Zytiga (abiraterone acetate) is now approved in the U.S. to treat metastatic high-risk castration-sensitive prostate cancer (CSPC) in combination with prednisone, Janssen Pharmaceutical Companies announced.
The U.S. Food and Drug Administration (FDA) granted its approval following results of the Phase 3 LATITUDE trial (NCT01715285), which showed that the combo therapy reduced the risk of death by 38 percent in newly diagnosed patients compared to placebo.
“LATITUDE was a large global trial which produced impressive and clinically significant results in overall survival,” Karim Fizazi, MD, PhD, the study’s lead author, said in a press release.
“This milestone is an exciting turning point for researchers and clinicians, and most importantly, for patients suffering from this disease and their families who now have an important additional therapeutic option,” added Andree Amelsberg, MD, vice president of oncology medical affairs at Janssen Biotech.
LATITUDE was a double-blind clinical trial comparing a once-daily combo of Zytiga plus prednisone with placebo in 1,199 patients with newly diagnosed, metastatic high-risk CSPC, who had not received prior chemotherapy treatment. All patients took a gonadotropin-releasing hormone (GnRH) analog — a medication designed to lower sex hormone levels — or had previous bilateral orchiectomy (removal of the testicles).
Investigators defined high-risk disease as having at least two of three risk factors at the start of the study: a total Gleason score of eight or higher (a method to determine the prognosis of a patient with suspected prostate cancer), three or more lesions on bone scans, or measurable visceral metastasis. Patients took Zytiga plus prednisone for a median duration of 24 months.
In addition to the decreased risk of death, Zytiga plus prednisone also delayed the initiation of chemotherapy.
The most common adverse events with Zytiga were fatigue, hypertension, joint pain, nausea, vomiting, edema, headache, and low blood level of potassium.
Results were presented at the 2017 American Society of Clinical Oncology (ASCO) Annual Meeting in Chicago. The study, “Abiraterone plus Prednisone in Metastatic, Castration-Sensitive Prostate Cancer,” was published in The New England Journal of Medicine.
In 2017, the European Commission approved Zytiga plus prednisone or prednisolone in combination with androgen deprivation therapy for the treatment of early-stage prostate cancer. Janssen filed similar submissions in Canada, Japan, Switzerland, Mexico, Singapore, and the Philippines. Approval has already been granted in Taiwan and Brazil.
Patients with metastatic CSPC, also called metastatic hormone-sensitive prostate cancer (HSPC), still respond to testosterone suppression therapy. Those with newly diagnosed metastatic disease and high-risk characteristics usually have a poorer prognosis.
In addition to CSPC, the combo therapy of Zytiga plus prednisone is also indicated for the treatment of metastatic castration-resistant prostate cancer (CRPC).
Zytiga is a type of hormone therapy classified as an adrenal inhibitor. Over 330,000 patients globally, including 113,000 in the U.S., have been treated with Zytiga since its approval in the U.S. in 2011, the company said. It was the most prescribed oral therapy for U.S. patients with metastatic CRPC in 2016, Janssen added.