPC). Phase I and II data show that tasquinimod’s long term safety is acceptable according to Dr. Armstrong. “Tasquinimod may therefore be a suitable therapy to evaluate at an early stage in management of CRPC, either as monotherapy or in combination with other effective agents for prostate cancer, as it does not jeopardize the patient’s chances to receive additional treatment.” For additional information on TASQ and its clinical trials, see the Drugs.com and Active Biotech websites. The web addresses are: http://www.drugs.com/clinical_trials/active-biotech-ipsen-report-tasquinimod-tasq-phase-ii-long-term-safety-data-27th-european-13084.html; and http://www.activebiotech.com/press-releases?pressurl=http://cws.huginonline.com/A/1002/PR/201212/1663501.xml.