I realize this is somewhat old news but I’d like to share it anyway. On February 14, the Food and Drug Administration (FDA) approved apalutamide (Erleada) for men with prostate cancer that has not spread (non-metastatic) and is resistant to standard hormone therapy, also called androgen deprivation therapy (ADT). In the clinical trial that led to its approval, treatment with apalutamide decreased the risk of metastasis or death by more than 70% compared with placebo.
In the phase 3 trial (dubbed SPARTAN) that led to the FDA approval, men with hormone-resistant prostate cancer and no metastatic disease detectable by standard imaging tests were randomly assigned to receive apalutamide or placebo in addition to ongoing ADT. All participants were at high risk of metastasis based on rapidly rising prostate-specific antigen (PSA) levels. The study was sponsored by Janssen Pharmaceutical Companies, the manufacturer of apalutamide.
The median length of time from the start of treatment to when tumors spread (metastasis-free survival) or the patient died was 16 months in the placebo group and 40 months in the apalutamide group. Men treated with apalutamide also went longer without worsening symptoms of cancer progression. Even when their cancer progressed on apalutamide and they went on to receive another therapy, these men had longer time to progression with the subsequent treatment than men in the placebo group. The median length of time patients were alive after the start of treatment (overall survival) was 39 months for those who received placebo and had not been reached at the time of the study analysis for those who received apalutamide. An early analysis suggests that apalutamide may reduce the risk of death from prostate cancer, but longer patient follow-up is needed before the researchers can confirm this.
Apalutamide is the first drug to be approved by FDA based on an improvement in metastasis-free survival. Traditionally, most approvals are based on an improvement in progression-free survival or overall survival.
“These are very dramatic results and, in many ways, exceeded our expectations,” said lead investigator Matthew Smith, M.D., Ph.D., of Massachusetts General Hospital Cancer Center. “We’re learning that using hormone therapy earlier in men with prostate cancer can delay metastasis and probably improve survival. But the balance of benefits and potential side effects will need to be evaluated on a patient-by-patient basis,” said William Dahut, M.D., head of the Prostate Cancer Clinical Research Section of National Cancer Institute’s Center for Cancer Research (NCI-CCR).
While apalutamide—and, potentially, enzalutamide (Xtandi)—gives men with non-metastatic hormone resistant disease a new treatment option, this patient population may decrease in the future, Dr. Dahut noted. That’s because traditional imaging techniques such as a CAT scan may not be able to detect tiny metastatic tumors, he explained. But a technique being used in research studies called molecular imaging can catch smaller tumors. If molecular imaging tests become part of clinical care, more men with prostate cancer might be classified as having metastatic disease. “It’s highly likely that apalutamide would be active in men with metastatic hormone-resistant prostate cancer, Dr. Dahut speculated. Trials to evaluate apalutamide in this patient population are already underway, Dr. Smith noted.
For additional information, see the March 8th, 2018 NCI Cancer Currents blog.