Tanya Dorff, MD
Two critical clinical trials—SPARTAN and PROSPER—served as the basis for the 2018 FDA approvals of apalutamide (Erleada) and enzalutamide (Xtandi), respectively, agents that have drastically changed the standard of care for patients with nonmetastatic castration-resistant prostate cancer (CRPC), said Tanya B. Dorff, MD.
during the meeting, Dorff, associate clinical professor in the Department of Medical Oncology and Therapeutics Research, and head of the genitourinary cancers program at City of Hope, discussed landmark approvals in nonmetastatic CRPC and anticipated developments in metastatic CRPC.
OncLive®: What trials have defined the field of nonmetastatic CRPC?
: For nonmetastatic CRPC, there were 2 landmark studies that have now changed the way we practice. First and foremost, it's important to image patients whose prostate-specific antigen (PSA) is rising despite castration therapy, so that we can correctly categorize them as metastatic or nonmetastatic––even oligometastatic versus large-volume metastatic disease. When we do find patients who are truly nonmetastatic castration-resistant, but we can't find anything on conventional imaging, we need to check their doubling time to categorize them as high-risk or not. We use a PSA doubling time cutoff of £10 months. That's what was used in both of the trials.
Additionally, QoL seems to be maintained on these drugs. The other major thing to emphasize is that fractures were seen on one of the studies. These men have been castrated for quite a while and are going to continue on castration therapy, so we have to pay attention to bone supportive therapy when we're treating men in this earlier-disease setting.
Do payers have a preference with regard to apalutamide and enzalutamide?
It's possible that insurers may have a preference. I did have that situation with one patient. [A payer may opt for one drug] if it is priced more favorably for their group. Falls or seizures are side effects we traditionally associate with enzalutamide. If a patient has had issues with falls or seizures, one might think we should choose apalutamide.
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