medwireNews: An interim analysis from the SPARTAN trial points to an overall survival (OS) benefit with the use of apalutamide alongside androgen deprivation therapy (ADT) for nonmetastatic castration-resistant prostate cancer (CRPC).
The addition of the androgen receptor inhibitor to ADT was associated with a significant 25% reduction in the risk for death relative to placebo plus ADT, although the median was unreached in both treatment arms, according to findings simultaneously reported at the ESMO Congress 2019 in Barcelona, Spain, and published in the Annals of Oncology.
But the p-value did not cross the prespecified threshold, and therefore a final OS analysis will be carried out when the required number of deaths have occurred, presenting author Matthew Smith (Massachusetts General Hospital Cancer Center, Boston, USA) told the conference delegates.
He highlighted, however, that the “OS benefit for apalutamide was observed despite crossover of placebo patients to apalutamide and higher rates of subsequent life-prolonging therapies for placebo patients,” and that the OS improvement was consistent across subgroups.
Smith commented that “these results further support apalutamide as a standard of care option” for this patient population.
The phase III SPARTAN trial recruited 1207 men with high-risk nonmetastatic CRPC and randomly assigned them to receive either apalutamide 240 mg/day or placebo alongside ADT.
The present analysis, conducted at a median follow-up of 41 months, also showed that apalutamide prolonged the time to initiation of cytotoxic chemotherapy versus placebo, with a hazard ratio (HR) of 0.60 favoring the androgen receptor inhibitor. The median was not reached in either group, and there was no formal test for significance owing to the hierarchical statistical plan. Fourteen percent of the apalutamide-treated patients initiated cytotoxic chemotherapy, as did 20% of those given placebo.
The exploratory endpoint of second progression-free survival – defined as progression or death during the first subsequent treatment of metastatic disease – was improved with apalutamide versus placebo, at a median of 55.6 and 43.8 months, respectively, and an HR of 0.55.
These findings suggest that the previously reported statistically significant gains in metastasis-free survival and time to symptomatic progression with apalutamide “may translate into a survival advantage in patients with [nonmetastatic] CRPC,” write the study authors.
They also stress that “the safety profile of apalutamide added to ongoing ADT remains unchanged, with no evidence of cumulative toxicity” after a further 20 months of follow-up since the initial analysis.
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ESMO Congress 2019; Barcelona, Spain: 27 September–1 October
Ann Oncol 2019; doi:10.1093/annonc/mdz397