New Data For Prolonging Hormonal Response In Locally Advanced And Metastatic Prostate Cancer
Treating locally advanced or metastatic prostate cancer patients — who experience disease progression after first-line, castration-based therapy — with 'step-up' to Combined Androgen Blockade (CAB) therapy can substantially prolong the 'hormonal response.' This is the key finding of new research presented at the European Association of Urology (EAU) meeting in Berlin, Germany.
Male hormones (also known as ‘androgens', such as testosterone and its metabolite dihydrotestosterone) stimulate prostate cancer growth, so one of the most important goals in treating the disease is to reduce the amount of circulating hormone. There is currently no standard treatment for patients who experience disease progression after first-line hormonal therapy.
All patients in this new study were treated with first-line goserelin (ZOLADEX) monotherapy, administered using the ZOLADEX SafeSystem. Goserelin — a luteinising hormone-releasing hormone agonist (LHRHa) — works by reducing the level of the hormone testosterone in the body. After disease progression, patients received CAB ‘step-up' treatment whereby they continued goserelin treatment but then boosted their androgen blockade by the addition of bicalutamide 50mg (CASODEX). Bicalutamide binds to receptors on tumour tissue and so prevents testosterone from binding and stimulating tumour growth.
Dr Heather Payne, Consultant in Clinical Oncology, University College Hospital, London, UK, who presented the study at EAU said: "These data tell us that CAB step-up therapy can reduce a patient's PSA count and keep it down, even after first-line, standard, hormonal therapy starts to fail."
"This is important because it gives physicians another chance to prolong a patient's response to hormonal treatment and extend the time the treatment keeps working, which means we can stave off hormone-refractory disease for longer, a disease setting that is much harder to treat."
Dr Payne presented an on-going analysis from 122 patients with locally advanced or metastatic prostate cancer who were treated with first-line goserelin (ZOLADEX) monotherapy. Goserelin has proven survival benefits across a broad range of prostate cancer settings, including adjuvant, neoadjuvant, and monotherapy in locally advanced disease. After disease progression, all 122 patients received CAB ‘step-up' treatment, by the addition of bicalutamide 50mg (CASODEX) to their existing goserelin treatment in order to boost their androgen blockade. The retrospective analysis shows:
- One in three (30.3%) patients experienced a PSA response (defined as a PSA decrease >50% at first assessment, followed by a subsequent PSA decrease at the second assessment point); in the overall study population of 122 patients, three out of four (74.6%) experienced at least a partial PSA response.
- For the 30.3% of patients who had a PSA response, the median time to treatment failure in this group was 291 days; in the overall study population, the median time to treatment failure following CAB was 193 days.
At the same meeting, Dr Payne also co-authored new research that showed physicians are supportive of CAB treatment. Seventy-one percent of physicians who took part in an international survey felt that CAB should be used more often for treating patients with advanced prostate cancer. The survey comprised the views and perceptions of 339 oncologists and urologists from 92 countries. While almost all survey respondents (95%) treating patients with advanced prostate cancer said they used CAB, less than half of them (47%) did so in more than 50% of their patients.
When exploring factors that could encourage increased CAB usage, 66% of physicians cited the need for clinical evidence. The survey explored physicians' views on current clinical guidelines for the management of advanced prostate cancer with CAB and showed that more than half of the respondents (52%) believe that the guidelines are too numerous, lack clarity or are outdated.
Dr Heather Payne commented: "While these survey findings show there is a good overall level of support for CAB, it seems very clear that the clinical community would welcome improved guidelines and greater clarity on the benefits of CAB, to ensure that patients with advanced prostate cancer have access to this treatment and the greatest chance for extending survival."
Source: AstraZeneca