The PARP inhibitor niraparib improves the time to cancer progression among patients with recurrent ovarian cancer when used as maintenance therapy during platinum-based chemotherapy.
Each year in the United States, approximately 22,000 women are diagnosed with ovarian cancer, and is the fifth most common cause of cancer-related deaths among women. Since there are no generalized screening methods for the early detection of ovarian cancer, the majority of ovarian cancer is detected in advanced stages, once it has spread from the ovaries.
Although patients often respond to initial therapy that includes platinum-based chemotherapy, approximately 90% of patients will experience a progression of their cancer within 2 years of their initial therapy.
Niraparib is classified as a poly (ADP-ribose) polymerase, or PARP inhibitor. The family of proteins referred to as PARP play many roles in the functioning of a cell. It is thought that PARP inhibitors suppress the ability of cells to fix their damaged DNA.
Researchers recently conducted a phase III trial referred to as the NOVA trial, to determine the effectiveness of niraparib in the treatment of recurrent ovarian cancer. The trial included approximately 500 women who had responded to platinum-based chemotherapy for recurrent ovarian cancer. One group of patients received niraparib following chemotherapy, while the other received placebo (inactive substitute) until their cancer started progressing.
One group of patients in the trial had a BRCA1 or BRCA2 germline gene mutation, which predisposes individuals to a significantly increased risk of developing ovarian cancer within their lifetime; one group of patients had homologous recombination deficiency (HRD) without germline BRCA1 or BRCA2 mutations; and one group of individuals had neither BRCA1 or BRCA2 germline mutations nor HRD.
- Among patients with germline BRCA1 or 2 mutations, median survival time without progression of cancer (progression-free survival, PFS) was 21 months among patients treated with niraparib, compared with only 5.5 months for those who received placebo.
- Among patients without germline BRCA1 or 2 mutations who were HRD-positive, the median PFS was 12.9 months for those treated with naraparib, compared with only 3.8 months for those who received placebo.
- Among patients without germline BRCA1 or 2 mutations who had either HRD-positive or HRD-negative cancers, median PFS was 9.3 months for those treated with naraparib, compared with 3.9 months for who received placebo.
- The most common serious side effects associated with niraparib were low blood cell levels.
Niraparib appears to significantly improve PFS when used as maintenance therapy among patients with recurrent ovarian cancer who respond to platinum-based chemotherapy. Patients with BRCA1 and BRCA2 germline mutations appear to derive the greatest benefit from niraparib; however, all patients in the NOVA trial experienced an improved PFS from treatment with niraparib. Filing for approval of niraparib is expected later this year.
Reference: Tesaro Inc., press release. Tesaro’s niraparib significantly improved progression-free survival for patients with ovarian cancer in both cohorts of the phase 3 NOVA trial. Available at: http://ir.tesarobio.com/releasedetail.cfm?ReleaseID=977524. Accessed July 6, 2016.
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