- Adding Johnson & Johnson's experimental prostate cancer drug apalutamide to standard treatment helped delay the development of metastases in patients with non-metastatic castration-resistant disease by just over 2 years, results from a Phase 3 study showed.
- The positive data, hinted at in prior releases from J&J but not disclosed until Monday, support an application for approval which J&J submitted last fall. If approved, apalutamide would bolster J&J's prostate cancer franchise at a time when patent protection for the pharma's marketed drug Zytiga looks shaky.
- Currently, there are no drugs approved in the U.S. for patients with non-metastatic CRPC. Yet J&J could find itself with competition. Data from another study, also released Monday afternoon, showed adding Astellas Pharma Inc. and Pfizer Inc.'s Xtandi to standard of care extended metastasis-free survival (MFS) by a similarly impressive 21.9 months over treatment with androgen-deprivation therapy alone.
Having secured Priority Review from the Food and Drug Administration in December, J&J expects a decision from the regulator on apalutamide by April. Approval of the drug would expand J&J's prostate cancer business into the earlier setting of non-metastatic castration-resistant prostate cancer (CRPC).
An OK would also give J&J a complement to its currently marketed drug Zytiga (abiraterone acetate), which is approved in combination with prednisone for metastatic CRPC.
Global sales of Zytiga climbed above $2.5 billion last year, making it J&J's top oncology product. Yet competition from Pfizer and Astellas' Xtandi has grown, while a recent patent decision that went against J&J could expose Zytiga to earlier generic competition.
All of that makes apalutamide more important.
SPARTAN, the trial that read out Monday, tested apalutamide versus placebo when given to non-metastatic CRPC patients already receiving androgen deprivation therapy (ADT).
Results from a study abstract posted ahead of the American Society of Clinical Oncology's Genitourinary Cancers Symposium showed that adding apalutamide to ADT resulted in a median MFS of 40.5 months — widely outshining the 16.2 month mark record in the group receiving placebo plus ADT. The benefit corresponded to a 72% reduction in the risk of developing metastases or death.
Mark Wildgust, a vice president of global medical affairs, oncology at J&J's Janssen unit, said data showed a strong trend toward an overall survival benefit, although the results remained immature.
"MFS itself has been shown to be a strong surrogate for overall survival," Wildgust in an interview Monday. "So seeing that strong trend in survival at this interim assessment for [MFS] is really excellent."
At a median follow-up of 20.3 months, 61% of patients in the apalutamide cohort remained on therapy, compared to only 30% of those in the placebo group. Discontinuation rates were higher in the treatment arm, at 10.7%, than the 6.3% seen in the control.
Full study results, including further safety details, are set to be disclosed later this week.
Men diagnosed with locally advanced prostate cancer usually undergo surgery or radiation before treatment with ADT. Once the disease becomes metastatic, however, survival rates drop. With no treatments approved at this stage, patients are consigned to monitoring for signs of progression.
With SPARTAN, J&J aims to position apalutamide as another layer of defense, delaying the development of metastases for as long as possible.
"The concept here was to stop that development of metastasis and slow that down. The primary endpoint clearly shows that," Wildgust said.
Patients who do eventually progress to metastatic disease could then go on to receive Zytiga, allowing J&J to cover a broader swathe of the treatment spectrum.
Pfizer and Astellas aren't letting J&J have the last word, however. Much-anticipated results from the companies PROSPER study in the same disease setting as SPARTAN showed a similar 71% reduction in the risk of MFS, although notching a slightly lower median MFS figure.
With broadly similar results between the two, expect the market competition to heat up if both drugs win FDA approval.