Treatment with apalutamide plus androgen deprivation therapy (ADT) resulted in a 25 percent reduction in the risk of death compared with placebo plus ADT in patients with non-metastatic castration-resistant prostate cancer (nmCRPC) who were at high risk of developing metastases.

These are the updated, longer-term results from the phase 3 SPARTAN study following a second interim analysis.

The updated findings showed overall survival (OS) results supported the first interim analysis, despite a crossover of patients receiving placebo to the apalutamide treatment group.

Results were presented in an oral session at the 2019 ESMO Annual Congress (abstract #843O), and simultaneously published in Annals of Oncology.

At the second interim analysis, a longer median follow-up of 41 months, four-year OS rates were 72.1 percent for patients treated with apalutamide and 64.7 percent for patients treated with placebo.

Overall, a 25 percent reduction in the risk of death was observed for patients receiving apalutamide compared with placebo [HR=0.75; 95 percent CI, 0.59-0.96; p=0.0197 (to reach statistical significance, a p-value of p<0.0121 needed to be observed)].

The OS benefit of apalutamide was consistent across baseline subgroups, such as race, prior treatments, baseline PSA and performance status.

This interim analysis took place when 67 percent of the required OS events had been observed, compared with the original report when only 24 percent of required OS events had occurred (HR=0.70; 95 percent CI, 0.47-1.04; p=0.07).

After unblinding the study and prior to the second interim analysis, 76 non-progressing patients in the placebo group (19 percent of all placebo patients) crossed over to open-label apalutamide; the OS rates in the placebo group included those patients who were crossed over to apalutamide treatment.

The rates of treatment-emergent adverse events for apalutamide at the second interim analysis were consistent with rates previously reported.1 In the SPARTAN study, the most common adverse events (≥10 percent) were fatigue, hypertension, rash, diarrhoea, nausea, weight decreased, arthralgia, falls, hot flush, decreased appetite, fracture and peripheral edema.

"Longer-term analyses help to present a more complete picture of a medication's benefits and potential risks over time.

This updated SPARTAN analysis shows an important survival benefit," said Matthew Smith, M.D., Ph.D., Director of the Genitourinary Malignancies Program at the Massachusetts General Hospital Cancer Center, Professor of Medicine at Harvard Medical School, and co-principal investigator of the SPARTAN study.

"These results add to the evidence supporting apalutamide as a standard option for treating patients with non-metastatic castration-resistant prostate cancer who remain at high risk of their cancer spreading."

Initial results from the SPARTAN trial were presented at the 2018 American Society of Clinical Oncology Genitourinary Cancers Symposium (ASCO GU) and simultaneously published in The New England Journal of Medicine.

"While there have been advances in the treatment of prostate cancer over the years, it is still a lethal illness, particularly when patients progress to later stages of metastatic disease," said Margaret Yu, M.D., Vice President, Prostate Cancer Disease Area Leader, Janssen Research & Development, LLC.

"Apalutamide is now being studied in five Phase 3 randomised controlled trials as part of the largest clinical program of androgen receptor inhibitors. Together, these trials highlight Janssen's commitment to making prostate cancer a manageable disease."

SPARTAN (NCT01946204) was a Phase 3, randomised, registrational, double-blind, placebo-controlled, multicentre study that evaluated apalutamide in combination with ADT in men with nmCRPC with a rapidly rising PSA (PSA Doubling Time ≤10 months).

The SPARTAN study enrolled 1,207 patients who were randomised 2:1 to receive either apalutamide orally at a dose of 240 mg once daily in combination with ADT (n=806) or placebo once daily in combination with ADT (n=401). 

Study results were initially reported at the 2018 ASCO Genitourinary Cancers Symposium and published in The New England Journal of Medicine.

Source: Janssen Pharmaceutica